WO2019135448A1 - Method for decoding video and apparatus therefor and method for encoding video and apparatus therefor - Google Patents

Abstract

Disclosed is a method for decoding video, comprising: determining a scan area containing all of effective transform coefficients in a current block; scanning information on the transform coefficients in the scan area according to a predetermined scan order; performing binary arithmetic decoding on the basis of information on the scanned transform coefficients to generate binary arithmetic decoded information; performing inverse binarization on the binary arithmetic decoded information to obtain the information on the transform coefficients of the current block; performing inverse quantization and inverse transform on the basis of the information on the transform coefficients of the current block to generate a residual block of the current block; and restoring the current block on the basis of the generated residual block. According to the disclosed video decoding method, the binary arithmetic decoding may be performed by using a context model determined on the basis of at least one of the size and the shape of the current block.

Description

VIDEO DECODING METHOD, DEVICE, AND VIDEO Coding METHOD AND DEVICE

A video decoding method and a video encoding method. And more particularly to entropy decoding and entropy encoding.

Background of the Invention [0002] As the development and dissemination of hardware capable of playing back and storing high-resolution or high-definition video content increases the need for video codecs to effectively encode or decode high-definition or high-definition video content. According to the existing video codec, video is encoded according to a limited encoding method based on a coding unit of a tree structure.

The image data in the spatial domain is transformed into coefficients in the frequency domain using frequency conversion. The video codec divides an image into blocks of a predetermined size for fast calculation of frequency conversion, performs DCT conversion on each block, and encodes frequency coefficients on a block-by-block basis. Compared to image data in the spatial domain, coefficients in the frequency domain have a form that is easy to compress. In particular, since the image pixel values of the spatial domain are expressed by prediction errors through inter prediction or intra prediction of the video codec, many data can be converted to 0 when the frequency transformation is performed on the prediction error. Video codecs reduce the amount of data by replacing consecutively repeated data with small-sized data.

According to various embodiments, entropy decoding efficiency can be increased by determining scan areas based on various factors, scanning information about coefficients, and performing binary arithmetic coding / decoding based on binarization / inverse binarization and context model .

According to various embodiments, in the process of entropy decoding the transform coefficients, a rectangular scan region including all the effective transform coefficients in the current block is determined, unnecessary scans are reduced by scanning effective transform coefficients in the rectangular scan region, The efficiency of entropy decoding can be improved by scanning the effective transform coefficients adjacent to each other. The entropy decoding efficiency can be increased by determining the context model related to the syntax regarding the transform coefficients based on various elements. Particularly, the entropy decoding efficiency can be increased by determining the context model for the syntax element related to the transform coefficient considering at least one of the size of the block and the shape of the block. In addition, the entropy decoding efficiency can be improved by determining the context model regarding the syntax regarding the transform coefficients in consideration of the scan area. The information on the coordinates specifying the scan area may be obtained by taking into consideration the relation between the horizontal direction coordinate and the vertical direction coordinate without independently decoding the information about the horizontal direction coordinate specifying the scan area and the information about the vertical direction coordinate The sub-decoding efficiency can be increased.

Readable recording medium on which a program for implementing the method according to various embodiments is recorded.

Of course, the technical objects of the various embodiments are not limited to the features mentioned above, and other technical subjects not mentioned can be clearly understood by those skilled in the art from the following description

The technical objects of the present invention are not limited to the features mentioned above, and other technical subjects not mentioned can be clearly understood by those skilled in the art from the following description.

A video decoding method according to various embodiments includes determining a scan region including all effective transform coefficients in a current block; Scanning the information about the in-scan conversion coefficients according to a predetermined scanning order; Performing binary arithmetic decoding based on information on the scanned transform coefficients to generate binary arithmetic decoded information; Performing inverse binarization on the binary arithmetic decoding information to obtain information on transform coefficients of the current block; Generating a residual block of a current block by performing inverse quantization and inverse transform based on information on transform coefficients of the current block; And restoring a current block based on the generated residual block,

The binary arithmetic decoding may be performed using a context model determined based on at least one of a size and a shape of the current block.

The quadrangle scan area includes all the effective transform coefficients in the current block, and the remaining area in the current block excluding the quadrangular scan area may include only 0, which is not an effective transform coefficient.

Wherein the scan area is a rectangular scan area,

The step of determining the scan area

Obtaining information on coordinates specifying the quadrangular scan area from a bitstream; And

And determining a rectangular scan area of the current intra-block transform coefficient based on information about coordinates specifying the rectangular scan area,

A horizontal direction coordinate specifying the quadrangular scan area indicates a coordinate of an effective transformation coefficient pixel located at the rightmost position in the current block,

Wherein the vertical coordinate specifying the quadrangular scan area indicates the coordinates of the effective transformation coefficient pixel located at the lowermost part in the current block,

Wherein flag information indicating whether or not the rectangular scan area includes a difference between horizontal and vertical coordinate values specifying the rectangular scan area is included in the bit stream,

The information on the coordinates specifying the quadrangular scan area is

When the flag information indicates that the difference between the horizontal and vertical coordinate values specifying the rectangular scan area is included,

Information indicating coordinates of one of a horizontal direction coordinate of a pixel of an effective transformation coefficient located at the rightmost position in the current block and a vertical direction coordinate of a pixel of an effective transformation coefficient located at the lowermost position in the current block, And information indicating a difference between the coordinates for the one direction and the coordinates for the remaining direction.

Wherein the size of the current block is determined based on at least one of a minimum value and a maximum value of a height and a width of the current block,

The shape of the current block may be determined based on whether the height and width of the current block are the same or whether the height is larger than the width or the width is larger than the height.

Wherein the step of determining a scan area including all transform coefficients in the current block comprises:

Generating a swapped current block by swapping horizontal and vertical coordinates indicating the positions of transform coefficients in the current block when the height and width of the current block are different from each other; And

Determining a scan area containing all the effective transform coefficients in the swapped current block,

Wherein the step of determining a scan area including all effective transform coefficients in the swapped current block comprises:

Wherein when the current block has a different height and width, the controller swaps the horizontal coordinate and the vertical coordinate specifying the scan region to each other, and based on the swapped horizontal and vertical coordinates, And determining a scan area.

Wherein the bit stream includes information indicating whether or not the bit stream includes flag information indicating whether or not the difference between the horizontal and vertical coordinate values specifying the scan area includes a difference and coordinates information specifying the scan area,

The information on the coordinates specifying the scan area includes information on the horizontal direction coordinates specifying the scan area and information on the vertical direction coordinates,

When the flag information indicates that the difference between the horizontal and vertical coordinate values specifying the rectangular scan area is included,

The information on the horizontal direction coordinate specifying the scan area and the information on the vertical direction coordinate are information indicating coordinates in one of the horizontal direction coordinate and the vertical direction coordinate and information indicating coordinates in the other direction The information indicating the difference between the coordinates related to the coordinates,

Wherein the step of determining a scan area including all effective transform coefficients in the swapped current block comprises:

If the height and width of the current block are different,

Swap horizontal coordinate and vertical coordinate obtained from information on the coordinates specifying the scan area, and determine the scan area based on the swapped horizontal and vertical coordinates Step < / RTI >

The context model related to the flag information of the current transform coefficient among the context models includes a size of the scan region, a count of counts that are scanned before the current transform coefficient in a predetermined scan order in the scan region, The relative position of the current transform coefficient and whether the current effective transform coefficient is the first transform coefficient among the transform coefficients scanned according to the predetermined scan order in the scan area.

When the context model related to the flag information of the current transform coefficient is determined based on the size of the scan area and the number of flag information of the transform coefficient scanned before the current coefficient according to the predetermined scan order,

A context model for flag information of the current transform coefficient based on a predetermined context offset corresponding to a case where the number of flag information of the transform coefficient scanned before the current coefficient is smaller than a predetermined value based on the size of the scan area, Can be determined.

When the context model related to the flag information of the current transform coefficient is determined based on the relative position of the current transform coefficient in the scan area,

The context model for the current transform coefficient may be determined based on a predetermined context offset corresponding to a case where the coordinate of the current transform coefficient is smaller than a predetermined value based on coordinates specifying the position of the scan region.

The information on the transform coefficients may be,

A flag indicating whether the transform coefficient is larger than a predetermined value, a remaining level information about an absolute value of the effective transform coefficient, sign information of the transform coefficient, and a binarization And parameter information,

The predetermined value may be at least one of 0, 1, and 2.

A video encoding method according to various embodiments includes: obtaining a transform coefficient of a current block; Determining a scan area including all effective transform coefficients in the current block; Scanning the information on the transform coefficients included in the scan region according to a predetermined scan order and performing binarization based on the information about the scanned transform coefficients to generate binarized information; Performing binary arithmetic coding on the binarized information to generate entropy-encoded information; And generating a bitstream including the entropy encoded information,

The binary arithmetic coding may be performed using a context model determined based on at least one of a size and a shape of the current block.

Wherein the scan area is a rectangular scan area,

A horizontal direction coordinate specifying the quadrangular scan area indicates a coordinate of an effective transformation coefficient pixel located at the rightmost position in the current block,

Wherein the vertical coordinate specifying the quadrangular scan area indicates the coordinates of the effective transformation coefficient pixel located at the lowermost part in the current block,

Flag information indicating whether or not the information on the coordinates specifying the quadrangular scan area and the information on the coordinates specifying the quadrangular scan area include a difference between horizontal and vertical coordinate values specifying the quadrangular scan area, Stream,

When the flag information indicates that the difference between the horizontal and vertical coordinate values specifying the rectangular scan area is included,

Wherein the information on the coordinates specifying the quadrangular scan area includes a horizontal coordinate for a pixel of an effective conversion coefficient located at the rightmost position in the current block and a vertical coordinate for a pixel of the effective conversion coefficient located at the lowermost position in the current block Information indicating the coordinates of one of the coordinates and information indicating the difference between the coordinates of the one direction and the coordinates of the remaining directions.

The video decoding apparatus according to various embodiments determines a scan area including all the effective conversion coefficients in the current block, scans information on the in-scan conversion coefficients according to a predetermined scan order, Decodes the binary arithmetic decoded information and performs inverse binarization on the binary arithmetic decoded information to obtain information on the transform coefficients of the current block, ; And

And an image restoration unit for generating a residual block of the current block by performing inverse quantization and inverse transformation based on the information about the transform coefficients of the current block and restoring the current block based on the generated residual block,

The binary arithmetic decoding may be performed using a context model determined based on at least one of a size and a shape of the current block.

The video encoding apparatus according to various embodiments obtains a transform coefficient of a current block, determines a scan region including all the effective transform coefficients in the current block, and outputs information about transform coefficients included in the scan region to a predetermined An entropy encoding process for generating entropy-encoded information by performing binary arithmetic encoding on the binarized information, performing entropy encoding on the binarized information by performing a binary arithmetic encoding on the binarized information, part; And a bitstream generation unit for generating a bitstream including the entropy-encoded information, wherein the binary arithmetic coding is performed using a context model determined based on at least one of a size and a shape of the current block .

Readable recording medium on which a program for implementing the method according to various embodiments is recorded.

FIG. 1A shows a block diagram of a video decoding apparatus according to various embodiments.

1B shows a flow diagram of a video decoding method according to various embodiments.

1C shows a block diagram of a video encoding apparatus according to various embodiments.

Figure 1D shows a flow diagram of a video encoding method according to various embodiments.

FIG. 1E shows a block diagram of an image decoding unit according to various embodiments.

1F shows a block diagram of an image encoding unit according to various embodiments

FIG. 2 is a diagram for explaining a method of scanning intra-block transform coefficients according to an embodiment.

3A is a diagram for explaining a method of scanning an intra-block transform coefficient according to an embodiment.

FIG. 3B is a view for explaining an operation of determining intra-block coefficient groups (sub-blocks) and an operation performed for each coefficient group according to an embodiment.

FIG. 4 is a diagram for explaining a process of determining a context model for decoding context-based binary arithmetic decoding information on transform coefficients according to an exemplary embodiment of the present invention.

FIG. 5 is a diagram for explaining a process of determining a context model for decoding context-based binary arithmetic decoding information on transform coefficients according to another embodiment.

FIG. 6A is a diagram for explaining a horizontal priority zigzag scan order for scanning information on intra-block transform coefficients according to an exemplary embodiment.

6B is a diagram for explaining a vertical priority zigzag scan order for scanning information on intra-block transform coefficients according to an embodiment.

FIG. 6C is a diagram for explaining a horizontal scanning order for scanning information on intra-block transform coefficients according to an embodiment.

FIG. 6D is a diagram for explaining a vertical scanning sequence for scanning information on intra-block transform coefficients according to an embodiment.

FIG. 6E is a diagram for explaining a diagonal scan order for scanning information on intra-block transform coefficients according to an embodiment.

FIG. 7A is a diagram for explaining a process of swapping a scan area by swapping horizontal and vertical coordinates of transform coefficient pixels in a rectangular scan area according to an exemplary embodiment.

FIG. 7B is a diagram for explaining a process of changing a scan area by swapping horizontal and vertical coordinates of transform coefficient pixels in a scan area according to another embodiment.

8 is a diagram for explaining a process of determining a context model for syntax element information of a transform coefficient in a current block based on at least one of a size of a current block and a shape of a current block according to an embodiment.

9A to 9C are diagrams for explaining a syntax structure of a residual coding according to an embodiment.

9D to 9F are diagrams for explaining a residual coding syntax structure according to another embodiment.

FIG. 10 illustrates a process in which at least one encoding unit is determined by dividing a current encoding unit according to an embodiment.

FIG. 11 illustrates a process in which at least one encoding unit is determined by dividing a non-square encoding unit according to an embodiment.

FIG. 12 illustrates a process in which an encoding unit is divided based on at least one of block type information and division type information according to an embodiment.

FIG. 13 illustrates a method of determining a predetermined encoding unit among odd number of encoding units according to an embodiment.

FIG. 14 shows a sequence in which a plurality of encoding units are processed when a current encoding unit is divided to determine a plurality of encoding units according to an embodiment.

FIG. 15 illustrates a process in which, when an encoding unit can not be processed in a predetermined order according to an embodiment, it is determined that the current encoding unit is divided into odd number of encoding units.

FIG. 16 illustrates a process in which a first encoding unit is divided into at least one encoding unit according to an embodiment of the present invention.

FIG. 17 shows that when the non-square type second coding unit determined by dividing the first coding unit according to an embodiment satisfies a predetermined condition, the form in which the second coding unit can be divided is limited .

FIG. 18 illustrates a process of dividing a square-shaped encoding unit when the division type information can not indicate division into four square-shaped encoding units according to an embodiment

FIG. 19 illustrates that the processing order among a plurality of coding units may be changed according to the division process of the coding unit according to an embodiment.

FIG. 20 illustrates a process of determining the depth of an encoding unit according to a change in type and size of an encoding unit when the encoding unit is recursively divided according to an embodiment to determine a plurality of encoding units.

FIG. 21 illustrates a depth index (PID) for coding unit classification and depth that can be determined according to the type and size of coding units according to an exemplary embodiment.

22 shows that a plurality of coding units are determined according to a plurality of predetermined data units included in a picture according to an embodiment.

FIG. 23 shows a processing block serving as a reference for determining a determination order of a reference encoding unit included in a picture according to an embodiment.

Hereinafter, 'video' may be a still image of a video or a video, that is, a video itself.

Hereinafter, 'sample' means data to be processed as data assigned to a sampling position of an image. For example, pixels in an image in the spatial domain may be samples.

Hereinafter, the 'current block' may refer to a block of an image to be encoded or decoded.

FIG. 1A shows a block diagram of a video decoding apparatus according to various embodiments.

The video decoding apparatus 100 according to various embodiments may include an entropy decoding unit 105 and an image restoring unit 120.

The entropy decoding unit 105 may obtain syntax element information received from the bitstream and entropy-decode the syntax element information. At this time, the syntax element information received from the bitstream may be information on various syntax elements related to the image.

The entropy decoding unit 105 can obtain syntax element information on the current intra-block transformation coefficient from the bitstream and entropy-decode the syntax element information on the current intra-block transformation coefficient. At this time, the current block may be a data unit that can be used in the process of attaching / decrypting an image described with reference to FIG. 10 to FIG.

The entropy decoding unit 105 may obtain information on the current intra-block transform coefficients by scanning the syntax element information about the transform coefficients in the current entropy-decoded block according to a predetermined scan order. The predetermined scan order may be a reverse scan order. Here, the reverse scan order may be a scan order from the pixels on the lower right side in the block to the transform coefficient pixels on the upper left side in the block. The order in which the transform coefficients are scanned in the order of the transform coefficients located on the lower left side from the upper left side transform coefficient pixels can be referred to as the forward scan order and the transform coefficients are scanned from the last transform coefficient located on the lower right side to the order of the upper left side transform coefficients May be referred to as the reverse scan order. The syntax element information on the current intra-block conversion coefficient may be flag information indicating whether the intra-block conversion coefficient is larger than a predetermined value. At this time, the predetermined value may be an integer value equal to or greater than zero. For example, 0, 1 or 2.

The syntax element information regarding the current intra-block transformation coefficient may be syntax element information indicating a remaining level absolute value. The residual level absolute value may mean the difference between the absolute value of the level of the transform coefficient and the absolute value of the base level. The absolute value of the base level may be determined based on the syntax element information indicating that the absolute value of the transform coefficient is larger than a predetermined value. For example, a flag indicating whether the absolute value of the transform coefficient is greater than 0 (or whether the transform coefficient is an effective transform coefficient, where the effective transform coefficient means a transform coefficient whose absolute value of the transform coefficient is larger than 0) Flag (Greater than 1 flag or coeff_abs_level_greater1_flag; hereinafter referred to as GT1 flag) indicating whether or not the value of the flag is greater than 2 and the value of the information (Greater than 0 flag or sig_coeff_flag; hereinafter referred to as GT0 flag) (The Greater than 2 flag or the coeff_abs_level_greater2_flag; referred to as the GT2 flag) may be the absolute value of the base level. Here, when the flag information indicating whether the absolute value of the transform coefficient is larger than the predetermined value is greater than the predetermined value, the value of the flag information may be 1, and if it is smaller than the predetermined value, May be zero. On the other hand, some of the flag information related to the magnitude of the transform coefficients may not be obtained from the bitstream. According to one embodiment, a flag GTn indicating whether the magnitude of the transform coefficient is larger than n (n is an integer), a flag GT (n + 1) indicating whether the magnitude of the transform coefficient is larger than (n + 1) (N + 1), which is a relatively smaller value among the reference values of n, n + 1 and n + 2, when the coefficient GT (n + It is possible to transmit only the flags GTn, GT (n + 1) indicating whether the absolute value of the coefficient is larger and not to include GT (n + 2) in the bitstream.

For example, when the GT0 flag information and the GT1 flag information each indicate that the absolute value of the transform coefficient is greater than 0 and 1, if the GT2 flag is not included in the bitstream, the entropy decoding unit 105 excludes the GT2 flag, The absolute value of the conversion coefficient obtained by subtracting 2 from the absolute value of the conversion coefficient can be determined as the absolute value of the residual level of the conversion coefficient using only the GT0 flag information and the GT1 flag information.

When the GT0 flag information, the GT1 flag information, and the GT2 flag information indicate respectively greater than 0, 1, and 2, the entropy decoding unit 105 determines that the absolute value of the transform coefficient is larger than 2, The absolute value can be determined as the absolute value of the residual level of the transform coefficient. That is, the absolute value of the residual level may indicate an absolute value difference between the absolute value of the effective transform coefficient and a predetermined absolute value determined based on information indicating whether the absolute value of the transform coefficient is larger than a predetermined value. ) Acquires the syntax element information received from the bitstream, performs binary arithmetic decoding on the syntax element information, and performs binary arithmetic decoding on the bin string, which is the output generated by the binary arithmetic decoding, It is possible to perform inverse binarization. The binary arithmetic decoding operation can be performed in the binary arithmetic decoding unit 110 and the inverse binarization operation can be performed in the inverse binarization unit 115. [

The binary arithmetic decoding unit 110 may perform binary arithmetic decoding based on a predetermined context model on the syntax element information obtained from the bitstream. Here, the context model may be information on the probability of occurrence of a bin. The information on the probability of occurrence of the bean includes information (valMPS) indicating one symbol of LPS (Least Propable Symbol), which is a relatively low probability of occurrence of two symbols 0 and 1, and a Least Probable Symbol (MPS) And information on the probability of occurrence of one symbol. The occurrence probability has a value between 0 and 1. Therefore, if the probability of one of the MPS and the LPS is determined, the information on the probability of occurrence of the other symbol is information on the probability of subtracting the occurrence probability for the predetermined symbol from 1, The binary arithmetic decoding unit 110 can determine the probability of occurrence of the remaining symbols. In this case, the probability of occurrence of one symbol to be determined first may be the probability of occurrence of LPS (Least Probable Symbol). On the other hand, the occurrence probabilities of symbols corresponding to the index values can be determined in advance in the table, and the occurrence probability information for the symbols can be information (pStateIdx) indicating an index indicating occurrence probabilities of symbols determined in the table.

The predetermined context model may be determined based on an index (bin index) indicating the location of the bean, a probability of occurrence of a bean included in a neighboring block of the block including the bean, and various elements of the current block or neighboring blocks.

Alternatively, the binary arithmetic decoding unit 110 may perform binary arithmetic decoding on the syntax element information obtained from the bitstream according to a by-pass mode. At this time, the probability of 0 or 1 for the current binary arithmetic decoding is fixed to 0.5, and binary arithmetic decoding can be performed on the syntax element information based on this probability.

The inverse binarization unit 115 may perform inverse binarization on the bin string, which is an output value generated by performing binary arithmetic decoding. The inverse binarization unit 115 may perform inverse binarization on the bin string based on the inverse binarization method corresponding to the predetermined binarization method. The predetermined binarization method may include a fixed length binarization method, a Rice binarization method, an exponential-Golomb binarization method, and a Golomb-Rice binarization method. Alternatively, the predetermined binarization method may be a binarization method in which the first binarization method and the second binarization method are combined. For example, the inverse binarization unit 115 performs inverse binarization on the first bin string, which is a part of the bin string of the syntax element, based on the inverse binarization method corresponding to the first binarization method, For bin strings, inverse binarization may be performed based on an inverse binarization method corresponding to the second binarization method. The part of the empty string may be a prefix or suffix of the empty string of the syntax element.

Both the binarization method and the inverse binarization method relate to a kind of code word that defines a 1: 1 correspondence of the empty string including at least one bin corresponding to the value of the syntax element. In accordance with one of the various types of binarization methods described above in terms of encoding, an empty string containing at least one bin corresponding to the value of the syntax element is determined, and in accordance with an inverse binarization method in terms of decoding, Can be determined. For example, when the bin string A corresponding to the value a (a is a real number) of the syntax element is determined according to a predetermined binarization / inverse binarization method, the process of determining the bin string A based on the value a of the syntax element is binarized , And the process of determining the value a of the syntax element based on the bin string A can be referred to as an inverse binarization process. However, as described above, the binarization and inverse binarization essentially define the mapping relationship between the value of the syntax element and the bin string, and the person skilled in the art can easily understand that binarization / inverse binarization is substantially the same.

The entropy decoding unit 105 can obtain information on the current intra-block transform coefficients by performing the entropy decoding by scanning the syntax element information about the current intra-block transform coefficient according to a predetermined scan order. The predetermined scan order may be a sequence according to a reverse zigzag scan or a sequence according to a diagonal scan in the reverse direction. However, the present invention is not limited to this, and the predetermined scan order may be various scan orders such as a reverse scan order according to a horizontal scan and a scan order according to a vertical scan. The predetermined scanning order is determined by the horizontal coordinate (for example, x coordinate (x is an integer) in the orthogonal coordinate system) of the effective conversion coefficient pixel located at the rightmost position in the current block and the effective conversion coefficient (E.g., the y coordinate of the Cartesian coordinate system (y is an integer)) values of the pixel. For example, the entropy decoding unit 105 may determine a predetermined scan order based on the size of the horizontal direction coordinate value and the size of the vertical direction coordinate value. The entropy decoding unit 105 can determine the vertical scanning order in the reverse direction in a predetermined scanning order when the horizontal direction coordinate value is larger than the vertical direction coordinate value. The entropy decoding unit 105 may determine a horizontal scanning order in the reverse direction as a predetermined scanning order when the vertical direction coordinate value is larger than the horizontal direction coordinate value.

Alternatively, the entropy decoding unit 105 may determine a vertical first zigzag scan order in a reverse scan direction in a predetermined scan order when the horizontal direction coordinate value is larger than the vertical direction coordinate value. Details of the vertical priority zigzag scan sequence will be described with reference to FIG. 6B. The entropy decoding unit 105 may determine a horizontal first zigzag scan order in a predetermined scanning order if the vertical direction coordinate value is larger than the horizontal direction coordinate value. The details of the horizontal priority zigzag scan sequence will be described with reference to FIG. 6A. The entropy decoding unit 105 may determine one of the reverse direction vertical priority zigzag scanning order and the horizontal priority zigzag scanning order in a predetermined scanning order when the vertical direction coordinate value is equal to the horizontal direction coordinate value.

Alternatively, if the horizontal coordinate value is larger than the vertical coordinate value, the entropy decoding unit 105 may determine a horizontal first zigzag scan order in a predetermined scanning order. On the other hand, if the horizontal direction coordinate value is not larger than the vertical direction coordinate value, the entropy decoding unit 105 may determine a reverse direction vertical first zigzag scan order in a predetermined scan order.

The entropy decoding unit 105 may determine a scan area including all the effective transform coefficients in the current block before scanning the information on the transform coefficients. In this case, the scan area includes all the effective conversion coefficients in the current block, and the remaining area within the current block excluding the scan area may include only the conversion coefficient of 0, which is not an effective conversion coefficient. At this time, when the scan area is scanned according to a predetermined forward scan order from the upper left corner of the scan area, the scan area includes the transform coefficients up to the last effective scan transform coefficient . ≪ / RTI > At this time, the coordinates specifying the scan area may be the coordinates of the effective scan conversion pixel to be scanned last.

The entropy decoding unit 105 may obtain information on the coordinates indicating the last effective transform coefficient from the bit stream and determine the scan region based on the information on the coordinates indicating the last effective transform coefficient. For example, the entropy decoding unit 105 may obtain information indicating the coordinate value in the horizontal direction of the last effective conversion coefficient and information indicating the vertical direction coordinate value of the last effective conversion coefficient from the bit stream. At this time, binary arithmetic decoding is performed on each piece of information to obtain a bin string for each piece of information, and an inverse binarization method corresponding to a predetermined binarization method is applied to each bin string to calculate a horizontal coordinate value And the vertical coordinate value of the last effective conversion coefficient.

The entropy decoding unit 105 performs a first inverse binarization method on the first bin string that is a part of the bin string to obtain a first value and performs a second inverse binarization method on a second bin string that is another part of the bin string To obtain a second value. It is possible to obtain the horizontal coordinate value of the last effective conversion coefficient and the vertical coordinate value of the last effective conversion coefficient based on the first value and the second value. In this case, the first bin string may be a prefix, and the first inverse binarization method may be an inverse binarization method corresponding to a fixed-length binarization method. The second bin string may be a suffix and the second inverse binarization method may be an inverse binarization method corresponding to a cutting type unary binarization method.

Alternatively, the scan region may be a quadrangle scan region, the quadrangle scan region may include a horizontal direction coordinate of an effective conversion coefficient pixel located at the rightmost of all effective conversion coefficients in the current block, and an effective conversion coefficient And may be an area specified by the vertical coordinate of the pixel.

The entropy decoding unit 105 may obtain information on the coordinates specifying the quadrangular scan region from the bit stream and determine the quadrangular scan region based on the information on the coordinates specifying the obtained quadrangular scan region. For example, the entropy decoding unit 105 extracts, from the bitstream, information indicating horizontal coordinate values of effective conversion coefficient pixels located at the rightmost of all the effective conversion coefficients in the current block, Information indicating the vertical coordinate value of the effective conversion coefficient pixel located at the lowermost position can be obtained. At this time, the entropy decoding unit 105 performs binary arithmetic decoding on each piece of information to obtain a bin string for each piece of information, and uses an inverse binarization method corresponding to a predetermined binarization method for an empty string, It is possible to obtain the horizontal coordinate values of the effective conversion coefficient pixels located at the rightmost of the effective conversion coefficients and the vertical coordinate values of the effective conversion coefficient pixels located at the bottom of the effective conversion coefficients. The entropy decoding unit 105 performs a first inverse binarization method on the first bin string that is a part of the bin string to obtain a first value and performs a second inverse binarization method on a second bin string that is another part of the bin string To obtain a second value. The horizontal coordinate value of the effective conversion coefficient pixel located at the rightmost of all the effective conversion coefficients in the current block and the vertical coordinate value of the effective conversion coefficient pixel located at the lowermost one among the effective conversion coefficients in the current block are calculated based on the first value and the second value, Can be obtained. In this case, the first bin string may be a prefix, and the first inverse binarization method may be an inverse binarization method corresponding to a fixed-lenth binarization method. The second bin string may be a suffix and the second inverse binarization method may be an inverse binarization method corresponding to a cutting type unary binarization method.

Alternatively, the entropy decoding unit 105 may extract, from the bitstream, the horizontal coordinate value of the effective conversion coefficient pixel located at the rightmost of all the effective conversion coefficients in the current block or the lowest position among all the effective conversion coefficients in the current block The information indicating the coordinate value of one of the vertical coordinate values of the effective conversion coefficient pixel and the information indicating the difference between the coordinate value of the one direction and the coordinate value of the remaining direction. The entropy decoding unit 105 can determine the one direction based on the height and width of the current block.

The entropy decoding unit 105 can obtain, from the bitstream, flag information indicating whether to acquire information indicating a difference between a coordinate value in one direction and a coordinate value in the other direction from the bitstream. If the flag information indicates that information indicating the difference between a coordinate value in one direction and a coordinate value in the other direction is obtained from the bitstream, the entropy decoding unit 105 extracts, from the bitstream, (Or the horizontal coordinate value of the last effective conversion factor pixel) of the effective conversion coefficient pixel located at the rightmost position or the effective direction conversion coefficient pixel located at the bottom of all the effective conversion coefficients in the current block, Value (or the vertical coordinate value of the last effective conversion coefficient pixel), and information indicating the difference between the coordinate value of the one direction and the coordinate value of the remaining direction.

If the flag information indicates that the flag information does not acquire information indicating the difference between the coordinate value in one direction and the coordinate value in the other direction from the bitstream, the entropy decoding unit 105 extracts all the effective transform coefficients Information indicating the horizontal coordinate value of the effective conversion coefficient pixel located at the rightmost position in the current block and information indicating the vertical coordinate value of the effective conversion coefficient pixel located at the lowermost position among all the effective conversion coefficients in the current block .

On the other hand, the entropy decoding unit 105 determines whether to acquire flag information indicating whether to acquire information indicating a difference between a coordinate value in one direction and a coordinate value in the remaining direction from the bit stream, based on the width and height of the current block Can be determined. For example, the entropy decoding unit 105 obtains information indicating a difference between a coordinate value in one direction and a coordinate value in the other direction from the bit stream when the width and height of the current block are different (i.e., when the width and height are different) And obtain flag information indicating whether the flag information is acquired.

For example, the entropy decoding unit 105 may obtain a coordinate value SR_x indicating a horizontal direction and a coordinate value SR_y indicating a vertical direction for specifying a scan region according to the following pseudo code 1.

[Water Code 1]

According to the pseudo code 1, the entropy decoding unit 105 outputs a variable isXfirst indicating whether to decode the information about the coordinate value in the horizontal direction first and a variable isXfirst indicating whether to decode the information on the coordinate value in the vertical direction first The value of isYfirst can be initialized to zero. Also, the entropy decoding unit 105 may initialize flag information srDeltaFlag, which indicates whether or not to acquire information indicating a difference between a coordinate value in one direction and a coordinate value in the other direction, to zero.

If the width W of the current block is larger than the height H of the current block or the height H of the current block is larger than the width W of the current block, the entropy decoding unit 105 obtains srDeltFlag from the bitstream and decodes srDeltaFlag have.

If the value of the decoded srDeltaFlag is 1 (that is, it indicates that information indicating the difference between the coordinate value in one direction and the coordinate value in the remaining direction is acquired), the width W of the current block is If it is smaller than the height H of the current block, the value of IsXfirst can be set to 1.

When the value of the decoded srDeltaFlag is 1 (that is, when it indicates that the information indicating the difference between the coordinate value in one direction and the coordinate value in the remaining direction is received), the entropy decoding unit 105 determines that the width W If it is greater than the height H of the block, the value of IsYfirst can be determined to be 1.

If the value of IsXfirst is 1 (indicating that the information on the coordinate value in the horizontal direction is to be decoded first), the entropy decoding unit 105 outputs the information Sr_x indicating the coordinate value in the horizontal direction and the coordinate value in the horizontal direction (Sr_delta) (Sr_y-Sr_x) indicating the difference between the coordinate values of the coordinates At this time, the coordinate value Sr_y in the vertical direction can be determined as Sr_x + Sr_delta.

If the value of IsYfirst is 1 (indicating that the information on the coordinate value in the vertical direction is decoded first), the entropy decoding unit 105 outputs the information Sr_y indicating the vertical coordinate value and the vertical coordinate value (Sr_delta) (Sr_x-Sr_y) indicating the difference between the coordinate values of the coordinates (Sr_x-Sr_y) from the bit stream. At this time, the coordinate value Sr_x in the vertical direction can be determined as Sr_y + Sr_delta.

If the value of the decoded srDeltaFlag is 0 (that is, when it indicates that the information indicating the difference between the coordinate value in one direction and the coordinate value in the remaining direction is not acquired), the entropy decoding unit 105 sets the horizontal coordinate value And information Sr_y indicating the coordinate values in the vertical direction can be obtained from the bit stream and decoded.

The entropy decoding unit 105 can determine the context model used for binary arithmetic decoding of all the syntax element information used for coefficient decoding based on at least one of the size of the current block and the shape of the current block have. For example, the size of the current block may be determined according to at least one of a minimum value and a maximum value of the height and width of the current block. The shape of the current block can be determined depending on whether or not the width and height of the current block are the same. All the syntax element information used for power decoding may include syntax element information for specifying a scan area and information about a transform coefficient in the scan area.

For example, the entropy decoding unit 105 can determine the information size_tu1 on the size of the current block based on Equation (1) below.

In this case, log2_width may be a value obtained by taking log2 as the width W of the current block, and log2_height may be a value obtained by taking log2 as the height H of the current block.

The entropy decoding unit 105 determines a context model corresponding to the information size_tu1 about the size of the current block, determines a context model for the syntax element information used for coefficient decoding, and uses the context model to perform coefficient decoding The syntax element information can be binary arithmetic-decoded.

Alternatively, the video decoding apparatus 100 can determine information size_tu2 on the size of the current block based on Equation (2) below.

The entropy decoding unit 105 determines the context model based on the information size_tu2 about the size of the current block, determines the context model for the syntax element information used for coefficient decoding, and uses the context model to decode the coefficients The syntax element information can be binary arithmetic-decoded.

Alternatively, the entropy decoding unit 105 may determine the context model based on the information size_tu1 and size_tu2 about the size of the current block, determine the context model for the syntax element information used for coefficient decoding, and use the context model It is possible to binary arithmetic-decode the syntax element information used for decoding.

The entropy decoding unit 105 determines what the minimum value and the maximum value of the current block size and height are, determines the context model based on the minimum and maximum values of the size and height of the current block, The context model for the syntax element information to be used for coefficient decoding can be determined and binary arithmetic decoding can be performed on the syntax element information used for coefficient decoding using the context model.

On the other hand, the entropy decoding unit 105 can determine the context model used for binary arithmetic decoding of all the syntax elements used for coefficient decoding based on the shape of the current block.

For example, the entropy decoding unit 105 may determine information shape_tu about the shape of the current block based on the following equation (3).

 According to Equation (3), the entropy decoding unit 105 determines shape_tu to be 2 when the width width of the current block is greater than the height height, and determines shape_tu to be 1 when the width width of the current block is smaller than the height height And shape_tu can be set to 0 if width width of the current block is equal to height height. That is, for a rectangle with a width greater than the height, shape_tu is determined to be 2. For a rectangle whose height is greater than the width, shape_tu may be determined to be 1, and for a square, shape_tu may be determined to be 0.

The entropy decoding unit 105 determines the context model based on the information shape_tu about the size of the current block, determines the context model for the syntax element information used for coefficient decoding, and uses the context model to decode The syntax element information can be binary arithmetic-decoded.

The entropy decoding unit 105 can determine the context model for the syntax element information used for coefficient decoding based on the size of the current block and the shape of the current block. For example, the video decoding apparatus 100 determines a context model for syntax element information to be used for coefficient decoding based on at least one of information size_tu1 and size_tu2 about the size of the current block and information shape_tu about the shape of the current block And binary arithmetic decoding of the syntax element information used for coefficient decoding using the context model can be performed.

The entropy decoding unit 105 may change the height and the width of the current block when either the height or width of the current block is different from the height or width of the current block. That is, the horizontal direction coordinate and the vertical direction coordinate of the pixels included in the current block can be swapped with each other. For example, if the width of the current block is greater than the height, the entropy decoding unit 105 may change the height and width of the current block. That is, the horizontal and vertical coordinate values of the pixels included in the current block can be swapped with each other. If the width of the current block is not greater than the height, the entropy decoding unit 105 may not swap horizontal and vertical coordinates of the pixels included in the current block with each other. Without being limited to this, the entropy decoding unit 105 can change the height and the width of the current block to each other when the height of the current block is larger than the width. That is, the horizontal and vertical coordinate values of the pixels included in the current block can be swapped with each other. The entropy decoding unit 105 extracts information on horizontal and vertical coordinates specifying the scan area from the bit stream when the horizontal direction coordinate and the vertical direction coordinate of the pixels included in the current block are swapped with each other And swap the coordinates of the horizontal direction coordinate and the vertical direction coordinate that specify the scan area with each other. The entropy decoding unit 105 may determine the first scan area in the current block that has been swapped based on the coordinates specifying the swapped scan area. The entropy decoding unit 105 scans the information about the transform coefficients included in the first scan region and obtains the first transform coefficient of the changed current block based on the information about the scanned transform coefficients have. When the horizontal direction coordinate and the vertical direction coordinate of the pixels included in the current block are swapped with each other, the entropy decoding unit 105 calculates the horizontal direction coordinate and the vertical direction coordinate with respect to the first transform coefficient of the changed current block, The second transform coefficient in the current block can be obtained. The entropy decoding unit 105 may perform inverse quantization and inverse transform on the second transform coefficient of the current block to generate a residual block of the current block.

For example, the entropy decoding unit 105 can change the horizontal coordinate (Sr_x or last_x) and the vertical coordinate (Sr_y or last_y) specifying the scanning region according to the water code 2.

[Water supply code 2]

The entropy decoding unit 105 decodes the current block TU (Transform Unit) if the width (TU_width) of the current block TU (Transform Unit) is larger than the height TU_height of the current block TU (Transform Unit) The width TU_width of the current block TU and the height TU_height of the current block TU can be mutually changed. The horizontal coordinate and the vertical coordinate of the four corners of the TU determined based on the height and width of the TU in the process of changing the height and the width of the TU may be mutually changed. In addition, the horizontal coordinate and the vertical coordinate of the pixels included in the TU may be swapped with each other. At this time, the entropy decoding unit 105 can determine the value of swap_flag, which indicates whether the height and the width of the TU are mutually changed,

The entropy decoding unit 105 determines the width TU_width of the current block TU if the width TU_width of the current block TU_width is not greater than the height TU_height of the current block TU, And the height (TU_height) of the current block TU (Transform Unit) may not be mutually changed.

At this time, the entropy decoding unit 105 can determine the value of swap_flag, which indicates whether the height and the width of the TU are mutually changed, as zero.

The entropy decoding unit 105 decodes coordinates [Sr_x, Sr_y] for specifying a quadrangular scan region from the bitstream to specify the scan region, or coordinates [last_x, Sr_y] of the effective transformation coefficient scanned last in the TU according to a forward scan order, last_y] can be parsed.

The entropy decoding unit 105 may change the coordinates [Sr_x, Sr_y] for specifying the quadrangular scan region to each other or change the coordinates of the effective transformation coefficient scanned last in the TU according to the forward scanning order [last_x, last_y] can be mutually changed.

For example, the entropy decoding unit 105 may change the horizontal direction coordinate (Sr_x or last_x) and the vertical direction coordinate (Sr_y or last_y) specifying the scan region according to the number code 3.

[Water code 3]

The entropy decoding unit 105 decodes the current block TU (Transform Unit) if the width (TU_width) of the current block TU (Transform Unit) is larger than the height TU_height of the current block TU (Transform Unit) The width TU_width of the current block TU and the height TU_height of the current block TU can be mutually changed. The horizontal coordinate and the vertical coordinate of the four corners of the TU determined based on the height and width of the TU in the process of changing the height and the width of the TU may be mutually changed. In addition, the horizontal coordinate and the vertical coordinate of the pixels included in the TU may be swapped with each other. At this time, the entropy decoding unit 105 can determine the value of swap_flag, which indicates whether the height and the width of the TU are mutually changed,

The entropy decoding unit 105 determines the width TU_width of the current block TU if the width TU_width of the current block TU_width is not greater than the height TU_height of the current block TU, And the height (TU_height) of the current block TU (Transform Unit) may not be mutually changed. At this time, the entropy decoding unit 105 can determine the value of swap_flag, which indicates whether the height and the width of the TU are mutually changed, as zero.

The entropy decoding unit 105 determines whether to obtain a coordinate value in the horizontal direction and a coordinate value in the vertical direction for specifying the scan region using the difference information between the coordinate value in the horizontal direction and the coordinate value in the vertical direction for specifying the scan region (DeltaXYflag) from the bitstream. The flag deltaXYflag may be generated to have a value of 1 when the coordinate value in the vertical direction is larger than the horizontal direction coordinate value in the video encoding apparatus, and may be generated to have a value of 0 otherwise. If deltaXYflag is 0, the entropy decoding unit 105 separately obtains information on the horizontal direction coordinate value and information on the vertical direction coordinate value, entropy decodes the entropy-decoded information, and outputs the coordinates Can be obtained.

If the value of deltaXYflag is 1, the entropy decoding unit 105 can parse the coordinate information for specifying the scan area from the bitstream. For example, the entropy decoding unit 105 parses information Sr_xy_delta, which is information Sr_x about horizontal coordinate values for specifying a quadrangular scan area and information about the difference between information about horizontal coordinate values and vertical coordinate values, from a bitstream can do. Alternatively, the entropy decoding unit 105 may extract information about the horizontal direction coordinate value of the effective transformation coefficient scanned last in the TU and the information about the horizontal direction coordinate value and the information about the vertical direction coordinate value in the vertical direction It is possible to parse the information last_xy_delta on the difference between the coordinate values.

The entropy decoding unit 105 may determine the horizontal direction coordinate value Sr_x for specifying the quadrangular scan region to be information Sr_x about the horizontal direction coordinate value parsed from the bitstream. The entropy decoding unit 105 may determine the vertical direction coordinate value Sr_y for specifying the quadrangular scan area as Sr_xy_delta parsed from the bit stream plus the information Sr_x about the horizontal coordinate value parsed from the bit stream.

Alternatively, if the value of deltaXYflag is 1, the entropy decoding unit 105 extracts the horizontal direction coordinate value last_x of the effective transformation coefficient scanned last in the TU according to the forward scan order for specifying the scan region from the bitstream It can be determined as information last_x about the horizontal direction coordinate value. The entropy decoding unit 105 extracts the vertical direction coordinate value last_y of the effective transform coefficient scanned last in the TU according to the forward scan order for specifying the scan area from the bit stream to the information last_xy_delta parsed from the bit stream in the horizontal direction The information about the coordinate value last_x can be determined as a sum

If the value of swap_flag is 1, the entropy decoding unit 105 changes the coordinates [Sr_x, Sr_y] for specifying the quadrangular scan region to each other or changes the coordinate [Sr_x, Sr_y] for the last scan in the TU according to the forward scan order for specifying the scan region The coordinates [last_x, last_y] of the effective transformation coefficients to be changed can be mutually changed.

The entropy decoding unit 105 can perform binary arithmetic decoding based on the context model on the information on the coordinates specifying the quadrangular scan area. The entropy decoding unit 105 may perform inverse binarization on the binary arithmetic decoded information based on the inverse binarization method corresponding to the predetermined binarization method to obtain inverse binarization information on the coordinates specifying the quadrangular scan area, Coordinates from which the quadrangular scan area is specified can be obtained from the inverse binarization information regarding the coordinates. At this time, the context model may be determined based on at least one of the size of the current block, the color component of the current block, and the bin index. The color component may include a luminance component and a chrominance component. The empty index may be information indicating the position of the bin that is currently binary arithmetic decoded among the bin strings related to the syntax element. The inverse binarization method corresponding to a predetermined binarization method may be at least one of a fixed length inverse binarization method and a truncated unary inverse binarization method. For example, the entropy decoding unit 105 performs inverse binarization using the fixed length inverse binarization method on the first bin string of the binary arithmetic decoded information to obtain the first inverse binarization information, The second inverse binarization information may be obtained by performing inverse binarization using the cutting type unary inverse inverse binarization method for the second bin string. The entropy decoding unit 105 may obtain coordinates specifying the quadrangular scan area based on the first inverse binarization information and the second inverse binarization information.

The entropy decoding unit 105 may perform binary arithmetic decoding based on information on the scan coefficients scanned in the current block to obtain binary arithmetic decoding information. At this time, the binary arithmetic decoding can be performed using the context model determined based on at least one of the size and shape of the current block.

The entropy decoding unit 105 may perform inverse binarization on the binary arithmetic decoding information to obtain information on the transform coefficients of the current block.

The entropy decoding unit 105 performs at least one of binary arithmetic decoding and inverse binarization based on the context model of the transform coefficients based on the information about the transform coefficients scanned in the scan area to obtain transform coefficients of the current block .

If the information on the transform coefficients is information indicating whether the absolute value of the current transform coefficient is larger than a predetermined value, and the residual level absolute value information and the sign information of the current transform coefficient, the entropy decoding unit 105 outputs the transform coefficients It is possible to perform binary arithmetic decoding based on the context model. The entropy decoding unit 105 may perform inverse binarization on the information on the binary-arithmetically decoded transform coefficients to obtain a transform coefficient of the current block. The first information on the transform coefficients is information indicating whether the absolute value of the current transform coefficient is larger than a predetermined value and the residual level absolute value information and the sign information of the current transform coefficient, In the case of the binarization parameter information related to the coefficient, the entropy decoding unit 105 may perform binary arithmetic decoding based on the context model with respect to the first information on the transform coefficient.

The entropy decoding unit 105 may perform inverse binarization based on the binary parameter information included in the second information with respect to the first information subjected to the binary arithmetic decoding so as to obtain the transform coefficient of the current block. The binarization parameter information may be Rice Parameter information for the current transform coefficient. The Rice parameter may be information for determining the length of the prefix included in the bin string. Without being limited thereto, the binarization parameter information may be various binarization parameter information for the current transform coefficient.

If the first information on the transform coefficients is the residual level absolute value information of the current transform coefficient, the entropy decoding unit 105 performs a (truncated) Rice binarization method on the residual level absolute value information of the current transform coefficient A value relating to the absolute value of the residual level of the current transform coefficient can be obtained by using the inverse binarization method corresponding to the corresponding inverse binarization method and the exponential Gollum binarization method. For example, the entropy decoding unit 105 performs inverse binarization on the prefix of the bin string of the residual level absolute value information of the current transform coefficient using an inverse binarization method corresponding to the Rice binarization method based on the Rice parameter The first value relating to the absolute value of the residual level of the current transform coefficient is obtained and the inverse binarization using the inverse binarization method corresponding to the exponential smoothed binarization method is performed on the suffix of the bin string of the residual level absolute value information Obtains a second value relating to an absolute value of a residual level of a current transform coefficient, and based on a first value relating to an absolute value of a residual level of the current transform coefficient and a second value relating to an absolute value of a residual level of the current transform coefficient, A value relating to the absolute value of the residual level of the residual level.

The context model for the first transform coefficient among the context models related to the transform coefficients includes information on at least one second transform coefficient previously scanned in accordance with a predetermined scan order, position and color of the first transform coefficient in the current block, Information about the right or lower peripheral transformation coefficient, and the scan position of the first transformation coefficient.

For example, the context model relating to the flag information indicating whether the first conversion coefficient is greater than 0 is based on the number of the right or lower conversion coefficients whose absolute value among the right or lower conversion coefficients of the predetermined position is larger than 0 Can be determined.

The context model for flag information indicating whether the first transform coefficient is greater than 0 is not limited to this, and the absolute value of n (n is a positive integer) transform coefficients previously scanned according to a predetermined scan order is greater than 0 Can be determined based on the number of large effective conversion coefficients.

Alternatively, the context model relating to the flag information indicating whether the first transform coefficient is greater than 0 may be determined based on the position of the first transform coefficient in the coefficient group and the corresponding peripheral right or lower effective coefficient group flags.

The entropy decoding unit 105 can determine the context model related to the flag information indicating whether the first transform coefficient is larger than 0 based on the position of the first transform coefficient in the current block. For example, if the sum of the horizontal coordinate value pos_x of the first transform coefficient in the current block and the vertical position pos_y in the current block is smaller than a predetermined threshold value thred1, the entropy decoding unit 105 sets the context index to a predetermined value It is possible to increase the context offset by the context offset, and determine the context model based on the increased context index. If the sum of the horizontal direction coordinate value pos_x of the first transform coefficient in the current block and the vertical direction position pos_y in the current block is smaller than the predetermined threshold value thred2, the entropy decoding unit 105 sets the context index to a predetermined context offset offset2 And determine the context model based on the increased context index. If the sum of the horizontal direction coordinate value pos_x of the first transform coefficient in the current block and the vertical direction pos_y in the current block is smaller than the predetermined threshold value thred3, the entropy decoding unit 105 sets the context index to a predetermined context offset offset3 And determine the context model based on the increased context index.

The entropy decoding unit 105 decodes the size of the scan area, the number of already scanned transform coefficients in the scan area, the relative position of the first transform coefficient in the scan area, and the relative position of the first transform coefficient in the first position where the first transform coefficient is scanned according to a predetermined scan order And determining whether the first conversion coefficient is greater than 0 based on at least one of the presence or absence of the coefficient.

For example, the entropy decoding unit 105 can determine the size size_sr of the quadrangular scan area on the basis of the following equation (4). That is, the size size_sr of the quadrangular scan region may mean the number of transform coefficients included in the quadrangular scan region.

However, without being limited thereto, if the scan area is specified by the coordinates of the last effective conversion factor pixel, then size_sr may be the number of the conversion factor pixels included in the scan area.

The entropy decoding unit 105 may determine the number cnt_pos of all the transform coefficients scanned before scanning the first transform coefficient among the transform coefficients in the quadrangular scan area. At this time, cnt_pos may indicate the position of the first transform coefficient among all the transform coefficients in the scan region scanned according to a predetermined scan order.

If the cnt_pos is smaller than the predetermined threshold value thred1, the entropy decoding unit 105 may increase the context index by a predetermined context offset, and determine the context model based on the increased context index. At this time, thred1 may be one. Or thred1 may be 1/4 * size_sr.

If the cnt_pos is smaller than the predetermined threshold thred2, the entropy decoding unit 105 may increase the context index by a predetermined context offset offset2 and determine the context model based on the increased context index. In this case, thred2 may be 1/4 * size_sr. Or thred2 may be 1/2 * size_sr.

If the cnt_pos is not smaller than the predetermined threshold values thred1 and thred2, the entropy decoding unit 105 may increase the context index by a predetermined context offset offset3 and determine the context model based on the increased context index. However, the threshold values thred1 and thred2 are merely examples, and various values can be determined based on the size_sr.

The entropy decoding unit 105 can determine the context model related to the flag information indicating whether the first transform coefficient is larger than 0 based on the relative positions of the first transform coefficients in the scan area.

The entropy decoding unit 105 determines whether or not the first transform coefficient is greater than 0 based on the horizontal direction coordinate value pos_x and the vertical direction coordinate value pos_y of the first transform coefficient in the current block and the coordinates Sr_x and Sr_y specifying the square scan region The context model relating to the flag information can be determined.

If the pos_x is smaller than thred1_x and the pos_y is smaller than thred1_y, the entropy decoding unit 105 can increase the context index by a predetermined context offset, and determine the context model based on the increased context index. At this time, [thred1_x, thred1_y] may be [1,1]. Alternatively, [thred1_x, thred1_y] may be [sr_x / 4, sr_y / 4] or [(sr_x + 1) / 4, (sr_y + 1) / 4].

If the pos_x is smaller than thred2_x and the pos_y is smaller than thred2_y, the entropy decoding unit 105 may increase the context index by a predetermined context offset offset2 and determine the context model based on the increased context index. At this time, [thred2_x, thred2_y] may be [srredx], [sr_x + 1) / 2, or [sr_y + 1) / 2.

However, the thresholds thred1_x, thred1_y, and thred2_y and thred2_y are merely examples, and those skilled in the art can easily understand that various values can be determined based on sr_x and sr_y.

The entropy decoding unit 105 can determine the context model of the flag information indicating whether the first transform coefficient is greater than 0 or not based on whether the first transform coefficient is a transform coefficient of the first position scanned in the reverse scan order . That is, the entropy decoding unit 105 determines the first context model related to the flag information indicating whether the first transform coefficient is greater than 0 when the first transform coefficient is the first position scanned in the reverse scan order, 1 conversion coefficient is not the first position to be scanned in the reverse scan order, the second context model may be determined regarding the flag information indicating whether the first conversion coefficient is greater than zero. In this case, the transform coefficients of the pixels positioned at the lower right corner of the quadrangular scan region may be the transform coefficients of the first position scanned in the reverse scan order.

Alternatively, the flag information (GT0 flag information) indicating whether the first transform coefficient is greater than 0 may be obtained by adding GT0 flag information of n (n is a positive integer) transform coefficients previously scanned according to a predetermined scan order, The GT0 flag information of the position, color component, and neighboring right or lower n (n is a positive integer) conversion coefficients of the first conversion coefficient, whether the first conversion coefficient on the scan order is the conversion coefficient of the first position in the scan area, And whether or not the first transformation coefficient in the scan order is a transformation coefficient of the final position in the scan area.

The context model relating to the flag information indicating whether the absolute value of the first conversion coefficient is larger than 1 is determined based on the number of the right or lower effective conversion coefficients whose absolute value of the right or lower conversion coefficient of the predetermined position is larger than 1 .

The entropy decoding unit 105 can determine the context model related to the flag information indicating whether the first transform coefficient is larger than 1 based on the position of the first transform coefficient in the current block. For example, if the sum of the horizontal coordinate value pos_x of the first transform coefficient in the current block and the vertical position pos_y in the current block is smaller than a predetermined threshold value thred1, the entropy decoding unit 105 sets the context index to a predetermined value It is possible to increase the context offset by the context offset, and determine the context model based on the increased context index. If the sum of the horizontal direction coordinate value pos_x of the first transform coefficient in the current block and the vertical direction position pos_y in the current block is smaller than the predetermined threshold value thred2, the entropy decoding unit 105 sets the context index to a predetermined context offset offset2 And determine the context model based on the increased context index.

If the sum of the horizontal direction coordinate value pos_x of the first transform coefficient in the current block and the vertical direction pos_y in the current block is smaller than the predetermined threshold value thred3, the entropy decoding unit 105 sets the context index to a predetermined context offset offset3 And determine the context model based on the increased context index. At this time, the offsets offset1, 2, and 3 associated with the context model relating to the flag information indicating whether the first conversion coefficient is greater than 1 and predetermined thresholds thred1, 2, and 3 are flag information indicating whether the first conversion coefficient is greater than 0 The offsets offset 1, 2 and 3 associated with the context model with respect to the threshold values thred 1, 2, and 3 and their values may be different.

The entropy decoding unit 105 calculates the number of transform coefficients that have already been scanned in the scan region, the relative position of the first transform coefficients in the scan region, and the first zero, that is, the first transform coefficient is scanned according to a predetermined scan order And determining whether the first conversion coefficient is larger than 1 based on at least one of whether or not the conversion coefficient is a non-conversion coefficient at a position other than the first conversion coefficient.

For example, the entropy decoding unit 105 can determine the size size_sr of the quadrangular scan area on the basis of the following equation (5). That is, the size size_sr of the quadrangular scan region may mean the number of transform coefficients included in the quadrangular scan region.

The entropy decoding unit 105 may determine the number cnt_pos of all the transform coefficients scanned before scanning the first transform coefficient among the transform coefficients in the quadrangular scan area. At this time, cnt_pos may indicate the position of the first transform coefficient among all the transform coefficients in the scan region scanned according to a predetermined scan order. However, the present invention is not limited to this, and cnt_pos may be the number of transform coefficients larger than all zero scanned before scanning the first transform coefficient among the transform coefficients in the rectangular scan region.

If the cnt_pos is smaller than the predetermined threshold value thred1, the entropy decoding unit 105 may increase the context index by a predetermined context offset, and determine the context model based on the increased context index. At this time, thred1 may be one. Or thred1 may be 1/4 * size_sr.

If the cnt_pos is smaller than the predetermined threshold thred2, the entropy decoding unit 105 may increase the context index by a predetermined context offset offset2 and determine the context model based on the increased context index. In this case, thred2 may be 1/4 * size_sr. Or thred2 may be 1/2 * size_sr.

If the cnt_pos is not smaller than the predetermined threshold values thred1 and thred2, the entropy decoding unit 105 may increase the context index by a predetermined context offset offset3 and determine the context model based on the increased context index.

However, the threshold values thred1 and thred2 are merely examples, and various values can be determined based on the size_sr. At this time, the offsets offset 1, 2, and 3 associated with the context model relating to the flag information indicating whether the first transform coefficient is greater than 1, and predetermined thresholds thred 1 and thred 2 are related to flag information indicating whether the first transform coefficient is greater than zero Those skilled in the art will readily understand that the offsets offset 1, 2, and 3 associated with the context model may differ from the threshold values thred 1 and thred 2 and their values.

The entropy decoding unit 105 can determine the context model related to the flag information indicating whether the first transform coefficient is greater than 1 based on the relative position of the first transform coefficients in the scan area.

The entropy decoding unit 105 determines whether or not the first transform coefficient is greater than 1 based on the horizontal direction coordinate value pos_x and the vertical direction coordinate value pos_y of the first transform coefficient in the current block and the coordinates Sr_x and Sr_y specifying the rectangular scan region The context model relating to the flag information can be determined.

When the pos_x is smaller than thred1_x and the pos_y is smaller than thred1_y, the video decoding apparatus 100 may increase the context index by a predetermined context offset, and determine the context model based on the increased context index. At this time, [thred1_x, thred1_y] may be [1,1]. Alternatively, [thred1_x, thred1_y] may be [sr_x / 4, sr_y / 4] or [(sr_x + 1) / 4, (sr_y + 1) / 4].

If the pos_x is smaller than thred2_x and the pos_y is smaller than thred2_y, the entropy decoding unit 105 may increase the context index by a predetermined context offset offset2 and determine the context model based on the increased context index. At this time, [thred2_x, thred2_y] may be [srredx], [sr_x + 1) / 2, or [sr_y + 1) / 2.

However, the thresholds thred1_x, thred1_y, and thred2_y and thred2_y are merely examples, and those skilled in the art can easily understand that various values can be determined based on sr_x and sr_y.

However, the thresholds thred1_x, thred1_y, thred2_x, and thred2_y are only examples, and various values can be determined based on the size_sr. At this time, the offsets offset 1, 2, and 3 associated with the context model relating to the flag information indicating whether the first conversion coefficient is greater than 1 and predetermined thresholds thred1_x, thred1_y, thred2_x, and thred2_y relate to the flags indicating whether the first conversion coefficient is greater than 0 It will be readily appreciated by those skilled in the art that the offsets offset 1, 2, and 3 associated with the context model for the information may differ from the threshold values thred1_x, thred1_y, thred2_x, and thred2_y.

The entropy decoding unit 105 determines whether or not the first conversion coefficient is larger than 1 based on whether the first conversion coefficient is a conversion coefficient of the first position among the conversion coefficients larger than 0 that are scanned in the reverse scan order Can be determined. That is, when the first transform coefficient is the first one of the transform coefficients larger than 0, which is scanned in the reverse scan order, the video decoding apparatus 100 determines whether the first transform coefficient is greater than 1, A second context model for flag information indicating whether the first transform coefficient is greater than one when the first transform coefficient is not the first one of the transform coefficients greater than 0 scanned in the reverse scan order, Can be determined.

The context model relating to the flag information indicating whether the absolute value of the first transform coefficient is larger than 1 is not limited to the absolute value of n (n is a positive integer) transform coefficients previously scanned according to a predetermined scan order Can be determined based on the number of effective transform coefficients greater than one.

Alternatively, the context model relating to flag information indicating whether the absolute value of the first transform coefficient is greater than 1 may be determined based on GT1 flag information previously decoded in the corresponding coefficient group and GT1 flag information previously decoded in the group.

Alternatively, the flag information (GT1 flag information) indicating whether the absolute value of the first transform coefficient is larger than 1 is obtained by adding GT1 flag information of n (n is a positive integer) transform coefficients previously scanned according to a predetermined scan order, The GT1 flag information of the position, color component, and neighboring right or lower n (n is a positive integer) conversion coefficients of the first transform coefficient in the block, whether the first transform coefficient is the transform coefficient of the first position in the scan area, And whether or not the first transform coefficient is a transform coefficient of the final position in the scan area.

The context model relating to the flag information indicating whether the absolute value of the first transform coefficient is larger than 2 can be determined based on the number of the right or lower effective transform coefficients whose absolute value is larger than 2.

The entropy decoding unit 105 can determine the context model related to the flag information indicating whether the first transform coefficient is larger than 2 based on the position of the first transform coefficient in the current block. For example, if the sum of the horizontal coordinate value pos_x of the first transform coefficient in the current block and the vertical position pos_y in the current block is smaller than a predetermined threshold value thred1, the entropy decoding unit 105 sets the context index to a predetermined value It is possible to increase the context offset by the context offset, and determine the context model based on the increased context index. If the sum of the horizontal direction coordinate value pos_x of the first transform coefficient in the current block and the vertical direction position pos_y in the current block is smaller than the predetermined threshold value thred2, the entropy decoding unit 105 sets the context index to a predetermined context offset offset2 And determine the context model based on the increased context index. If the sum of the horizontal direction coordinate value pos_x of the first transform coefficient in the current block and the vertical direction pos_y in the current block is smaller than the predetermined threshold value thred3, the entropy decoding unit 105 sets the context index to a predetermined context offset offset3 And determine the context model based on the increased context index. At this time, the offsets offset1, 2 and 3 associated with the context model relating to the flag information indicating whether the first transform coefficient is larger than 2 and predetermined thresholds thred1, 2 and 3 indicate whether the first transform coefficient is larger than 0 and 1 The offsets offset 1, 2, and 3 associated with the context model for the flag information and the predetermined threshold values thred 1, 2, and 3 may differ.

The entropy decoding unit 105 calculates the number of transform coefficients that have already been scanned in the scan region, the relative position of the first transform coefficients in the scan region, and the first zero, that is, the first transform coefficient is scanned according to a predetermined scan order And determining whether the first transform coefficient is greater than one based on at least one of whether the transform coefficient is a transform coefficient of a position (or a transform coefficient of a transform coefficient larger than 1).

For example, the entropy decoding unit 105 can determine the size size_sr of the quadrangular scan area on the basis of the following equation (6). That is, the size size_sr of the quadrangular scan region may mean the number of transform coefficients included in the quadrangular scan region.

The entropy decoding unit 105 may determine the number cnt_pos of all the transform coefficients scanned before scanning the first transform coefficient among the transform coefficients in the quadrangular scan area. At this time, cnt_pos may indicate the position of the first transform coefficient among all the transform coefficients in the scan region scanned according to a predetermined scan order. However, cnt_pos may be the number of all transform coefficients whose absolute value scanned before scanning the first transform coefficient among the transform coefficients in the quadrangular scan area is larger than unity.

If the cnt_pos is smaller than the predetermined threshold value thred1, the entropy decoding unit 105 may increase the context index by a predetermined context offset, and determine the context model based on the increased context index. At this time, thred1 may be one. Or thred1 may be 1/4 * size_sr.

If the cnt_pos is smaller than the predetermined threshold thred2, the entropy decoding unit 105 may increase the context index by a predetermined context offset offset2 and determine the context model based on the increased context index. In this case, thred2 may be 1/4 * size_sr. Or thred2 may be 1/2 * size_sr.

If the cnt_pos is not smaller than the predetermined threshold values thred1 and thred2, the entropy decoding unit 105 may increase the context index by a predetermined context offset offset3 and determine the context model based on the increased context index.

However, the threshold values thred1 and thred2 are merely examples, and various values can be determined based on the size_sr. At this time, the offsets offset 1, 2, and 3 associated with the context model relating to the flag information indicating whether the first conversion coefficient is greater than 0 or 1 and predetermined thresholds thred 1 and thred 2 indicate whether the first conversion coefficient is greater than 0 or 1 Those skilled in the art will readily understand that the offsets offset 1, 2, and 3 associated with the context model for flag information may differ from the threshold values thred 1 and thred 2 and their values.

The entropy decoding unit 105 can determine the context model related to the flag information indicating whether the first transform coefficient is larger than 2 based on the relative positions of the first transform coefficients in the scan area.

The entropy decoding unit 105 determines whether or not the first transformation coefficient is greater than 2 based on the horizontal direction coordinate value pos_x and the vertical direction coordinate value pos_y of the first transform coefficient in the current block and the coordinates Sr_x and Sr_y specifying the rectangular scan region The context model relating to the flag information can be determined.

If the pos_x is smaller than thred1_x and the pos_y is smaller than thred1_y, the entropy decoding unit 105 can increase the context index by a predetermined context offset, and determine the context model based on the increased context index. At this time, [thred1_x, thred1_y] may be [1,1]. Alternatively, [thred1_x, thred1_y] may be [sr_x / 4, sr_y / 4] or [(sr_x + 1) / 4, (sr_y + 1) / 4].

If the pos_x is smaller than thred2_x and the pos_y is smaller than thred2_y, the entropy decoding unit 105 may increase the context index by a predetermined context offset offset2 and determine the context model based on the increased context index. At this time, [thred2_x, thred2_y] may be [srredx], [sr_x + 1) / 2, or [sr_y + 1) / 2.

However, the thresholds thred1_x, thred1_y, and thred2_y and thred2_y are merely examples, and those skilled in the art can easily understand that various values can be determined based on sr_x and sr_y.

However, the thresholds thred1_x, thred1_y, thred2_x, and thred2_y are only examples, and various values can be determined based on the size_sr. At this time, the offsets offset 1, 2, and 3 associated with the context model related to flag information indicating whether the first conversion coefficient is greater than 0 or 1 and predetermined thresholds thred1_x, thred1_y, thred2_x, and thred2_y, Those skilled in the art can easily understand that the offsets offset 1, 2, and 3 associated with the context model related to the flag information indicating may be different from the threshold values thred1_x, thred1_y, thred2_x, and thred2_y.

The entropy decoding unit 105 determines whether or not the first transform coefficient is larger than 2 based on whether the first transform coefficient is a transform coefficient of the first position among the transform coefficients larger than 0 that are scanned in the reverse scan order Can be determined. That is, if the first transform coefficient is the first one of the transform coefficients larger than 0, which is scanned in the reverse scan order, the entropy decoding unit 105 outputs the first transform coefficient, A second context model for flag information indicating whether the first transform coefficient is greater than one when the first transform coefficient is not the first one of the transform coefficients greater than 0 scanned in the reverse scan order, Can be determined.

However, the present invention is not limited to this, and the entropy decoding unit 105 may determine whether or not the first transform coefficient is equal to or greater than 2 based on whether the first transform coefficient is the transform coefficient of the first position among the transform coefficients larger than 1, The context model can be determined. That is, if the first transform coefficient is the first one of the transform coefficients larger than 1, which is scanned in the reverse scan order, the entropy decoding unit 105 determines whether the first transform coefficient is greater than 1, A second context model for flag information indicating whether the first transform coefficient is greater than two if the first transform coefficient is not the first one of the transform coefficients greater than one scanned in the reverse scan order, Can be determined.

The context model for flag information indicating whether the first transform coefficient is greater than 2 is not limited to this, and the absolute value of n (n is a positive integer) transform coefficients previously scanned according to a predetermined scan order is greater than 2 Can be determined based on the number of large effective conversion coefficients.

Alternatively, the context model on the flag information indicating whether the absolute value of the first transform coefficient is larger than 2 may be determined based on the previously decoded GT2 flag information and the previously decoded in-group GT2 flag information in the corresponding coefficient group.

Alternatively, the flag information (hereinafter referred to as GT2 flag information) indicating whether the absolute value of the first transform coefficient is greater than 2 may be used as the GT2 flag of the previously scanned n (n is a positive integer) Information and the position of the first transform coefficient in the current block, the color component, and GT2 flag information of the adjacent right or lower n (n is a positive integer) transform coefficients, the transform coefficient of the first position in the scan area And whether or not the first transform coefficient is a transform coefficient of the final position in the scan area.

Alternatively, flag information (hereinafter referred to as GTm flag information) indicating whether the first transform coefficient is larger than m (m is an integer larger than 2) is n (n is a positive integer) scanned previously according to a predetermined scan order The GTm flag information of the transform coefficients, the position of the first transform coefficient in the current block, the chrominance component, and the GTm flag information of the adjacent right or lower n (n is a positive integer) transform coefficients, Whether it is a transform coefficient of the initial position, and whether or not the first transform coefficient is a transform coefficient of the final position in the scan area.

On the other hand, the binarization parameter information on the absolute value of the residual level of the first transform coefficient may be determined based on the absolute level of the level of the peripheral effective transform coefficient on the right side or the lower side of the first transform coefficient.

For example, the binarization parameter information on the absolute value of the residual level of the first transform coefficient may be determined based on the sum of the absolute level of the level of the predetermined peripheral effective transform coefficient on the right side or the lower side of the first transform coefficient.

Alternatively, the binarization parameter information on the absolute value of the residual level of the first transform coefficient may be determined based on the previously encoded level value.

Alternatively, the binarization parameter information on the absolute value of the residual level of the first transform coefficient may be obtained from the level of n (n is an integer) transform coefficients previously scanned according to a predetermined scan order, the position of the first transform coefficient in the current block, (N is a positive integer) number of adjacent right or lower n-th conversion coefficients, whether the first conversion coefficient in the scan order is a conversion coefficient of the first position in the scan area, Whether it is a transform coefficient of the final position in the region, whether or not the first transform coefficient in the scan order is a coefficient of the initial position in the coefficient group, and the like.

The entropy decoding unit 105 determines whether or not the position of the transform coefficient currently scanned in the scan region is [SRx, 0] (where SRx is an integer and SRx is the horizontal coordinate value of the right boundary pixel of the scan region on the basis of the left upper- (Y is an integer greater than 0 and less than or equal to SRy, and SRy represents a lower boundary of the scan region with respect to the upper left corner coordinate of the scan region in accordance with a predetermined scan order) The GT0 flag information of the transform coefficient currently scanned from the bit stream is not acquired and the value of the GT0 flag information can be determined to be 1. [

Likewise, the entropy decoding unit 105 determines that the position of the transform coefficient currently scanned in the scan region is [0, SRy] (where SRy is an integer and SRy is the vertical coordinate of the lower boundary of the scan region on the basis of the upper left corner coordinate of the scan region) (X, SRy) (where X is an integer greater than 0 and less than or equal to SRx, SRx is an integer equal to or greater than 0, The GT0 flag information of the currently scanned transform coefficient is not obtained from the bit stream and the value of the GT0 flag information can be determined to be 1 .

On the other hand, the entropy decoding unit 105 can determine the maximum number of GT1 flag information of the current effective conversion coefficient in the block, and receive the GT1 flag information in the current block from the bit stream within the maximum coefficient of the determined effective conversion coefficient . That is, when the entropy decoding unit 105 receives the maximum number of GT1 flag information of the effective conversion coefficient received from the bitstream, the entropy decoding unit 105 determines whether the GT1 flag information of the effective conversion coefficient exists in the bitstream I can not check it anymore.

The entropy decoding unit 105 can determine all non-zero effective conversion coefficients as the maximum number of GT1 flag information in the current block. Alternatively, the entropy decoding unit 105 can determine the maximum number of GT1 flag information in the current block based on the size of the scan area. For example, the entropy decoding unit 105 can determine the maximum number MaxCount_GT1 of the GT1 flag information based on Equation (7) below.

In this case, sizeSR may mean the size (width) of the square scan area, and sizeSR may be (Sr_x + 1) * (Sr_y + 1). Sr_x can be the horizontal coordinate of the rightmost effective transformation coefficient pixel based on the upper left corner coordinate of the scan area. In other words, Sr_x can mean the horizontal coordinate of the right boundary pixel based on the upper left corner coordinate of the scan area. Sr_y may mean the vertical coordinate of the lowest effective conversion factor pixel based on the upper left corner coordinate of the scan area. In other words, Sr_y may mean the vertical coordinate of the lower boundary pixel based on the upper left corner coordinate of the scan area.

K1 can be the magnitude of the scan area and the adjustment factor between the GT1 flags. For example, it may be an integer greater than one. Th1 may be a predetermined threshold value. For example, Th1 may be 16,8. Those skilled in the art can easily understand that K1 and Th1 can have various values, without being limited thereto.

The entropy decoding unit 105 may determine the maximum number of GT2 flag information in the current block and receive GT2 flag information in the current block from the bit stream within the maximum coefficient of the determined effective transform coefficient. That is, when the entropy decoding unit 105 receives the maximum number of GT2 flag information of the effective conversion coefficient received from the bitstream, the entropy decoding unit 105 determines whether the GT2 flag information of the effective conversion coefficient exists in the bitstream I can not check it anymore.

The entropy decoding unit 105 can determine all non-zero effective conversion coefficients as the maximum number of GT2 flag information in the current block. Alternatively, the entropy decoding unit 105 can determine the maximum number of GT2 flag information in the current block based on the size of the scan area. For example, the entropy decoding unit 105 can determine the maximum number of GT2 flag information MaxCount_GT2 based on the following expression (8).

&Quot; (8) "

In this case, sizeSR may mean the size (width) of the square scan area, and sizeSR may be (Sr_x + 1) * (Sr_y + 1). Sr_x can be the horizontal coordinate of the rightmost effective transformation coefficient pixel based on the upper left corner coordinate of the scan area. In other words, Sr_x can mean the horizontal coordinate of the right boundary pixel based on the upper left corner coordinate of the scan area. Sr_y may mean the vertical coordinate of the lowest effective conversion factor pixel based on the upper left corner coordinate of the scan area. In other words, Sr_y may mean the vertical coordinate of the lower boundary pixel based on the upper left corner coordinate of the scan area. K2 can be the magnitude of the scan area and the adjustment factor between GT2 flags. For example, it may be an integer greater than one. K2 may be a predetermined threshold value. For example, Th2 may be 16,8. Those skilled in the art can easily understand that K2 and Th2 can have various values, without being limited thereto.

The entropy decoding unit 105 can obtain information on the current intra-block coefficient group from the bitstream. Here, the information on the coefficient group may be flag information indicating whether or not the coefficient group includes at least one effective transform coefficient (or whether or not the coefficient group includes only a transform coefficient of zero). The flag information may be referred to as significant coefficient group flag information. The entropy decoding unit 105 can scan information on the current coefficient group intra-coefficient transform coefficients based on the information on the current coefficient group obtained from the bit stream. For example, if the information on the coefficient group indicates that the coefficient group does not contain at least one effective transform coefficient, the entropy decoding unit 105 sets the value of the transform coefficient in the coefficient group without scanning the information about the transform coefficient 0 < / RTI > If the information on the coefficient group indicates that the coefficient group includes at least one effective transform coefficient, the entropy decoding unit 105 scans information on the transform coefficient according to a predetermined scan order to acquire a transform coefficient in the coefficient group .

At this time, the entropy decoding unit 105 can determine one coefficient group for every predetermined K number of transform coefficients included in the scan region (K is an integer) scanned according to a predetermined scan order. That is, one coefficient group may include K transform coefficients. In this case, the scan order may be a forward scan order that is the opposite direction of the predetermined reverse scan order.

Accordingly, the entropy decoding unit 105 can determine a coefficient group by scanning in a forward scan order from a DC coefficient that is a coefficient adjacent to the upper left corner in the current block. If the number of transform coefficients included in the current block is not an integral multiple of K, the last coefficient group among the groups of coefficients scanned according to the forward scan order may include a smaller number of transform coefficients.

However, the present invention is not limited to this, and the entropy decoding unit 105 may perform a reverse scan order in which the coefficients located at the lower right end among the transform coefficients included in the current block are scanned up to a coefficient located at the upper left of the transform coefficients included in the current block It will be readily appreciated by those skilled in the art that scanning may be performed in accordance with the present invention to determine a coefficient group.

Those skilled in the art can easily understand that the entropy decoding unit 105 can determine a coefficient group according to a predetermined scanning order without acquiring information on the current intra-block coefficient group from the bitstream. The reason for determining the coefficient group is to perform an operation (such as sign data hiding) for the entropy decoding unit 105 to process according to the coefficient group. If one of the groups of coefficients scanned according to a predetermined scan order includes only one transform coefficient, the entropy decoding unit 105 does not acquire information on the corresponding coefficient group from the bitstream, Information can be obtained from the bitstream.

The entropy decoding unit 105 can determine whether to hide the sign of at least one transform coefficient for each coefficient group included in the current block. For example, the entropy decoding unit may decide to hide the sign of one or two transform coefficients for each coefficient group included in the current block, as the case may be.

The entropy decoding unit 105 may scan the information on the transform coefficients in the quadrangular scan area according to a predetermined scan order. The predetermined scan order may include a reverse zigzag scan order, a reverse diagonal scan order, a reverse vertical scan order, and a horizontal scan order. However, those skilled in the art will readily understand that the predetermined scan order is not limited to the above-mentioned reverse scan order and may include various reverse scan orders.

The entropy decoding unit 105 can obtain the transform coefficients of the current block based on the information about the scanned transform coefficients.

The image restoring unit 120 may generate a residual block of the current block by performing inverse quantization and inverse transformation on the transform coefficients of the current block.

The image restoring unit 120 may restore the current block based on the residual block of the current block.

The image restoring unit 120 may perform inter-prediction or intra-prediction on the current block to generate a prediction block of the current block. The image restoring unit 120 may restore the current block based on the prediction block of the current block and the residual block of the current block. That is, the image restoring unit 120 may restore the values of the pixels included in the current block by adding the values of the pixels included in the prediction block and the values of the pixels included in the residual block.

The entropy decoding unit 105 can perform binary arithmetic decoding based on the context model on the information on the coordinates specifying the quadrangular scan area. The entropy decoding unit 105 can perform inverse binarization using the inverse binarization method on the binary arithmetic decoded information to obtain inverse binarization information related to the coordinates specifying the quadrangular scan area, Coordinates to specify a rectangular scan area can be obtained based on the information. At this time, the context model may be determined based on at least one of the size of the current block, the color component of the current block, and the empty index. The color component may include a luminance component and a chrominance component. The empty index may be information indicating the position of the bin that is currently binary arithmetic decoded among the bin strings related to the syntax element. Here, the predetermined inverse binarization method may be at least one of a fixed length inverse binarization method and a cutting type unary inverse binarization method.

The entropy decoding unit 105 may perform at least one of binary arithmetic decoding and inverse binarization based on the context model for the effective transform coefficients based on the information about the scanned effective transform coefficients to obtain transform coefficients of the current block have. If the information on the effective transform coefficients is information indicating whether the absolute value of the current effective transform coefficient is greater than a predetermined value, the residual level information, and the sign information of the current effective transform coefficient, the entropy decoding unit 105 performs the effective transform Binary arithmetic decoding based on the context model can be performed on the information about the coefficients. The entropy decoding unit 105 may perform inverse binarization on the binary arithmetic decoding decoded information on the effective transform coefficients to obtain a transform coefficient of the current block. Wherein the first information on the effective transform coefficients is information indicating whether the information on the effective transform coefficients is larger than the absolute value of the current effective transform coefficient and the residual level information and the sign information of the current effective transform coefficient, When the second information on the coefficients is binarization parameter information, the entropy decoding unit 105 can perform binary arithmetic decoding based on the context model on the first information on the effective transform coefficients. The entropy decoding unit 105 may perform inverse binarization based on the binary parameter information included in the second information with respect to the first information subjected to the binary arithmetic decoding so as to obtain the transform coefficient of the current block. The context model related to the first transform coefficient among the context models related to the flag information of the transform coefficients may be previously scanned according to a predetermined scan order Based on at least one of information about at least one second transform coefficient, position and color components of the first transform coefficient in the current block, information about the right or lower peripheral transform coefficient, and the scan position of the first transform coefficient have.

The context model relating to the flag information indicating whether the first conversion coefficient is larger than 0 can be determined based on the number of the right and lower effective conversion coefficients whose absolute values are larger than zero.

The context model for flag information indicating whether the first transform coefficient is greater than 0 is not limited to this, and the absolute value of n (n is a positive integer) transform coefficients previously scanned according to a predetermined scan order is greater than 0 Can be determined based on the number of large effective conversion coefficients.

Alternatively, the flag information (hereinafter referred to as GT0 flag information) indicating whether the first conversion coefficient is greater than 0 may include GT0 flag information of n (n is a positive integer) conversion coefficients previously scanned according to a predetermined scan order, The GT0 flag information of the position of the first transform coefficient in the block, the color component and the adjacent right or lower n (n is a positive integer) transform coefficients, whether the first transform coefficient is the transform coefficient of the first position in the scan area, And whether or not the first transform coefficient is a transform coefficient of the final position in the scan area.

The context model relating to the flag information indicating whether the first transform coefficient is larger than 1 can be determined based on the number of the right and lower effective transform coefficients whose absolute values are larger than 1.

The context model of the flag information indicating whether the first transform coefficient is greater than 1 is not limited to this, and the absolute value of n (n is a positive integer) transform coefficients previously scanned according to a predetermined scan order is larger than 1 Can be determined based on the number of large effective conversion coefficients.

Alternatively, the flag information (hereinafter referred to as GT1 flag information) indicating whether the first conversion coefficient is greater than 1 is obtained by adding GT1 flag information of n (n is a positive integer) conversion coefficients previously scanned according to a predetermined scan order, The GT1 flag information of the position of the first transform coefficient in the block, the color component, and the adjacent right or lower n (n is a positive integer) transform coefficients, whether the first transform coefficient is the transform coefficient of the first position in the scan area, And whether or not the first transform coefficient is a transform coefficient of the final position in the scan area.

The context model relating to the flag information indicating whether the first conversion coefficient is larger than 2 can be determined based on the number of the right and lower effective conversion coefficients whose absolute values are larger than 2. 2 At this time, the context model relating to the flag information indicating whether the first conversion coefficient is larger than 2 is not limited to the second, and the context model of the n (n is a positive integer) Can be determined based on the number of effective transform coefficients whose absolute values are greater than two.

Alternatively, flag information (hereinafter, referred to as GT2 flag information) indicating whether the first conversion coefficient is greater than 2 may be obtained by adding GT1 flag information of n (n is a positive integer) conversion coefficients previously scanned according to a predetermined scan order, The GT1 flag information of the position of the first transform coefficient in the block, the color component, and the adjacent right or lower n (n is a positive integer) transform coefficients, whether the first transform coefficient is the transform coefficient of the first position in the scan area, And whether or not the first transform coefficient is a transform coefficient of the final position in the scan area.

Alternatively, flag information (hereinafter referred to as GTm flag information) indicating whether the first transform coefficient is larger than m (m is an integer larger than 2) is n (n is a positive integer) scanned previously according to a predetermined scan order The GTm flag information of the transform coefficients, the position of the first transform coefficient in the current block, the chrominance component, and the GTm flag information of the adjacent right or lower n (n is a positive integer) transform coefficients, Whether the first transform coefficient is the transform coefficient of the first position, and whether the first transform coefficient is the transform coefficient of the final position in the scan area.

On the other hand, the binarization parameter information on the absolute value of the residual level of the first transform coefficient may be determined based on the absolute level of the level of the peripheral effective transform coefficients on the right side and the lower side of the first transform coefficient.

For example, the binarization parameter information on the absolute value of the residual level of the first transform coefficient may be determined based on the sum of the absolute levels of the levels of the right and lower peripheral effective transform coefficients of the first transform coefficient.

The context model for flag information indicating whether the first transform coefficient is greater than 2 is not limited to this, and the absolute value of n (n is a positive integer) transform coefficients previously scanned according to a predetermined scan order is greater than 2 Can be determined based on the number of large effective conversion coefficients.

The context model relating to the flag information indicating whether the first transform coefficient is larger than 1 can be determined based on the number of the right and lower effective transform coefficients whose absolute values are larger than 1.

The context model relating to the flag information indicating whether the first conversion coefficient is larger than 2 can be determined based on the number of the right and lower effective conversion coefficients whose absolute values are larger than 2.

On the other hand, the binarization parameter information on the absolute value of the residual level of the first transform coefficient may be determined based on the absolute level of the level of the peripheral effective transform coefficients on the right side and the lower side of the first transform coefficient. For example, the binarization parameter information on the absolute value of the residual level of the first transform coefficient may be determined based on the sum of the absolute levels of the levels of the right and lower peripheral effective transform coefficients of the first transform coefficient.

The binarization parameter information on the absolute value of the residual level of the first transform coefficient is obtained by dividing the level of the previously-scanned n (n is an integer) transform coefficients according to a predetermined scan order, the position of the first transform coefficient in the current block, (N is a positive integer) number of adjacent right or lower n-th transform coefficients, whether the first transform coefficient in the scan order is the transform coefficient of the first position in the scan region, whether the first transform coefficient is in the scan region Whether it is a transform coefficient of the final position, whether or not the first transform coefficient in the scan order is a coefficient of the first position in the coefficient group, and the like.

The entropy decoding unit 105 determines whether or not the position of the transform coefficient currently scanned in the scan region is [SRx, 0] (where SRx is an integer and SRx is the horizontal coordinate value of the right boundary pixel of the scan region on the basis of the left upper- (Y is an integer greater than 0 and less than or equal to SRy, and SRy represents a lower boundary of the scan region with respect to the upper left corner coordinate of the scan region in accordance with a predetermined scan order) The GT0 flag information of the transform coefficient currently scanned from the bit stream is not acquired and the value of the GT0 flag information can be determined to be 1. [

Likewise, the entropy decoding unit 105 determines that the position of the transform coefficient currently scanned in the scan region is [0, SRy] (where SRy is an integer and SRy is the vertical coordinate of the lower boundary of the scan region on the basis of the upper left corner coordinate of the scan region) (X, SRy) (where X is an integer greater than 0 and less than or equal to SRx, SRx is an integer equal to or greater than 0, The GT0 flag information of the currently scanned transform coefficient is not obtained from the bit stream and the value of the GT0 flag information can be determined to be 1 .

On the other hand, the entropy decoding unit 105 can determine the maximum number of GT1 flag information of the current effective conversion coefficient in the block, and receive the GT1 flag information in the current block from the bit stream within the maximum coefficient of the determined effective conversion coefficient . That is, when the entropy decoding unit 105 receives the maximum number of GT1 flag information of the effective conversion coefficient received from the bitstream, the entropy decoding unit 105 determines whether the GT1 flag information of the effective conversion coefficient exists from the bitstream I can not check it anymore.

The entropy decoding unit 105 can determine all non-zero effective conversion coefficients as the maximum number of GT1 flag information in the current block. Or the entropy decoding unit 105 can determine the maximum number of GT1 flag information in the current block based on the size of the scan area. For example, the entropy decoding unit 105 can determine the maximum number MaxCount_GT1 of the GT1 flag information based on Equation (9) below.

In this case, sizeSR may mean the size (width) of the square scan area, and sizeSR may be (Sr_x + 1) * (Sr_y + 1). Sr_x can be the horizontal coordinate of the rightmost effective transformation coefficient pixel based on the upper left corner coordinate of the scan area. In other words, Sr_x can mean the horizontal coordinate of the right boundary pixel based on the upper left corner coordinate of the scan area. Sr_y may mean the vertical coordinate of the lowest effective conversion factor pixel based on the upper left corner coordinate of the scan area. In other words, Sr_y may mean the vertical coordinate of the lower boundary pixel based on the upper left corner coordinate of the scan area. K1 can be the magnitude of the scan area and the adjustment factor between the GT1 flags. For example, it may be an integer greater than one. Th1 may be a predetermined threshold value. For example, Th1 may be 16,8. Those skilled in the art can easily understand that K1 and Th1 can have various values, without being limited thereto.

The entropy decoding unit 105 may determine the maximum number of GT2 flag information in the current block and receive GT2 flag information in the current block from the bit stream within the maximum coefficient of the determined effective transform coefficient. That is, when the entropy decoding unit 105 receives the maximum number of GT2 flag information of the effective conversion coefficient received from the bitstream, the entropy decoding unit 105 determines whether the GT2 flag information of the effective conversion coefficient exists from the bitstream I can not check it anymore.

The entropy decoding unit 105 can determine all non-zero effective conversion coefficients as the maximum number of GT2 flag information in the current block. Or the entropy decoding unit 105 can determine the maximum number of GT2 flag information in the current block based on the size of the scan area. For example, the entropy decoding unit 105 can determine the maximum number MaxCount_GT2 of the GT2 flag information based on the following expression (10).

In this case, sizeSR may mean the size (width) of the square scan area, and sizeSR may be (Sr_x + 1) * (Sr_y + 1). Sr_x can be the horizontal coordinate of the rightmost effective transformation coefficient pixel based on the upper left corner coordinate of the scan area. In other words, Sr_x can mean the horizontal coordinate of the right boundary pixel based on the upper left corner coordinate of the scan area. Sr_y may mean the vertical coordinate of the lowest effective conversion factor pixel based on the upper left corner coordinate of the scan area. In other words, Sr_y may mean the vertical coordinate of the lower boundary pixel based on the upper left corner coordinate of the scan area. K2 can be an adjustment factor. For example, it may be an integer greater than one. K2 may be a predetermined threshold value. For example, Th2 may be 16,8. Those skilled in the art can easily understand that K2 and Th2 can have various values, without being limited thereto.

The entropy decoding unit 105 can obtain information on the current intra-block coefficient group from the bitstream. The information on the coefficient group may be flag information indicating whether the coefficient group includes at least one effective transform coefficient. At this time, the entropy decoding unit 105 may determine one coefficient group for every predetermined K number of transform coefficients included in the scan region (K is an integer) scanned according to the scan order. That is, one coefficient group may include K transform coefficients. In this case, the scan order may be a forward scan order that is the opposite direction of the predetermined reverse scan order. The predetermined backward scan order referred to herein may mean a scan order from a coefficient located at the lower right of the transform coefficients included in the current block to a coefficient located at the upper left of the transform coefficients included in the current block.

Accordingly, the entropy decoding unit 105 can determine a coefficient group by scanning in a forward scan order from a DC coefficient that is a coefficient adjacent to the upper left corner in the current block. If the number of transform coefficients included in the current block is not an integral multiple of K, the last coefficient group among the groups of coefficients scanned according to the forward scan order may include a smaller number of transform coefficients. However, the present invention is not limited to this, and the entropy decoding unit 105 may perform a reverse scan order in which the coefficients located at the lower right end among the transform coefficients included in the current block are scanned up to a coefficient located at the upper left of the transform coefficients included in the current block It will be readily appreciated by those skilled in the art that scanning may be performed in accordance with the present invention to determine a coefficient group.

The entropy decoding unit 105 does not acquire the information on the coefficient group from the bitstream and outputs only the GT0 flag information if the last coefficient group among the groups of coefficients scanned according to a predetermined scanning order includes only one transform coefficient Can be obtained from the bitstream.

The entropy decoding unit 105 can determine whether to hide the sign of at least one transform coefficient for each coefficient group included in the current block. For example, the entropy decoding unit may decide to hide the sign of one or two transform coefficients for each coefficient group included in the current block, as the case may be.

The entropy decoding unit 105 may scan the information on the effective transformation coefficients in the quadrangular scan area according to a predetermined scan order. The predetermined scan order may include a reverse zigzag scan order, a reverse diagonal scan order, a reverse vertical scan order, and a horizontal scan order. However, those skilled in the art will readily understand that the predetermined scan order is not limited to the above-mentioned reverse scan order and may include various reverse scan orders.

The entropy decoding unit 105 can obtain the transform coefficients of the current block based on the information about the scanned effective transform coefficients.

The image restoring unit 120 may generate a residual block of the current block by performing inverse quantization and inverse transformation on the transform coefficients of the current block.

The image restoring unit 120 may restore the current block based on the residual block of the current block.

The image restoring unit 120 may perform inter-prediction or intra-prediction on the current block to generate a prediction block of the current block. The image restoring unit 120 may restore the current block based on the prediction block of the current block and the residual block of the current block. That is, the image restoring unit 120 may restore the values of the pixels included in the current block by adding the values of the pixels included in the prediction block and the values of the pixels included in the residual block. The optical flow will be described later with reference to FIG. 3A.

The video decoding apparatus 100 may include an image decoding unit (not shown), and the image decoding unit (not shown) may include an entropy decoding unit 105 and an image restoring unit 120. The video decoding unit will be described with reference to FIG. 1E. FIG. 1B shows a flowchart of a video decoding method according to various embodiments.

In step S105, the video decoding apparatus 100 can determine a scan area including all the effective transform coefficients in the current block. At this time, when the scan area is scanned according to a predetermined forward scan order from the upper left corner of the scan area, the scan area includes the transform coefficients up to the last effective scan transform coefficient . ≪ / RTI > At this time, the coordinates specifying the scan area may be the coordinates of the effective scan conversion pixel to be scanned last. The video decoding apparatus 100 may obtain information on the coordinate indicating the last effective transform coefficient from the bit stream and determine the scan area based on the information on the coordinate indicating the obtained last effective transform coefficient.

Alternatively, the scan area may be a rectangular scan area, the rectangular scan area may include horizontal coordinate of the effective conversion coefficient pixel positioned at the rightmost of all the effective conversion coefficients in the current block, and effective conversion coefficient pixel located at the lowermost position in the current block And may be an area specified by the vertical direction coordinates of the pixel. The video decoding apparatus 100 may obtain information on the coordinates specifying the quadrangular scan area from the bitstream and determine the quadrangular scan area based on the information on the coordinates specifying the obtained quadrangle scan area.

In step S110, the video decoding apparatus 100 may scan the information on the intra-scan conversion coefficients in a predetermined scanning order. The predetermined scan order may include a reverse zigzag scan order or a reverse diagonal scan order. The zigzag scan order may include a vertical priority zigzag scan order or a horizontal priority zigzag scan order. In step S115, the video decoding apparatus 100 performs binary arithmetic decoding based on information on the scanned transform coefficients, It is possible to generate arithmetically decoded information. At this time, the video decoding apparatus 100 may perform binary arithmetic decoding using the context model determined based on at least one of the size and shape of the current block.

In step S120, the video decoding apparatus 100 scans the information about the transform coefficients included in the scan area according to a predetermined scan order, performs inverse binarization on the binary arithmetic decoded information, Can be obtained.

In step S125, the video decoding apparatus 100 may generate a residual block of the current block by performing inverse quantization and inverse transform based on the information on the transform coefficients of the current block. That is, the video decoding apparatus 100 obtains the transform coefficients of the current block based on the information on the transform coefficients of the current block, performs inverse quantization and inverse transform on the transform coefficients of the current block, Can be generated.

In step S130, the video decoding apparatus 100 may restore the current block based on the residual block. The video decoding apparatus 100 performs inter prediction or intra prediction to generate a prediction block of a current block. The video decoding apparatus 100 adds the pixel values of the residual blocks to the pixel values included in the prediction blocks of the current block The pixel value of the reconstruction block of the current block can be generated.

1C shows a block diagram of a video encoding apparatus according to various embodiments.

The video encoding apparatus 150 according to various embodiments includes an entropy encoding unit 155 and a bitstream generation unit 170.

The entropy encoding unit 155 can perform entropy encoding on the syntax element related to the intra-block transformation coefficient. The entropy encoding unit 155 scans the two-dimensional array information about the current intra-block transform coefficients according to a predetermined scan order to generate one-dimensional array information about the current intra-block transform coefficients, Can be entropy-encoded with respect to the one-dimensional array information about the one-dimensional array information.

The syntax element related to the conversion coefficient may be a flag indicating whether the conversion coefficient is larger than a predetermined value. At this time, the predetermined value may be a value equal to or greater than zero. For example, 0, 1 or 2. It may also be a syntax element indicating the absolute level of the remaining level with respect to the transform coefficients. That is, the absolute value of the remaining level may indicate an absolute value difference between a predetermined absolute value determined based on whether the absolute value of the conversion coefficient is larger than a predetermined value. The syntax element related to the effective conversion coefficient may be a syntax element related to the sign of the effective conversion coefficient.

First, the entropy encoding unit 155 may perform binarization on the syntax element to generate an empty string, and perform binary arithmetic encoding on the empty string to generate entropy-encoded information for the syntax element. At this time, the binarization may be performed in the binarization unit 160, and the binary arithmetic encoding may be performed in the binary arithmetic encoding unit 165.

The binarization unit 160 may perform binarization on a predetermined syntax element to generate an empty string. The binarization unit 160 may perform binarization on a predetermined syntax element based on a predetermined binarization method. The predetermined binarization method may include a fixed length binarization method, a Rice binarization method, an exponential Golomb binarization method, and a Golomb-Rice binarization method. Or the predetermined binarization method may be a binarization method in which the first binarization method and the second binarization method are combined. For example, the binarization unit 160 may binarize a portion of a syntax element based on a first binarization method to generate a first bin string, and for another portion of the syntax element, a second binarization method To generate a second bin string. ≪ RTI ID = 0.0 > Here, the first empty string may be part of the empty string of the syntax element, and the second empty string may be another part of the empty string of the syntax element. A portion of the empty string may be a prefix or a suffix.

The binary arithmetic coding unit 165 may perform binary arithmetic coding based on a predetermined context model for an empty string regarding a predetermined syntax element. Alternatively, the binary arithmetic coding unit 165 may perform binary arithmetic coding on a bin string relating to a predetermined syntax element without a predetermined context model. At this time, the probability of 0 or 1 for the current binary arithmetic coding bin is fixed to 0, and binary arithmetic coding can be performed based on this probability.

The entropy encoding unit 155 can obtain the transform coefficients of the current block. That is, the video encoding apparatus 150 can generate a prediction block of the current block by performing inter prediction or intra prediction, and generates a residual block of the current block based on the original block of the current block and the prediction block of the current block can do. The video encoding apparatus 150 may convert and quantize the residual block of the current block to generate a transform coefficient of the current block. The entropy encoding unit 155 may obtain the transform coefficients of the generated current block.

The entropy encoding unit 155 determines information on the transform coefficients of the current block, generates information about the transform coefficients of the current block in accordance with a predetermined scan order, generates one-dimensional array information on the transform coefficients of the current block , And entropy encoding can be performed on the one-dimensional array information. The predetermined scan order may be a sequence according to an inverse zigzag scan or an order according to an inverse diagonal scan. But the present invention is not limited thereto, and may be various scanning sequences such as a sequence according to reverse horizontal scanning and a scanning sequence according to reverse vertical scanning. The predetermined scan order may be determined based on at least one of the horizontal coordinate of the effective conversion coefficient pixel located at the rightmost position in the current block and the vertical direction of the effective conversion coefficient pixel located at the bottommost position in the current block. The entropy encoding unit 155 can determine a predetermined scan order based on the size of the horizontal direction coordinate value and the size of the vertical direction coordinate value. For example, if the horizontal direction coordinate value is larger than the vertical direction coordinate value, the entropy encoding unit 155 can determine the reverse vertical scanning order in a predetermined scanning order. The entropy encoding unit 155 may determine the horizontal scan order in the reverse direction as a predetermined scan order when the vertical direction coordinate value is larger than the horizontal direction coordinate value.

Alternatively, the entropy encoding unit 155 may determine the reverse direction vertical priority zigzag scan order in a predetermined scan order when the horizontal direction coordinate value is larger than the vertical direction coordinate value. The entropy encoding unit 155 can determine the horizontal priority zigzag scan order in the reverse direction in a predetermined scan order when the vertical direction coordinate value is larger than the horizontal direction coordinate value. The entropy encoding unit 155 may determine one of the vertical first zigzag scan order and the horizontal priority zigzag scan order in the reverse direction in a predetermined scan order when the vertical direction coordinate value is equal to the horizontal direction coordinate value.

Alternatively, if the horizontal direction coordinate value is larger than the vertical direction coordinate value, the entropy encoding unit 155 can determine the reverse horizontal zigzag scanning order in a predetermined scanning order. The entropy encoding unit 155 may determine a horizontal first zigzag scan order in the reverse direction in a predetermined scan order when the horizontal direction coordinate value is not larger than the vertical direction coordinate value.

First, the entropy encoding unit 155 can determine a scan area including all the effective transform coefficients in the current block. At this time, the scan area includes all the effective conversion coefficients in the current block, and the remaining area in the current block excluding the scan area may include only the conversion coefficient having a value of 0, which is not an effective conversion coefficient. At this time, when the scan area is scanned according to a predetermined forward scan order from the upper left corner of the scan area, the scan area includes the transform coefficients up to the last effective scan transform coefficient . ≪ / RTI > At this time, the coordinates specifying the scan area may be the coordinates of the effective scan conversion pixel to be scanned last.

The entropy encoding unit 155 can generate information on the coordinates indicating the last effective transformation coefficient. For example, the entropy decoding unit 105 may generate syntax element information indicating a coordinate value in the horizontal direction of the last valid conversion coefficient and syntax element information indicating a vertical coordinate value of the last valid conversion coefficient. In this case, The encoding unit 155 binarizes the syntax element indicating the coordinate value in the horizontal direction of the last effective transformation coefficient and the syntax element indicating the vertical coordinate value of the last effective transformation coefficient to generate an empty string, Decoding can be performed to generate syntax element information indicating horizontal coordinate values of the last valid conversion coefficient and syntax element information indicating vertical coordinate values of the last valid conversion coefficient.

The entropy encoding unit 155 generates a first bin string by performing a first binarization method on some first values of the syntax element values and performs a second binarization method on a second part of the syntax element values 2 You can create an empty string. A first empty string, and a second empty string. In this case, the first bin string may be a prefix, and the first binarization method may be a fixed-length binarization method. The second bin string may be a suffix and the second inverse binning method may be a cutting type unary binarization method.

Alternatively, the entropy encoding unit 155 may obtain information indicating a coordinate value of one of the horizontal coordinate value of the last effective conversion coefficient pixel or the vertical coordinate value of the last effective conversion coefficient pixel among all the effective conversion coefficients in the current block, and Information indicating a difference between the coordinate value in the one direction and the coordinate value in the remaining direction can be generated.

Alternatively, the scan region may be a quadrangle scan region, the quadrangle scan region may include a horizontal direction coordinate of an effective conversion coefficient pixel located at the rightmost of all effective conversion coefficients in the current block, and an effective conversion coefficient And may be an area specified by the vertical coordinate of the pixel.

The entropy encoding unit 155 can generate syntax element information about coordinates specifying a quadrangular scan area. For example, the entropy encoding unit 155 encodes the syntax element information indicating the horizontal coordinate value of the effective conversion coefficient pixel located at the rightmost of all the effective conversion coefficients in the current block, It is possible to generate the syntax element information indicating the vertical coordinate value of the effective conversion coefficient pixel located on the lower side. At this time, the entropy encoding unit 155 encodes the syntax element indicating the horizontal direction coordinate value of the effective transformation coefficient pixel located at the rightmost among all the effective transformation coefficients in the current block, The binary element arithmetic decoding unit performs binary arithmetic decoding on the empty string to generate syntax element information indicating the coordinate value in the horizontal direction of the last effective transformation coefficient, It is possible to generate syntax element information indicating the vertical coordinate value of the last effective transformation coefficient.

The entropy encoding unit 155 generates a first bin string by performing a first binarization method on some first values of the syntax element values and performs a second binarization method on a second part of the syntax element values 2 You can create an empty string. A first empty string, and a second empty string. In this case, the first bin string may be a prefix, and the first binarization method may be a fixed-length binarization method. The second bin string may be a suffix and the second inverse binning method may be a cutting type unary binarization method.

Alternatively, the entropy coding unit 155 may calculate the horizontal coordinate value of the effective transformation coefficient pixel located at the rightmost of all the effective transformation coefficients in the current block, or the effective transformation coefficient located at the lowermost position among all the effective transformation coefficients in the current block Information indicating a coordinate value of one of the vertical coordinate values of the pixel and information indicating a difference between the coordinate value of the one direction and the coordinate value of the remaining direction. The entropy encoding unit 155 can determine the one direction based on the height and width of the current block.

The entropy encoding unit 155 can generate flag information indicating whether to acquire information indicating a difference between a coordinate value in one direction and a coordinate value in the remaining direction.

On the other hand, the entropy encoding unit 155 can determine whether to generate flag information indicating whether to acquire information indicating a difference between a coordinate value in one direction and a coordinate value in the other direction based on the width and height of the current block have. For example, the entropy encoding unit 155 determines whether information indicating a difference between a coordinate value in one direction and a coordinate value in the remaining direction is obtained when the width and height of the current block are different (i.e., when the width is a rectangle) , And generates flag information.

The entropy encoding unit 155 may determine the context model used for binary arithmetic coding of all syntax elements used for coefficient encoding based on at least one of the size of the current block and the shape of the current block . For example, the size of the current block may be determined according to at least one of a minimum value and a maximum value of the height and width of the current block. The shape of the current block can be determined depending on whether or not the width and height of the current block are the same. All of the syntax elements used for the gain encoding may include a syntax element for specifying a scan area and a syntax element for a transformation coefficient in the scan area.

For example, the entropy encoding unit 155 can determine information size_tu1 on the size of the current block based on Equation (11) below.

The entropy encoding unit 155 determines the context model corresponding to the information size_tu1 on the size of the current block, determines the context model for the syntax element used in the coefficient encoding, and uses the context model to calculate the syntax Element can be binary arithmetic-coded.

Alternatively, the entropy encoding unit 155 may determine information size_tu2 on the size of the current block based on Equation (12).

The entropy encoding unit 155 determines the context model based on the information size_tu2 about the size of the current block, determines the context model for the syntax element used in the coefficient encoding, and uses the context model to calculate the syntax Element can be binary arithmetic-coded.

Alternatively, the entropy encoding unit 155 may determine the context model based on the information size_tu1 and size_tu2 about the size of the current block, determine the context model for the syntax element used for the coefficient encoding, and perform the coefficient encoding Can be binary arithmetic-coded.

The entropy encoding unit 155 determines what is the minimum value and the maximum value of the size and height of the current block, determines the context model based on the minimum and maximum values of the size and height of the current block, The context model for the syntax element used in the context model can be determined, and the syntax element used in the coefficient encoding can be binary arithmetic-coded using the context model.

On the other hand, the entropy encoding unit 155 can determine the context model used for the binary arithmetic coding of all the syntax elements used for coefficient encoding, based on the shape of the current block.

For example, the entropy encoding unit 155 may determine information shape_tu about the shape of the current block based on Equation (13) below.

 According to Equation (13), the entropy encoding unit 155 determines shape_tu to be 2 when the width width of the current block is greater than the height height, and determines shape_tu to be 1 when the width width of the current block is smaller than the height height And shape_tu can be set to 0 if width width of the current block is equal to height height. That is, for a rectangle with a width greater than the height, shape_tu is determined to be 2. For a rectangle whose height is greater than the width, shape_tu may be determined to be 1, and for a square, shape_tu may be determined to be 0.

The entropy encoding unit 155 determines the context model based on the information shape_tu about the size of the current block, determines the context model for the syntax element used for coefficient encoding, and uses the context model to calculate the syntax Element can be binary arithmetic-coded.

The entropy encoding unit 155 can determine the context model for the syntax element used for coefficient encoding based on the size of the current block and the shape of the current block. For example, the entropy decoding unit 155 determines a context model for a syntax element used for coefficient encoding based on at least one of information size_tu1 and size_tu2 about the size of the current block and information shape_tu about the shape of the current block , The context model can be used to perform binary arithmetic coding on syntax elements used for coefficient encoding.

The entropy encoding unit 155 may change the height and the width of the current block when either the height or width of the current block is different from the height or width of the current block. That is, the horizontal direction coordinates and the vertical direction coordinates of the pixels included in the current block can be swapped with each other. For example, if the width of the current block is greater than the height, the entropy encoding unit 155 may change the height and width of the current block. That is, the horizontal and vertical coordinate values of the pixels included in the current block can be swapped with each other. If the width of the current block is not greater than the height, the entropy encoding unit 155 may not swap horizontal and vertical coordinates of the pixels included in the current block with each other. Without being limited thereto, the entropy encoding unit 155 may change the height and the width of the current block if the height of the current block is larger than the width. That is, the horizontal and vertical coordinate values of the pixels included in the current block can be swapped with each other. When the horizontal coordinate and the vertical coordinate of the pixels included in the current block are swapped with each other, the entropy coding unit 155 sets the horizontal coordinate and the vertical coordinate specifying the current block scanning area as a scan area The coordinates of the horizontal direction coordinate and the vertical direction coordinate can be swapped with each other. The entropy encoding unit 155 may determine the first scan area in the current block that has been swapped based on the coordinates specifying the swapped scan area. The entropy encoding unit 155 scans the information about the transform coefficients included in the first scan region and performs entropy encoding on the information about the scanned transform coefficients. And information on the coordinates specifying the quadrangular scan area can be entropy-encoded. That is, the entropy encoding unit 155 may generate a bin string by performing a binarization based on a predetermined binarization method on a syntax element related to a coordinate specifying a quadrangular scan area. Here, the predetermined binarization method may be at least one of a fixed length binarization method and a cutting type unary binarization method.

The entropy encoding unit 155 can perform binary arithmetic coding based on the context model on the bin string regarding the syntax element related to the coordinates specifying the quadrangular scan area. At this time, the context model may be determined based on at least one of the size of the current block, the color component of the current block, and the empty index. The color component may include a luminance component and a chrominance component. The empty index may be information indicating the position of the bin that is currently binary arithmetic-coded among the bin strings related to the syntax element.

The entropy encoding unit 155 may generate at least one of binarization based on information on the scanned transform coefficients and binary arithmetic encoding based on the context model of the transform coefficients to generate entropy-encoded information.

The first information on the transform coefficients is information indicating whether the absolute value of the current transform coefficient is larger than a predetermined value, the residual level absolute value information and the sign information of the current transform coefficient, and the second information on the transform coefficients is the residual level In the case of the absolute value of the binarization parameter information, the entropy encoding unit 155 may binarize the first information on the transform coefficients based on the second information to generate a bin string for the first information have. The entropy encoding unit 155 may perform binary arithmetic encoding on a bin string related to the first information to generate entropy-encoded information.

The second information includes information on at least one second transform coefficient previously scanned in accordance with a predetermined scan order, information on the position, color component, right or lower peripheral transformation coefficient of the first transform coefficient in the current block, 1 < / RTI > conversion coefficient. For example, the binarization parameter information on the absolute value of the residual level of the first transform coefficient may be determined based on the absolute level of the level of the peripheral effective transform coefficient on the right side or the lower side of the first transform coefficient. The binarization parameter information on the absolute value of the residual level of the first transform coefficient may be determined based on the sum of the absolute levels of the levels of the peripheral effective transform coefficients on the right side or the lower side of the first transform coefficient.

Alternatively, the binarization parameter information on the absolute value of the residual level of the first transform coefficient may be obtained from the level of n (n is an integer) transform coefficients previously scanned according to a predetermined scan order, the position of the first transform coefficient in the current block, (N is a positive integer) number of adjacent right or lower n-th conversion coefficients, whether the first conversion coefficient in the scan order is a conversion coefficient of the first position in the scan area, Whether the first transform coefficient in the scan order is a coefficient of the first position in the coefficient group, whether the transform coefficient is the last position in the area, whether the transform coefficient is the last position in the area, and whether the first transform coefficient in the scan order is a coefficient of the first position in the coefficient group.

If the information on the transform coefficients is information indicating whether the absolute value of the current transform coefficient is larger than a predetermined value, the residual level absolute value information, and the sign information of the current transform coefficient, the entropy coding unit 155 calculates You can perform binarization on the information to create an empty string. The entropy encoding unit 155 may perform binary arithmetic coding based on the context model on the bin strings to generate binary arithmetic coded information. The context model of the first transform coefficient among the context models related to the transform coefficients includes information on at least one second transform coefficient previously scanned in accordance with a predetermined scan order, position of the first transform coefficient in the current block, Information about the right or lower peripheral transformation coefficient, and the scan position of the first transformation coefficient.

The context model relating to the flag information indicating whether the first conversion coefficient is larger than 0 can be determined based on the number of the right or lower effective conversion coefficients whose absolute values are larger than zero.

The entropy encoding unit 155 can determine the context model related to the flag information indicating whether the first transform coefficient is greater than 0 based on the position of the first transform coefficient in the current block. For example, when the sum of the horizontal coordinate value pos_x of the first transform coefficient in the current block and the vertical position pos_y in the current block is smaller than the predetermined threshold value thred1, the entropy encoding unit 155 sets the context index to a predetermined value It is possible to increase the context offset by the context offset, and determine the context model based on the increased context index. If the sum of the horizontal direction coordinate value pos_x of the first transform coefficient in the current block and the vertical direction position pos_y in the current block is smaller than the predetermined threshold value thred2, the entropy encoding unit 155 sets the context index to the predetermined context offset offset2 And determine the context model based on the increased context index. If the sum of the horizontal coordinate value pos_x of the first transform coefficient in the current block and the vertical position pos_y in the current block is smaller than the predetermined threshold value thred3, the entropy coding unit 155 sets the context index to the predetermined context offset offset3 And determine the context model based on the increased context index.

The entropy encoding unit 155 calculates the number of transform coefficients that have already been scanned in the scan region, the relative positions of the first transform coefficients in the scan region, and the relative positions of the first transform coefficients in the first position where the first transform coefficient is scanned according to a predetermined scan order And determining whether the first conversion coefficient is greater than 0 based on at least one of the presence or absence of the coefficient.

For example, the entropy encoding unit 155 can determine the size size_sr of the quadrangular scan area on the basis of the following expression (14). That is, the size size_sr of the quadrangular scan region may mean the number of transform coefficients included in the quadrangular scan region.

However, the present invention is not limited to this, and when the scan area is a scan area specified by the coordinates of the last effective conversion factor pixel, the size_sr may indicate the number of conversion coefficients included in the scan area.

The entropy encoding unit 155 can determine the number cnt_pos of all the transform coefficients scanned before the first transform coefficient among the transform coefficients in the rectangular scan region. At this time, cnt_pos may indicate the position of the first transform coefficient among all the transform coefficients in the scan region scanned according to a predetermined scan order.

If the cnt_pos is smaller than the predetermined threshold value thred1, the entropy encoding unit 155 may increase the context index by a predetermined context offset, and determine the context model based on the increased context index. At this time, thred1 may be one. Or thred1 may be 1/4 * size_sr.

If the cnt_pos is smaller than the predetermined threshold value thred2, the entropy encoding unit 155 may increase the context index by a predetermined context offset offset2 and determine the context model based on the increased context index. In this case, thred2 may be 1/4 * size_sr. Or thred2 may be 1/2 * size_sr.

If the cnt_pos is not smaller than the predetermined threshold values thred1 and thred2, the entropy encoding unit 155 may increase the context index by a predetermined context offset offset3 and determine the context model based on the increased context index. However, the threshold values thred1 and thred2 are merely examples, and various values can be determined based on the size_sr.

The entropy encoding unit 155 can determine the context model related to the flag information indicating whether the first transform coefficient is larger than 0 based on the relative position of the first transform coefficients in the scan area.

The entropy encoding unit 155 determines whether or not the first transformation coefficient is greater than 0 based on the horizontal direction coordinate value pos_x and the vertical direction coordinate value pos_y of the first transform coefficient in the current block and the coordinates Sr_x and Sr_y specifying the rectangular scan region The context model relating to the flag information can be determined.

If the pos_x is smaller than thred1_x and the pos_y is smaller than thred1_y, the entropy encoding unit 155 may increase the context index by a predetermined context offset, and determine the context model based on the increased context index. At this time, [thred1_x, thred1_y] may be [1,1]. Alternatively, [thred1_x, thred1_y] may be [sr_x / 4, sr_y / 4] or [(sr_x + 1) / 4, (sr_y + 1) / 4].

If the pos_x is smaller than thred2_x and the pos_y is smaller than thred2_y, the entropy encoding unit 155 may increase the context index by a predetermined context offset offset2 and determine the context model based on the increased context index. At this time, [thred2_x, thred2_y] may be [srredx], [sr_x + 1) / 2, or [sr_y + 1) / 2.

However, the thresholds thred1_x, thred1_y, and thred2_y and thred2_y are merely examples, and those skilled in the art can easily understand that various values can be determined based on sr_x and sr_y.

The entropy encoding unit 155 can determine the context model related to the flag information indicating whether the first transform coefficient is greater than 0 or not based on whether the first transform coefficient is a transform coefficient of the first position scanned in the reverse scan order . That is, the entropy decoding unit 155 determines the first context model related to the flag information indicating whether the first transform coefficient is greater than 0 when the first transform coefficient is the first position scanned in the reverse scan order, 1 conversion coefficient is not the first position to be scanned in the reverse scan order, the second context model may be determined regarding the flag information indicating whether the first conversion coefficient is greater than zero. In this case, the transform coefficients of the pixels positioned at the lower right corner of the quadrangular scan region may be the transform coefficients of the first position scanned in the reverse scan order.

The context model for flag information indicating whether the first transform coefficient is greater than 0 is not limited to this, and the absolute value of n (n is a positive integer) transform coefficients previously scanned according to a predetermined scan order is greater than 0 Can be determined based on the number of large effective conversion coefficients.

The context model relating to the flag information indicating whether the first conversion coefficient is larger than 1 can be determined based on the number of the right or lower effective conversion coefficients whose absolute values are larger than 1.

The entropy encoding unit 155 can determine the context model related to the flag information indicating whether the first transform coefficient is larger than 1 based on the position of the first transform coefficient in the current block. For example, when the sum of the horizontal coordinate value pos_x of the first transform coefficient in the current block and the vertical position pos_y in the current block is smaller than the predetermined threshold value thred1, the entropy encoding unit 155 sets the context index to a predetermined value It is possible to increase the context offset by the context offset, and determine the context model based on the increased context index. If the sum of the horizontal direction coordinate value pos_x of the first transform coefficient in the current block and the vertical direction position pos_y in the current block is smaller than the predetermined threshold value thred2, the entropy encoding unit 155 sets the context index to the predetermined context offset offset2 And determine the context model based on the increased context index.

If the sum of the horizontal coordinate value pos_x of the first transform coefficient in the current block and the vertical position pos_y in the current block is smaller than the predetermined threshold value thred3, the entropy coding unit 155 sets the context index to the predetermined context offset offset3 And determine the context model based on the increased context index. At this time, the offsets offset1, 2, and 3 associated with the context model relating to the flag information indicating whether the first conversion coefficient is greater than 1 and predetermined thresholds thred1, 2, and 3 are flag information indicating whether the first conversion coefficient is greater than 0 The offsets offset 1, 2 and 3 associated with the context model with respect to the threshold values thred 1, 2, and 3 and their values may be different.

The entropy encoding unit 155 encodes the size of the scan area, the number of already scanned transform coefficients in the scan area, the relative position of the first transform coefficient in the scan area, and the first zero, And determining whether the first conversion coefficient is larger than 1 based on at least one of whether or not the conversion coefficient is a non-conversion coefficient at a position other than the first conversion coefficient.

For example, the entropy encoding unit 155 can determine the size size_sr of the quadrangular scan area on the basis of the following expression (15). That is, the size size_sr of the quadrangular scan region may mean the number of transform coefficients included in the quadrangular scan region.

The entropy encoding unit 155 can determine the number cnt_pos of all the transform coefficients scanned before the first transform coefficient among the transform coefficients in the rectangular scan region. At this time, cnt_pos may indicate the position of the first transform coefficient among all the transform coefficients in the scan region scanned according to a predetermined scan order. However, the present invention is not limited to this, and cnt_pos may be the number of transform coefficients larger than all zero scanned before scanning the first transform coefficient among the transform coefficients in the rectangular scan region.

If the cnt_pos is smaller than the predetermined threshold value thred1, the entropy encoding unit 155 may increase the context index by a predetermined context offset, and determine the context model based on the increased context index. At this time, thred1 may be one. Or thred1 may be 1/4 * size_sr.

If the cnt_pos is smaller than the predetermined threshold value thred2, the entropy encoding unit 155 may increase the context index by a predetermined context offset offset2 and determine the context model based on the increased context index. In this case, thred2 may be 1/4 * size_sr. Or thred2 may be 1/2 * size_sr.

If the cnt_pos is not smaller than the predetermined threshold values thred1 and thred2, the entropy encoding unit 155 may increase the context index by a predetermined context offset offset3 and determine the context model based on the increased context index.

However, the threshold values thred1 and thred2 are merely examples, and various values can be determined based on the size_sr. At this time, the offsets offset 1, 2, and 3 associated with the context model relating to the flag information indicating whether the first transform coefficient is greater than 1, and predetermined thresholds thred 1 and thred 2 are related to flag information indicating whether the first transform coefficient is greater than zero Those skilled in the art will readily understand that the offsets offset 1, 2, and 3 associated with the context model may differ from the threshold values thred 1 and thred 2 and their values.

The entropy encoding unit 155 can determine the context model related to the flag information indicating whether the first transform coefficient is larger than 1 based on the relative position of the first transform coefficients in the scan area.

The entropy encoding unit 155 determines whether or not the first transform coefficient is greater than 1 based on the horizontal direction coordinate value pos_x and the vertical direction coordinate value pos_y of the first transform coefficient in the current block and the coordinates Sr_x and Sr_y specifying the rectangular scan region The context model relating to the flag information can be determined.

If the pos_x is smaller than thred1_x and the pos_y is smaller than thred1_y, the entropy encoding unit 155 may increase the context index by a predetermined context offset, and determine the context model based on the increased context index. At this time, [thred1_x, thred1_y] may be [1,1]. Alternatively, [thred1_x, thred1_y] may be [sr_x / 4, sr_y / 4] or [(sr_x + 1) / 4, (sr_y + 1) / 4].

If the pos_x is smaller than thred2_x and the pos_y is smaller than thred2_y, the entropy encoding unit 155 may increase the context index by a predetermined context offset offset2 and determine the context model based on the increased context index. At this time, [thred2_x, thred2_y] may be [srredx], [sr_x + 1) / 2, or [sr_y + 1) / 2.

However, the thresholds thred1_x, thred1_y, and thred2_y and thred2_y are merely examples, and those skilled in the art can easily understand that various values can be determined based on sr_x and sr_y.

However, the thresholds thred1_x, thred1_y, thred2_x, and thred2_y are only examples, and various values can be determined based on the size_sr. At this time, the offsets offset 1, 2, and 3 associated with the context model relating to the flag information indicating whether the first conversion coefficient is greater than 1 and predetermined thresholds thred1_x, thred1_y, thred2_x, and thred2_y relate to the flags indicating whether the first conversion coefficient is greater than 0 It will be readily appreciated by those skilled in the art that the offsets offset 1, 2, and 3 associated with the context model for the information may differ from the threshold values thred1_x, thred1_y, thred2_x, and thred2_y.

The entropy encoding unit 155 determines whether or not the first transform coefficient is larger than 1 based on whether the first transform coefficient is a transform coefficient of the first position among the transform coefficients larger than 0 scanned in the reverse scan order Can be determined. That is, when the first transform coefficient is the first one of the transform coefficients larger than 0, which is scanned in the reverse scan order, the video decoding apparatus 100 determines whether the first transform coefficient is greater than 1, A second context model for flag information indicating whether the first transform coefficient is greater than one when the first transform coefficient is not the first one of the transform coefficients greater than 0 scanned in the reverse scan order, Can be determined.

The context model of the flag information indicating whether the first transform coefficient is greater than 1 is not limited to this, and the absolute value of n (n is a positive integer) transform coefficients previously scanned according to a predetermined scan order is larger than 1 Can be determined based on the number of large effective conversion coefficients.

The context model relating to the flag information indicating whether the first conversion coefficient is larger than 2 can be determined based on the number of the right or lower effective conversion coefficients whose absolute values are larger than 2.

The entropy encoding unit 155 can determine the context model related to the flag information indicating whether the first transform coefficient is larger than 2 based on the position of the first transform coefficient in the current block. For example, when the sum of the horizontal coordinate value pos_x of the first transform coefficient in the current block and the vertical position pos_y in the current block is smaller than the predetermined threshold value thred1, the entropy encoding unit 155 sets the context index to a predetermined value It is possible to increase the context offset by the context offset, and determine the context model based on the increased context index. If the sum of the horizontal direction coordinate value pos_x of the first transform coefficient in the current block and the vertical direction position pos_y in the current block is smaller than the predetermined threshold value thred2, the entropy encoding unit 155 sets the context index to the predetermined context offset offset2 And determine the context model based on the increased context index. If the sum of the horizontal coordinate value pos_x of the first transform coefficient in the current block and the vertical position pos_y in the current block is smaller than the predetermined threshold value thred3, the entropy coding unit 155 sets the context index to the predetermined context offset offset3 And determine the context model based on the increased context index. At this time, the offsets offset1, 2 and 3 associated with the context model relating to the flag information indicating whether the first transform coefficient is larger than 2 and predetermined thresholds thred1, 2 and 3 indicate whether the first transform coefficient is larger than 0 and 1 The offsets offset 1, 2, and 3 associated with the context model for the flag information and the predetermined threshold values thred 1, 2, and 3 may differ.

The entropy encoding unit 155 encodes the size of the scan area, the number of already scanned transform coefficients in the scan area, the relative position of the first transform coefficient in the scan area, and the first zero, And determining whether the first transform coefficient is greater than one based on at least one of whether the transform coefficient is a transform coefficient of a position (or a transform coefficient of a transform coefficient larger than 1).

For example, the entropy encoding unit 155 can determine the size size_sr of the quadrangular scan area on the basis of the following expression (16). That is, the size size_sr of the quadrangular scan region may mean the number of transform coefficients included in the quadrangular scan region.

The entropy encoding unit 155 can determine the number cnt_pos of all the transform coefficients scanned before the first transform coefficient among the transform coefficients in the rectangular scan region. At this time, cnt_pos may indicate the position of the first transform coefficient among all the transform coefficients in the scan region scanned according to a predetermined scan order. However, cnt_pos may be the number of all transform coefficients whose absolute value scanned before scanning the first transform coefficient among the transform coefficients in the quadrangular scan area is larger than unity.

If the cnt_pos is smaller than the predetermined threshold value thred1, the entropy encoding unit 155 may increase the context index by a predetermined context offset, and determine the context model based on the increased context index. At this time, thred1 may be one. Or thred1 may be 1/4 * size_sr.

If the cnt_pos is smaller than the predetermined threshold value thred2, the entropy encoding unit 155 may increase the context index by a predetermined context offset offset2 and determine the context model based on the increased context index. In this case, thred2 may be 1/4 * size_sr. Or thred2 may be 1/2 * size_sr.

If the cnt_pos is not smaller than the predetermined threshold values thred1 and thred2, the entropy encoding unit 155 may increase the context index by a predetermined context offset offset3 and determine the context model based on the increased context index.

However, the threshold values thred1 and thred2 are merely examples, and various values can be determined based on the size_sr. At this time, the offsets offset 1, 2, and 3 associated with the context model relating to the flag information indicating whether the first conversion coefficient is greater than 0 or 1 and predetermined thresholds thred 1 and thred 2 indicate whether the first conversion coefficient is greater than 0 or 1 Those skilled in the art will readily understand that the offsets offset 1, 2, and 3 associated with the context model for flag information may differ from the threshold values thred 1 and thred 2 and their values.

The entropy encoding unit 155 can determine the context model related to the flag information indicating whether the first transform coefficient is larger than 2 based on the relative positions of the first transform coefficients in the scan area.

The entropy encoding unit 155 determines whether or not the first transform coefficient is greater than 2 based on the horizontal direction coordinate value pos_x and the vertical direction coordinate value pos_y of the first transform coefficient in the current block and the coordinates Sr_x and Sr_y specifying the square scan region The context model relating to the flag information can be determined.

If the pos_x is smaller than thred1_x and the pos_y is smaller than thred1_y, the entropy encoding unit 155 may increase the context index by a predetermined context offset, and determine the context model based on the increased context index. At this time, [thred1_x, thred1_y] may be [1,1]. Alternatively, [thred1_x, thred1_y] may be [sr_x / 4, sr_y / 4] or [(sr_x + 1) / 4, (sr_y + 1) / 4].

If the pos_x is smaller than thred2_x and the pos_y is smaller than thred2_y, the entropy encoding unit 155 may increase the context index by a predetermined context offset offset2 and determine the context model based on the increased context index. At this time, [thred2_x, thred2_y] may be [srredx], [sr_x + 1) / 2, or [sr_y + 1) / 2.

However, the thresholds thred1_x, thred1_y, and thred2_y and thred2_y are merely examples, and those skilled in the art can easily understand that various values can be determined based on sr_x and sr_y.

However, the thresholds thred1_x, thred1_y, thred2_x, and thred2_y are only examples, and various values can be determined based on the size_sr. At this time, the offsets offset 1, 2, and 3 associated with the context model related to flag information indicating whether the first conversion coefficient is greater than 0 or 1 and predetermined thresholds thred1_x, thred1_y, thred2_x, and thred2_y, Those skilled in the art can easily understand that the offsets offset 1, 2, and 3 associated with the context model related to the flag information indicating may be different from the threshold values thred1_x, thred1_y, thred2_x, and thred2_y.

The entropy encoding unit 155 generates flag information indicating whether the first transform coefficient is greater than 2 or not based on whether the first transform coefficient is a transform coefficient of the first position among the transform coefficients larger than 0 scanned in the reverse scan order Can be determined. That is, if the first transform coefficient is the first one of the transform coefficients larger than 0, which is scanned in the reverse scan order, the entropy encoding unit 155 outputs the first transform coefficient, A second context model for flag information indicating whether the first transform coefficient is greater than one when the first transform coefficient is not the first one of the transform coefficients greater than 0 scanned in the reverse scan order, Can be determined.

However, the present invention is not limited to this, and the entropy encoding unit 155 may determine whether or not the first transform coefficient is equal to or greater than 2 based on whether the first transform coefficient is the transform coefficient of the first position among the transform coefficients larger than 1, The context model can be determined. That is, if the first transform coefficient is the first one of the transform coefficients larger than 1, which is scanned in the reverse scan order, the entropy encoding unit 155 outputs the first transform coefficient, A second context model for flag information indicating whether the first transform coefficient is greater than two if the first transform coefficient is not the first one of the transform coefficients greater than one scanned in the reverse scan order, The context model relating to the flag information indicating whether the first transform coefficient is greater than 2 may be used to determine whether or not n (n is a positive integer) transform coefficients among the previously scanned transform coefficients Can be determined based on the number of effective transform coefficients whose absolute values are greater than two.

The entropy encoding unit 155 encodes the position of the transform coefficient currently scanned in the scan region by [SRx, 0] (where SRx is an integer and SRx is the horizontal coordinate value of the right boundary pixel of the scan region on the basis of the left upper- (Y is an integer greater than 0 and less than or equal to SRy, and SRy represents a lower boundary of the scan region with respect to the upper left corner coordinate of the scan region in accordance with a predetermined scan order) (I.e., the vertical direction coordinate value of the pixel), the GT0 flag information of the currently scanned conversion coefficient may not be generated.

Likewise, the entropy encoding unit 155 determines whether or not the position of the transform coefficient currently scanned in the scan region is [0, SRy] (where SRy is an integer and SRy is the vertical coordinate of the lower boundary of the scan region on the basis of the upper left corner coordinate of the scan region (X, SRy) (where X is an integer greater than 0 and less than or equal to SRx, SRx is an integer equal to or greater than 0, (I.e., the vertical direction coordinate value of the boundary pixel). If the transform coefficients of the positions are all zeros, the GT0 flag information of the currently scanned transform coefficients may not be generated.

On the other hand, the entropy encoding unit 155 can determine the maximum number of GT1 flag information of the current intra-block effective transform coefficient and generate the GT1 flag information in the current block within the maximum coefficient of the determined effective transform coefficient. That is, if the entropy encoding unit 155 generates the maximum number of GT1 flag information of the effective conversion coefficient, the entropy encoding unit 155 may not generate the GT1 flag information of the effective conversion coefficient thereafter.

The entropy encoding unit 155 can determine all non-zero effective conversion coefficients as the maximum number of GT1 flag information in the current block. Or the entropy encoding unit 155 can determine the maximum number of GT1 flag information in the current block based on the size of the scan area. For example, the entropy encoding unit 155 can determine the maximum number MaxCount_GT1 of the GT1 flag information based on the following expression (17).

In this case, sizeSR may mean the size (width) of the square scan area, and sizeSR may be (Sr_x + 1) * (Sr_y + 1). Sr_x can be the horizontal coordinate of the rightmost effective transformation coefficient pixel based on the upper left corner coordinate of the scan area. In other words, Sr_x can mean the horizontal coordinate of the right boundary pixel based on the upper left corner coordinate of the scan area. Sr_y may mean the vertical coordinate of the lowest effective conversion factor pixel based on the upper left corner coordinate of the scan area. In other words, Sr_y may mean the vertical coordinate of the lower boundary pixel based on the upper left corner coordinate of the scan area. K1 can be the magnitude of the scan area and the adjustment factor between the GT1 flags. For example, K1 may be an integer greater than one. Th1 may be a predetermined threshold value. For example, Th1 may be 16,8. Those skilled in the art can easily understand that K1 and Th1 can have various values, without being limited thereto.

The entropy encoding unit 155 can determine the maximum number of GT2 flag information in the current block and generate the GT2 flag information in the current block within the maximum coefficient of the determined effective transform coefficient. That is, if the entropy encoding unit 155 generates the maximum number of GT2 flag information of the effective conversion coefficient, the entropy encoding unit 155 may not generate the GT2 flag information of the effective conversion coefficient thereafter.

The entropy encoding unit 155 can determine all non-zero effective conversion coefficients as the maximum number of GT2 flag information in the current block. Alternatively, the entropy encoding unit 155 can determine the maximum number of GT2 flag information in the current block based on the size of the scan area. For example, the entropy encoding unit 155 can determine the maximum number MaxCount_GT2 of the GT2 flag information based on the following expression (18).

In this case, sizeSR may mean the size (width) of the square scan area, and sizeSR may be (Sr_x + 1) * (Sr_y + 1). Sr_x can be the horizontal coordinate of the rightmost effective transformation coefficient pixel based on the upper left corner coordinate of the scan area. In other words, Sr_x can mean the horizontal coordinate of the right boundary pixel based on the upper left corner coordinate of the scan area. Sr_y may mean the vertical coordinate of the lowest effective conversion factor pixel based on the upper left corner coordinate of the scan area. In other words, Sr_y may mean the vertical coordinate of the lower boundary pixel based on the upper left corner coordinate of the scan area. K2 can be the magnitude of the scan area and the adjustment factor between GT2 flags. For example, K2 may be an integer greater than one. Th2 may be a predetermined threshold value. For example, Th2 may be 16,8. Those skilled in the art can easily understand that K2 and Th2 can have various values, without being limited thereto.

The entropy encoding unit 155 can generate information on the current intra-block coefficient group. The information on the coefficient group may be flag information indicating whether the coefficient group includes at least one effective transform coefficient. At this time, the entropy encoding unit 155 can determine one coefficient group for every predetermined K number of transform coefficients included in the scan region (K is an integer) scanned according to the scan order. That is, one coefficient group may include K transform coefficients. In this case, the scan order may be a forward scan order that is the opposite direction of the predetermined reverse scan order. The predetermined backward scan order referred to herein may mean a scan order from a coefficient located at the lower right of the transform coefficients included in the current block to a coefficient located at the upper left of the transform coefficients included in the current block.

Accordingly, the entropy encoding unit 155 can determine the coefficient group by scanning in the forward scan order from the DC coefficient, which is a coefficient adjacent to the upper left corner in the current block. If the number of transform coefficients included in the current block is not an integral multiple of K, the last coefficient group among the groups of coefficients scanned according to the forward scan order may include a smaller number of transform coefficients. However, the present invention is not limited to this, and the entropy coding unit 155 may perform the inverse scanning order in which the coefficients located in the lower right of the transform coefficients included in the current block are scanned up to the coefficient located in the upper left of the transform coefficients included in the current block It will be readily appreciated by those skilled in the art that scanning may be performed in accordance with the present invention to determine a coefficient group.

If one of the groups of coefficients scanned according to a predetermined scan order includes only one transform coefficient, the entropy encoding unit 155 does not generate information about the corresponding coefficient group and outputs the GT0 flag information immediately Can be generated.

The entropy encoding unit 155 can determine whether to hide the sign of at least one transform coefficient for each coefficient group included in the current block. For example, the entropy encoding unit 155 may decide to hide the sign of one or two transform coefficients for each coefficient group included in the current block, as the case may be.

The entropy encoding unit 155 may scan the information on the transform coefficients in the quadrangular scan area according to a predetermined scan order. The predetermined scan order may include a reverse zigzag scan order, a reverse diagonal scan order, a reverse vertical scan order, and a horizontal scan order. However, those skilled in the art will readily understand that the predetermined scan order is not limited to the above-mentioned reverse scan order and may include various reverse scan orders.

The bitstream generator 170 may generate a bitstream including entropy-encoded information. That is, the bitstream generator 170 may scan the information about the transform coefficients in the entropy encoder 160 and generate a bitstream including the entropy-encoded information based on the information about the scanned transform coefficients .

The bitstream generating unit 170 may generate a bitstream including information on coordinates specifying a scan area, which is an area for scanning information on transform coefficients.

The video encoding apparatus 150 may include an image encoding unit (not shown), and the image encoding unit (not shown) may include an entropy encoding unit 155 and a bitstream generating unit 170. The image encoding unit will be described with reference to FIG.

Figure 1D shows a flow diagram of a video encoding method according to various embodiments.

Referring to FIG. 1D, in operation S150, the video encoding apparatus 150 may obtain the transform coefficients of the current block. The current block may be a data unit that can be used in the process of attaching / decrypting an image described with reference to FIGS. The video encoding apparatus 150 can generate a prediction block of the current block by performing inter prediction or intra prediction and generate a residual block of the current block based on the original block of the current block and the prediction block of the current block have. The video encoding apparatus 150 may transform and quantize the residual block of the current block to generate transform coefficients of the current block.

In step S155, the video encoding device 150 may determine a scan area including all the effective transform coefficients in the current block. In this case, the scan area includes all the effective conversion coefficients in the current block, and the remaining area in the current block excluding the scan area may include only 0, not an effective conversion coefficient.

In step S160, the video encoding apparatus 150 may scan the information on the transform coefficients included in the scan area according to a predetermined scan order. The information on the transform coefficient may include flag information indicating whether the transform coefficient is larger than a predetermined value. At this time, the predetermined value may be at least one of 0, 1, and 2. Residual level information on the absolute value of the transform coefficient, sign information of the transform coefficient, and binarization parameter information of the absolute value of the residual level. The predetermined scan order may include a reverse zigzag scan order, a reverse diagonal scan order, a reverse vertical scan order, and a horizontal scan order. However, those skilled in the art will readily understand that the predetermined scan order is not limited to the above-mentioned reverse scan order and may include various reverse scan orders.

In step S165, the video encoding device 150 may generate binarized information by performing binarization based on the information about the scanned transform coefficients.

In operation S170, the video coding apparatus 150 may perform binary arithmetic coding on the binarized information to generate entropy-encoded information. At this time, the video encoding apparatus 150 may perform binary arithmetic coding using the context model determined based on at least one of the size and shape of the current block.

In operation S175, the video encoding apparatus 150 may generate a bitstream including entropy-encoded information. The video encoding apparatus 150 may scan the information on the transform coefficients in the entropy encoding unit 160 and generate a bitstream including the entropy-encoded information based on the information about the scanned transform coefficients. The video encoding apparatus 150 may generate a bitstream including information on coordinates specifying a scan area, which is an area for scanning information on the transform coefficients.

FIG. 1E shows a block diagram of an image decoding unit 6000 according to various embodiments.

The image decoding unit 6000 according to various embodiments performs operations to encode image data in a video decoding unit (not shown) of the video decoding apparatus 100. [

Referring to FIG. 1E, the entropy decoding unit 6150 parses the encoded image data to be decoded and the encoding information necessary for decoding from the bitstream 6050. The encoded image data is a quantized transform coefficient, and the inverse quantization unit 6200 and the inverse transform unit 6250 reconstruct the residue data from the quantized transform coefficients. The entropy decoding unit 6150 of FIG. 1E may correspond to the entropy decoding unit 105 of FIG. 1A.

The intra prediction unit 6400 performs intra prediction on a block-by-block basis. The inter-prediction unit 6350 performs inter-prediction using the reference image obtained in the reconstruction picture buffer 6300 for each block. The spatial data for the block of the current image 6050 is restored by adding the predictive data and residue data for each block generated by the intra predictor 6400 or the inter predictor 6350, 6450 and the SAO performing unit 6500 may perform loop filtering on the data of the reconstructed spatial region and output the filtered reconstructed image 6600. [ In addition, restored images stored in the restored picture buffer 6300 can be output as a reference image.

In order to decode the image data in the decoding unit (not shown) of the video decoding apparatus 100, the stepwise operations of the image decoding unit 6000 according to various embodiments may be performed block by block.

FIG. 1F shows a block diagram of an image encoding unit according to various embodiments.

The image encoding unit 7000 according to various embodiments performs operations to encode image data in an image encoding unit (not shown) of the video encoding device 150.

That is, the intra predictor 7200 performs intraprediction on a block-by-block basis among the current image 7050, and the inter-prediction unit 7150 performs intra prediction on the current image 7050 and the reference image obtained from the reconstructed picture buffer 7100 To perform inter prediction.

The transform unit 7250 generates residue data by subtracting the prediction data for each block output from the intra prediction unit 7200 or the inter prediction unit 7150 from the data for the block to be encoded of the current image 7050, And quantization unit 7300 may perform conversion and quantization on the residue data and output the quantized transform coefficients on a block-by-block basis. The inverse quantization unit 7450 and the inverse transformation unit 7500 can perform inverse quantization and inverse transformation on the quantized transform coefficients to restore the residue data in the spatial domain. Residue data of the reconstructed spatial region is reconstructed into spatial domain data for a block of the current image 7050 by adding predictive data for each block output from the intra predictor 7200 or the inter predictor 7150 . The deblocking unit 7550 and the SAO performing unit perform in-loop filtering on the data of the reconstructed spatial region to generate a filtered reconstructed image. The generated restored image is stored in the restored picture buffer 7100. The reconstructed images stored in the reconstructed picture buffer 7100 can be used as reference images for inter prediction of other images. The entropy encoding unit 7350 entropy-codes the quantized transform coefficients, and the entropy-encoded coefficients can be output as a bitstream 7400. The entropy encoding unit 7350 of FIG. 1F may correspond to the entropy encoding unit 155 of FIG. 1C.

In order for the image encoding unit 7000 according to various embodiments to be applied to the video encoding device 150, the stepwise operations of the image encoding unit 7000 according to various embodiments may be performed for each block.

Hereinafter, '0' and '1' shown for the pixels in the current block of FIG. 2 and FIGS. 3A and 3B are assumed to be values of the effective conversion coefficient flag (flag indicating whether the absolute value of the coefficient is greater than 0) The method of scanning the in-block transform coefficients will be described in detail.

FIG. 2 is a diagram for explaining a method of scanning intra-block transform coefficients according to an embodiment.

Referring to FIG. 2, the current block 200 is a block including a plurality of transform coefficients. The current block 200 is a data unit for performing an inverse transform operation, and may be a block of MxN (M, N is a positive integer) size. For example, as shown in FIG. 2, the current block 200 may be a 16x16 block.

The video decoding apparatus 100 may divide the current block 200 into coefficient groups (or sub-blocks) 205 having a predetermined size. The coefficient group may be a block of size XxY (where X and Y are positive integers). For example, as shown in FIG. 2, the coefficient group 205 may be a 4x4 block.

The video decoding apparatus 100 performs a process of scanning the current block 200 from the upper left transform coefficient to the lower right transform coefficient in accordance with the forward scan order, 210 from the bit stream. Information on the coordinates of the pixels 210 of the final effective conversion coefficients may include information on the horizontal direction coordinates of the pixels of the final effective conversion coefficients and information on the vertical direction coordinates of the pixels of the final effective conversion coefficients.

The video decoding apparatus 100 obtains the coordinates of the pixel 210 of the final effective conversion coefficient based on the information on the coordinates of the pixel 210 of the final effective conversion coefficient, The information of the transform coefficient may be scanned from the effective transform coefficient related to the final effective transform coefficient 210 according to a predetermined reverse scan order 215. [ For example, as illustrated in FIG. 2, the predetermined reverse scan order 215 may be a reverse diagonal scan order.

The video decoding apparatus 100 may scan the coefficient groups 205 according to a predetermined scanning order and perform a scanning operation on each coefficient group 205 according to a predetermined scanning order. The video decoding apparatus 100 may scan information about the coefficient groups according to a predetermined scanning order with respect to the coefficient groups. Information about the coefficient group may be obtained or derived from the bitstream. The information about the coefficient group may be derived to indicate that it includes at least one effective transform coefficient for the first coefficient group scanned according to the forward (reverse) scan order and for the last coefficient group. That is, the information about the coefficient group may not be included in the bitstream for the first coefficient group and the last coefficient group scanned in the forward (reverse) scan order.

At this time, the video decoding apparatus 100 may determine a predetermined reverse scan order based on at least one of the size of the block and the prediction mode. For example, when the current block size is 4x4 and the prediction mode of the current block is the intra prediction mode, the video decoding apparatus 100 may set one of the reverse horizontal scanning order, vertical scanning order, It can be determined in reverse scan order. When the current block size is 8x8 and the prediction mode of the current block is the intra prediction mode, the video decoding apparatus 100 performs one of the reverse horizontal scanning order, the vertical scanning order, or the diagonal scanning order in a predetermined reverse scan Can be determined in order.

The video decoding apparatus 100 can determine the reverse diagonal scanning order in a predetermined reverse scanning order if the current block size is not 4x4 or 8x8 or if the prediction mode of the current block is not the inter prediction mode.

When the video decoding apparatus 100 indicates that the information on the coefficient group 205 includes at least one coefficient of validity in the coefficient group 205, The information on the transform coefficients in the coefficient group can be scanned according to a predetermined scanning order 215. [

On the other hand, the video decoding apparatus 100 can determine whether to hide at least one sign among the effective transform coefficients included in each coefficient group 205.

3A is a diagram for explaining a method of scanning an intra-block transform coefficient according to another embodiment.

Referring to FIG. 3A, a current block 300 is a block including a plurality of transform coefficients. The current block 300 is a unit of data for performing an inverse transform operation, and may be a block of MxN (M, N is a positive integer) size. For example, as shown in FIG. 3, the current block 300 may be a 16x16 block.

Referring to FIG. 3A, the video decoding apparatus 100 may determine a rectangular scan area 340 including all the effective transform coefficients existing in the current block 300. At this time, the quadrangular scan region 340 may be determined by the coordinates of the pixel 330 located at the lower right of the quadrangular scan region 340. The horizontal coordinate of the pixel 330 positioned at the lower right of the scan region 340 is the horizontal coordinate of the effective transformation coefficient pixel 320 located at the rightmost of all the effective transformation coefficients in the current block 300 have. The vertical direction coordinate of the pixel 330 positioned at the lower right of the scan region 340 is the vertical direction coordinate of the effective transformation coefficient pixel 310 located at the bottom of all the effective transformation coefficients in the current block 300 have. The information about the pixel 330 may include information about the upper left corner position of the pixel 330. The information about the pixel 330 may include information about the position of the bottom right corner of the pixel 330. [

The video decoding apparatus 100 receives information on the coordinates of the pixel 330 specifying the quadrangular scan region 340 from the bit stream and generates the quadrangular scan region 340 based on the information about the received pixel 330. [ Can be determined. The video decoding apparatus 100 can scan information on the transform coefficients from the pixel 330 to the upper left pixel 345 of the rectangular scan area 340 according to a predetermined reverse scan order 355. [ At this time, the coefficient group may be determined for every K (K is a positive integer) scan coefficient scanned according to a predetermined forward scan order from the upper left transform coefficient of the rectangular scan region 340. [ It is easily understood by those skilled in the art that the number of K (K is a positive integer) scan coefficient scanned according to a predetermined reverse scan order can be determined from the transform coefficient at the lower right end. Details of the coefficient group will be described later with reference to FIG. 3B.

On the other hand, the video decoding apparatus 100 can determine that a sign for at least one effective transform coefficient is hidden for each coefficient group, and can restore the sign for at least one effective transform coefficient that is hidden . Details of performing the operation of restoring the hidden code for each coefficient group will be described later with reference to FIG. 3B.

FIG. 3B is a view for explaining an operation of determining intra-block coefficient groups (sub-blocks) and an operation performed for each coefficient group according to an embodiment.

The video decoding apparatus 100 can determine a coefficient group for each of K (K is a positive integer) conversion coefficient pixels according to a predetermined scanning order 355 in the current block 350 in the forward direction. The video decoding apparatus 100 may determine a coefficient group including K transform coefficient pixels. For example, as shown in FIG. 3B, the video decoding apparatus 100 may determine the coefficient group 360 for every 16 pixels.

The video decoding apparatus 100 determines that a sign for at least one effective transform coefficient is hidden for every coefficient group 360 and a sign for at least one effective transform coefficient for each coefficient group 360 is You can decide that it is hidden. For example, the video decoding apparatus 100 can determine that a sign (Sign) for at least one effective transform coefficient is hidden for the current coefficient group based on the distance of previously decoded effective transform coefficients in the current coefficient group . Specifically, the video decoding apparatus 100 encodes a sign for at least one effective transform coefficient for the current coefficient group based on the distance between the first effective transform coefficient and the last valid transform coefficient scanned according to a predetermined reverse scan order, Can be determined to be hidden. In this case, the distance may be a difference in the positions of the coefficients scanned in the reverse scan order.

For example, when the distance between the first effective conversion coefficient and the last effective conversion coefficient scanned according to a predetermined reverse scan order is greater than a predetermined value, the video decoding apparatus 100 may determine It can be determined that the sign is hidden. At this time, the predetermined value may be various integer values. For example, the predetermined value may be three.

If it is determined that the sign for at least one effective transform coefficient is hidden for the current coefficient group, the video decoding apparatus 100 determines whether or not the current coefficient group includes at least A hidden code for one effective transform coefficient can be restored. For example, when the parity sum with respect to the level of the effective transform coefficients in the current coefficient group is odd or even, the video decoding apparatus 100 determines the sign of at least one effective transform coefficient as 0 or 1 . At this time, the sign of the effective transform coefficient to be reconstructed may include a sign related to the final effective transform coefficient scanned in the reverse scan order. However, it is easily understood by those skilled in the art that a code at a predetermined position in a coefficient group can be restored according to a predetermined scanning order without being limited thereto.

The video decoding apparatus 100 acquires information on the coefficient group from the bitstream according to a predetermined scanning order in the reverse direction and when the information on the coefficient group indicates that the coefficient group includes at least one transform coefficient, Information about the transform coefficient in the coefficient group can be scanned. When the information on the coefficient group indicates that the coefficient group includes only the transform coefficient having a value of 0, all of the transform coefficients in the coefficient group can be determined as 0.

If the number of transform coefficients included in the square scan region in the current block 300 is not K integer times, the process of determining the last coefficient group according to the forward scan order may perform a smaller number of transforms A coefficient pixel may be present. In this case, the video decoding apparatus 100 may determine a coefficient group 365 that includes fewer than K number of conversion coefficient pixels. For example, as shown in FIG. 3B, the video decoding apparatus 100 may determine a coefficient group 365 including two transform coefficients.

The video decoding apparatus 100 can obtain information on the coefficient groups 355 and 360 from the bitstream. Here, the information on the coefficient groups 355 and 360 includes flag information indicating whether at least one of the conversion coefficients included in the coefficient groups 355 and 360 is an effective conversion coefficient or only conversion coefficients whose coefficient groups 355 and 360 are 0 Group flag information).

On the other hand, if the coefficient group including only one transform coefficient is determined, the video decoding apparatus 100 does not acquire information (for example, effective coefficient group flag information) about the coefficient group from the bitstream, Information about the coefficient can be obtained.

The video decoding apparatus 100 generates a context for binary arithmetic decoding information on the current coefficient group on the basis of the information on the coefficient group of the coefficient group scanned earlier than the current coefficient group according to the predetermined scanning order 355 in the reverse direction The model can be determined.

FIG. 4 is a diagram for explaining a process of determining a context model for decoding context-based binary arithmetic decoding information on transform coefficients according to an exemplary embodiment of the present invention.

Referring to FIG. 4, the video decoding apparatus 100 may determine a context model of the information about the currently scanned transform coefficient pixel 405 based on the transform coefficient pixels 410. FIG. In FIG. 4, the neighboring transform coefficient pixels 405 may be five pixels existing at a predetermined position on the right side or the lower side of the currently scanned transform coefficient pixel 405. It is easily understood by those skilled in the art that the peripheral transformation coefficient pixels 405 may be n (n is a positive integer) pixels existing at a predetermined position on the right side or the lower side, without limitation thereto.

For example, the video decoding apparatus 100 may compare the context model of the flag information indicating whether the level absolute value of the currently scanned conversion coefficient pixel 405 is greater than 0, Can be determined based on the number of larger coefficient pixels.

The video decoding apparatus 100 further includes a context model of flag information indicating whether the level absolute value of the currently scanned conversion coefficient pixel 405 is greater than 1, Can be determined based on the number of pixels

The video decoding apparatus 100 converts the context model of the flag information indicating whether the level absolute value of the currently scanned conversion coefficient pixel 405 is greater than 2, Can be determined based on the number.

The video decoding apparatus 100 converts the context model of the flag information indicating whether the level value of the currently scanned conversion coefficient pixel 405 is larger than N (N is an integer larger than 2) Can be determined based on the number of coefficient pixels larger than N. [

The video decoding apparatus 100 may determine a parameter for binarizing the residual level absolute value of the currently scanned conversion coefficient pixel 405 based on the sum of the absolute level values of the peripheral conversion coefficient pixels 410. [ At this time, the binarization parameter may be a Rice parameter.

FIG. 5 is a diagram for explaining a process of determining a context model for decoding context-based binary arithmetic decoding information on transform coefficients according to an embodiment.

5, the video decoding apparatus 100 transmits a context model of information on the currently scanned transform coefficient pixel 505 to previously scanned transform coefficient pixels 510 according to a predetermined reverse scan sequence 515, . ≪ / RTI > As shown in FIG. 5, the transform coefficient pixels 510 may be five pixels previously scanned according to a predetermined reverse echo scan order 515 than the currently scanned transform coefficient pixel 505. Those skilled in the art will readily understand that the transform coefficient pixels 505 may be n (n is a positive integer) pixels previously scanned in accordance with a given reverse echo scan order 515 . As shown in FIG. 5, the predetermined reverse scan order 515 may be a reverse zigzag scan order, but the present invention is not limited thereto. For example, those skilled in the art can understand that the reverse scan order 515 includes a horizontal scan order, a vertical scan order, It can be easily understood. In particular, the predetermined reverse scan order may be determined in one of a plurality of scan orders based on the magnitude of the horizontal direction coordinate value specifying the scan region and the vertical direction coordinate value.

For example, the video decoding apparatus 100 may compare the context model of the flag information, which indicates whether the level absolute value of the currently scanned conversion factor pixel 505 is greater than 0, Can be determined based on the number of large coefficient pixels.

The video decoding apparatus 100 further includes a context model of flag information indicating whether the level absolute value of the currently scanned conversion coefficient pixel 505 is greater than 1, As shown in FIG.

The video decoding apparatus 100 converts the context model of the flag information indicating whether the level absolute value of the currently scanned conversion coefficient pixel 505 is larger than 2, Can be determined based on the number.

The video decoding apparatus 100 transmits a context model of flag information indicating whether the level absolute value of the currently scanned conversion coefficient pixel 505 is larger than N (N is an integer larger than 2) The value can be determined based on the number of coefficient pixels larger than N. [

The video decoding apparatus 100 may determine a parameter for binarizing the residual level absolute value of the currently scanned transform coefficient pixel 505 based on the sum of the absolute value levels of the neighboring transform coefficient pixels 510. [ At this time, the binarization parameter may be a Rice parameter.

FIG. 6A is a diagram for explaining a zigzag scanning order for scanning information on effective conversion coefficients in a block according to an exemplary embodiment. Referring to FIG.

Referring to FIG. 6A, the video decoding apparatus 100 scans the information on the transform coefficient of the current block 600 from the transform coefficient pixel of the lower right end of the current block 600 according to the zig- You can scan up to the conversion factor pixel at the top.

Specifically, in accordance with the zigzag scan sequence 602, the video decoding apparatus 100 scans the lower-left conversion coefficient pixel 604, then scans the left pixel 606 of the pixel 604, And then scans the pixel 608 located in the diagonal direction of the upper right corner. The video decoding apparatus 100 scans the pixel 610 adjacent to the upper side of the pixel 608. [ The video decoding apparatus 100 scans the pixels 612 located in the diagonal direction of the lower left corner of the pixel. The video decoding apparatus 100 scans the pixels 614 located on the left side of the pixels adjacent to the boundary of the current block 600 among the pixels 612. [ In a similar manner, the video decoding apparatus 100 may scan information about the remaining transform coefficient pixels according to the zigzag scan sequence 602. [

Meanwhile, the zigzag scanning procedure 602 according to an exemplary embodiment of the present invention scans the left directional pixel 606 located in the horizontal direction immediately after the pixel 604 is scanned, so that the zigzag scanning order 602 is referred to as a horizontal priority zigzag sequence Can be called.

6B is a diagram for explaining a vertical priority zigzag scan sequence for scanning information on intra-block transform coefficients according to another embodiment.

6B, the video decoding apparatus 100 scans the information on the transform coefficient of the current block 600 from the transform coefficient pixel of the lower right end of the current block 600 according to the zigzag scan sequence 616, You can scan up to the conversion factor pixel at the top.

Specifically, in accordance with the zigzag scan sequence 616, the video decoding apparatus 100 scans the upper-side pixel 620 of the pixel 618 after scanning the lower-right conversion coefficient pixel 618, And then scans the pixel 622 located in the diagonal direction of the lower left corner. The video decoding apparatus 100 scans the pixel 624 adjacent to the left side of the pixel 622. [ The video decoding apparatus 100 scans the pixels 626 positioned in the diagonal direction of the upper right corner of the pixel. The video decoding apparatus 100 scans the pixel 628 located on the upper side of the pixel adjacent to the boundary of the current block 600 among the pixels 626. [ In a similar manner, the video decoding apparatus 100 may scan information about the remaining transform coefficient pixels according to the zigzag scan sequence 616. [

Meanwhile, the zigzag scan sequence 616 according to an exemplary embodiment of the present invention scans the upward directional pixel 620 located immediately after the scan of the pixel 618, so that the zigzag scan sequence 616 is referred to as a vertical priority zigzag sequence Can be called.

FIG. 6C is a diagram for explaining a horizontal scanning order for scanning information on intra-block transform coefficients according to an embodiment.

Referring to FIG. 6C, the video decoding apparatus 100 scans the information on the transform coefficient of the current block 600 from the transform coefficient pixel of the lower right end of the current block 600 according to the horizontal scan order 630, You can scan up to the conversion factor pixel at the top.

Specifically, in the horizontal scanning order 630, the video decoding apparatus 100 scans the lower right transform coefficient pixel 632 and then sequentially scans the pixels 634 located in the horizontal direction, , And scans the pixels of the pixels 634 adjacent to the left boundary of the current block 600 and then scans the rightmost pixel 636 of the immediately preceding row. The video decoding apparatus 100 scans the pixels 638 located in the horizontal direction in the same manner as the pixels of the previous row 634 are scanned. In a similar manner, the video decoding apparatus 100 may scan information about the remaining transform coefficient pixels according to the horizontal scan order 630. [

FIG. 6D is a diagram for explaining a vertical scanning sequence for scanning information on intra-block transform coefficients according to an embodiment.

6D, the video decoding apparatus 100 scans the information on the transform coefficient of the current block 600 from the transform coefficient pixel of the lower right end of the current block 600 according to the vertical scan sequence 640, You can scan up to the conversion factor pixel at the top.

Specifically, in the vertical scanning order 640, the video decoding apparatus 100 sequentially scans the pixels 644 positioned in the vertical direction, which is the vertical direction, after scanning the conversion coefficient pixel 642 at the lower right end , And scans the pixels of the pixels 644 adjacent to the upper boundary of the current block 600 and then immediately scans the lowermost pixel 646 of the column on the left side. The video decoding apparatus 100 scans the pixels 648 positioned in the vertical direction in the same manner as the pixels in the previous column 644 are scanned. In a similar manner, the video decoding apparatus 100 may scan information on the remaining transform coefficient pixels according to the vertical scan sequence 640. [

6E is a diagram for explaining a diagonal scan order for scanning information on intra-block transform coefficients according to an embodiment.

6E, the video decoding apparatus 100 reads the transform coefficients of the current block 600 from the transform coefficient pixels of the lower right end of the current block 600 according to the diagonal scan order 650 to scan information on the transform coefficients of the current block 600, You can scan up to the conversion factor pixel at the top.

Specifically, in accordance with the diagonal scan sequence 650, the video decoding apparatus 100 scans the upper right pixel 652 of the pixel 652 after scanning the lower right conversion coefficient pixel 652, And then scans the pixel 656 located in the lower left diagonal direction. The video decoding apparatus 100 scans the pixel 658 adjacent to the upper side of the pixel 654. [ The video decoding apparatus 100 scans the pixels 660 located in the diagonal direction of the lower left end of the pixel 658. [ In a similar manner, the video decoding apparatus 100 may scan information about the remaining transform coefficient pixels according to the diagonal scan sequence 650. [

6A to 6E, various scan sequences for scanning information on effective conversion coefficients in a block have been described. The scan orders described with reference to FIGS. 6A through 6E can be easily understood in a reverse scan order, or a forward scan order in which a person skilled in the art scans in the reverse order of the reverse scan order.

FIG. 7A is a diagram for explaining a process of changing a scan area by swapping horizontal and vertical coordinates of transform coefficient pixels in a scan area according to an exemplary embodiment.

7A, the current block 700 may be a rectangle whose width is greater than the height.

The video decoding apparatus 100 may obtain a flag indicating that the horizontal coordinate and the vertical coordinate of the conversion coefficient pixel included in the current block 700 are changed to each other. When the video decoding apparatus 100 indicates that the flag activates the operation of changing the horizontal direction coordinate and the vertical direction coordinate of the transform coefficient pixel included in the current block 700, Can be determined.

The video decoding apparatus 100 can determine the swapped block 710 by changing the width and the height of the current block to each other if the width of the current block is greater than the height.

 That is, the video decoding apparatus 100 can change the horizontal direction coordinate and the vertical direction coordinate of the transform coefficient pixel included in the current block 700 to determine the pixel position of the transform coefficient included in the changed block 710 .

The video decoding apparatus 100 may obtain information on the coordinates for specifying the rectangular scan area 705 including all the effective transformation coefficients from the bitstream. Here, the horizontal direction coordinate of the coordinates for specifying the rectangular scan area 705 may be the horizontal direction coordinate of the effective transformation coefficient pixel located at the rightmost of all the effective transformation coefficients in the current block. The vertical direction coordinate of the coordinates for specifying the quadrangular scan region may be the vertical direction coordinate of the effective transformation coefficient pixel located at the lowermost of all the effective conversion coefficients in the current block. The information on the coordinates for specifying the rectangular scan area 705 includes information on the horizontal coordinate values of the effective conversion coefficient pixels located at the rightmost of all the effective conversion coefficients in the current block, And the vertical coordinate value of the effective conversion coefficient pixel located at the lowermost position of the effective conversion coefficient pixel. Alternatively, the information on the coordinates for specifying the quadrangular scan area 705 may be the horizontal coordinate value of the effective conversion coefficient pixel located at the rightmost of all the effective conversion coefficients, Information on one coordinate value among the vertical coordinate values of the effective conversion coefficient pixel to be located, and information indicating a difference between the one coordinate value and the other coordinate value.

When the width and height of the current block are different from each other, the video decoding apparatus 100 determines whether the information on the coordinates for specifying the quadrangular scan region 705 from the bitstream is a horizontal coordinate value for specifying the quadrangular scan region 705 (Hereinafter referred to as " delta flag information ") indicating whether or not the information indicating the difference between the vertical direction coordinate value and the vertical direction coordinate value is included. Based on the delta flag information, the video decoding apparatus 100 extracts information indicating a coordinate value indicating one of a horizontal direction coordinate value and a vertical direction coordinate value for specifying the quadrangular scan area 705 from the bit stream and one coordinate value Information indicating a difference between different coordinate values can be obtained.

The video decoding apparatus 100 obtains the coordinates for specifying the quadrangular scan area 705 based on the information about the coordinates for specifying the quadrangular scan area 705 including all the effective transformation coefficients obtained from the bitstream . At this time, the coordinates for specifying the quadrangular scan region 705 acquired by the video decoding apparatus 100 are coordinates for specifying the quadrangular scan region 705 in the current block 700, The video decoding apparatus 100 can obtain the coordinate value for specifying the quadrangular scan area 715 of the changed block 710 by mutually changing the horizontal coordinate value and the horizontal coordinate value of the coordinate to be changed.

The video decoding apparatus 100 can scan the information on the transform coefficients based on the rectangular scan area 715 of the changed block 710 according to a predetermined scan order. At this time, the predetermined scan order is a horizontal coordinate value of the transform coefficient pixel scanned according to a predetermined scan order for the current block 700 in a scan order corresponding to a predetermined scan order for the current block 700, Direction may be a scanning order according to a coordinate value obtained by mutually changing the coordinate values of the directions. For example, if the coordinate values of the conversion coefficient pixels scanned according to a predetermined scan order for the current block 700 are (4,4) -> (3,4) -> (4,3) -> ... , The coordinate values of the transform coefficient pixels scanned in a predetermined order with respect to the changed block 710 may be (4,4) -> (4,3) -> (3,4) -> 쪋.

The video decoding apparatus 100 may binary-arithmetically decode information on the transform coefficients scanned in the changed block 710 based on a predetermined context model, and reverse-binarize the transform coefficients to obtain transform coefficients of the changed block 710. [ The video decoding apparatus 100 may obtain the transform coefficients of the current block 700 by changing the horizontal direction coordinate value and the vertical direction value of the transform coefficients of the changed block 710 to each other.

When the width of the current block is greater than the height, the video decoding apparatus 100 swaps the horizontal direction coordinate and the vertical direction coordinate of the transform coefficient pixel included in the current block, The information on the transform coefficient related to the block in which the height of the current block is always greater than or equal to the width can be entropy-decoded. Therefore, it is possible to reduce the complexity of entropy decoding by using only the context model for a block whose height is greater than or equal to the width of the current block, without using a separate context model for the case where the width of the current block is greater than the height.

The video encoding apparatus 150 and the video decoding apparatus 100 have been described as acquiring the delta flag information when the current block has different widths and heights, If the width and height of the block are different, information indicating the difference between the horizontal direction coordinate value and the vertical direction coordinate value for specifying the quadrangular scan area 715 from the bit stream can be obtained without obtaining the delta flag information Those skilled in the art will readily understand.

Without being limited to this, the video decoding apparatus 100 may obtain the information indicating the difference between the horizontal direction coordinate value and the vertical direction coordinate value, without generating the delta flag information regardless of whether the width and the height of the current block are the same or different It will be readily understood by those skilled in the art.

Based on a flag indicating that the anomaly video encoding apparatus 150 generates a change flag and the video decrypting apparatus 100 activates an operation of changing the horizontal direction coordinate and the vertical direction coordinate of the transform coefficient pixel included in the current block The video decoding apparatus 100 determines whether to change the horizontal direction coordinate and the vertical direction coordinate of the transform coefficient pixels included in the current block to each other. However, the present invention is not limited thereto, and if the width of the current block is greater than the height, Those skilled in the art can easily understand that the horizontal direction coordinate and the vertical direction coordinate can be mutually changed.

If the video decoding apparatus 100 swaps the horizontal direction coordinate and the vertical direction coordinate of the conversion coefficient pixel included in the current block, if the width of the current block is larger than the height, Those skilled in the art can easily understand that the horizontal direction and the vertical direction coordinates of the transform coefficient pixels included in the current block can be changed when the height of the current block is larger than the width.

The video decoding apparatus 100 changes the horizontal direction coordinate and the vertical direction coordinate of the current block and changes the horizontal direction coordinate and the vertical direction coordinate of the scan region to scan the information about the transform coefficient, But the present invention is not limited to this. However, the present invention is not limited to this, and the present invention is not limited to this, The transformation coefficients in the scan area are obtained by performing scan and entropy decoding of information on the intra-scan transform coefficients by changing only the horizontal direction coordinate and the vertical direction coordinate of the scan area without changing the coordinate and the vertical direction coordinate, The horizontal direction and the vertical direction coordinates of the transformation coefficients in the scan area are mutually changed, Those skilled in the art can easily understand that the transform coefficients can be obtained.

The video decoding apparatus 100 changes the horizontal direction coordinate and the vertical direction coordinate of the current block and changes the horizontal direction coordinate and the vertical direction coordinate of the scan region to scan the information about the transform coefficient, But the present invention is not limited to this. However, the present invention is not limited to this, and the present invention is not limited to this. For example, the horizontal direction of the transform coefficients And transforming only the horizontal coordinate and the vertical coordinate of the scan area without changing the vertical coordinate, decodes the information, scans and entropy decodes information on the intra-scan conversion coefficient to obtain the intra-scan conversion coefficient, It is easily understood by those skilled in the art that the current in-block transform coefficients can be obtained.

That is, when the width of the current block is greater than the height, the video encoding apparatus 150 may change the horizontal and vertical coordinates of the scan area of the current block and transmit information indicating the same. In this case, generally, when the width of the current block is greater than the height, the width of the scan area is greater than the height, and the coordinates in the horizontal direction specifying the scan area are larger than the coordinates in the vertical direction. , The changed coordinate value in the horizontal direction becomes smaller than the changed vertical coordinate value. Therefore, it is possible to reduce the number of bits by transmitting the information about the changed coordinate values in the horizontal direction and the difference information about the changed coordinate values in the horizontal direction and the changed coordinate values in the vertical direction. However, if the width of the current block is greater than the height and the height of the scan area is larger than the width, the video encoding apparatus 150 displays the changed coordinate value information in the horizontal direction, the changed coordinate value in the horizontal direction, Information can be transmitted as it is. That is, difference information may not be transmitted. In this case, the changed horizontal coordinate value is larger than the changed vertical coordinate value.

The video encoding apparatus 150 may transmit a flag indicating whether or not to transmit the difference information together. The video decoding apparatus 100 may decide to change the horizontal direction coordinate value and the vertical direction coordinate value specifying the scan area to each other when the width of the current block is larger than the height, 1 (indicating that the difference information is transmitted), information on the changed coordinate value in the horizontal direction and difference information on the changed coordinate value in the horizontal direction and the coordinate value in the changed vertical direction are obtained, and the changed scanning area is specified Can be obtained.

If the value of the flag is 0 (indicating that differential information is not transmitted), information on the changed coordinate values in the horizontal direction and information on the changed coordinate values in the vertical direction are obtained, and coordinate values Can be obtained.

The video decoding apparatus 100 can identify the final scan region by changing the obtained horizontal direction coordinate value and the vertical direction coordinate value, and scan the information about the intra-scan conversion coefficient.

However, the present invention is not limited to the case where the width of the current block is larger than the height, and a person skilled in the art can easily understand that a similar operation can be performed even when the height of the current block is larger than the width.

FIG. 7B is a diagram for explaining a process of swapping a scan area by swapping horizontal and vertical coordinates of transform coefficient pixels in a rectangular scan area according to another embodiment.

7B, the current block 720 may be a rectangle whose width is greater than the height.

The video decoding apparatus 100 may obtain a flag indicating that the operation of changing the horizontal direction coordinate and the vertical direction coordinate of the transform coefficient pixel included in the current block 720 to each other is activated. When the video decoding apparatus 100 indicates that the flag activates the operation of changing the horizontal direction coordinate and the vertical direction coordinate of the transform coefficient pixels contained in the current block 720, the width of the current block 720 is set to a height Can be determined.

The video decoding apparatus 100 can determine the swapped block 730 by changing the width and the height of the current block to each other if the width of the current block is greater than the height.

 That is, the video decoding apparatus 100 can change the horizontal direction coordinate and the vertical direction coordinate of the transform coefficient pixel included in the current block 720 to determine the pixel position of the transform coefficient included in the changed block 730 .

The video decoding apparatus 100 may obtain information on the coordinates for specifying the scan area 725 including all the effective transform coefficients from the bit stream. Here, the coordinates for specifying the scan area 725 may be horizontal and vertical coordinates of the last effective conversion factor pixel when scanning according to a predetermined forward scan order. The information about the coordinates for specifying the scan area 725 may include information about the horizontal coordinate of the last effective conversion coefficient pixel 725 and information about the vertical coordinate. Alternatively, the information on the coordinates for specifying the scan area 725 may include information on one of the horizontal direction coordinate and the vertical direction coordinate of the last effective conversion coefficient pixel, and information on the coordinate value of the difference between the one coordinate value and the other coordinate value Lt; / RTI >

When the width and height of the current block are different from each other, the video decoding apparatus 100 determines whether the information related to the coordinates for specifying the scan area 725 from the bit stream corresponds to the horizontal direction coordinate value for specifying the scan area 725, (Hereinafter referred to as " delta flag information ") indicating whether or not the information indicating the difference between the direction coordinate values is included. The video decoding apparatus 100 displays information indicating a coordinate value indicating one of a horizontal direction coordinate value and a vertical direction coordinate value for specifying the scan area 725 from the bit stream based on the delta flag information, Information indicating a difference between coordinate values can be obtained.

The video decoding apparatus 100 can obtain the coordinates for specifying the scan area 725 based on the information about the coordinates for specifying the scan area 725 including all the effective transformation coefficients obtained from the bit stream . The coordinate for specifying the scan area 725 acquired by the video decoding apparatus 100 is a coordinate for specifying the scan area 725 in the current block 720. The coordinates for specifying the scan area 725 include coordinates The video decoding apparatus 100 can obtain the coordinate value for specifying the scan area 725 of the changed block 730 by changing the horizontal direction coordinate value and the horizontal direction coordinate value of the changed block 730 from each other.

The video decoding apparatus 100 can scan the information on the transform coefficients according to a predetermined scan order based on the scan area 735 of the changed block 730. [ At this time, the predetermined scan order is a horizontal coordinate value of the conversion factor pixel scanned according to a predetermined scan order for the current block 720 in a scan order corresponding to a predetermined scan order for the current block 720, Direction may be a scanning order according to a coordinate value obtained by mutually changing the coordinate values of the directions. For example, if the coordinate values of the conversion coefficient pixels scanned according to a predetermined scan order for the current block 720 are (4,4) -> (3,4) -> (4,3) -> ... (4,4) - > (4,3) - > (3,4) - > ..., the coordinate values of the conversion coefficient pixels scanned in a predetermined order with respect to the changed block 730 have.

The video decoding apparatus 100 can binary-arithmetically decode information on the transform coefficients scanned in the changed block 730 based on a predetermined context model, and inverse-binarize the transform coefficients to obtain transform coefficients of the changed block 730. [ The video decoding apparatus 100 may obtain the transform coefficients of the current block 720 by changing the horizontal direction coordinate values and the vertical direction values of the transform coefficients of the changed block 730 to each other.

When the width of the current block is greater than the height, the video decoding apparatus 100 swaps the horizontal direction coordinate and the vertical direction coordinate of the transform coefficient pixel included in the current block, and changes the transform coefficient in the changed block 720 The information on the transform coefficient related to the block in which the height of the current block is always greater than or equal to the width can be entropy-decoded. Therefore, it is possible to reduce the complexity of entropy decoding by using only the context model for a block whose height is greater than or equal to the width of the current block, without using a separate context model for the case where the width of the current block is greater than the height.

The video encoding apparatus 150 and the video decoding apparatus 100 have been described as acquiring the delta flag information when the current block has different widths and heights, It is possible to obtain information indicating the difference between the horizontal direction coordinate value and the vertical direction coordinate value for specifying the scan area 720 from the bit stream without obtaining delta flag information when the width and height of the block are different from each other Can be easily understood.

Without being limited to this, the video decoding apparatus 100 may obtain the information indicating the difference between the horizontal direction coordinate value and the vertical direction coordinate value, without generating the delta flag information regardless of whether the width and the height of the current block are the same or different It will be readily understood by those skilled in the art.

Based on a flag indicating that the anomaly video encoding device 150 generates a change flag and the video decrypting device 150 activates an operation of changing the horizontal direction coordinate and the vertical direction coordinate of the transform coefficient pixel included in the current block The video decoding apparatus 100 determines whether to change the horizontal direction coordinate and the vertical direction coordinate of the transform coefficient pixels included in the current block to each other. However, the present invention is not limited to this, and if the width of the current block is greater than the height, Those skilled in the art can easily understand that the horizontal direction coordinate and the vertical direction coordinate can be mutually changed.

If the video decoding apparatus 100 swaps the horizontal direction coordinate and the vertical direction coordinate of the conversion coefficient pixel included in the current block, if the width of the current block is larger than the height, Those skilled in the art can easily understand that the horizontal direction and the vertical direction coordinates of the transform coefficient pixels included in the current block can be changed when the height of the current block is larger than the width.

The video decoding apparatus 100 changes the horizontal direction coordinate and the vertical direction coordinate of the current block and changes the horizontal direction coordinate and the vertical direction coordinate of the scan region to scan the information about the transform coefficient, But the present invention is not limited to this. However, the present invention is not limited to this, and the present invention is not limited to this, The transformation coefficients in the scan area are obtained by performing scan and entropy decoding of information on the intra-scan transform coefficients by changing only the horizontal direction coordinate and the vertical direction coordinate of the scan area without changing the coordinate and the vertical direction coordinate, The horizontal direction and the vertical direction coordinates of the transformation coefficients in the scan area are mutually changed, Those skilled in the art can easily understand that the transform coefficients can be obtained.

The video decoding apparatus 100 changes the horizontal direction coordinate and the vertical direction coordinate of the current block and changes the horizontal direction coordinate and the vertical direction coordinate of the scan region to scan the information about the transform coefficient, But the present invention is not limited to this. However, the present invention is not limited to this, and the present invention is not limited to this. For example, the horizontal direction of the transform coefficients And transforming only the horizontal coordinate and the vertical coordinate of the scan area without changing the vertical coordinate, decodes the information, scans and entropy decodes information on the intra-scan conversion coefficient to obtain the intra-scan conversion coefficient, It is easily understood by those skilled in the art that the current in-block transform coefficients can be obtained.

That is, when the width of the current block is greater than the height, the video encoding apparatus 150 may change the horizontal and vertical coordinates of the scan area of the current block and transmit information indicating the same. In this case, generally, when the width of the current block is greater than the height, the width of the scan area is greater than the height, and the coordinates in the horizontal direction specifying the scan area are larger than the coordinates in the vertical direction. , The changed coordinate value in the horizontal direction becomes smaller than the changed vertical coordinate value. Therefore, it is possible to reduce the number of bits by transmitting the information about the changed coordinate values in the horizontal direction and the difference information about the changed coordinate values in the horizontal direction and the changed coordinate values in the vertical direction. However, if the width of the current block is greater than the height and the height of the scan area is larger than the width, the video encoding apparatus 150 displays the changed coordinate value information in the horizontal direction, the changed coordinate value in the horizontal direction, Information can be transmitted as it is. That is, difference information may not be transmitted. In this case, the changed horizontal coordinate value is larger than the changed vertical coordinate value.

The video encoding apparatus 150 may transmit a flag indicating whether or not to transmit the difference information together. The video decoding apparatus 100 may decide to change the horizontal direction coordinate value and the vertical direction coordinate value specifying the scan area to each other when the width of the current block is larger than the height, 1 (indicating that the difference information is transmitted), information on the changed coordinate value in the horizontal direction and difference information on the changed coordinate value in the horizontal direction and the coordinate value in the changed vertical direction are obtained, and the changed scanning area is specified Can be obtained.

If the value of the flag is 0 (indicating that differential information is not transmitted), information on the changed coordinate values in the horizontal direction and information on the changed coordinate values in the vertical direction are obtained, and coordinate values Can be obtained.

The video decoding apparatus 100 can identify the final scan region by changing the obtained horizontal direction coordinate value and the vertical direction coordinate value, and scan the information about the intra-scan conversion coefficient.

However, the present invention is not limited to the case where the width of the current block is larger than the height, and a person skilled in the art can easily understand that a similar operation can be performed even when the height of the current block is larger than the width.

8 is a diagram for explaining a process of determining a context model for syntax element information of a transform coefficient in a current block based on at least one of a size of a current block and a shape of a current block according to an embodiment.

Referring to FIG. 8, the current block may have a shape of one of the first block 805, the second block 810, and the third block 815. The first block may be a rectangular block whose height is greater than the width, the second block may be a rectangular block whose width is greater than the height, and the third block 815 may be a square block Lt; / RTI >

The video decoding apparatus 100 can determine the context model related to the syntax element information of the current intra-block transform coefficients based on the size_tu0 determined according to the equation (19).

Here, log2_width may be a value obtained by taking log2 as the width of the current block, and log2_height may be a value obtained by taking log2 as the height and height of the current block. Referring to FIG. 8, if the current block is the first block 805, size_tu may be (log ₂ a + log ₂ b) / 2 (where a and b are positive integers). If the current block is the second block (810), size_tu may be a (log- log ₂ c + ₂ d) / 2 (c, d is a positive integer). If the current block is the third block 815, size_tu may be log ₂ e (e is a positive integer).

Alternatively, the video decoding apparatus 100 may determine a value relating to the size of the current block, which is an element that determines the context model, based on the minimum of the width of the current block and the height of the current block. For example, the video decoding apparatus can determine a value size_tu1 related to the size of the current block, which is an element that determines the context model, based on the following expression (20).

Here, the Min () function may be a function that outputs the minimum value among the input values. Referring to FIG. 8, if the current block is the first block 805, size_tu may be log ₂ a (where a is a positive integer). If the current block is the second block (810), size_tu may be a log- ₂ d (d is a positive integer). If the current block is the third block 815, size_tu may be log ₂ e (e is a positive integer).

The video decoding apparatus 100 can determine the context model related to the syntax element information of the current intra-block transform coefficient based on the size_tu1 determined according to the equation (20).

Alternatively, the video decoding apparatus 100 may determine a value relating to the size of the current block, which is an element determining the context model, based on the maximum value of the width of the current block and the height of the current block. For example, the video decoding apparatus can determine a value size_tu2 related to the size of the current block, which is an element for determining the context model, based on the following expression (21).

Here, the Max () function may be a function that outputs the maximum value among the function input values.

The video decoding apparatus 100 can determine the context model related to the syntax element information of the current intra-block transform coefficient based on the size_tu2 determined according to (Expression 21).

If a is 4, b is 16, and e is 8, size_tu for the first block 805 and size_tu0 for the third block 815 may be equal to three.

The video decoding apparatus 100 determines the same context model for the first block 805 and the third block 815 based on the size_tu0 even though the conversion coefficient tends to be distributed on the wider side of the height and width of the current block . However, if the video decoding apparatus 100 determines the context models for the first block 805 and the third block 815 based on size_tu1 or size_tu2, the context models may be different from each other, and thus, based on size_tu0 The efficiency of binary arithmetic decoding can be improved as compared to when determining the context model.

The video decoding apparatus 100 can determine a value relating to the size of the current block which is an element for determining the context model based on the shape of the current block. For example, the video decoding apparatus 100 can determine a value shape_tu related to the shape of the current block, which is an element that determines the context model, based on the following equation (22).

For example, when the current block is the first block 805, shape_tu may be 1, and if the current block is the second block 810, shape_tu may be 2. [ If the current block is the third block 815, shape_tu may be zero. That is, if the current block has a rectangular shape whose width is greater than the height of the current block, size_tu may be 2. If the current block has a rectangular shape whose height is larger than the width of the current block, If the current block has a square shape with the same width and height as the current block, size_tu may be zero.

It is easily understood by those skilled in the art that the height of the current block and the width of the width of the current block are used in the present embodiment, but not limited thereto, and can be determined based on log2_width and log2_height as in [Equation 21] have. It is to be noted that shape_tu is determined to be one of 0 to 2 in Equation (22), but it is not limited thereto and other values can be assigned, and the shape of the current block represented by each value can be easily changed I can understand.

If a is 4, b is 16, and e is 8, the size_tu for the first block 805 may be 3 and the size_tu for the third block 815 may be equal to 3.

The video decoding apparatus 100 can determine the same context model for the first block and the third block based on the size_tu0 even though the conversion coefficient tends to be distributed to a wider one of the height and the width of the current block. However, if the video decoding apparatus 100 determines the context models for the first block 805 and the third block 815 based on the shape_tu, the context models may be different from each other, and accordingly, the context model The efficiency of binary arithmetic decoding can be improved.

On the other hand, the video decoding apparatus 100 can determine the context model related to the transform coefficient based on the ratio between the minimum value and the maximum value of the current block calculated based on the minimum value size_tu1 and the maximum value size_tu2 of the height and width of the current block. For example, when the ratio between the minimum value and the maximum value is within a predetermined value range, the video decoding apparatus 100 may determine a context index corresponding to the range and determine a context model related to the transformation coefficient based on the determined context index have. For example, if the height of the current block is greater than the width, if the ratio between the minimum value (width) and the maximum value (height) is in the range between 1 and 2, the corresponding context index is determined, If the value of the ratio is in the range of 2 or more, the corresponding context index can be determined.

On the other hand, the video decoding apparatus 100 can determine the context model for the transform coefficients based on the shape and size of the current block. That is, the video decoding apparatus 100 can determine the context model for the transform coefficients based on the size of the current block and the shape of the current block.

The video decoding apparatus 100 determines a context index for a transform coefficient based on at least one of values size_tu1 and size_tu2 related to the size of a current block and a value shape_tu related to the shape of the current block and outputs the context model corresponding to the determined context index Can be determined.

9A to 9C are diagrams for explaining a residual coding syntax structure according to an embodiment.

9A to 9C, the video decoding apparatus 100 may scan the syntax element information about the transform coefficients to recover the transform coefficients, and may decode the transform coefficients based on the scanned syntax element information.

First, the video decoding apparatus 100 may obtain syntax element information scan_region_x and scan_region_y indicating coordinates for specifying a quadrangular scan region from a bitstream. At this time, the syntax element information scan_region_x may indicate the value of the horizontal direction (x-axis direction) coordinate of the effective transformation coefficient located at the rightmost position in the current block with reference to the upper left corner coordinate of the current block, and the syntax element information scan_region_y indicates (Y-axis direction) coordinate of the effective transformation coefficient located at the lowermost position in the current block with reference to the upper left corner coordinate of the block. The video decoding apparatus 100 can determine the coordinates srX and srY for specifying the scan area based on the syntax element information scan_region_x and scan_region_y.

The video decoding apparatus 100 can determine the scan order (ScanOrder (srX + 1, srY + 1)) based on the coordinates srX and srY for specifying the scan region.

The video decoding apparatus 100 may determine index information (lastSet) indicating a coefficient group to be scanned last in a forward scan order based on the coordinates srX and srY for specifying a scan region. That is, the video decoding apparatus 100 performs an operation (" 4 ") for bit-shifting the value of (srX + 1) * (srY + The index information (lastSet) of the coefficient group to be scanned can be determined. That is, the output value of the right shifting operation by 4 can be the same as the quotient determined by dividing by 16. That is, since the video decoding apparatus 100 determines one coefficient group for every 16 transform coefficients, if the total transform coefficient scanned in the scan region is divided by 16, the number of total coefficient groups (or the end of the forward scan order) A value obtained by adding 1 to an index value indicating a group of scanned coefficients) can be determined.

The video decoding apparatus 100 determines the position (lastScanPos) of the last scanned coefficient in the forward scan order based on the coordinates srX and srY for specifying the scan region and sets the position Pos of the current transformation coefficient as the forward scan The position of the last scanned coefficient in the sequence (lastScanPos) can be determined.

The video decoding apparatus 100 may initialize i to last set, reduce i by 1 if i is greater than 0, and perform the operations included in the loop statement (for statement) 905. [ The video decoding apparatus 100 may perform the operations included in the for-statement (for statement) 905 until the value becomes less than zero. In this case, i may be an index indicating a coefficient group. That is, the video decoding apparatus 100 may perform an operation on one coefficient group every time the operation included in the loop statement (for statement) 905 is performed.

The video decoding apparatus 100 can determine the setPos by performing an operation (i << 4) of multiplying i by 16. setPos can represent the index information of the transform coefficient located at the first position of the transform group.

The video decoding apparatus 100 determines n as 15 (lastScanPos-setPos) obtained by subtracting setPos from lastScanPos when i is the last coefficient group (i == lastSet) If greater than or equal to, i can be reduced by one and the operations contained in the loop statement (for statement) 910 can be performed. The video decoding apparatus 100 can perform the operation (sig_flag related operation) included in the forbidden statement (for statement) 910 until the value becomes less than zero. In this case, n may be index information indicating the position of the transform coefficient in the coefficient group according to the forward scan order.

For example, if the total number of transform coefficients included in the scan area is not an integer multiple of 16, the value obtained by subtracting setPos from lastScanPos for the last scanned coefficient group (i = last set) according to the forward scan is greater than zero Or equal to or less than 15, and the value thereof is determined as n, and a loop statement (for statement) 910 can be performed.

The video decoding apparatus 100 may determine the position (blkpos) of the current transform coefficient as a value obtained by adding n to the index information (setPos) indicating the position of the first coefficient of the current coefficient group in the ScanOrder array. The ScanOrder array may be an array indicating the position of the transform coefficients according to the forward scan order.

The video decoding apparatus 100 can determine the value sx of the coordinate in the horizontal direction (x-axis direction) currently scanned based on the position (blkpos) of the current transform coefficient and the width of the scan area. In addition, the video decoding apparatus 100 can determine the value sy of the coordinate in the vertical direction (y-axis direction) based on the position (blkpos) of the transform coefficient to be decoded and the width (log2width) of the scan area.

The video decoding apparatus 100 determines whether sx is 0, sy is srY, is_last_y is 0 (sx == 0 && sy == srY && is_last_y == 0), sy is 0, sx is srX, is_last_x 0), the video decoding apparatus 100 does not acquire the effective conversion coefficient flag sig_flag (sig_flag [blkpos]) for the current conversion coefficient from the bitstream, but does not acquire the current conversion coefficient flag sig_flag (sig_flag [blkpos] The value of sig_flag for the conversion coefficient can be determined as 1. [ Here, is_last_x may be a value indicating whether there is an effective transform coefficient whose absolute value is greater than 0 among the transform coefficients scanned before the current transform coefficient among the transform coefficients included in the lowermost row in the scan area. is_last_y may be a value indicating whether there is an effective transform coefficient whose absolute value is greater than 0 among the transform coefficients included in the rightmost column in the scan area and scanned before the current transform coefficient.

The video decoding apparatus 100 determines whether sy is 0, sy is srY, is_last_y is 0 (sx == 0 && sy == srY && is_last_y == 0), sy is 0, sx is srX, is_last_x is 0 (Sy == 0 && sx == srX && is_last_x == 0), the effective transform coefficient flag sig_flag [blkpos] for the transform coefficient to be decoded from the bit stream can be obtained.

The video decoding apparatus 100 sets is_last_x to 1 if the coordinate value sx in the x-axis direction of the current transform coefficient is equal to srX (sx == srX) when the effective transform coefficient flag sig_flag of the current transform coefficient is 1 , And if the coordinate value sy in the y-axis direction of the current transformation coefficient is equal to srY (sy == srY), then is_last_y can be set to 1.

In addition, the video decoding apparatus 100 may determine lastSigScanPos to be n if lastSigScanPos is -1 (i.e., initial value). That is, since the index n indicating the position where the first effective transform coefficient of the coefficient group exists in the backward scan order is determined by lastSigScanPos, lastSigScanPos is an index indicating the position where the last valid transform coefficient exists in the forward scan order coefficient group Information. On the other hand, the video decoding apparatus 100 can determine firstSigScanPos as n. If the effective conversion coefficient flag sig_flag of the current conversion coefficient is 1, the value of firstSigScanPos is updated to n, which is the index information indicating the position of the current conversion coefficient, so that the operation is performed on the conversion coefficients included in the specific coefficient group i The firstSigScanPos may be index information indicating a position where the first effective transform coefficient in the forward scan order coefficient group exists.

The video decoding apparatus 100 increases cnt_nz by one. That is, cnt_nz indicating the number of coefficients having a non-zero value in the current block (or scan area) is updated each time the current transform coefficient is an effective transform coefficient. In addition, the video decoding apparatus 100 increases cg_nz [i], which indicates the number of coefficients having non-zero values in the current coefficient group i, by one. That is, cg_nz [i] indicating the number of coefficients having a non-zero value in the current coefficient group i is updated every time the current transform coefficient is an effective transform coefficient.

  The video decoding apparatus 100 determines n as 15 (lastScanPos-setPos) obtained by subtracting setPos from lastScanPos when i is the last coefficient group (i == lastSet) If it is greater than or equal to i, i can be reduced by 1 and the operations included in the loop statement (for statement) 915 can be performed. The video decoding apparatus 100 may perform the operations (coeff_abs_level_greater1_flag and coeff_abs_level_greater2_flag related operations) included in the forbidden statement (for statement) 915 until the value becomes less than zero.

The video decoding apparatus 100 may determine the position (blkpos) of the current transform coefficient as a value obtained by adding n to the index information (setPos) indicating the position of the first coefficient of the current coefficient group in the ScanOrder array.

The video decoding apparatus 100 can obtain the absolute value abs_coef for the current transform coefficient based on the current transform coefficient information gt0 flag, gt1 flag, gt2 flag, remainining_abolute value level.

When the effective conversion coefficient flag (sig_flag [blkpos]) of the current conversion coefficient is 1, the video decoding apparatus 100 determines that the absolute value of the conversion coefficient among the conversion coefficients included in the previously scanned coefficient groups is a conversion The number of coefficients cnt_g1 and the number c1 of transform coefficients obtained from the bitstream of previously scanned transform coefficients obtained from coeff_abs_level_greater1_flag obtained from coeff_abs_level_greater_flag from the bit stream among the transform coefficients having an absolute value larger than 1 The video decoding apparatus 100 can obtain coeff_abs_level_greater1_flag [blkpos] for the current transform coefficient from the bitstream when the maximum number of transform coefficients is smaller than num_gt1. coeff_abs_level_greater1_flag may be a flag indicating whether the absolute value of the current transform coefficient is greater than one. The video decoding apparatus 100 can determine the flag gt1_flag (gt1flag [blkpos]) of the current transform coefficient based on coeff_abs_level_greater1_flag obtained from the bitstream.

The video decoding apparatus 100 can increase c1 by 1 when the value of the flag gt1_flag of the current transform coefficient is 1. If the flag gt1_flag of the current transform coefficient is 1, the value of c1 is increased by 1 and the value of c1 is updated. Therefore, when performing the loop operation (for statement) () on the next transform coefficients, The number of transform coefficients obtained by obtaining coeff_abs_level_greater1_flag from the bitstream among the previously scanned transform coefficients in the group.

When the effective conversion coefficient flag (sig_flag [blkpos]) of the current conversion coefficient is 1, the video decoding apparatus 100 determines that the absolute value of the conversion coefficient among the conversion coefficients in the previously scanned coefficient groups is greater than 2 The number cnt_g2 of the coefficients and the number c2 of transform coefficients obtained from the previously scanned bit stream in coeff_abs_level_greater2_flag is smaller than the sum of the coefficients cnt_g2 and cnt2 of the transform coefficients that can obtain coeff_abs_level_greater_flag from the bit stream among the transform coefficients having an absolute value of the coefficient greater than 2 If it is smaller than the maximum number num_gt2, the video decoding apparatus 100 can obtain coeff_abs_level_greater2_flag for the current transform coefficient from the bitstream. coeff_abs_level_greater2_flag may be a flag indicating whether the absolute value of the current transform coefficient is greater than two. The video decoding apparatus 100 can determine the flag gt2_flag of the current transform coefficient based on coeff_abs_level_greater2_flag obtained from the bitstream.

The video decoding apparatus 100 can increase the number c2 of the current gt2 flags by 1 when the value of the flag gt2_flag of the current conversion coefficient is 1. When the flag gt2_flag of the current transform coefficient is 1, the value of c2 is increased by 1 and the value of c2 is updated. Therefore, when performing the loop operation (for statement) () on the next transform coefficients, The number of transform coefficients obtained by obtaining coeff_abs_level_greater1_flag from the bitstream among the previously scanned transform coefficients in the group.

In addition, the video decoding apparatus 100 may determine that escapeDataPresent is set to 1. The escapeDataPresent may be information indicating that there is additional information (e.g., residual level absolute value information coeff_abs_level_remaining) to determine the value of the transform coefficient in the current transform group.

When the effective conversion coefficient flag (sig_flag [blkpos]) of the current conversion coefficient is 1, the video decoding apparatus 100 determines that the absolute value of the conversion coefficient among the conversion coefficients in the previously scanned coefficient groups is greater than 2 The number cnt_g2 of the coefficients and the number c2 of transform coefficients obtained from the previously scanned bit stream in coeff_abs_level_greater2_flag is smaller than the sum of the coefficients cnt_g2 and cnt2 of the transform coefficients that can obtain coeff_abs_level_greater_flag from the bit stream among the transform coefficients having an absolute value of the coefficient greater than 2 If it is not smaller than the maximum number num_gt2, the video decoding apparatus 100 can determine the escapeDataPresent to be 1. [

The video decoding apparatus 100 decodes the number of transform coefficients cnt_g1 having an absolute value of the transform coefficient among the transform coefficients included in the previously scanned coefficient groups greater than 1, When the sum of the number of transform coefficients c1 obtained from coeff_abs_level_greater1_flag is not smaller than num_gt1 which is the maximum number of transform coefficients capable of obtaining coeff_abs_level_greater_flag from the bit stream among the transform coefficients having an absolute value larger than 1, 100) can determine escapeDataPresent to be 1.

The video decoding apparatus 100 determines n as a value obtained by subtracting setPos from lastScanPos (lastScanPos-setPos) when i is the last coefficient group when escapeDataPresent is 1, and n is 15 And if n is greater than or equal to 0, i may be decreased by 1 and the operations contained in the loop statement (for statement) 920 may be performed. The video decoding apparatus 100 may perform an operation (an operation related to coeff_abs_level_reamining) included in the forbidden statement (for statement) 920 until the value becomes less than zero.

The video decoding apparatus 100 may determine the position (blkpos) of the current transform coefficient as a value obtained by adding n to the index information (setPos) indicating the position of the first coefficient of the current coefficient group in the ScanOrder array.

The video decoding apparatus 100 can determine the base level when the absolute value of the current transform coefficient is larger than 1 (sig_flag [blkpos]). Current transform coefficient in current coefficient group number of transform coefficients having an absolute value larger than 1 among transform coefficients scanned before cnt_gt1 coeff_abs_level_greater_flag can be obtained from a bit stream among transform coefficients having an absolute value larger than 2 Cnt_gt2 where the absolute value of the transform coefficients of the transform coefficients scanned prior to the current transform coefficient in the current coefficient group is greater than 2, when the absolute value of the transform coefficient is smaller than 2 The video decoding apparatus 100 can determine the base level to be 3 when the bit rate is smaller than the maximum number num_gt2 of conversion coefficients capable of obtaining coeff_abs_level_greater_flag from the bitstream. If cnt_gt1 is smaller than num_gt1 that can be obtained from the bitstream, the video decoding apparatus 100 can determine the base level to be 2 if cnt_gt2 is smaller than num_gt2. If cnt_gt1 is not smaller than num_gt1, the video decoding apparatus 100 can determine the base level to be 1.

The video decoding apparatus 100 can determine the absolute value level abs_coef of the current transform coefficient by adding 1 to the value obtained by adding the value of gt1flag and the value of gt2flag to the current transform coefficient. The video decoding apparatus 100 can obtain the residual absolute value level coeff_abs_level_remaining for the current transform coefficient from the bitstream if the absolute value of the current transform coefficient has the same value as the base level (abs_coef [blkpos] == base_level) . The video decoding apparatus 100 may determine the absolute value level abs_coef for the current transform coefficient by adding the residual absolute value level level_remaining to the current transform coefficient to abs_coef.

The video decoding apparatus 100 can increase cnt_gt2 by 1 if the absolute value level abs_coef for the current transform coefficient is greater than 2. Also, if the absolute value level abs_coef for the current transform coefficient is greater than 1, the video decoding apparatus 100 may increase cnt_gt1 by one.

If escapeDataPresent is 0, if i represents the last coefficient group (i == lastSet), n is determined by subtracting setPos from lastScanPos (lastScanPos-setPos), otherwise n is determined to be 15, If it is greater than or equal to i, then i may be reduced by one and the operations contained in the loop statement (for statement) 925 may be performed. The video decoding apparatus 100 may perform the operation (abs_coef related operation) contained in the forbidden statement (for statement) 925 until the value becomes less than zero. The index information (setPos) indicating the position of the first coefficient of the current coefficient group in the ScanOrder array can be determined by adding n to the index information (setPos).

The video decoding apparatus 100 can increase the cnt_gt2 by 1 if the effective conversion coefficient flag for the current conversion coefficient is 1 and abs_coef, which is an absolute value for the current conversion coefficient, is greater than or equal to 2. When the effective conversion coefficient flag for the current conversion coefficient is 1, if the absolute value abs_coef for the current conversion coefficient is greater than or equal to 1, cnt_gt1 can be increased by one.

When the difference between the position lastSigScanPos of the last effective transform coefficient in the current coefficient group i scanned in the forward scan order and the position firstSigScanPos of the first effective transform coefficient is greater than 3, the video decoding apparatus 100 determines that at least one The signHidden value (signHidden [i]) indicating that the sign of the sign is hidden is set to 1. If the difference between the position lastSigScanPos of the last effective transform coefficient in the current coefficient group scanned in the forward scan order and the position firstSigScanPos of the first effective transform coefficient is not greater than 3, the video decoding apparatus 100 determines that at least one The signHidden value (signHidden [i]) indicating that the sign of the signHidden is hidden can be determined as 0.

The video decoding apparatus 100 may initialize i to 0 and increment i by 1 if i is less than or equal to lateSet and perform the operations contained in the loop statement (for statement) 930. [ The video decoding apparatus 100 can perform the operations included in the forbidden statement (for statement) 930 until i becomes larger than lateSet. In this case, i may be an index indicating a coefficient group. That is, the video decoding apparatus 100 may perform an operation for one coefficient group every time the operation included in the loop statement (for statement) 930 is performed.

If rsp (residual sign prediction) is applied (rsp_apply),

The video decoding apparatus 100 determines n as 15 (lastScanPos-setPos) obtained by subtracting setPos from lastScanPos when i is the last coefficient group (i == lastSet) If it is greater than or equal to i, then i can be decreased by 1 and the operation contained in the loop statement (for statement) 935 can be performed. The video decoding apparatus 100 may perform the operations included in the forbidden statement (for statement) 935 until the value is less than zero.

The video decoding apparatus 100 may determine the position (blkpos) of the currently decoded transform coefficient as a value obtained by adding n to the index information setPos indicating the position of the first coefficient of the current coefficient group in the ScanOrder array according to the forward scan order .

If the position blkpos of the transform coefficient to be currently decoded is not rsp_pos, the video decoding apparatus 100 outputs information (sign [blkpos]) about the sign of the transform coefficient to be currently decoded if the sign of the transform coefficient is the position hidden_pos of the hidden transform coefficient, Can be determined by information hidden_sign on the sign of the hidden transform coefficient.

If the sign of the transform coefficient is not the position hidden_pos of the hidden transform coefficient, the video decoding apparatus 100 can obtain the information (sign [blkpos]) about the sign of the transform coefficient currently being decoded from the bit stream.

The video decoding apparatus 100 can obtain the information (sign_rsp [blkpos]) regarding the rsp code of the transform coefficient currently being decoded from the bitstream if the position blkpos of the transform coefficient to be currently decoded is rsp_pos.

If rsp is not applied, the video decoding apparatus 100 determines n to be a value obtained by subtracting setPos from lastScanPos (lastScanPos-setPos) if i is the last coefficient group (i == lastSet) And if n is greater than or equal to zero, i may be decremented by one and the operations contained in the loop statement (for statement) 940 may be performed. The video decoding apparatus 100 may perform the operation included in the forbidden statement (for statement) 940 until the value is less than zero.

The video decoding apparatus 100 may determine the position (blkpos) of the current transform coefficient as a value obtained by adding n to the index information setPos indicating the position of the first coefficient of the current coefficient group in the ScanOrder array according to the forward scan order.

If the value of the flag sign_data_hiding_enabled_flag indicating whether the value of the effective conversion coefficient flag of the current conversion coefficient is 1 and activating the hiding of the sign data is 0 or if there is no code hidden for the current group (! SignHidden [i]), Information (sign [blkpos]) concerning the sign of the current transform coefficient can be obtained from the bit stream when the position of the current transform coefficient in the current scan group is not the position of the first effective transform coefficient in the scan order.

9D to 9F are diagrams for explaining a residual coding syntax structure according to another embodiment.

9B to 9F, the video decoding apparatus 100 may scan the syntax element information about the transform coefficients to recover the transform coefficients, and may decode the transform coefficients based on the scanned syntax element information.

First, the video decoding apparatus 100 may obtain syntax element information last_sig_coeff_x and last_sig_coeff_y indicating coordinates for specifying a scan area from a bitstream. At this time, the syntax element information last_sig_coeff_x can represent the value of the horizontal direction (x-axis direction) coordinate of the effective transformation coefficient located last in the forward scan order based on the upper left corner coordinate of the current block, and the syntax element information last_sig_coeff_y may indicate the value of the vertical direction (y-axis direction) coordinate of the effective transformation coefficient positioned at the end in the current block according to the forward scan order based on the upper left corner coordinate of the current block. The video decoding apparatus 100 may determine the coordinates LastSigcoeffX and LastSigCoeffY for specifying the scan area based on the syntax element information last_sig_coeff_x and last_sig_coeff_y.

The video decoding apparatus 100 may initialize the position lastScanPos of the effective transformation coefficient located last in the forward scan order in the subblock to 16. The video decoding apparatus 100 may initialize the lastSubBlock indicating the sub-block in which the last valid transform coefficient is located according to the forward scan order in the sub-block. At this time, the initialized value may indicate the last sub-block of the current block scanned according to the forward scan order. That is, the lastSubBlock may be initialized to a value indicating the last sub-block among the sub-blocks scanned in the forward scan order based on the height and width of the current block.

The video decoding apparatus 100 performs an operation in the Do-while loop statement 950 when the position xC in the horizontal direction of the current coefficient is not LastSigcoeffX or the position yC in the vertical direction of the current coefficient is not LastSigcoeffY, If LastSigcoeffX and position yC in the vertical direction of the current coefficient is LastSigcoeffY, the operation in the do-while loop statement 950 may no longer be performed.

The video decoding apparatus 100 may determine the lastScanPos to be 16 and reduce the lastSubblock by 1 if lastScanPos is zero. That is, when the scan in one sub-block is completed (lastScanPos is 0) according to the reverse scan order, lastScanPos is initialized to 16 to scan the next sub-block according to the reverse scan order, the lastSubblock can be reduced by one. The video decoding apparatus 100 may scan the transform coefficients in the current subblock lastSubblock according to a reverse scan order while decrementing lastScanPos by one.

The video decoding apparatus 100 can determine the horizontal position xS and the vertical position yS of the current subblock. The video decoding apparatus 100 may determine the position of the current subblock based on the ScanOrder array determined according to a predetermined forward scan order with respect to the current block. That is, the video decoding apparatus 100 can determine the position of the current sub-block based on the height (log2height) and the width (log2width) of the current block, the scan index scanIdx indicating the predetermined scan order, and the value lastSubBlock indicating the current sub- have. Here, xS and yS may be positions of subblocks when treating subblocks as one pixel, rather than positions of actual subblocks. That is, the width and the height of the sub-block may be ignored, and the difference between the sub-block horizontal direction and the vertical direction between adjacent sub-blocks may be one.

In addition, the video decoding apparatus 100 can determine the horizontal direction position xC and the vertical direction position yC of the current transform coefficient based on the ScanOrder array determined in accordance with a predetermined forward scan order for the current subblock. That is, the video decoding apparatus 100 determines the height (log ₂ 4 = 2) and the width (log ₂ 4 = 2) of the current subblock, the scan index scanIdx indicating a predetermined scan order, ) And a value lastScanPos indicating the position of the current transform coefficient in the current subblock, the position (xC, yC) of the current transform coefficient can be determined.

The video decoding apparatus 100 will no longer perform the operation in the do-while loop statement 950 when the vertical direction position yC of the current transform coefficient is LastSigcoeffY, lastScanPos may be index information indicating the position of the last valid transform coefficient in the subblock including the last valid transform coefficient in the current block scanned in the forward scan order, and lastSubBlock may be index information indicating the position of the last valid transform coefficient in the current block And may be index information indicating a block.

The video decoding apparatus 100 may initialize i to lastSubBlock, reduce i by 1 if i is greater than 0, and perform the operations contained in the loop statement (for statement) 960. [ The video decoding apparatus 100 may perform the operation included in the forbidden statement (for statement) 960 until the value is less than zero. In this case, i may be an index indicating a coefficient group. That is, the video decoding apparatus 100 may perform an operation on one subblock each time the operation included in the loop statement (for statement) 960 is performed.

The video decoding apparatus 100 can determine the horizontal position xS and the vertical position yS of the current subblock.

The video decoding apparatus 100 refers to a sub-block having a value smaller than a value (lastSubBlock) indicating a sub-block in which the current effective transform coefficient is located, indicating a current sub-block, or a sub-block including a DC coefficient Quot; coded_sub_block_flag [xS] [yS] for the current subblock i can be obtained when the subblock has a value larger than the value (0). coded_sub_block_flag [xS] [yS] may be flag information indicating whether the coded_sub_block_flag [xS] [yS] includes at least one valid conversion coefficient in the current subblock i.

The video decoding apparatus 100 initializes n to lastScanPos-1 if the current subblock is the lastSubBlock including the last valid transform coefficient, otherwise initializes to 15 and if n is greater than or equal to 0 In this case, n can be reduced by 1, and the operation included in the loop (for statement) () can be performed. The video decoding apparatus 100 can perform the operations included in the loop statement (for statement) 960 until n becomes less than 0. Here, n is an index indicating the position of the current transform coefficient in the sub-block Lt; / RTI &gt; That is, the video decoding apparatus 100 can perform an operation on one coefficient group every time the operation included in the loop statement (for statement) () is performed once. That is, the video decoding apparatus 100 may perform an operation (operation related to sig_coeff_flag) for one subblock each time the operation included in the loop statement (for statement) 960 is performed.

The video decoding apparatus 100 can determine the positions xC and yC of the current transform coefficient n.

When the coded_sub_block_flag [xS] [yS] for the current sub-block is 1, n is greater than 0 or inferSbDcSigCoeffFlag is 0, the video decoding apparatus 100 sets the flag sig_coeff_flag [xC] [yC] Can be obtained from the stream. sig_coeff_flag [xC] [yC] may be a flag indicating whether the current conversion coefficient is an effective conversion coefficient.

If the value of sig_coeff_flag [xC] [yC] is 1, inferSbDcSigCoeffFlag can be determined to be 0.

The video decoding apparatus 100 initializes the value of the firstScanPos position of the transform coefficient scanned first in the current subblock according to the forward scan order and outputs the position of the transform coefficient scanned last in the current subblock according to the forward scan order You can initialize the value of lastSigScanPos. The video decoding apparatus 100 may initialize the value of numGreater1Flag indicating the number of Greater1Flag and initialize the value of the last position lastGreater1ScanPos at which Greater1Flag is acquired according to the forward scanning order.

The video decoding apparatus 100 can initialize cg_nz [i] indicating the number of non-zero transform coefficients in subblock i.

The video decoding apparatus 100 initializes n to 15. If n is greater than or equal to 0, n can be decreased by 1, and the operation within the loop statement (for statement) 965 can be performed until n is less than zero.

The video decoding apparatus 100 can determine the positions xC and Yc of the current transform coefficient n.

The video decoding apparatus 100 acquires coeff_level_greater1_flag [n] for the current transform coefficient n if numGreater1Flag is smaller than 8 when the effective transform coefficient flag sig_coeff_flag for the current transform coefficient is 1, and increases the value of numGreater1Flag by 1 . coeff_level_greater1_flag [n] may be flag information indicating whether the absolute value of the level of the conversion coefficient n is greater than one. The video decoding apparatus 100 can determine Greater1Flag [n] based on coeff_level_greater1_flag [n] d.

If the value of coeff_abs_level_greater_flag for the current transform coefficient is 1 and the value of lastreater1ScanPos is the initial value, the video decoding apparatus 100 can determine the lastGreater1ScanPos as the current transform coefficient position n in the current subblock. Therefore, lastGreater1ScanPos may be index information indicating the position of a coefficient having a value of coeff_abs_level_greater_flag positioned last in the current subblock according to the forward scan order. Otherwise (not the case where the value of coeff_abs_level_greater1_flag for the current transform coefficient is 1 and the value of lastreater1ScanPos is the initial value), and if coeff_abs_level_greater1_flag is 1, escapeDataPresent can be set to 1.

The video decoding apparatus 100 can determine escapeDataPresent to be 1 if numGreater1Flag is not smaller than 8.

The video decoding apparatus 100 may determine lastSigScanPos to be the current position n of the intra-subblock transform coefficient when the lastSigScanPos indicating the position of the effective transform coefficient located at the end in the current subblock has an initial value according to the forward scan order .

The video decoding apparatus 100 may determine firstSigScanPos, which indicates the position of the effective transform coefficient located first in the current subblock, as the current transform coefficient position n in the current subblock according to the forward scan order. If the effective conversion coefficient flag sig_coeff_flag [xC] [yC] of the current conversion coefficient is 1, the value of firstSigScanPos continues to be updated to n, which is the index information indicating the position of the current transform coefficient in the current subblock. The firstSigScanPos may be the index information indicating the position where the first effective transform coefficient exists in the subblock in the forward scan order.

The video decoding apparatus 100 may determine the sigHidden value to be 1 if the difference between lastSigScanPos and firstSigScanPos is greater than 3 and may determine the sigHidden value to be 0 if the difference between lastSigScanPos and firstSigScanPos is not greater than 3. In this case, sigHidden may be a value indicating that the sign of at least one transform coefficient is hidden for the current subblock.

If coeff_abs_level_greater1_flag of the coeff_abs_level_greater1_flag (Greater1Flag) for the transform coefficient obtained from the scanned bitstream according to the forward scan order is not the initial value (i.e., at least one Greater1Flag from the bitstream) Is obtained in the current subblock), the video decoding apparatus 100 can obtain the flag coeff_abs_level_greater2_flag [lastGreater1ScanPos] for the transform coefficient of the lastGreater1ScanPos position from the bitstream. coeff_abs_level_greater2_flag may be a flag indicating whether the absolute value of the transform coefficient is greater than two. If the value of the flag coeff_abs_level_greater2_flag [lastGreater1ScanPos] for the conversion coefficient at the lastGreater1ScanPos position is 1, the video decoding apparatus 100 can determine the escapeDataPresent to be 1. [ The video decoding apparatus 100 can determine Greater2Flag [n] based on coeff_level_greater2_flag [n].

The video decoding apparatus 100 can initialize numSigCoeff. In this case, numSigCoeff may mean the number of effective transform coefficients among the transform coefficients scanned before the current transform coefficient according to the reverse scan order.

The video decoding apparatus 100 initializes n to 15. If n is greater than or equal to 0, n is decreased by 1 and an operation within the for 970 is performed. If n is smaller than 0, the for decoding 970 ) My action may no longer be performed. The video decoding apparatus 100 may perform an operation of scanning information on the current intra-block transform coefficients in a backward scan order.

The video decoding apparatus 100 can determine the position xC, yC of the current transform coefficient based on the position n of the current transform coefficient in the current subblock.

When the value of the effective conversion coefficient flag sig_coeff_flag [xC] [yC] related to the current conversion coefficient is 1, the video decoding apparatus 100 sets the value of the flag coeff_abs_level_greater1_flag related to the current conversion coefficient, the value of the flag coeff_abs_level_greater2_flag You can determine baseLevel by adding the sum to the sum.

If numSigCoeff is less than 8 and the position n of the current transform coefficient is lastGreater1ScanPos, if the base level is 3, the video decoding apparatus 100 extracts the residual level value information coeff_abs_level_remaining [n] for the current transform coefficient n from the bitstream Can be obtained.

If numSigCoeff is less than 8 and the current position n of the transform coefficient is not lastGreater1ScanPos, if the base level is 2, the video decoding apparatus 100 extracts residual level value information coeff_abs_level_remaining [n Can be obtained. If numSigCoeff is greater than 8, if the base level is 1, the video decoding apparatus 100 may obtain the residual level value information coeff_abs_level_remaining [n] for the current transform coefficient n from the bitstream.

The video decoding apparatus 100 obtains the TransCoeffLevel [x0] [y0] [cIdx] [xC] [yC], which is the level value of the current transform coefficient in the current block, by summing the base level for the current transform coefficient and the residual level value for the current transform coefficient. Can be determined. Here, cIdx may be an index indicating a color component.

If i increases from 0 to 1, it can perform the operations contained in the forbidden statement (for statement) 975 until it becomes less than or equal to the value of lastSubBlock. In this case, i may be an index indicating a sub-block. That is, the video decoding apparatus 100 can perform an operation for one coefficient group every time the syntax in the for statement 975 is performed once.

If the flag coded_sub_block_flag [xS] [yS] for the current subblock i is 1 and rsp is applied (rsp_apply), the video decoding apparatus 100 determines n to be 15, and if n is greater than 0 If it is the same, the for statement (980) operation can be performed again if n is greater than or equal to 0 after performing the operation in the for statement (980) and decrementing n by 1. If n is less than 0, the operation in the for statement (980) may not be performed any more.

The video decoding apparatus 100 can determine the horizontal position and the vertical position xC and yC of the current transform coefficient corresponding to the position n of the current transform coefficient in the current subblock. The video decoding apparatus 100 can determine the position (blkpos) of the current transform coefficient based on xC and yC.

If the position blkpos of the current transform coefficient is not rsp_pos, the video decoding apparatus 100 can determine the sign of the current transform coefficient as the sign hidden_sign of the hidden transform coefficient if the code is the position hidden_pos of the transform coefficient hidden therein.

If not, the video decoding apparatus 100 can obtain the information sign [xC] [yC] concerning the sign of the current transform coefficient from the bitstream, if the code is not the position hidden_pos of the hidden transform coefficient.

The video decoding apparatus 100 can obtain the information sign_rsp [xC] [yC] regarding the rsp code of the current transform coefficient from the bit stream when the current transform coefficient position is rsp_pos.

If rsp is not applied, the video decoding apparatus 100 determines n to be 15. If n is greater than 0, the video decoding apparatus 100 performs the operation in the for statement (985), reduces n by 1, If greater than or equal to, the for statement (985) operation can be performed again, and if n is less than 0, the operation within the for statement (985) may no longer be performed.

The video decoding apparatus 100 can determine the horizontal position and the vertical position xC and yC of the current transform coefficient corresponding to the position n of the current transform coefficient in the current subblock. The video decoding apparatus 100 can determine the position (blkpos) of the current transform coefficient based on xC and yC.

If the value of the flag sign_data_hiding_enabled_flag indicating whether the value of the effective conversion coefficient flag sig_coeff_flag [xC] [yC] of the current conversion coefficient is 1 and activating the hiding of the sign data is 0, or if there is no hidden code for the current subblock (! SignHidden If the position of the current transform coefficient in the current sub-block in the forward scan order is not the first effective transform coefficient position firstSigScanPos is 0, the sign information sign [xC] [yC] of the current transform coefficient is calculated from the bit stream Can be obtained.

Hereinafter, a method of determining a data unit usable in the process of decoding a video by the video decoding apparatus 100 according to an embodiment will be described with reference to FIGS. 10 to 23. FIG. The operation of the video encoding apparatus 150 may be similar to or opposite to the various embodiments of the operation of the video decoding apparatus 100 described later.

FIG. 10 illustrates a process in which the video decoding apparatus 100 determines at least one encoding unit by dividing a current encoding unit according to an embodiment.

According to an embodiment, the video decoding apparatus 100 can determine the type of an encoding unit using block type information, and can determine a type of an encoding unit to be divided using the type information. That is, the division method of the coding unit indicated by the division type information can be determined according to which block type the block type information used by the video decoding apparatus 100 represents.

According to an embodiment, the video decoding apparatus 100 may use block type information indicating that the current encoding unit is a square type. For example, the video decoding apparatus 100 can determine whether to divide a square encoding unit according to division type information, vertically divide, horizontally divide, or divide into four encoding units. 10, if the block type information of the current encoding unit 1000 indicates a square shape, the video decoding apparatus 100 may calculate the size of the current encoding unit 1000 according to the division type information indicating that the current block is not divided, (1010b), 1010c (1010d, etc.) based on the division type information indicating the predetermined division method.

Referring to FIG. 10, the video decoding apparatus 100 determines two coding units 1010b obtained by dividing the current coding unit 1000 in the vertical direction based on division type information indicating division in the vertical direction according to an embodiment . The video decoding apparatus 100 can determine two coding units 1010c obtained by dividing the current coding unit 1000 in the horizontal direction based on the division type information indicating that the coding unit is divided in the horizontal direction. The video decoding apparatus 100 can determine four coding units 1010d obtained by dividing the current coding unit 1000 in the vertical direction and the horizontal direction based on the division type information indicating that the coding unit 1000 is divided in the vertical direction and the horizontal direction. However, the division type in which the square coding unit can be divided should not be limited to the above-mentioned form, but may include various forms in which the division type information can be represented. The predetermined divisional form in which the square encoding unit is divided will be described in detail by way of various embodiments below.

FIG. 11 illustrates a process in which the video decoding apparatus 100 determines at least one encoding unit by dividing an encoding unit in the form of a non-square according to an embodiment.

According to an exemplary embodiment, the video decoding apparatus 100 may use block type information indicating that the current encoding unit is a non-square format. The video decoding apparatus 100 can determine whether to divide the non-square current encoding unit according to the division type information or not in a predetermined method. 11, if the block type information of the current encoding unit 1100 or 1150 indicates a non-square shape, the video decoding apparatus 100 determines the current encoding unit 1100 or 1150 according to the division type information indicating that the current block is not divided 1130a, 1130b, 1130c, 1170a, 1130a, 1130a, 1130a, 1130a, 1130a, 1130a, 1130a, 1130a, 1130a, 1130a, 1130a, 1130a, 1170b, 1180a, 1180b, and 1180c. The predetermined division method in which the non-square coding unit is divided will be described in detail through various embodiments.

According to an embodiment, the video decoding apparatus 100 may determine a type in which a coding unit is divided using the division type information. In this case, the division type information indicates a number of at least one coding unit generated by dividing an encoding unit . 11, when the division type information indicates that the current encoding unit 1100 or 1150 is divided into two encoding units, the video decoding apparatus 100 determines the current encoding unit 1100 or 1150 based on the division type information, To determine two encoding units 1120a, 11420b, or 1170a and 1170b included in the current encoding unit.

When the video decoding apparatus 100 divides the current encoding unit 1100 or 1150 in the form of non-square based on the division type information according to an embodiment, the non-square current encoding unit 1100 or 1150 The current encoding unit can be divided in consideration of the position of the long side. For example, the video decoding apparatus 100 divides the current encoding unit 1100 or 1150 in the direction of dividing the long side of the current encoding unit 1100 or 1150 in consideration of the type of the current encoding unit 1100 or 1150 So that a plurality of encoding units can be determined.

According to an embodiment, when the division type information indicates division of an encoding unit into odd number of blocks, the video decoding apparatus 100 may determine an odd number of encoding units included in the current encoding unit 1100 or 1150. For example, when the division type information indicates that the current encoding unit 1100 or 1150 is divided into three encoding units, the video decoding apparatus 100 divides the current encoding unit 1100 or 1150 into three encoding units 1130a , 1130b, 1130c, 1180a, 1180b, 1180c. According to an embodiment, the video decoding apparatus 100 may determine an odd number of encoding units included in the current encoding unit 1100 or 1150, and the sizes of the determined encoding units may not be the same. For example, the size of a predetermined encoding unit 1130b or 1180b among the determined odd number of encoding units 1130a, 1130b, 1130c, 1180a, 1180b, and 1180c is different from that of other encoding units 1130a, 1130c, 1180a, and 1180c . That is, an encoding unit that can be determined by dividing the current encoding unit 1100 or 1150 may have a plurality of types of sizes, and an odd number of encoding units 1130a, 1130b, 1130c, 1180a, 1180b, May have different sizes.

According to an embodiment, when the division type information indicates that an encoding unit is divided into an odd number of blocks, the video decoding apparatus 100 can determine an odd number of encoding units included in the current encoding unit 1100 or 1150, The video decoding apparatus 100 may limit a coding unit of at least one of odd number of coding units generated by division. Referring to FIG. 11, the video decoding apparatus 100 includes an encoding unit 1130a, 1130b, 1130c, 1180a, 1180b, and 1180c generated by dividing a current encoding unit 1100 or 1150, 1130b, and 1180b may be different from the other encoding units 1130a, 1130c, 1180a, and 1180c. For example, in the video decoding apparatus 100, unlike the other encoding units 1130a, 1130c, 1180a, and 1180c, the encoding units 1130b and 1180b positioned at the center are restricted so as not to be further divided, It can be limited to be divided.

12 shows a process in which the video decoding apparatus 100 divides an encoding unit based on at least one of block type information and division type information according to an embodiment.

According to an embodiment, the video decoding apparatus 100 may determine to divide or not divide the first coding unit 1200 in units of coding units into coding units based on at least one of the block type information and the division type information. According to an embodiment, when the division type information indicates that the first encoding unit 1200 is divided in the horizontal direction, the video decoding apparatus 100 divides the first encoding unit 1200 in the horizontal direction, (1210). The first encoding unit, the second encoding unit, and the third encoding unit used according to an embodiment are terms used to understand the relation before and after the division between encoding units. For example, if the first encoding unit is divided, the second encoding unit can be determined, and if the second encoding unit is divided, the third encoding unit can be determined. Hereinafter, the relationship between the first coding unit, the second coding unit and the third coding unit used can be understood to be in accordance with the above-mentioned characteristic.

According to an embodiment, the video decoding apparatus 100 may determine that the determined second encoding unit 1210 is not divided or divided into encoding units based on at least one of the block type information and the division type information. 12, the video decoding apparatus 100 includes a second encoding unit 1210 of a non-square shape determined by dividing a first encoding unit 1200 based on at least one of block type information and division type information, It may be divided into at least one third encoding unit 1220a, 1220b, 1220c, 1220d, or the like, or the second encoding unit 1210 may not be divided. The video decoding apparatus 100 can acquire at least one of block type information and division type information and the video decoding apparatus 100 can acquire at least one of the first encoding unit 1200 The second encoding unit 1210 may divide a plurality of second encoding units (for example, 1210) of various types into a first encoding unit 1210 based on at least one of block type information and division type information, The unit 1200 can be divided according to the divided method. According to one embodiment, when the first encoding unit 1200 is divided into the second encoding units 1210 based on at least one of the block type information and the division type information for the first encoding unit 1200, The encoding unit 1210 may also be divided into a third encoding unit (e.g., 1220a, 1220b, 1220c, 1220d, etc.) based on at least one of block type information and division type information for the second encoding unit 1210 have. That is, an encoding unit can be recursively divided based on at least one of division type information and block type information associated with each encoding unit. Therefore, a square encoding unit may be determined in a non-square encoding unit, and a non-square encoding unit may be determined by dividing the square encoding unit recursively. Referring to FIG. 12, among the odd third encoding units 1220b, 1220c, and 1220d in which the non-square second encoding unit 1210 is divided and determined, predetermined encoding units (for example, An encoding unit or a square-shaped encoding unit) can be recursively divided. According to an exemplary embodiment, the third encoding unit 1220c in the form of a square, which is one of the odd numbered third encoding units 1220b, 1220c, and 1220d, may be divided in the horizontal direction and divided into a plurality of fourth encoding units. The non-square fourth encoding unit 1240, which is one of the plurality of fourth encoding units, may be further divided into a plurality of encoding units. For example, the non-square-shaped fourth encoding unit 1240 may be further divided into odd-numbered encoding units 1250a, 1250b, and 1250c.

A method which can be used for recursive division of an encoding unit will be described later in various embodiments.

According to one embodiment, the video decoding apparatus 100 divides each of the third encoding units 1220a, 1220b, 1220c, and 1220d into units of encoding based on at least one of block type information and division type information, It can be determined that the unit 1210 is not divided. The video decoding apparatus 100 may divide the second encoding unit 1210 in a non-square form into third encoding units 1220b, 1220c, and 1220d in an odd number according to an embodiment. The video decoding apparatus 100 may set a predetermined restriction on a predetermined third encoding unit among odd numbered third encoding units 1220b, 1220c, and 1220d. For example, the video decoding apparatus 100 may restrict the encoding unit 1220c located in the middle among the odd-numbered third encoding units 1220b, 1220c, and 1220d to no longer be divided, or be divided into a set number of times . 12, the video decoding apparatus 100 may include an encoding unit (not shown) located in the middle among the odd third encoding units 1220b, 1220c, and 1220d included in the second encoding unit 1210 in the non- 1220c may not be further divided or may be limited to being divided into a predetermined division type (for example, divided into four coding units or divided into a form corresponding to the divided form of the second coding unit 1210) (For example, dividing only n times, n > 0). The above restriction on the encoding unit 1220c positioned in the center is merely an example and should not be construed to be limited to the above embodiments and the encoding unit 1220c located in the center is not limited to the other encoding units 1220b and 1220d Quot;), &lt; / RTI &gt; which can be decoded differently.

According to an embodiment, the video decoding apparatus 100 can acquire at least one of the block type information and the division type information used for dividing the current encoding unit at a predetermined position in the current encoding unit.

FIG. 13 illustrates a method for the video decoding apparatus 100 to determine a predetermined encoding unit among an odd number of encoding units according to an embodiment. 13, at least one of the block type information and the division type information of the current encoding unit 1300 is a sample of a predetermined position among a plurality of samples included in the current encoding unit 1300 (for example, Sample 1340). However, the predetermined position in the current coding unit 1300 in which at least one of the block type information and the division type information can be obtained should not be limited to the middle position shown in FIG. 13, and the current coding unit 1300 (E.g., top, bottom, left, right, top left, bottom left, top right or bottom right, etc.) The video decoding apparatus 100 may determine that the current encoding unit is not divided or divided into the encoding units of various types and sizes by acquiring at least one of the block type information and the division type information obtained from the predetermined position.

According to an exemplary embodiment, when the current encoding unit is divided into a predetermined number of encoding units, the video decoding apparatus 100 may select one of the encoding units. The method for selecting one of the plurality of encoding units may be various, and description of these methods will be described later in various embodiments.

According to an embodiment, the video decoding apparatus 100 may divide the current encoding unit into a plurality of encoding units and determine a unit of encoding at a predetermined position.

FIG. 13 illustrates a method for the video decoding apparatus 100 to determine an encoding unit of a predetermined position among odd number of encoding units according to an embodiment.

According to an embodiment, the video decoding apparatus 100 may use information indicating positions of odd-numbered encoding units in order to determine an encoding unit located in the middle among odd-numbered encoding units. Referring to FIG. 13, the video decoding apparatus 100 may determine an odd number of encoding units 1320a, 1320b, and 1320c by dividing the current encoding unit 1300. FIG. The video decoding apparatus 100 may determine the center encoding unit 1320b using information on the positions of odd number of encoding units 1320a, 1320b, and 1320c. For example, the video decoding apparatus 100 determines the positions of the encoding units 1320a, 1320b, and 1320c based on information indicating the positions of predetermined samples included in the encoding units 1320a, 1320b, and 1320c, Can be determined. More specifically, the video decoding apparatus 100 decodes the coding units 1320a, 1320b, and 1320c based on information indicating the positions of the upper left samples 1330a, 1330b, and 1330c of the coding units 1320a, 1320b, By determining the position, the coding unit 1320b located in the center can be determined.

Information indicating the positions of the upper left samples 1330a, 1330b, and 1330c included in the coding units 1320a, 1320b, and 1320c according to an exemplary embodiment is a position in the picture of the coding units 1320a, 1320b, and 1320c Or information about the coordinates. Information indicating the positions of the upper left samples 1330a, 1330b, and 1330c included in the coding units 1320a, 1320b, and 1320c according to one embodiment is stored in the coding units 1320a and 1320b included in the current coding unit 1300 And 1320c, and the width or height may correspond to information indicating a difference between coordinates in the picture of the encoding units 1320a, 1320b, and 1320c. That is, the video decoding apparatus 100 can directly use the information on the position or the coordinates in the picture of the coding units 1320a, 1320b, and 1320c or the information on the width or height of the coding unit corresponding to the difference value between the coordinates The encoding unit 1320b located in the center can be determined.

The information indicating the position of the upper left sample 1330a of the upper coding unit 1320a may indicate the coordinates (xa, ya) and the upper left sample 1330b of the middle coding unit 1320b May represent the coordinates (xb, yb), and the information indicating the position of the upper left sample 1330c of the lower coding unit 1320c may indicate the coordinates (xc, yc). The video decoding apparatus 100 can determine the center encoding unit 1320b using the coordinates of the upper left samples 1330a, 1330b, and 1330c included in the encoding units 1320a, 1320b, and 1320c. For example, when the coordinates of the upper left samples 1330a, 1330b, and 1330c are sorted in ascending or descending order, the coding unit 1320b including the coordinates (xb, yb) of the sample 1330b positioned at the center, May be determined as a coding unit located in the middle of the coding units 1320a, 1320b, and 1320c determined by dividing the current coding unit 1300. [ However, the coordinates indicating the positions of the samples 1330a, 1330b, and 1330c in the upper left corner may indicate the coordinates indicating the absolute position in the picture, and the position of the upper left sample 1330a of the upper coding unit 1320a may be (Dxb, dyb), which is the information indicating the relative position of the sample 1330b at the upper left of the middle encoding unit 1320b, and the relative position of the sample 1330c at the upper left of the lower encoding unit 1320c Information dyn (dxc, dyc) coordinates may also be used. Also, the method of determining the coding unit at a predetermined position by using the coordinates of the sample as information indicating the position of the sample included in the coding unit should not be limited to the above-described method, and various arithmetic Should be interpreted as a method.

The video decoding apparatus 100 may divide the current encoding unit 1300 into a plurality of encoding units 1320a, 1320b, and 1320c and may convert the encoding units 1320a, 1320b, The encoding unit can be selected. For example, the video decoding apparatus 100 can select an encoding unit 1320b having a different size from among the encoding units 1320a, 1320b, and 1320c.

According to an embodiment, the video decoding apparatus 100 may be configured to include (xa, ya) coordinates, which is information indicating the position of the upper left sample 1330a of the upper encoding unit 1320a, (Xc, yc) coordinates, which is information indicating the position of the lower-stage coding unit 1330b and the position of the upper-left sample 1330c of the lower- stage coding unit 1320c, 1320b, and 1320c, respectively. The video decoding apparatus 100 encodes the encoding units 1320a, 1320b, and 1320c using the coordinates (xa, ya), (xb, yb), (xc, yc) indicating the positions of the encoding units 1320a, ) Can be determined.

According to one embodiment, the video decoding apparatus 100 can determine the width of the upper encoding unit 1320a as xb-xa and the height as yb-ya. According to an embodiment, the video decoding apparatus 100 can determine the width of the middle encoding unit 1320b as xc-xb and the height as yc-yb. The video decoding apparatus 100 may determine the width or height of the lower encoding unit using the width or height of the current encoding unit and the width and height of the upper encoding unit 1320a and the middle encoding unit 1320b . The video decoding apparatus 100 may determine an encoding unit having a different size from the other encoding units based on the widths and heights of the determined encoding units 1320a, 1320b, and 1320c. Referring to FIG. 13, the video decoding apparatus 100 may determine a coding unit 1320b as a coding unit at a predetermined position while having a size different from that of the upper coding unit 1320a and the lower coding unit 1320c. However, the process of the above-described video decoding apparatus 100 determining an encoding unit having a size different from that of the other encoding units may be the same as the process of determining an encoding unit at a predetermined position using the size of an encoding unit determined based on sample coordinates , Various processes may be used for determining the encoding unit at a predetermined position by comparing the sizes of the encoding units determined according to predetermined sample coordinates.

However, the position of the sample to be considered for determining the position of the coding unit should not be interpreted as being limited to the left upper end, and information about the position of any sample included in the coding unit can be interpreted as being available.

According to an embodiment, the video decoding apparatus 100 may select a coding unit at a predetermined position among the odd number of coding units in which the current coding unit is divided by considering the type of the current coding unit. For example, if the current coding unit is a non-square shape having a width greater than the height, the video decoding apparatus 100 can determine a coding unit at a predetermined position along the horizontal direction. That is, the video decoding apparatus 100 may determine one of the encoding units that are located in the horizontal direction and set a restriction on the encoding unit. If the current coding unit is a non-square shape having a height greater than the width, the video decoding apparatus 100 can determine a coding unit at a predetermined position in the vertical direction. That is, the video decoding apparatus 100 may determine one of the encoding units which are located in the vertical direction and limit the encoding unit.

According to an exemplary embodiment, the video decoding apparatus 100 may use information indicating positions of even-numbered encoding units to determine encoding units at predetermined positions among the even-numbered encoding units. The video decoding apparatus 100 can determine an even number of encoding units by dividing the current encoding unit and determine a encoding unit at a predetermined position using information on the positions of the even number of encoding units. A concrete procedure for this is omitted because it may be a process corresponding to a process of determining a coding unit of a predetermined position (for example, a middle position) among the above-mentioned odd number of coding units.

According to one embodiment, when a non-square current encoding unit is divided into a plurality of encoding units, in order to determine an encoding unit at a predetermined position among a plurality of encoding units, Can be used. For example, in order to determine a coding unit located in the middle among the coding units in which the current coding unit is divided into a plurality of coding units, the video decoding apparatus 100 may include block type information stored in a sample included in the middle coding unit, Information can be used.

13, the video decoding apparatus 100 may divide the current encoding unit 1300 into a plurality of encoding units 1320a, 1320b, and 1320c based on at least one of the block type information and the division type information, The encoding unit 1320b positioned in the middle of the plurality of encoding units 1320a, 1320b, and 1320c can be determined. Furthermore, the video decoding apparatus 100 may determine a coding unit 1320b positioned at the center in consideration of a position where at least one of the block type information and the division type information is obtained. That is, at least one of the block type information and the division type information of the current encoding unit 1300 can be acquired in the sample 1340 located in the middle of the current encoding unit 1300, and the block type information and the division type information If the current encoding unit 1300 is divided into a plurality of encoding units 1320a, 1320b, and 1320c based on at least one of the encoding units 1320a to 1320c and 1320c, You can decide. However, the information used for determining the coding unit located in the middle should not be limited to at least one of the block type information and the division type information, and various kinds of information may be used in the process of determining the coding unit located in the middle .

According to an embodiment, predetermined information for identifying a coding unit at a predetermined position may be obtained from a predetermined sample included in a coding unit to be determined. 13, the video decoding apparatus 100 includes a plurality of coding units 1320a, 1320b, and 1320c, which are determined by dividing the current coding unit 1300, and encoding units (for example, (For example, a sample located in the middle of the current encoding unit 1300) at a predetermined position in the current encoding unit 1300 in order to determine an encoding unit located in the middle of the encoding unit, And at least one of division type information. . That is, the video decoding apparatus 100 can determine the sample of the predetermined position in consideration of the block block type of the current encoding unit 1300, and the video decoding apparatus 100 determines that the current encoding unit 1300 is divided A coding unit 1320b including a sample from which predetermined information (for example, at least one of block type information and division type information) can be obtained is determined among a plurality of coding units 1320a, 1320b, and 1320c A predetermined limit can be set. Referring to FIG. 13, the video decoding apparatus 100 may determine a sample 1340 located in the middle of a current encoding unit 1300 as a sample from which predetermined information can be obtained, The coding unit 100 may limit the coding unit 1320b including the sample 1340 to a predetermined limit in the decoding process. However, the position of the sample from which predetermined information can be obtained can not be construed to be limited to the above-mentioned position, but can be interpreted as samples at arbitrary positions included in the encoding unit 1320b to be determined for limiting.

The position of a sample from which predetermined information can be obtained according to an embodiment may be determined according to the type of the current encoding unit 1300. According to one embodiment, the block type information can determine whether the current encoding unit is a square or a non-square, and determine the position of a sample from which predetermined information can be obtained according to the shape. For example, the video decoding apparatus 100 may use at least one of the information on the width of the current encoding unit and the information on the height, and may be located on a boundary that divides at least one of the width and the height of the current encoding unit by half The sample can be determined as a sample from which predetermined information can be obtained. In another example, when the video decoding apparatus 100 indicates that the block type information related to the current encoding unit is a non-square format, one of the samples adjacent to the boundary dividing the long side of the current encoding unit into half is divided into a predetermined Can be determined as a sample from which the information of &lt; / RTI &gt;

According to an exemplary embodiment, when the current encoding unit is divided into a plurality of encoding units, the video decoding apparatus 100 may determine at least one of the block type information and the division type information One can be used. According to an embodiment, the video decoding apparatus 100 can acquire at least one of the block type information and the division type information from a sample at a predetermined position included in an encoding unit, and the video decoding apparatus 100 determines whether the current encoding unit is divided And divide the generated plurality of coding units by using at least one of division type information and block type information obtained from samples at predetermined positions included in each of the plurality of coding units. That is, the coding unit can be recursively divided using at least one of the block type information and the division type information obtained in the sample at the predetermined position included in each of the coding units. Since the recursive division process of the encoding unit has been described with reference to FIG. 12, a detailed description will be omitted.

According to an embodiment, the video decoding apparatus 100 may determine at least one encoding unit by dividing the current encoding unit, and the order in which the at least one encoding unit is decoded is determined as a predetermined block (for example, ). &Lt; / RTI &gt;

FIG. 14 shows a sequence in which a plurality of coding units are processed when the video decoding apparatus 100 determines a plurality of coding units by dividing a current coding unit according to an embodiment.

According to an embodiment, the video decoding apparatus 100 divides the first encoding unit 1400 in the vertical direction according to the block type information and the division type information to determine the second encoding units 1410a and 1410b, 1450b, 1450c, and 1450d by dividing the first coding unit 1400 in the horizontal direction to determine the second coding units 1430a and 1430b or dividing the first coding unit 1400 in the vertical direction and the horizontal direction, Can be determined.

Referring to FIG. 14, the video decoding apparatus 100 may determine the order in which the second encoding units 1410a and 1410b determined by dividing the first encoding unit 1400 in the vertical direction are processed in the horizontal direction 1410c . The video decoding apparatus 100 may determine the processing order of the second encoding units 1430a and 1430b determined by dividing the first encoding unit 1400 in the horizontal direction as the vertical direction 1430c. The video decoding apparatus 100 processes the encoding units located in one row of the second encoding units 1450a, 1450b, 1450c, and 1450d determined by dividing the first encoding unit 1400 in the vertical direction and the horizontal direction (For example, a raster scan order or a z scan order 1450e) in which the encoding units located in the next row are processed.

According to an embodiment, the video decoding apparatus 100 may recursively divide encoding units. 14, the video decoding apparatus 100 may determine a plurality of encoding units 1410a, 1410b, 1430a, 1430b, 1450a, 1450b, 1450c, and 1450d by dividing the first encoding unit 1400, It is possible to recursively divide each of the determined plurality of encoding units 1410a, 1410b, 1430a, 1430b, 1450a, 1450b, 1450c, and 1450d. The method of dividing the plurality of encoding units 1410a, 1410b, 1430a, 1430b, 1450a, 1450b, 1450c, and 1450d may be a method corresponding to the method of dividing the first encoding unit 1400. [ Accordingly, the plurality of coding units 1410a, 1410b, 1430a, 1430b, 1450a, 1450b, 1450c, and 1450d may be independently divided into a plurality of coding units. Referring to FIG. 14, the video decoding apparatus 100 may determine the second encoding units 1410a and 1410b by dividing the first encoding unit 1400 in the vertical direction, and may further determine the second encoding units 1410a and 1410b Can be determined not to divide or separate independently.

The video decoding apparatus 100 may divide the left second encoding unit 1410a in the horizontal direction into the third encoding units 1420a and 1420b and the second encoding units 1410b ) May not be divided.

According to an embodiment, the processing order of the encoding units may be determined based on the division process of the encoding units. In other words, the processing order of the divided coding units can be determined based on the processing order of the coding units immediately before being divided. The video decoding apparatus 100 can determine the order in which the third coding units 1420a and 1420b determined by dividing the left second coding unit 1410a are processed independently of the second coding unit 1410b on the right side. The third coding units 1420a and 1420b may be processed in the vertical direction 1420c since the second coding units 1410a on the left side are divided in the horizontal direction and the third coding units 1420a and 1420b are determined. Since the order in which the left second encoding unit 1410a and the right second encoding unit 1410b are processed corresponds to the horizontal direction 1410c, the third encoding unit 1410a included in the left second encoding unit 1410a, The right encoding unit 1410b can be processed after the blocks 1420a and 1420b are processed in the vertical direction 1420c. The above description is intended to explain the process sequence in which encoding units are determined according to the encoding units before division. Therefore, it should not be construed to be limited to the above-described embodiments, It should be construed as being used in various ways that can be handled independently in sequence.

FIG. 15 illustrates a process of determining that the current encoding unit is divided into odd number of encoding units when the video decoding apparatus 100 can not process the encoding units in a predetermined order according to an embodiment.

According to an embodiment, the video decoding apparatus 100 may determine that the current encoding unit is divided into odd number of encoding units based on the obtained block type information and the division type information. Referring to FIG. 15, the first encoding unit 1500 in a square form may be divided into second non-square encoding units 1510a and 1510b, and the second encoding units 1510a and 1510b may be independently 3 encoding units 1520a, 1520b, 1520c, 1520d, and 1520e. According to an embodiment, the video decoding apparatus 100 may determine a plurality of third encoding units 1520a and 1520b by dividing the left encoding unit 1510a of the second encoding unit in the horizontal direction, May be divided into an odd number of third encoding units 1520c, 1520d, and 1520e.

According to one embodiment, the video decoding apparatus 100 determines whether or not the third encoding units 1520a, 1520b, 1520c, 1520d, and 1520e can be processed in a predetermined order and determines whether there are odd-numbered encoding units You can decide. Referring to FIG. 15, the video decoding apparatus 100 may recursively divide the first encoding unit 1500 to determine the third encoding units 1520a, 1520b, 1520c, 1520d, and 1520e. The video decoding apparatus 100 may further include a first coding unit 1500, a second coding unit 1510a and 1510b or a third coding unit 1520a, 1520b, 1520c, and 1520c based on at least one of block type information and division type information, 1520d, and 1520e may be divided into odd number of coding units among the divided types. For example, an encoding unit located on the right of the second encoding units 1510a and 1510b may be divided into odd third encoding units 1520c, 1520d, and 1520e. The order in which the plurality of coding units included in the first coding unit 1500 are processed may be a predetermined order (for example, a z-scan order 1530) 100 can determine whether the third encoding units 1520c, 1520d, and 1520e determined by dividing the right second encoding unit 1510b into odd numbers satisfy the condition that the third encoding units 1520c, 1520d, and 1520e can be processed according to the predetermined order.

According to an embodiment, the video decoding apparatus 100 satisfies a condition that third encoding units 1520a, 1520b, 1520c, 1520d, and 1520e included in the first encoding unit 1500 can be processed in a predetermined order And it is determined whether or not at least one of the width and the height of the second encoding units 1510a and 1510b is divided in half according to the boundaries of the third encoding units 1520a, 1520b, 1520c, 1520d, and 1520e . For example, the third coding units 1520a and 1520b determined by dividing the height of the left-side second coding unit 1510a in the non-square form by half are satisfied, but the right second coding unit 1510b is set to 3 Since the boundaries of the third encoding units 1520c, 1520d, and 1520e determined by dividing the number of encoding units 1520c, 1520d, and 1520e can not divide the width or height of the right second encoding unit 1510b in half, The video decoding apparatus 100 may determine that the condition is not satisfied and the video decoding apparatus 100 determines that the scanning order is disconnection in the case of such unsatisfactory condition and the right second encoding unit 1510b is based on the determination result It can be determined to be divided into odd number of encoding units. According to an exemplary embodiment, when the video decoding apparatus 100 is divided into odd-numbered coding units, the video decoding apparatus 100 may limit a coding unit of a predetermined position among the divided coding units. Since the embodiment has been described above, a detailed description thereof will be omitted.

16 illustrates a process in which the video decoding apparatus 100 determines at least one encoding unit by dividing a first encoding unit 1600 according to an embodiment. The video decoding apparatus 100 may divide the first encoding unit 1600 based on at least one of the block type information and the division type information acquired through the acquisition unit 110. [ The first encoding unit 1600 in the form of a square may be divided into four encoding units having a square shape or may be divided into a plurality of non-square encoding units. For example, referring to FIG. 16, when the block type information indicates that the first encoding unit 1600 is square and the division type information is divided into non-square encoding units, the video decoding apparatus 100 transmits the first encoding unit The encoding unit 1600 may be divided into a plurality of non-square encoding units. More specifically, when the division type information indicates that the first encoding unit 1600 is divided horizontally or vertically to determine an odd number of encoding units, the video decoding apparatus 100 includes a first encoding unit 1600 in the form of a square 1620b, and 1610c divided in the vertical direction as the odd number of coding units, or into the second coding units 1620a, 1620b, and 1620c determined by being divided in the horizontal direction.

According to an embodiment, the video decoding apparatus 100 may be configured such that the second encoding units 1610a, 1610b, 1610c, 1620a, 1620b, and 1620c included in the first encoding unit 1600 can be processed in a predetermined order And the condition is that at least one of the width and height of the first encoding unit 1600 is divided in half according to the boundaries of the second encoding units 1610a, 1610b, 1610c, 1620a, 1620b, and 1620c . 16, the boundaries of the second encoding units 1610a, 1610b, and 1610c, which are determined by dividing the first encoding unit 1600 in the vertical direction, are divided in half by the width of the first encoding unit 1600 The first encoding unit 1600 can be determined as not satisfying a condition that can be processed in a predetermined order. In addition, since the boundaries of the second encoding units 1620a, 1620b, and 1620c determined by dividing the first encoding unit 1600 in the horizontal direction into the horizontal direction can not divide the width of the first encoding unit 1600 in half, 1 encoding unit 1600 may be determined as not satisfying a condition that can be processed in a predetermined order. The video decoding apparatus 100 may determine that the scan sequence is disconnection in the case of such unsatisfactory condition and determine that the first encoding unit 1600 is divided into odd number of encoding units based on the determination result. According to an exemplary embodiment, when the video decoding apparatus 100 is divided into odd-numbered coding units, the video decoding apparatus 100 may limit a coding unit of a predetermined position among the divided coding units. Since the embodiment has been described above, a detailed description thereof will be omitted.

According to an embodiment, the video decoding apparatus 100 may determine the encoding units of various types by dividing the first encoding unit.

16, the video decoding apparatus 100 may divide a first coding unit 1600 in a square form and a first coding unit 1630 or 1650 in a non-square form into various types of coding units .

17 is a diagram illustrating a case where the second encoding unit is divided when the non-square second encoding unit determined by dividing the first encoding unit 1700 by the video decoding apparatus 100 satisfies a predetermined condition Lt; RTI ID = 0.0 &gt; limited. &Lt; / RTI &gt;

According to an embodiment, the video decoding apparatus 100 may convert a first encoded unit 1700 of a square form into a non-square format (e.g., a first encoded unit 1700) based on at least one of the block type information and the division type information acquired through the acquisition unit 105 It can be determined to divide it into the second encoding units 1710a, 1710b, 1720a, and 1720b. The second encoding units 1710a, 1710b, 1720a, and 1720b may be independently divided. Accordingly, the video decoding apparatus 100 determines whether to divide or not divide into a plurality of coding units based on at least one of the block type information and the division type information related to each of the second coding units 1710a, 1710b, 1720a, and 1720b . According to an embodiment, the video decoding apparatus 100 divides the left second encoding unit 1710a in the non-square form determined by dividing the first encoding unit 1700 in the vertical direction into the horizontal direction, 1712a, and 1712b. However, in the case where the left second encoding unit 1710a is divided in the horizontal direction, the right side second encoding unit 1710b is arranged in the horizontal direction in the same way as the direction in which the left second encoding unit 1710a is divided, As shown in Fig. When the right second encoding unit 1710b is divided in the same direction and the third encoding units 1714a and 1714b are determined, the left second encoding unit 1710a and the right second encoding unit 1710b are arranged in the horizontal direction The third encoding units 1712a, 1712b, 1714a, and 1714b can be determined by being independently divided. However, the video decoding apparatus 100 divides the first encoding unit 1700 into four square-shaped second encoding units 1730a, 1730b, 1730c, and 1730d based on at least one of the block type information and the division type information. And this may be inefficient in terms of image decoding.

According to an embodiment, the video decoding apparatus 100 divides the second encoding unit 1720a or 1720b in the non-square form determined by dividing the first encoding unit 11300 in the horizontal direction into the vertical direction, (1722a, 1722b, 1724a, 1724b). However, when one of the second coding units (for example, the upper second coding unit 1720a) is divided in the vertical direction, the video decoding apparatus 100 may generate a second coding unit (for example, Coding unit 1720b) can be restricted such that the upper second encoding unit 1720a can not be divided vertically in the same direction as the divided direction.

FIG. 18 illustrates a process in which the video decoding apparatus 100 divides a square-shaped encoding unit when the division type information can not be divided into four square-shaped encoding units according to an embodiment.

According to an embodiment, the video decoding apparatus 100 divides the first encoding unit 1800 based on at least one of the block type information and the division type information, and outputs the second encoding units 1810a, 1810b, 1820a, and 1820b You can decide. The division type information may include information on various types in which the coding unit can be divided, but information on various types may not include information for dividing into four square units of coding units. According to the division type information, the video decoding apparatus 100 can not divide the first encoding unit 1800 in the square form into the second encoding units 1830a, 1830b, 1830c, and 1830d in the form of four squares. Based on the division type information, the video decoding apparatus 100 can determine the second encoding units 1810a, 1810b, 1820a, and 1820b in the non-square form.

According to an embodiment, the video decoding apparatus 100 may independently divide the second encoding units 1810a, 1810b, 1820a, and 1820b in the non-square form. Each of the second encoding units 1810a, 1810b, 1820a, 1820b, and the like may be divided in a predetermined order through a recursive method, and the first encoding unit 1800 May be a partitioning method corresponding to a method in which a partition is divided.

For example, the video decoding apparatus 100 can determine the third encoding units 1812a and 1812b in the form of a square by dividing the left second encoding unit 1810a in the horizontal direction, and the right second encoding unit 1810b It is possible to determine the third encoding units 1814a and 1814b in the form of a square by being divided in the horizontal direction. Further, the video decoding apparatus 100 may divide the left second encoding unit 1810a and the right second encoding unit 1810b in the horizontal direction to determine the square-shaped third encoding units 1816a, 1816b, 1816c, and 1816d have. In this case, the encoding unit may be determined in the same manner as the first encoding unit 1800 is divided into the four second-type second encoding units 1830a, 1830b, 1830c, and 1830d.

 In another example, the video decoding apparatus 100 can determine the third encoding units 1822a and 1822b in the form of a square by dividing the upper second encoding unit 1820a in the vertical direction, and the lower second encoding units 1820b May be divided in the vertical direction to determine the third encoding units 1824a and 1824b in the form of a square. Further, the video decoding apparatus 100 may divide the upper second encoding unit 1820a and the lower second encoding unit 1820b in the vertical direction to determine the square-shaped third encoding units 1822a, 1822b, 1824a, and 1824b have. In this case, the encoding unit may be determined in the same manner as the first encoding unit 1800 is divided into the four second-type second encoding units 1830a, 1830b, 1830c, and 1830d.

FIG. 19 illustrates that the processing order among a plurality of coding units may be changed according to the division process of the coding unit according to an embodiment.

According to an embodiment, the video decoding apparatus 100 may divide the first encoding unit 1900 based on the block type information and the division type information. When the block type information indicates a square shape and the division type information indicates that the first encoding unit 1900 is divided into at least one of a horizontal direction and a vertical direction, the video decoding apparatus 100 includes a first encoding unit 1900 (For example, 1910a, 1910b, 1920a, 1920b, 1930a, 1930b, 1930c, 1930d, etc.) can be determined. Referring to FIG. 19, the non-square second encoding units 1910a, 1910b, 1920a, and 1920b, which are determined by dividing the first encoding unit 1900 only in the horizontal direction or the vertical direction, As shown in FIG. For example, the video decoding apparatus 100 divides the second encoding units 1910a and 1910b, which are generated by dividing the first encoding unit 1900 in the vertical direction, in the horizontal direction to generate third encoding units 1916a, 1916b, 1926c and 1916d can be determined and the second encoding units 1920a and 1920b generated by dividing the first encoding unit 1900 in the horizontal direction are divided in the horizontal direction and the third encoding units 1926a, 1926b, and 1926c , 1926d) can be determined. Since the process of dividing the second encoding units 1910a, 1910b, 1920a, and 1920b has been described in detail with reference to FIG. 17, a detailed description thereof will be omitted.

According to an embodiment, the video decoding apparatus 100 may process an encoding unit in a predetermined order. The features of the processing of the encoding unit in the predetermined order have been described in detail with reference to FIG. 14, and a detailed description thereof will be omitted. 19, the video decoding apparatus 100 divides a first encoding unit 1900 in a square form into four quadrangle-shaped third encoding units 1916a, 1916b, 1916c, 1916d, 1926a, 1926b, 1926c, and 1926d Can be determined. According to an embodiment, the video decoding apparatus 100 may process the third encoding units 1916a, 1916b, 1916c, 1916d, 1926a, 1926b, 1926c, and 1926d according to the form in which the first encoding unit 1900 is divided You can decide.

According to an embodiment, the video decoding apparatus 100 divides the second encoding units 1910a and 1910b generated in the vertical direction and divides them in the horizontal direction to determine the third encoding units 1916a, 1916b, 1916c, and 1916d And the video decoding apparatus 100 first processes the third encoding units 1916a and 1916b included in the left second encoding unit 1910a in the vertical direction and then processes the third encoding units 1916a and 1916b included in the right second encoding unit 1910b The third encoding units 1916a, 1916b, 1916c, and 1916d can be processed in accordance with the order 1917 of processing the third encoding units 1916c and 1916d in the vertical direction.

According to an embodiment, the video decoding apparatus 100 divides the second encoding units 1920a and 1920b generated in the horizontal direction into vertical directions to determine the third encoding units 1926a, 1926b, 1926c, and 1926d And the video decoding apparatus 100 first processes the third encoding units 1926a and 1926b included in the upper second encoding unit 1920a in the horizontal direction and then processes the third encoding units 1926a and 1926b included in the lower second encoding unit 1920b The third encoding units 1926a, 1926b, 1926c, and 1926d can be processed according to the order 1927 of processing the third encoding units 1926c and 1926d in the horizontal direction.

Referring to FIG. 19, the second encoding units 1910a, 1910b, 1920a, and 1920b are divided to determine the third encoding units 1916a, 1916b, 1916c, 1916d, 1926a, 1926b, 1926c, and 1926d, have. The second encoding units 1910a and 1910b determined to be divided in the vertical direction and the second encoding units 1920a and 1920b determined to be divided in the horizontal direction are divided into different formats, but the third encoding unit 1916a , 1916b, 1916c, 1916d, 1926a, 1926b, 1926c, and 1926d, the result is that the first encoding unit 1900 is divided into the same type of encoding units. Accordingly, the video decoding apparatus 100 recursively divides the encoding units through different processes based on at least one of the block type information and the division type information, thereby eventually determining the same type of encoding units, Lt; RTI ID = 0.0 &gt; units of &lt; / RTI &gt;

FIG. 20 illustrates a process of determining the depth of an encoding unit according to a change in type and size of an encoding unit when the encoding unit is recursively divided according to an embodiment to determine a plurality of encoding units.

According to an embodiment, the video decoding apparatus 100 may determine the depth of a coding unit according to a predetermined criterion. For example, a predetermined criterion may be a length of a long side of a coding unit. When the length of the long side of the current coding unit is divided by 2n (n > 0) times longer than the length of the long side of the coding unit before the current coding unit is divided, the depth of the current coding unit is smaller than the depth of the coding unit before being divided it can be determined that the depth is increased by n. Hereinafter, an encoding unit with an increased depth is expressed as a lower-depth encoding unit.

Referring to FIG. 20, on the basis of block type information (for example, block type information may indicate '0: SQUARE') indicating a square form according to an embodiment, the video decoding apparatus 100 generates a square 1 coding unit 2000 can be divided to determine the second coding unit 2002, the third coding unit 2004, etc. of the lower depth. If the size of the first encoding unit 2000 in the form of a square is 2Nx2N, the second encoding unit 2002 determined by dividing the width and height of the first encoding unit 2000 by 1/21 times may have a size of NxN have. Furthermore, the third encoding unit 2004 determined by dividing the width and height of the second encoding unit 2002 by a half size may have a size of N / 2xN / 2. In this case, the width and the height of the third encoding unit 2004 correspond to 1/22 of the first encoding unit 2000. When the depth of the first encoding unit 2000 is D, the depth of the second encoding unit 2002, which is 1/21 times the width and height of the first encoding unit 2000, may be D + 1, The depth of the third encoding unit 2004, which is one-22 times the width and height of the second encoding unit 2000, may be D + 2.

According to an exemplary embodiment, block type information indicating a non-square shape (for example, block type information is' 1: NS_VER 'indicating that the height is a non-square having a width greater than the width or' 2 &gt;: NS_HOR '), the video decoding apparatus 100 divides the first coding unit 2010 or 2020 in a non-square form to generate a second coding unit 2012 or 2022 of lower depth, The third encoding unit 2014 or 2024, or the like.

The video decoding apparatus 100 may determine a second encoding unit (e.g., 2002, 2012, 2022, etc.) by dividing at least one of the width and the height of the first encoding unit 2010 of Nx2N size. That is, the video decoding apparatus 100 can determine the second encoding unit 2002 of the NxN size or the second encoding unit 2022 of the NxN / 2 size by dividing the first encoding unit 2010 in the horizontal direction, The second encoding unit 2012 may be divided into the horizontal direction and the vertical direction to determine the second encoding unit 2012 of N / 2xN size.

According to an embodiment, the video decoding apparatus 100 divides at least one of the width and the height of the 2NxN-size first encoding unit 2020 to determine a second encoding unit (for example, 2002, 2012, 2022, etc.) It is possible. That is, the video decoding apparatus 100 can determine the second encoding unit 2002 of NxN size or the second encoding unit 2012 of N / 2xN size by dividing the first encoding unit 2020 in the vertical direction, The second encoding unit 2022 of the NxN / 2 size may be determined by dividing the image data in the horizontal direction and the vertical direction.

According to an embodiment, the video decoding apparatus 100 divides at least one of the width and the height of the second encoding unit 2002 of NxN size to determine a third encoding unit (for example, 2004, 2014, 2024, etc.) It is possible. That is, the video decoding apparatus 100 determines the third encoding unit 2004 of N / 2xN / 2 size by dividing the second encoding unit 2002 in the vertical direction and the horizontal direction, 3 encoding unit 2014 or a third encoding unit 2024 of N / 2xN / 22 size.

According to an embodiment, the video decoding apparatus 100 divides at least one of the width and the height of the second encoding unit 2012 of N / 2xN size, and encodes the third encoding unit (for example, 2004, 2014, 2024, . That is, the video decoding apparatus 100 divides the second encoding unit 2012 in the horizontal direction to generate a third encoding unit 2004 of N / 2xN / 2 or a third encoding unit 2024 of N / 2xN / 22 size ) Or may be divided into vertical and horizontal directions to determine a third encoding unit 2014 of N / 22xN / 2 size.

According to an embodiment, the video decoding apparatus 100 divides at least one of the width and the height of the second encoding unit 2014 of NxN / 2 size into a third encoding unit (e.g., 2004, 2014, 2024, etc.) . That is, the video decoding apparatus 100 divides the second encoding unit 2012 in the vertical direction to obtain a third encoding unit 2004 of N / 2xN / 2 or a third encoding unit 2014 of N / 22xN / 2 size ) Or may be divided into vertical and horizontal directions to determine a third encoding unit 2024 of N / 2xN / 22 size.

According to an embodiment, the video decoding apparatus 100 may divide a square-shaped encoding unit (for example, 2000, 2002, 2004) into a horizontal direction or a vertical direction. For example, the first encoding unit 2000 of the size 2Nx2N is divided in the vertical direction to determine the first encoding unit 2010 of the size Nx2N or the horizontal direction to determine the first encoding unit 2020 of 2NxN size . If the depth is determined based on the length of the longest side of the encoding unit according to one embodiment, the depth of the encoding unit in which the first encoding unit 2000, 2002, or 2004 of size 2Nx2N is divided in the horizontal direction or the vertical direction is determined May be the same as the depth of the first encoding unit (2000, 2002 or 2004).

According to one embodiment, the width and height of the third encoding unit 2014 or 2024 may correspond to 1/22 of the first encoding unit (2010 or 2020). When the depth of the first coding unit 2010 or 2020 is D, the depth of the second coding unit 2012 or 2014, which is half the width and height of the first coding unit 2010 or 2020, is D + 1 And the depth of the third coding unit 2014 or 2024 which is 1/22 times the width and height of the first coding unit 2010 or 2020 may be D + 2.

FIG. 21 illustrates a depth index (PID) for coding unit classification and depth that can be determined according to the type and size of coding units according to an exemplary embodiment.

According to an embodiment, the video decoding apparatus 100 may divide the first encoding unit 2100 in a square form to determine various types of second encoding units. 21, the video decoding apparatus 100 divides the first coding unit 2100 into at least one of a vertical direction and a horizontal direction according to the division type information, and outputs the second coding units 2102a, 2102b, 2104a, 2104b, 2106a, 2106b, 2106c, and 2106d. That is, the video decoding apparatus 100 can determine the second encoding units 2102a, 2102b, 2104a, 2104b, 2106a, 2106b, 2106c, and 2106d based on the division type information for the first encoding unit 2100. [

The second encoding units 2102a, 2102b, 2104a, 2104b, 2106a, 2106b, 2106c, and 2106d, which are determined according to the division type information for the first encoding unit 2100 in a square form, Depth can be determined based on. For example, since the length of one side of the first encoding unit 2100 in the square form is the same as the length of long sides of the second encoding units 2102a, 2102b, 2104a, and 2104b in the non-square form, 2100 and the non-square type second encoding units 2102a, 2102b, 2104a, and 2104b are denoted by D in the same manner. On the other hand, when the video decoding apparatus 100 divides the first encoding unit 2100 into four square-shaped second encoding units 2106a, 2106b, 2106c, and 2106d based on the division type information, The length of one side of the second encoding units 2106a, 2106b, 2106c and 2106d is one-half the length of one side of the first encoding unit 2100. Therefore, the depths of the second encoding units 2106a, 2106b, May be a depth of D + 1 that is one depth lower than D, which is the depth of the first encoding unit 2100.

According to an embodiment, the video decoding apparatus 100 divides a first coding unit 2110 having a height greater than a width in a horizontal direction according to the division type information, and generates a plurality of second coding units 2112a, 2112b, 2114a, 2114b, and 2114c. According to an embodiment, the video decoding apparatus 100 divides the first coding unit 2120 of a shape whose width is longer than a height in the vertical direction according to the division type information, and generates a plurality of second coding units 2122a, 2122b, 2124a, 2124b, and 2124c.

The second encoding units 2112a, 2112b, 2114a, 2114b, 2116a, 2116b, 2116c, and 2116d determined according to the division type information for the first encoding unit 2110 or 2120 in the non- The depth can be determined based on the length of the long side. For example, since the length of one side of the square-shaped second encoding units 2112a and 2112b is 1/2 times the length of one side of the non-square first encoding unit 2110 whose height is longer than the width, The depth of the second encoding units 2102a, 2102b, 2104a and 2104b in the form of D + 1 is one depth lower than the depth D of the first encoding unit 2110 in the non-square form.

Furthermore, the video decoding apparatus 100 may divide the non-square first encoding unit 2110 into odd second encoding units 2114a, 2114b, and 2114c based on the division type information. The odd number of second encoding units 2114a, 2114b and 2114c may include non-square second encoding units 2114a and 2114c and a square second encoding unit 2114b. In this case, the length of the longer sides of the non-square second encoding units 2114a and 2114c and the length of one side of the second encoding unit 2114b of the square shape are 1 / The depth of the second encoding units 2114a, 2114b and 2114c may be a depth of D + 1 which is one depth lower than the depth D of the first encoding unit 2110. [ The video decoding apparatus 100 is connected to the first encoding unit 2120 in the form of a non-square shape whose width is longer than the height in a manner corresponding to the scheme for determining the depths of the encoding units associated with the first encoding unit 2110 The depth of the encoding units can be determined.

According to an exemplary embodiment, the video decoding apparatus 100 determines an index (PID) for distinguishing divided coding units. If the odd-numbered coding units are not the same size, The index can be determined based on the index. 21, an encoding unit 2114b positioned at the center among the odd-numbered encoding units 2114a, 2114b, and 2114c has the same width as other encoding units 2114a and 2114c, May be two times as high as the height of the first and second electrodes 2114a and 2114c. That is, in this case, the coding unit 2114b positioned at the center may include two of the other coding units 2114a and 2114c. Accordingly, if the index (PID) of the coding unit 2114b positioned at the center is 1 according to the scanning order, the coding unit 2114c positioned next to the coding unit 2114c may be three days in which the index is increased by two. That is, there may be a discontinuity in the value of the index. According to an embodiment, the video decoding apparatus 100 may determine whether odd-numbered encoding units are not the same size based on the presence or absence of an index discontinuity for distinguishing between the divided encoding units.

According to an embodiment, the video decoding apparatus 100 may determine whether the video decoding apparatus 100 is divided into a specific division type based on a value of an index for identifying a plurality of coding units divided and determined from the current coding unit. 21, the video decoding apparatus 100 divides a rectangular first encoding unit 2110 having a height greater than the width to determine even-numbered encoding units 2112a and 2112b or odd-numbered encoding units 2114a and 2114b , 2114c can be determined. The video decoding apparatus 100 may use an index (PID) indicating each coding unit in order to identify each of the plurality of coding units. According to one embodiment, the PID may be obtained at a sample of a predetermined position of each coding unit (e.g., the upper left sample).

According to an embodiment, the video decoding apparatus 100 may determine a coding unit at a predetermined position among the coding units divided and determined using an index for classifying a coding unit. According to an embodiment, when the division type information for the rectangular first type encoding unit 2110 whose height is longer than the width is divided into three encoding units, the video decoding apparatus 100 transmits the first encoding unit 2110 It can be divided into three encoding units 2114a, 2114b, and 2114c. The video decoding apparatus 100 can assign an index to each of the three encoding units 2114a, 2114b, and 2114c. The video decoding apparatus 100 may compare the indexes of the respective encoding units in order to determine the middle encoding unit among the encoding units divided into odd numbers. The video decoding apparatus 100 encodes an encoding unit 2114b having an index corresponding to a middle value among indices based on indexes of encoding units into an encoding unit 2114b encoding an intermediate position among encoding units determined by dividing the first encoding unit 2110 Can be determined as a unit. According to an embodiment, the video decoding apparatus 100 may determine an index based on a size ratio between coding units when the coding units are not the same size in determining the index for dividing the divided coding units . 21, the coding unit 2114b generated by dividing the first coding unit 2110 is divided into coding units 2114a and 2114c having the same width as the coding units 2114a and 2114c but different in height Can be double the height. In this case, if the index (PID) of the coding unit 2114b positioned at the center is 1, the coding unit 2114c located next to the coding unit 2114c may be three (3) In this case, if the index increases uniformly and the increment increases, the video decoding apparatus 100 may determine that the encoding unit is divided into a plurality of encoding units including encoding units having different sizes from other encoding units. , The video decoding apparatus 100 determines that the encoding unit (for example, the middle encoding unit) at a predetermined position among the odd number of encoding units has a format different from that of the other encoding units The current encoding unit can be divided into. In this case, the video decoding apparatus 100 may determine an encoding unit having a different size by using an index (PID) for the encoding unit. However, the index and the size or position of the encoding unit at a predetermined position to be determined are specific for explaining an embodiment, and thus should not be construed to be limited thereto, and various indexes, positions and sizes of encoding units can be used Should be interpreted.

According to an embodiment, the video decoding apparatus 100 may use a predetermined data unit in which recursive division of an encoding unit starts.

22 shows that a plurality of coding units are determined according to a plurality of predetermined data units included in a picture according to an embodiment.

According to an exemplary embodiment, a predetermined data unit may be defined as a data unit in which an encoding unit starts to be recursively segmented using at least one of block type information and partition type information. That is, it may correspond to a coding unit of the highest depth used in the process of determining a plurality of coding units for dividing the current picture. Hereinafter, such a predetermined data unit is referred to as a reference data unit for convenience of explanation.

According to one embodiment, the reference data unit may represent a predetermined size and shape. According to one embodiment, the reference encoding unit may comprise samples of MxN. Here, M and N may be equal to each other, or may be an integer represented by a multiplier of 2. That is, the reference data unit may represent a square or a non-square shape, and may be divided into an integer number of encoding units.

According to an embodiment, the video decoding apparatus 100 may divide the current picture into a plurality of reference data units. According to an embodiment, the video decoding apparatus 100 may divide a plurality of reference data units for dividing a current picture into pieces using division information for each reference data unit. The segmentation process of the reference data unit may correspond to the segmentation process using a quad-tree structure.

According to an embodiment, the video decoding apparatus 100 may determine in advance the minimum size that the reference data unit included in the current picture can have. Accordingly, the video decoding apparatus 100 can determine reference data units of various sizes having sizes equal to or larger than a minimum size, and determine at least one coding unit using block type information and division type information based on the determined reference data unit You can decide.

22, the video decoding apparatus 100 may use a reference encoding unit 2200 in a square form or a reference encoding unit 2202 in a non-square form. According to an exemplary embodiment, the type and size of the reference encoding unit may include various data units (e.g., a sequence, a picture, a slice, a slice segment a slice segment, a maximum encoding unit, and the like).

According to an embodiment, the obtaining unit 105 of the video decoding apparatus 100 may obtain at least one of the information on the type of the reference encoding unit and the size of the reference encoding unit from the bit stream for each of the various data units have. The process of determining at least one encoding unit included in the reference-type encoding unit 2200 in the form of a square is described in detail in the process of dividing the current encoding unit 300 of FIG. 10, and the non- Is determined in the process of dividing the current encoding unit 1100 or 1150 of FIG. 11, so that a detailed description thereof will be omitted.

In order to determine the size and type of the reference encoding unit according to a predetermined data unit predetermined based on a predetermined condition, the video decoding apparatus 100 may include an index for identifying the size and type of the reference encoding unit Can be used. That is, the acquiring unit 105 acquires from the bitstream a predetermined condition (for example, a data unit having a size equal to or smaller than a slice) among the various data units (e.g., sequence, picture, slice, slice segment, ), It is possible to obtain only an index for identification of the size and type of the reference encoding unit for each slice, slice segment, maximum encoding unit, and the like. The video decoding apparatus 100 can determine the size and type of the reference data unit for each data unit satisfying the predetermined condition by using the index. When the information on the type of the reference encoding unit and the information on the size of the reference encoding unit are obtained from the bitstream for each relatively small data unit and used, the use efficiency of the bitstream may not be good. Therefore, Information on the size of the reference encoding unit and information on the size of the reference encoding unit can be acquired and used. In this case, at least one of the size and the type of the reference encoding unit corresponding to the index indicating the size and type of the reference encoding unit may be predetermined. That is, the video decoding apparatus 100 selects at least one of the size and the type of the reference encoding unit included in the data unit that is the basis of the index acquisition by selecting at least one of the size and the shape of the predetermined reference encoding unit You can decide.

According to an exemplary embodiment, the video decoding apparatus 100 may use at least one reference encoding unit included in one maximum encoding unit. That is, the maximum encoding unit for dividing an image may include at least one reference encoding unit, and the encoding unit may be determined through a recursive division process of each reference encoding unit. According to an exemplary embodiment, at least one of the width and the height of the maximum encoding unit may correspond to at least one integer multiple of the width and height of the reference encoding unit. According to an exemplary embodiment, the size of the reference encoding unit may be a size obtained by dividing the maximum encoding unit n times according to a quadtree structure. That is, the video decoding apparatus 100 may determine the reference encoding unit by dividing the maximum encoding unit n times according to the quad tree structure, and may determine the reference encoding unit based on at least one of the block type information and the division type information As shown in FIG.

23 shows a processing block serving as a reference for determining a determination order of the reference encoding units included in the picture 2300 according to an embodiment.

According to one embodiment, the video decoding apparatus 100 may determine at least one processing block that divides a picture. The processing block is a data unit including at least one reference encoding unit for dividing an image, and at least one reference encoding unit included in the processing block may be determined in a specific order. That is, the order of determination of at least one reference encoding unit determined in each processing block may correspond to one of various kinds of order in which the reference encoding unit can be determined, and the reference encoding unit determination order determined in each processing block May be different for each processing block. The order of determination of the reference encoding unit determined for each processing block is a raster scan, a Z scan, an N scan, an up-right diagonal scan, a horizontal scan a horizontal scan, and a vertical scan. However, the order that can be determined should not be limited to the scan orders.

According to an embodiment, the video decoding apparatus 100 may obtain information on the size of the processing block to determine the size of the at least one processing block included in the image. The video decoding apparatus 100 may obtain information on the size of the processing block from the bitstream to determine the size of the at least one processing block included in the image. The size of such a processing block may be a predetermined size of a data unit represented by information on the size of the processing block.

According to an embodiment, the obtaining unit 105 of the video decoding apparatus 100 may obtain information on the size of the processing block from the bitstream for each specific data unit. For example, information on the size of a processing block can be obtained from a bitstream in units of data such as an image, a sequence, a picture, a slice, a slice segment, and the like. That is, the obtaining unit 105 may obtain information on the size of the processing block from the bitstream for each of the plurality of data units, and the video decoding apparatus 100 divides the picture using information on the size of the obtained processing block The size of the at least one processing block may be determined, and the size of the processing block may be an integer multiple of the reference encoding unit.

According to one embodiment, the video decoding apparatus 100 may determine the size of the processing blocks 2302 and 2312 included in the picture 2300. For example, the video decoding apparatus 100 may determine the size of the processing block based on information on the size of the processing block obtained from the bitstream. Referring to FIG. 23, the video decoding apparatus 100 according to an exemplary embodiment of the present invention has a horizontal size of the processing blocks 2302 and 2312 of four times the horizontal size of the reference encoding unit, a vertical size of four times the vertical size of the reference encoding unit You can decide. The video decoding apparatus 100 may determine an order in which at least one reference encoding unit is determined in at least one processing block.

According to one embodiment, the video decoding apparatus 100 may determine each of the processing blocks 2302 and 2312 included in the picture 2300 based on the size of the processing block, and may include in the processing blocks 2302 and 2312 The determination order of at least one reference encoding unit is determined. The determination of the reference encoding unit may include determining the size of the reference encoding unit according to an embodiment.

According to an embodiment, the video decoding apparatus 100 may obtain information on a determination order of at least one reference encoding unit included in at least one processing block from a bitstream, So that the order in which at least one reference encoding unit is determined can be determined. The information on the decision order can be defined in the order or direction in which the reference encoding units are determined in the processing block. That is, the order in which the reference encoding units are determined may be independently determined for each processing block.

According to an embodiment, the video decoding apparatus 100 may acquire information on a determination order of a reference encoding unit from a bitstream for each specific data unit. For example, the acquiring unit 105 can acquire information on the order of determination of the reference encoding unit from a bitstream for each data unit such as an image, a sequence, a picture, a slice, a slice segment, and a processing block. Since the information on the determination order of the reference encoding unit indicates the reference encoding unit determination order in the processing block, the information on the determination order can be obtained for each specific data unit including an integer number of processing blocks.

The video decoding apparatus 100 may determine at least one reference encoding unit based on the determined order according to an embodiment.

According to one embodiment, the acquiring unit 105 may acquire information on the reference encoding unit determination order from the bitstream as information related to the processing blocks 2302 and 2312, and the video decoding apparatus 100 may acquire information It is possible to determine the order of determining at least one reference encoding unit included in the pictures 2302 and 2312 and determine at least one reference encoding unit included in the picture 2300 according to the determination order of the encoding units. Referring to FIG. 23, the video decoding apparatus 100 can determine the determination order 2304 and 2314 of at least one reference encoding unit associated with each processing block 2302 and 2312. For example, when information on a determination order of reference encoding units is obtained for each processing block, the reference encoding unit determination order associated with each processing block 2302, 2312 may be different for each processing block. When the reference encoding unit determination order 2304 related to the processing block 2302 is a raster scan order, the reference encoding unit included in the processing block 2302 can be determined according to the raster scan order. On the other hand, when the reference encoding unit determination order 2314 related to the other processing block 2312 is in the reverse order of the raster scan order, the reference encoding unit included in the processing block 2312 can be determined according to the reverse order of the raster scan order.

The video decoding apparatus 100 may decode the determined at least one reference encoding unit according to an embodiment. The video decoding apparatus 100 can decode an image based on the reference encoding unit determined through the above-described embodiment. The method of decoding the reference encoding unit may include various methods of decoding the image.

According to an embodiment, the video decoding apparatus 100 may obtain block type information indicating a type of a current encoding unit or division type information indicating a method of dividing a current encoding unit from a bitstream. The block type information or the division type information may be included in a bitstream related to various data units. For example, the video decoding apparatus 100 may include a sequence parameter set, a picture parameter set, a video parameter set, a slice header, a slice segment header slice segment type information included in the segment header can be used. Further, the video decoding apparatus 100 may obtain a syntax corresponding to the maximum encoding unit, the reference encoding unit, and the block type information or the division type information from the bitstream for each processing block, from the bitstream.

Various embodiments have been described above. It will be understood by those skilled in the art that the present disclosure may be embodied in various forms without departing from the essential characteristics of the present disclosure. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present disclosure is set forth in the appended claims rather than the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present disclosure.

Meanwhile, the above-described embodiments of the present disclosure can be implemented in a general-purpose digital computer that can be created as a program that can be executed by a computer and operates the program using a computer-readable recording medium. The computer-readable recording medium includes a storage medium such as a magnetic storage medium (e.g., ROM, floppy disk, hard disk, etc.), optical reading medium (e.g., CD ROM,

Claims (15)

1. Determining a scan area including all effective transform coefficients in a current block;

   Scanning the information about the in-scan conversion coefficients according to a predetermined scanning order;

   Performing binary arithmetic decoding based on information on the scanned transform coefficients to generate binary arithmetic decoded information;

   Performing inverse binarization on the binary arithmetic decoding information to obtain information on transform coefficients of the current block;

   Generating a residual block of a current block by performing inverse quantization and inverse transform based on information on transform coefficients of the current block; And

   And reconstructing a current block based on the generated residual block,

   Wherein the binary arithmetic decoding is performed using a context model determined based on at least one of a size and a shape of the current block.
2. The method according to claim 1,

   Wherein the rectangular scan area includes all effective transformation coefficients in the current block,

   Wherein the remaining region in the current block excluding the quadrangular scan region includes only &lt; RTI ID = 0.0 &gt; 0 &lt; / RTI &gt;
3. The method according to claim 1,

   Wherein the scan area is a rectangular scan area,

   The step of determining the scan area

   Obtaining information on coordinates specifying the quadrangular scan area from a bitstream; And

   And determining a rectangular scan area of the current intra-block transform coefficient based on information about coordinates specifying the rectangular scan area,

   A horizontal direction coordinate specifying the quadrangular scan area indicates a coordinate of an effective transformation coefficient pixel located at the rightmost position in the current block,

   Wherein the vertical coordinate specifying the quadrangular scan area indicates the coordinates of the effective transformation coefficient pixel located at the lowermost part in the current block,

   Wherein flag information indicating whether or not the rectangular scan area includes a difference between horizontal and vertical coordinate values specifying the rectangular scan area is included in the bit stream,

   The information on the coordinates specifying the quadrangular scan area is

   When the flag information indicates that the difference between the horizontal and vertical coordinate values specifying the rectangular scan area is included,

   Information indicating coordinates of one of a horizontal direction coordinate of a pixel of an effective transformation coefficient located at the rightmost position in the current block and a vertical direction coordinate of a pixel of an effective transformation coefficient located at the lowermost position in the current block, And information indicating a difference between the coordinates of the one direction and the coordinates of the remaining direction.
4. The method according to claim 1,

   Wherein the size of the current block is determined based on at least one of a minimum value and a maximum value of a height and a width of the current block,

   Wherein the shape of the current block is determined based on whether the height and width of the current block are the same or whether the height is greater than the width or the width is greater than the height.
5. The method according to claim 1,

   Wherein the step of determining a scan area including all transform coefficients in the current block comprises:

   Generating a swapped current block by swapping horizontal and vertical coordinates indicating the positions of transform coefficients in the current block when the height and width of the current block are different from each other; And

   Determining a scan area containing all the effective transform coefficients in the swapped current block,

   Wherein the step of determining a scan area including all effective transform coefficients in the swapped current block comprises:

   Wherein when the current block has a different height and width, the controller swaps the horizontal coordinate and the vertical coordinate specifying the scan region to each other, and based on the swapped horizontal and vertical coordinates, And determining a scan area.
6. 6. The method of claim 5,

   Wherein the bit stream includes information indicating whether or not the bit stream includes flag information indicating whether or not the difference between the horizontal and vertical coordinate values specifying the scan area includes a difference and coordinates information specifying the scan area,

   The information on the coordinates specifying the scan area includes information on the horizontal direction coordinates specifying the scan area and information on the vertical direction coordinates,

   When the flag information indicates that the difference between the horizontal and vertical coordinate values specifying the rectangular scan area is included,

   The information on the horizontal direction coordinate specifying the scan area and the information on the vertical direction coordinate are information indicating coordinates in one of the horizontal direction coordinate and the vertical direction coordinate and information indicating coordinates in the other direction The information indicating the difference between the coordinates related to the coordinates,

   Wherein the step of determining a scan area including all effective transform coefficients in the swapped current block comprises:

   If the height and width of the current block are different,

   Swap horizontal coordinate and vertical coordinate obtained from information on the coordinates specifying the scan area, and determine the scan area based on the swapped horizontal and vertical coordinates And decoding the video data.
7. The method according to claim 1,

   The context model related to the flag information of the current transform coefficient among the context models includes a size of the scan region, a count of counts that are scanned before the current transform coefficient in a predetermined scan order in the scan region, Whether or not the current effective transform coefficient is a first transform coefficient among the transform coefficients scanned according to the predetermined scan order in the scan area, Decoding method.
8. 8. The method of claim 7,

   When the context model related to the flag information of the current transform coefficient is determined based on the size of the scan area and the number of flag information of the transform coefficient scanned before the current coefficient according to the predetermined scan order,

   A context model for flag information of the current transform coefficient based on a predetermined context offset corresponding to a case where the number of flag information of the transform coefficient scanned before the current coefficient is smaller than a predetermined value based on the size of the scan area, Is determined.
9. 8. The method of claim 7,

   When the context model related to the flag information of the current transform coefficient is determined based on the relative position of the current transform coefficient in the scan area,

   Wherein the context model for the current transform coefficient is determined based on a predetermined context offset corresponding to a case where the coordinate of the current transform coefficient is smaller than a predetermined value based on coordinates specifying the position of the scan region. Decoding method.
10. The method according to claim 1,

    The information on the transform coefficients may be,

    A flag indicating whether the transform coefficient is larger than a predetermined value, a remaining level information about an absolute value of the effective transform coefficient, sign information of the transform coefficient, and a binarization And parameter information,

    Wherein the predetermined value is at least one of 0, 1, and 2.
11. Obtaining a transform coefficient of a current block;

    Determining a scan area including all effective transform coefficients in the current block;

    Scanning the information on the transform coefficients included in the scan region according to a predetermined scan order and performing binarization based on the information about the scanned transform coefficients to generate binarized information;

    Performing binary arithmetic coding on the binarized information to generate entropy-encoded information; And

    And generating a bitstream including the entropy-encoded information,

    Wherein the binary arithmetic coding is performed using a context model determined based on at least one of a size and a shape of the current block.
12. 10. The method of claim 9,

    Wherein the scan area is a rectangular scan area,

    A horizontal direction coordinate specifying the quadrangular scan area indicates a coordinate of an effective transformation coefficient pixel located at the rightmost position in the current block,

    Wherein the vertical coordinate specifying the quadrangular scan area indicates the coordinates of the effective transformation coefficient pixel located at the lowermost part in the current block,

    Flag information indicating whether or not the information on the coordinates specifying the quadrangular scan area and the information on the coordinates specifying the quadrangular scan area include a difference between horizontal and vertical coordinate values specifying the quadrangular scan area, Stream,

    When the flag information indicates that the difference between the horizontal and vertical coordinate values specifying the rectangular scan area is included,

    Wherein the information on the coordinates specifying the quadrangular scan area includes a horizontal coordinate for a pixel of an effective conversion coefficient located at the rightmost position in the current block and a vertical coordinate for a pixel of the effective conversion coefficient located at the lowermost position in the current block Information indicating a coordinate of one of the coordinates and information indicating a difference between coordinates of the one direction and coordinates of the remaining directions.
13. The method comprising the steps of: determining a scan area including all valid conversion coefficients in a current block; scanning information on the in-scan conversion coefficients according to a predetermined scanning order; and performing binary arithmetic decoding An entropy decoding unit for generating binary arithmetic decoding information and performing inverse binarization on the binary arithmetic decoding information to obtain information on transform coefficients of the current block; And

    And an image restoration unit for generating a residual block of the current block by performing inverse quantization and inverse transformation based on the information about the transform coefficients of the current block and restoring the current block based on the generated residual block,

    Wherein the binary arithmetic decoding is performed using a context model determined based on at least one of a size and a shape of the current block.
14. Acquires a conversion coefficient of the current block, determines a scan area including all the effective conversion coefficients in the current block, scans information on the conversion coefficient included in the scan area according to a predetermined scan order, An entropy encoding unit for generating binarized information by performing binarization based on information on the transform coefficients, and performing binary arithmetic encoding on the binarized information to generate entropy-encoded information; And

    And a bitstream generator for generating a bitstream including the entropy-encoded information,

    Wherein the binary arithmetic coding is performed using a context model determined based on at least one of a size and a shape of the current block.
15. A computer-readable recording medium on which a program for implementing the video decoding method of claim 1 is recorded.

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