KR101483174B1 - Motion Vector Encoding/Decoding Method and Apparatus and Video Encoding/Decoding Method and Apparatus - Google Patents

Abstract

The present invention relates to a motion vector coding method and apparatus, and a method and apparatus for image coding / decoding using the same.
An apparatus for encoding a motion vector, the apparatus comprising: a prediction candidate selector for selecting one or more motion vector prediction candidates; A predicted motion vector determiner for determining a predicted motion vector from one or more motion vector prediction candidates; And a difference vector encoder for calculating a difference vector by subtracting the predicted motion vector determined in the current motion vector and encoding the difference vector.
According to the present invention, it is possible to improve the compression efficiency by reducing the amount of bits for coding the information on the predictive motion vector while encoding the motion vector using the predicted motion vector more accurately.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motion vector coding method and apparatus, and a video coding / decoding method and apparatus using the same.

The present invention relates to a motion vector coding method and apparatus, and a method and apparatus for image coding / decoding using the same. In more detail, inter prediction is performed using pixels that are coded, decoded and reconstructed before a block to be currently encoded, motion vectors used for inter prediction are efficiently encoded or decoded, and the still image or moving picture data And more particularly, to a method and apparatus for encoding or decoding a video signal.

JPEG, JPEG-2000, and H.261, H.263, MPEG-2, and MPEG-4 are examples of still image compression methods for efficiently compressing video signals. In addition, MPEG-4 Advanced Video Coding (AVC), which provides further improved compression efficiency while inheriting the technologies of MPEG-2 and MPEG-4, is standardized in 2003 by ISO (International Standardization Organization).

The encoding of data for a moving picture is performed by intraprediction encoding and inter prediction encoding. Such intraprediction coding or inter prediction coding is an effective method for reducing correlation between data and is widely used for various data compression. In particular, since the motion vector of the current block, which is determined by estimating the motion of the current block to be coded in inter prediction coding, is closely correlated with the motion vector of the neighboring block, the motion vector of the current block A differential motion vector (DMV) (hereinafter referred to as 'differential vector') is calculated without calculating a motion vector value of the current block after calculating a predicted motion vector (PMV) Quot;), the amount of bits to be coded can be significantly reduced and the coding efficiency can be increased accordingly.

In other words, when performing inter-prediction coding in most conventional image compression standards such as MPEG-4 AVC, the encoder calculates a predicted motion vector determined by estimating motion of a current block in a reference frame that has been previously encoded and decoded and restored, Only a differential vector which is a difference value from the motion vector is encoded and transmitted. The decoding unit estimates a motion vector of a current block using motion vectors of neighboring blocks decoded in advance, and adds the transmitted difference vector and the predicted motion vector to recover the current motion vector.

However, if a motion vector is coded according to the conventional image compression standards as described above, if the predicted motion vector is not correlated with the current motion vector, the difference vector becomes large. Therefore, In addition, even when information on a predictive motion vector is further encoded in an encoder to reduce a difference vector, there is a problem that an amount of bits for encoding the additional information increases and the compression efficiency is lowered.

In order to solve the above-described problems, the present invention has a main purpose of improving a compression efficiency by reducing a bit amount for coding information on a predictive motion vector, while encoding a motion vector using a more precisely predicted motion vector .

According to an aspect of the present invention, there is provided an apparatus for coding a motion vector, the apparatus comprising: a prediction candidate selector for selecting one or more motion vector prediction candidates; A predicted motion vector determiner for determining a predicted motion vector from one or more motion vector prediction candidates; And a difference vector encoder for calculating a difference vector by subtracting the predicted motion vector determined in the current motion vector and encoding the difference vector.

According to another aspect of the present invention, there is provided a method of coding a motion vector, comprising: a prediction candidate selection step of selecting at least one motion vector prediction candidate; A predicted motion vector determining step of determining one of the at least one motion vector prediction candidate as a predicted motion vector; And a differential vector coding step of calculating a difference vector by subtracting the predicted motion vector determined in the current motion vector and encoding the difference vector.

According to another aspect of the present invention, there is provided an apparatus for decoding a motion vector, comprising: a differential vector decoder for decoding a coded differential vector to reconstruct a differential vector; And a motion vector reconstructor that determines one of the motion vector prediction candidates as a predicted motion vector and adds the determined predicted motion vector and the reconstructed difference vector to reconstruct the current motion vector of the current block And a motion vector decoding unit.

According to another aspect of the present invention, there is provided a method of decoding a motion vector, comprising: a differential vector decoding step of decoding a coded differential vector to recover a difference vector; And a motion vector restoration step of restoring a current motion vector of the current block by determining one of the motion vector prediction candidates as a predicted motion vector and adding the determined predicted motion vector and the restored difference vector, The motion vector decoding method of the present invention is characterized by comprising:

According to another aspect of the present invention, there is provided an apparatus for encoding an image, the apparatus comprising: a predictor for determining a current motion vector of a current block and generating a predictive block using the determined current motion vector; A subtractor for generating a residual block by subtracting a current block from a prediction block; A transformer for transforming the residual block; A quantizer for quantizing the transformed residual block; And a quantized residual block, a motion vector prediction candidate for one or more motion vector prediction candidates is determined as a predicted motion vector, a difference vector obtained by subtracting a predicted motion vector determined from the current motion vector is encoded, And an encoder for generating and outputting a bitstream including a block and an encoded difference vector.

According to another aspect of the present invention, there is provided a method of coding an image, the method comprising: a prediction step of determining a current motion vector of a current block and generating a prediction block using the determined current motion vector; A subtractor for generating a residual block by subtracting a current block from a prediction block; A transforming step of transforming the residual block; A quantization step of quantizing the transformed residual block; A residual block coding step of coding a quantized residual block; A differential vector coding step of determining a motion vector prediction candidate among the at least one motion vector prediction candidate as a predicted motion vector and coding a difference vector obtained by subtracting a predicted motion vector determined from the current motion vector; And a bitstream generation step of generating and outputting a bitstream including an encoded residual block and an encoded difference vector.

According to still another aspect of the present invention, there is provided an apparatus for decoding an image, comprising: a decoding unit for extracting and decoding a coded residual block and a coded residual block from a bitstream to recover a residual block and a difference vector, A decoder for determining one motion vector prediction candidate as a predicted motion vector among the candidates and adding the determined predicted motion vector and the reconstructed difference vector to reconstruct the current motion vector of the current block; An inverse quantizer for inversely quantizing the reconstructed residual block; An inverse transformer for inversely transforming the dequantized residual block; A predictor for generating a prediction block using the restored current motion vector; And an adder for adding the inverse transformed residual block and the generated prediction block to reconstruct a current block.

According to another aspect of the present invention, there is provided a method of decoding an image, the method comprising: a residual block decoding step of extracting and decoding a coded residual block from a bitstream to restore a residual block; A difference vector decoding step of extracting and decoding a coded difference vector from a bit stream to recover a difference vector; A motion vector restoring step of restoring a current motion vector of a current block by selecting one of the at least one motion vector prediction candidate as a predicted motion vector and using a selected predictive motion vector and a reconstructed difference vector; An inverse quantization step of inversely quantizing the reconstructed residual block; An inverse transform step of inversely transforming the dequantized residual block; A prediction step of generating a prediction block using the restored current motion vector; And adding the inverse transformed residual block and the generated prediction block to reconstruct a current block.

As described above, according to the present invention, it is possible to improve the compression efficiency by reducing the amount of bits for coding the information on the predictive motion vector, while encoding the motion vector using the predicted motion vector more accurately.

1 is a block diagram schematically illustrating an image encoding apparatus according to an embodiment of the present invention.
2 is a block diagram schematically showing a motion vector coding apparatus according to an embodiment of the present invention.
3 is an exemplary view showing a zigzag scanning direction,
FIG. 4 is an exemplary view showing neighboring blocks of a current block,
5 is an exemplary view showing a current block and a neighboring block of a current frame,
6 is an exemplary diagram illustrating exemplary blocks of a current frame and a reference frame,
7 is an exemplary diagram for explaining an instruction vector,
8 is an exemplary diagram for explaining a process of calculating a threshold value,
FIG. 9 is a diagram illustrating a motion vector prediction candidate and a current motion vector separately for each component,
10 is an exemplary view showing a prediction candidate identification flag according to a plurality of threshold values,
11 is an exemplary view showing transmission bits of a prediction candidate identification flag,
12 is a flowchart for explaining a motion vector coding method according to an embodiment of the present invention;
13 is a flowchart illustrating an image encoding method according to an embodiment of the present invention.
FIG. 14 is a block diagram schematically showing an image decoding apparatus according to an embodiment of the present invention;
15 is a block diagram schematically illustrating a motion vector decoding apparatus according to an embodiment of the present invention.
16 is a flowchart for explaining a motion vector decoding method according to an embodiment of the present invention,
17 is a flowchart illustrating an image decoding method according to an embodiment of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. It should be noted that, in adding reference numerals to the constituent elements of the drawings, the same constituent elements are denoted by the same reference numerals even though they are shown in different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

In describing the components of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are intended to distinguish the constituent elements from other constituent elements, and the terms do not limit the nature, order or order of the constituent elements. When a component is described as being "connected", "coupled", or "connected" to another component, the component may be directly connected or connected to the other component, Quot; may be "connected," "coupled," or "connected. &Quot;

1 is a block diagram schematically illustrating an image encoding apparatus according to an embodiment of the present invention.

An image encoding apparatus 100 according to an embodiment of the present invention includes a predictor 110, a subtracter 120, a transformer 130, a quantizer 140, an encoder 150, an inverse quantizer 160, An adder 170, an adder 180, and a memory 190. Here, the dequantizer 160, the inverse transformer 170, the adder 180, and the memory 190 may be selectively included in the image encoding apparatus 100. The image encoding apparatus 100 may be a personal computer (PC), a notebook computer, a personal digital assistant (PDA), a portable multimedia player (PMP), a PlayStation Portable ), A mobile communication terminal, and the like, and may be a communication device such as a communication modem for performing communication with various devices or wired / wireless communication networks, a memory for storing various programs for encoding an image and data, a program And a microprocessor for calculating and controlling the microprocessor.

The predictor 110 determines a current motion vector, which is a motion vector of the current block, and generates a prediction block using the determined current motion vector. That is, the predictor 110 predicts the pixel value of each pixel of the current block to be encoded in the image using the current motion vector, and outputs the predicted pixel value of the predicted pixel value (Predicted Block). The predictor 110 may determine the current motion vector using various techniques such as Rate-Distortion Optimization (RDO), and the determined current motion vector may be an optimal motion vector.

The subtracter 120 subtracts the current block and the prediction block to generate a residual block. That is, the subtractor 120 calculates the difference between the pixel value of each pixel of the current block to be encoded and the predicted pixel value of each pixel of the predicted block predicted by the predictor 110, and outputs a residual signal (residual signal) Thereby generating a residual block.

The transformer 130 transforms the residual block. That is, the converter 130 converts the residual signal of the residual block output from the subtracter 120 into the frequency domain, and converts each pixel value of the residual block into a frequency coefficient. Here, the transformer 130 transforms image signals on the spatial axis, such as Hadamard Transform and DCT-based Transform (DCT based Transform) The signal can be transformed into the frequency domain, and the residual signal transformed into the frequency domain becomes the frequency coefficient.

The quantizer 140 quantizes the transformed residual block. That is, the quantizer 140 quantizes the frequency coefficient of the residual block output from the transformer 130, and outputs a residual block having a quantized frequency coefficient. Here, the quantizer 140 may quantize quantization using Dead Zone Uniform Threshold Quantization (DZUTQ), a Quantization Weighted Matrix, or an improved quantization technique .

Although the image encoding apparatus 100 according to an embodiment of the present invention includes the converter 130 and the quantizer 140 as described above, the converter 130 and the quantizer 140 may be optional . That is, the image encoding apparatus 100 according to an embodiment of the present invention may convert the residual signal of the residual block to generate the residual block having the frequency coefficient and not perform the quantization process, Not only the quantization process but also the conversion and the quantization process can be performed.

The encoder 150 encodes the quantized residual block, determines a predictive motion vector from one or more motion vector prediction candidates, subtracts the predicted motion vector from the current motion vector, (Differential Motion Vector), and generates and outputs a bitstream including the coded residual block and the coded difference vector. That is, the encoder 150 scans the quantization frequency coefficients of the residual block output from the quantizer 140 according to various scan methods, such as zigzag scan, as illustrated in FIG. 3 to generate a quantized frequency coefficient sequence and perform entropy encoding Entropy coding) technique.

In addition, the encoder 150 encodes the current motion vector, selects one or more motion vector prediction candidates, and determines a predicted motion vector from the selected one or more motion vector prediction candidates. For this purpose, the encoder 150 generates a motion vector of a current block, a motion vector of a Col (Colocated Block) block located at the same position as the current block in the reference frame, a motion vector of a neighboring block of the Col block, One or more of the indicator vectors indicating a specific block of the reference frame may be selected as one or more motion vector prediction candidates. Here, the specific block may be a block having a motion vector which is horizontal to the indicating vector or whose difference between the indicating vector is smaller than a preset threshold value.

For example, when determining one of the motion vector prediction candidates as a predicted motion vector, the encoder 150 determines a predicted motion vector using an intermediate value, as exemplarily shown in FIG. 4 . 4, it is assumed that the current block is X, the left block of the current block is A, the upper block of the current block is B, and the upper right block of the current block is C, and the motion vector of the left block A is MV_A , The motion vector of the uppermost block B is MV_B, and the motion vector of the upper right block C is MV_C, the predicted motion vector of the current block A can be calculated using an intermediate value as shown in Equation (1).

The encoder 150 can determine a predicted motion vector from one or more motion vector prediction candidates using an intermediate value. However, the intermediate value is not necessarily used, and the predicted motion vector can be determined using various other methods. This will be described in detail with reference to FIG. 2 in the following process.

Also, the encoder 150 may generate and encode a prediction candidate identification flag that identifies a motion vector prediction candidate determined as a predicted motion vector, and may further include the prediction candidate identification flag in the bitstream. That is, the bitstream may include an encoded residual block and an encoded difference vector as well as an encoded prediction candidate identification flag.

In addition, the encoder 150 can independently determine each of the x-component and the y-component of the predicted motion vector. That is, the encoder 150 determines the x-component of one motion vector prediction candidate among the x-components of one or more motion vector prediction candidates as the x-component of the predicted motion vector, The y-component of one of the motion vector prediction candidates may be determined as the y-component of the predicted motion vector.

Also, the encoder 150 may determine that at least one of the absolute value of the x-component of the difference vector and the absolute value of the y-component of the difference vector is greater than or equal to one or more of the predetermined x- Component of the predicted motion vector and the y-component of the predicted motion vector, and generates a prediction candidate identification flag for identifying a motion vector prediction candidate determined as at least one of the x-component of the predicted motion vector and the y-component of the predicted motion vector, . The encoder 150 will be described later in detail with reference to FIG.

The inverse quantizer 160 inverse quantizes the residual block quantized by the quantizer 140. The inverse transformer 170 performs an inverse transform on the inversely quantized residual block by the inverse quantizer 160. Here, the inverse quantizer 160 and the inverse transformer 170 can perform inverse quantization and inverse transform using the quantization method and the transformation method used in the quantizer 140 and the transformer 130 inversely. In addition, when the transformer 130 and the inverse quantizer 140 perform only quantization and do not perform the transform, only the inverse quantization is performed, and the inverse transform is not performed. If both the transform and the quantization are not performed, the inverse quantizer 160 and the inverse transformer 170 may neither perform inverse transform nor dequantization nor be included in the image encoding apparatus 100 and may be omitted.

The adder 180 adds the prediction block predicted by the predictor 110 and the residual block reconstructed by the inverse transformer 170 to reconstruct the current block. The memory 190 stores the reconstructed current block output from the adder 180 as a reference frame on a frame-by-frame basis so that the predictor 110 can use the restored current block as a reference frame when coding the next block or another block in the current block .

Although not shown in FIG. 1, the image encoding apparatus 100 according to an embodiment of the present invention described above may be configured to perform intra prediction for intra prediction, based on the H.264 / AVC standard, A deblocking filter for deblocking filtering, and the like. Here, deblocking filtering refers to a task of reducing block distortion caused by coding an image block by block. The deblocking filter may be applied to a block boundary or a macro block boundary, a deblocking filter may be applied to a macro block boundary, Can be selectively used.

2 is a block diagram schematically illustrating a motion vector coding apparatus according to an embodiment of the present invention.

The motion vector coding apparatus according to an embodiment of the present invention can be implemented by the encoder 150 of the image coding apparatus 100 according to an embodiment of the present invention described above with reference to FIG. Hereinafter, a motion vector coding apparatus according to an embodiment of the present invention will be referred to as an encoder 150 for convenience of explanation. The encoder 150 according to the embodiment of the present invention may further include an image encoder for encoding the quantized residual block and outputting the encoded residual block as described above with reference to FIG. The encoder will be apparent to those skilled in the art, and a detailed description thereof will be omitted.

The encoder 150 according to an exemplary embodiment of the present invention includes a prediction candidate selector 210, a predictive motion vector determiner 220, a differential vector encoder 230, a prediction candidate identification flag encoder 240 and a prediction candidate selection flag encoder 250). Here, the encoder 150 does not necessarily include at least one of the prediction candidate identification flag encoder 240 and the prediction candidate selection flag encoder 250, but may selectively include the encoder.

The prediction candidate selector 210 selects one or more motion vector prediction candidates. The predictive motion vector determiner 220 determines one of the one or more motion vector prediction candidates as a predictive motion vector. The difference vector encoder 230 subtracts the predicted motion vector from the current motion vector to calculate and encode the difference vector. The prediction candidate identification flag encoder 240 generates and encodes a prediction candidate identification flag for identifying a motion vector prediction candidate determined as a predictive motion vector. The prediction candidate selection flag encoder 250 generates prediction candidates for identifying which motion vector prediction candidates are selected by the prediction candidate selector 210 for each region (e.g., a slice in H.264) of an image Generates and encodes a selection flag.

The difference vector can be calculated as shown in Equation (2). In Equation (2), MVd denotes a difference vector, MV denotes a current motion vector, and MVp_opt denotes a predicted motion vector.

The differential vector coded by the difference vector encoder 230 and the coded residual block output from the image encoder may be included in the bitstream and transmitted to the image decoding apparatus. The bitstream may further include at least one of a prediction candidate selection flag encoded by the prediction candidate selection flag encoder 250 and a prediction candidate identification flag encoded by the prediction candidate identification flag encoder 240. [

Here, the prediction candidate selector 210 may select a motion vector of a neighboring block of the current block as one or more motion vector prediction candidates. 5, the one or more motion vector prediction candidates may include a neighboring block located near the current block X in the current frame in which the current block X to be currently coded is located, L, UL, U, and UR motion vectors. 5, only the left block L, the upper left block UL, the upper block U, and the upper right block UR of the current block are shown as neighboring blocks. However, the motion vector prediction candidate includes not only neighboring blocks other than the current block, Vectors.

Also, the prediction candidate selector 210 may select one or more of a motion vector of a Col block and a motion vector of a neighboring block of the Col block that are located at the same position as the current block in the reference frame, as one or more motion vector prediction candidates. 6, the one or more motion vector prediction candidates are classified into a Col block and a Col block, which are blocks located at the same position as the current block X in the reference frame frame t-1, they may be a motion vector of a neighboring block (UL _{Col, Col} U, UR _{Col, Col} L, _Col R, BL _{Col, Col} B, BR _Col). 6, only neighboring blocks ( _Col , _Ucol , _URcol , _Lcol , _Rcol , _BLcol , _Bcol , and _BRcol ) of the Col block and the Col block are shown. May be motion vectors of other blocks not adjacent to each other, as well as adjacent blocks.

In addition, the prediction candidate selector 210 may select, as one or more motion vector prediction candidates, an indicator vector indicating a specific block of the reference frame in the current block of the current frame. That is, referring to FIG. 7 exemplarily illustrated for explaining the instruction vector, a vector indicating a block Par located in the first reference frame frame t-1 in the current block X located in the current frame frame t, If the motion vector of any block Par located at frame t-1 is horizontal or smaller than the predetermined threshold, a vector indicating any block Par of reference frame frame t-1 in current block X of current frame frame t And can be selected as a motion vector prediction candidate. Here, the vector indicating any block Par of the reference picture frame t-1 at the position of the current block X of the current frame f is an indicator vector. Therefore, the above-described specific block may be a block having a motion vector whose horizontal direction is different from the indicator vector or whose difference from the indicator vector is smaller than a predetermined threshold value.

When the prediction candidate selector 210 selects one or more motion vectors, the prediction candidate selection flag encoder 250 generates and codes a prediction candidate selection flag for identifying the motion vector prediction candidate selected by the prediction candidate selector 210 And the encoded prediction candidate selection flag can be inserted into the header of the bitstream.

As another example, the prediction candidate selector 210 may select some motion vector prediction candidates from one or more motion vector prediction candidates. That is, the prediction candidate selector 210 may select a number of motion vector prediction candidates from among one or more motion vector prediction candidates according to the characteristics of the image, and determine a prediction motion vector only among the selected motion vector prediction candidates. In this case, the predictive candidate selection flag encoder 250 selects one of the motion vector prediction candidates selected by the prediction candidate selector 210 to identify which of the motion vector prediction candidates has been selected as a part of the motion vector prediction candidates A prediction candidate selection flag for identifying a motion vector prediction candidate can be generated and encoded.

Here, the predetermined criterion may be a probability that each of the one or more motion vector prediction candidates can be determined as a current motion vector. When using this probability, the prediction candidate selector 210 uses each of the one or more motion vector prediction candidates By encoding one or more regions of the current frame, a probability that is determined as a current motion vector for each of the one or more motion vector prediction candidates can be calculated, and a part of the motion vector prediction candidates can be selected according to the calculated probability. For example, assuming that one or more motion vector prediction candidates are total five, A, B, C, D, and E, each of the five motion vector prediction candidates is used to virtually encode arbitrary areas of the current frame, (A), B: 10%, C: 5%, D: 3%, and E: 2%, which are calculated as a motion vector If it is calculated as a probability, A or A and B motion vector prediction candidates can be selected as some motion vector prediction candidates.

If the correlation is used, the prediction candidate selector 210 selects one or more candidate motion vector prediction candidates having correlation among one or more motion vector prediction candidates as one or more groups, The representative representative motion vector can be selected as a part of the motion vector prediction candidates. Here, the representative motion vector may be an intermediate value or an average value of the motion vector prediction candidates in each selected group.

For example, if one or more motion vector prediction candidates are motion vectors as described above with reference to FIG. 5 to FIG. 7, the neighboring blocks L, UL, U, UR of some of the neighboring blocks of the current block, MV_U, MV_UR, MV_U, and MV_UR are selected as a group A, the MV_Group A calculated through the intermediate value calculation is determined as a representative motion vector, As a motion vector prediction candidate of the motion vector estimation unit.

Further, Fig through 6 described above Col block and the block of vertical and horizontal of the neighboring blocks of the Col block motion vectors of (Col, U _Col, L _Col, R _Col, B _Col) (MV_Col, MV_U _col, MV_L _col, MV_R _col , MV_B _col ) are selected as one group B, and the MV MV_Group A calculated through the average value calculation is determined as a representative motion vector and a representative motion vector is selected as a part of the motion vector prediction candidates have.

Further, FIG aforementioned through 6 Col block and the neighboring blocks of the Col block motion vectors of (UL _Col, U _Col, UR _Col, L _Col, R _Col, BL _Col, B _Col, BR _Col) (MV_Col, MV_UL _col , MV_U _col , MV_UR _col , MV_L _col , MV_R _col , MV_BL _col , MV_B _col , MV_BR _col ) are grouped into one group C and represented by the intermediate value calculation MVp_Group C And the representative motion vector may be selected as a part of the motion vector prediction candidates.

As described above, the representative motion vector calculated by Equations (4) to (5) and the indicator vector described above with reference to FIG. 7 can be selected as a part of the motion vector prediction candidates. In this case, 250 may generate and predict a prediction candidate selection flag to indicate that MVp_groupA, MVp_groupB, MVp_groupC, MV_col, and MV_par are selected as some motion vector prediction candidates. Of course, the prediction candidate identification flag encoder 240 generates a prediction candidate identification flag for indicating which of the motion vector prediction candidates MVp_groupA, MVp_groupB, MVp_groupC, MV_col and MV_par is used as a prediction motion vector, can do.

Also, the prediction candidate selector 210 may select one or more motion vector prediction candidates, which are predetermined from among the one or more motion vector prediction candidates, as partial motion vector prediction candidates. Here, one or more predetermined motion vector prediction candidates may be arbitrarily selected by the user.

In addition, the predictive motion vector determiner 220 may determine a predictive motion vector in various manners. For example, the predictive motion vector determiner 220 may determine that the amount of bits required to encode the differential vector calculated using each motion vector prediction candidate among the one or more motion vector prediction candidates selected by the prediction candidate selector 210 is the minimum Can be determined as a predicted motion vector. Accordingly, the predictive motion vector determiner 220 calculates a differential vector on the assumption that each motion vector predictive candidate is a predictive motion vector, and encodes the calculated differential vector to obtain a motion vector predictive candidate having the minimum coded data as a predictive motion vector You can decide. In this case, when the motion vector of the current block is coded (that is, when coding the difference vector between the current motion vector and the determined predicted motion vector), the predictive candidate identification flag encoder 240 generates any motion A prediction candidate identification flag for identifying a motion vector prediction candidate determined as a prediction motion vector to identify whether the vector prediction candidate is determined as a prediction motion vector may be generated and encoded.

As another example, the predictive motion vector determiner 220 may independently determine each of the x-component and the y-component of the predicted motion vector. That is, the predictive motion vector determiner 220 determines the x-component of one motion vector prediction candidate among the x-components of one or more motion vector prediction candidates as the x-component of the predicted motion vector, component of one motion vector prediction candidate in the y-component as the y-component of the predicted motion vector. For example, in coding the difference vector, if the bit amount of the difference vector is proportional to the absolute value of the difference vector magnitude and one or more motion vector prediction candidates are (-4, -4), (2, 2) (2, 2) or (4, 4) can be determined as a predicted motion vector, assuming that the current motion vector is (0, 4) The x-component of the motion vector may be selected to be 2 out of -4, 2, 4, or 14, and the y-component of the predicted motion vector may be selected to be 4 out of -4, 2, 4, That is, instead of separating the x-component and the y-component as before, the x-component and the y-component can be separated and the optimal value can be determined as the predicted motion vector.

In this case, the prediction candidate identification flag encoder 240 determines whether or not the absolute value of the x-component of the difference vector and the absolute value of the y-component of the difference vector are greater than a preset x-component threshold value and a predetermined y- Value, the prediction candidate identification flag may not be generated, and the prediction candidate identification flag may be encoded and not transmitted. In addition, the prediction candidate identification flag encoder 240 determines whether or not at least one of the absolute value of the x-component of the difference vector and the absolute value of the y-component of the difference vector is greater than a preset x- A prediction candidate identification flag that identifies a motion vector prediction candidate determined by at least one of the x-component of the predicted motion vector and the y-component of the predicted motion vector may be generated and encoded. That is, if two of the two components (x-component and y-component) of the predicted motion vector are both greater than the threshold value, the prediction candidate identification flag is not generated. If only one component is smaller than the threshold value, And generates a prediction candidate identification flag that identifies which motion vector prediction candidate is used as a larger component. If neither of the two components is greater than the threshold value, it is determined whether a motion vector prediction candidate is used as two components It is possible to generate and to code a prediction candidate identification flag to identify.

Here, when the absolute value of each component of the difference vector is larger than the threshold value of each component, a prediction candidate identification flag is generated and not encoded, and when the absolute value of each component of the difference vector is smaller than or equal to the threshold value of each component, When the identification flag is generated and encoded, a prediction candidate identification flag that identifies which of the motion vector prediction candidates selected for each motion vector prediction candidate is determined as a prediction motion vector may separately be generated and encoded. Since the absolute value of each component of the difference vector is larger than the corresponding component threshold value and the predictive candidate identification flag is not transmitted and the absolute value of each component of the differential vector is smaller than or equal to the corresponding component threshold value in the video decoding apparatus, The motion vector prediction candidates may be separately decoded to determine a predicted motion vector.

For example, if one of the selected motion vector prediction candidates of the group A is determined as a predicted motion vector to calculate a difference vector, and if the absolute value of each component of the difference vector is greater than a threshold value of the corresponding component, If the absolute value of each component of the difference vector is smaller than the threshold value of the corresponding component, one of the selected motion vector prediction candidates of the group B is determined as a predicted motion vector to calculate a difference vector, A prediction candidate identification flag that identifies which of the selected motion vector prediction candidates of B has been determined as a prediction motion vector is generated and encoded. That is, if the absolute value of each component of the difference vector is larger than the threshold value of the corresponding component, the selected motion vector prediction candidates of the group A are used. If the absolute value of each component of the difference vector is smaller than or equal to the threshold value of the corresponding component The selected motion vector prediction candidates of group B can be used.

Here, each component threshold value (x-component threshold value and y-component threshold value) can be calculated in various ways. For example, the x-component threshold may be the maximum of the differences between the x-components of the two closest of the x-components of one or more motion vector prediction candidates divided by a predetermined number, The threshold value may be a maximum value obtained by dividing the difference value between the y-components of the two closest motion vector prediction candidates among the y-components of the at least one motion vector prediction candidate by a predetermined number. That is, as shown in Equation (6), each component has two motion vector prediction candidates MVp _Cand (i) and MVp _Cand MVp _Cand after calculating each thre _ij for each (j)), may be calculated as the maximum value of the calculated thre _ij.

Referring to FIG. 8 illustrating an exemplary process for calculating a threshold value, a value of an x-component of a motion vector prediction candidate is '-4', '2', '4' , '14', the value obtained by dividing the difference value of the value of the x-component of each motion vector prediction candidate by 2 is '3' in the section ①, '1' in the section ②, and '5' And the maximum value is '5', so that the threshold value becomes '5'.

Referring to FIG. 9, which illustrates the motion vector prediction candidate and the current motion vector separately for each component, the threshold value of the x-component is '2' and the threshold value of the y-component is '3'. In this case, the x-component of the predicted motion vector is determined to be '3' (MVp_cand [2]) so that the x-component of the differential vector becomes -3 and the y-component of the predicted motion vector is '2' [0]), and the y-component of the difference vector becomes '+4'. Since the absolute values of the two components of the differential vector are greater than the threshold values of the respective components, the prediction candidate identification flag encoder 240 generates prediction candidates for indicating which of the motion vector prediction candidates is determined as a prediction motion vector An identification flag may be generated and not encoded. With this principle, when restoring the current motion vector in the video decoding apparatus, even when it is not possible to know which motion vector prediction candidate is determined as the predicted motion vector from among one or more motion vector prediction candidates due to the absence of the prediction candidate identification flag, Component is greater than a threshold value of each component, and if the x-component and the y-component of the motion vector prediction candidate are larger than the threshold value, it is possible to determine which motion vector prediction candidate is determined as a predicted motion vector.

In another example, the x-component threshold may be a value obtained by dividing the difference value between the x-components of the two closest motion vector prediction candidates among the x-components of the at least one motion vector prediction candidate by a predetermined number, The threshold value may be a value obtained by dividing the difference value between the y-components of the two closest motion vector prediction candidates among the y-components of the at least one motion vector prediction candidate by a predetermined number. That is, each component threshold is not the largest value obtained by dividing the distance between each motion vector prediction candidate by 2, as shown in Equation (6), but a value obtained by dividing the distance between each motion vector prediction candidate by 2 Lt; / RTI &gt; Therefore, when there are N motion vector prediction candidates, the threshold value of each component may be N-1. In Equation (7), 0? N <N.

For example, in the case of FIG. 8, the first threshold Threshold ₁ of the x-component may be '3', the second threshold Threshold ₂ may be '1' The threshold value (Threshold ₃ ) may be '5'.

In this case, the prediction candidate identification flag encoder 240 can generate and encode the prediction candidate identification flag differently according to the magnitude of the absolute value of each component of the difference vector and each component threshold value. That is, if the absolute value of each component of the difference vector is smaller than or equal to the smallest threshold value of the corresponding component, the prediction candidate identification flag encoder 240 arranges N-1 threshold values in descending order, A prediction candidate identification flag that identifies which motion vector prediction candidate is determined as a prediction motion vector among the prediction candidates is generated and encoded, and the absolute value of each component of the difference vector is smaller than or equal to a second smallest threshold value of the corresponding component , It is assumed that there is no current motion vector between the two motion vector prediction candidates having the smallest threshold value of the component and if any motion vector prediction candidate among the N-1 selected motion vector prediction candidates is determined as a prediction motion vector And generates a prediction candidate identification flag . If the absolute value of each component of the difference vector is less than or equal to the third smallest threshold value of the component, it is assumed that there is no current motion vector between the two motion vector prediction candidates having the smallest threshold value of the component , It is assumed that there is no current motion vector between two motion vector prediction candidates having the second smallest threshold value of the corresponding component, and any motion vector prediction candidate among N-2 selected motion vector prediction candidates is determined as a predicted motion vector And generates a prediction candidate identification flag for identifying whether or not the video signal has been encoded.

In this way, the absolute value of each component of the difference vector is sequentially compared with each threshold value of the corresponding component, and a prediction candidate identification flag is generated and encoded. When the absolute value of each component of the differential vector is larger than all threshold values of the corresponding component , There is no need to generate and code a prediction candidate identification flag for identifying which motion vector prediction candidate is determined as a prediction motion vector from among the N motion vector prediction candidates. In this way, the length of the prediction candidate identification flag for identifying which motion vector prediction candidate is determined as the predicted motion vector may be changed according to the absolute values of the respective components of the difference vector and the threshold values of the corresponding component.

According to the above method, when the absolute value of each component of the difference vector is larger than all the threshold values, a predictive motion vector can be determined by selecting individually for each component of the motion vector prediction candidate. If only one component of the absolute values of the components of the difference vector is larger than all of the threshold values, motion vector prediction candidates of the motion vector prediction candidates are predicted only for the component of the difference vector having an absolute value not larger than all the threshold values And transmits a prediction candidate identification flag for identifying whether it is determined as a vector.

That is, when only one of the absolute values of the two components of the difference vector exceeds the maximum threshold value, a prediction candidate identification flag for identifying a motion vector prediction candidate having a component having an absolute value not exceeding the largest threshold value is generated Can be encoded. If the absolute values of the two components of the difference vector are not greater than the largest threshold value, a prediction candidate identification flag for identifying which motion vector prediction candidate is determined as a prediction motion vector independently for each component is generated, , But a prediction candidate identification flag for identifying a motion vector prediction candidate in which two components are simultaneously determined as a prediction motion vector can be generated and encoded.

For example, referring to FIG. 8 and FIG. 10 illustrating a prediction candidate identification flag according to the plurality of threshold values, the number of prediction candidates is four and each threshold value is '1', '3' '5'. Accordingly, in FIG. 10, a section divided by three threshold values is shown. The interval indicated by (1) represents the x-component of the motion vector prediction candidates, and the interval indicated by (2) represents the current motion vector when the absolute value of the x-component of the difference vector is smaller than or equal to the smallest threshold value of the x- component, and the interval indicated by (3) indicates that the x-component of the current motion vector when the absolute value of the x-component of the difference vector is smaller than or equal to the second smallest threshold value of the x- Component, and the section indicated by (4) represents a section where the x-component of the current motion vector is located when the absolute value of the x-component of the difference vector is smaller than or equal to the largest threshold value of the x-component , The interval indicated by (5) indicates that the x-component of the current motion vector in the case where the absolute value of the x-component of the difference vector is larger than the largest threshold value of the x- A shows a section in which location.

The prediction candidate identification flag encoder 240 can generate and code a prediction candidate identification flag that identifies which of the four motion vector prediction candidates has been determined as a prediction motion vector in the section indicated by 2, A prediction candidate identification flag for identifying which motion vector prediction candidate has been determined as a prediction motion vector from among the three motion vector prediction candidates can be generated and coded. In the section indicated by 4, any of the two motion vector prediction candidates A prediction candidate identification flag that identifies whether the motion vector prediction candidate is determined as a prediction motion vector may be generated and coded. In the section indicated by (5), the prediction candidate identification flag may not be generated.

If the x-component of the current motion vector is '8', the x-component of the predicted motion vector is '4'. Since the absolute value of the x-component of the difference vector is '+4', its absolute value is smaller than the largest threshold value '5' of the x-component and greater than the second threshold value '3' A prediction candidate identification flag for identifying one of the candidate x-components '4' and '14' may be generated and encoded.

Since the x-component of the difference vector is '+4' in the image decoding apparatus, if the x-component '-4' of the motion vector prediction candidate is assumed to be the x-component of the predicted motion vector, Quot; 0 &quot;. However, when it is assumed that the x-component of the current motion vector is '0', the x-component of the predicted motion vector that is optimal (i.e., minimizes the x-component value of the difference vector) becomes '2' It can be seen that the x-component '-4' of the vector prediction candidate is not a predicted motion vector. In this way, it can be seen that the x-components '-4' and '2' of the motion vector prediction candidate are not determined as the predicted motion vector. Accordingly, a prediction candidate identification flag for identifying which of the x-components '4' and '14' of the motion vector prediction candidate that can be determined as the predictive motion vector is determined as the x-component of the predictive motion vector is generated, . As described above, when a plurality of threshold values are calculated for each component and the absolute values of the components of the difference vector are compared with a plurality of threshold values of the component to generate a prediction candidate identification flag differently and encoded, It is possible to reduce the amount of encoded bits of the prediction candidate identification flag to be transmitted at the time of encoding, thereby improving the compression efficiency.

The video decoding apparatus can identify which motion vector prediction candidate is determined as a predicted motion vector using only the prediction candidate identification flag.

As another example, when the distance between each motion vector prediction candidate among the selected motion vector prediction candidates is smaller than a certain threshold value, the predictive motion vector determiner 220 selects either one of two motion vector prediction candidates smaller than a certain threshold value It is possible to exclude other motion vector prediction candidates from the motion vector prediction candidates by considering them as being selected and determine one motion vector prediction candidate among the remaining motion vector prediction candidates as the prediction motion vector. If the distance between the motion vector prediction candidates in the video decoding apparatus is less than a certain threshold value, it is assumed that only one of the two motion vector prediction candidates smaller than the arbitrary threshold value is selected and the other motion vector prediction candidate is selected as the motion vector It is possible to determine one of the remaining motion vector prediction candidates as a predicted motion vector.

For example, when an arbitrary threshold value is '2' and three motion vector prediction candidates are selected, the first motion vector prediction candidate is '-5', the second motion vector prediction candidate is '8' If the motion vector prediction candidate is '9', since the distance between the second motion vector prediction candidate and the third motion vector prediction candidate is smaller than a certain threshold value, the third motion vector prediction candidate is excluded from the motion vector prediction candidates, It is possible to determine one of the motion vector prediction candidate and the second motion vector prediction candidate as a prediction motion vector. With this method, the number of selected motion vector prediction candidates can be reduced to reduce the bit amount for encoding the prediction candidate identification flag.

Further, when generating the prediction candidate identification flag, the prediction candidate identification flag encoder 240 can generate the prediction candidate identification flag in various manners. For example, when the motion vector prediction candidate determined as the predicted motion vector is the motion vector prediction candidate having the highest probability of being determined as the current motion vector among the one or more motion vector prediction candidates, the prediction candidate identification flag It is possible to generate the prediction candidate identification flag so as to be the minimum bit.

That is, the maximum length L required to encode the prediction candidate identification flag is calculated using the number of motion vector prediction candidates NumOfMVp _Cand , as shown in Equation (8).

11, when the value of M obtained by subtracting '1' from the number of calculated motion vector prediction candidates and taking log ₂ is an integer, as shown in Equation (9), the predictive motion When a motion vector prediction flag for identifying a motion vector prediction candidate determined as a vector is generated and encoded, the prediction candidate identification flag is generated and encoded with one bit when the most probable motion vector prediction candidate is a prediction motion vector.

For example, when the number of selected motion vector prediction candidates is 3 (MVp_cand [i]: 0? I <3), the maximum bit length L required for coding is '2', so that any of the selected motion vector prediction candidates The prediction candidate identification flag that identifies whether the prediction candidate motion vector has been determined as a predictive motion vector. Since the value of M is an integer according to Equation (9), the motion vector prediction candidate having the highest probability is generated and encoded with one bit. The motion vector prediction candidate having the highest probability is determined as a prediction motion vector when the prediction candidate identification flag of one bit is '1', and the motion vector prediction candidate having the highest probability is determined as the prediction motion vector So that additional bits are generated and encoded to generate 2 bits for identifying the remaining two motion vector prediction candidates and then encoded. If M is an integer, the video decoding apparatus reads only one bit of the prediction candidate identification flag to identify whether the motion vector prediction candidate having the highest probability is determined as a prediction motion vector, and determines that the motion vector prediction candidate having the highest probability is determined as a prediction motion vector The bit is further read to identify which motion vector prediction candidate has been determined as a predicted motion vector.

At this time, the prediction candidate identification flag encoder 240 may calculate one or more regions of the current frame using one or more motion vector prediction candidates, thereby calculating a probability of determining the current motion vector for each of the one or more motion vector prediction candidates, The motion vector prediction candidate set according to the probability that is arbitrarily designated and set or arbitrarily designated can be selected as the motion vector prediction candidate having the highest probability.

As another example, the prediction candidate identification flag encoder 240 may generate and code a prediction candidate identification flag only when at least one of the one or more motion vector prediction candidates is not the same. That is, the selected motion vector prediction candidates regard the same prediction candidates as one. If all the selected prediction candidates are the same, no matter which motion vector prediction candidate is determined as the predicted motion vector, the corresponding motion vector prediction candidate becomes optimal, so that it is identified which of the motion vector prediction candidates is determined as the predicted motion vector It is possible to generate the prediction candidate identification flag and not to encode it. In this case, the video decoding apparatus does not decode the prediction candidate identification flag.

As another example, the prediction candidate identification flag encoder 240 generates a prediction candidate identification flag for each case when the block type of the current block is SKIP mode, or when it is at least one of P block and B block Can be encoded. That is, the predictive motion vector determiner 220 can select different motion vector prediction candidates for the current block, the SK block, the P block, and the B block, respectively. In this case, the prediction candidate identification flag encoder 240 can generate and code the prediction candidate selection flag differently according to each case. At this time, in the prediction candidate selector 220 and the prediction candidate selection encoder 250, the motion vector prediction candidates selected differently according to the case of the block type SKIP mode, the case of the P block, the case of the B block, And transmits it. In the video decoding apparatus, motion vector prediction candidates differently selected according to the block type of the current block, the skip mode, the P block, and the B block can be decoded and determined.

12 is a flowchart illustrating a motion vector coding method according to an embodiment of the present invention.

The encoder 150 selects one or more motion vector prediction candidates (S1210), determines one motion vector prediction candidate among the one or more motion vector prediction candidates as a predicted motion vector (S1220) (S1230), and the calculated difference vector is encoded (S1240).

Here, the encoder 150 may generate and encode a prediction candidate identification flag that identifies which motion vector prediction candidate is determined as a prediction motion vector from among the one or more motion vectors selected in step S1210. The method of selecting one or more motion vector prediction candidates, the method of determining a predicted motion vector, and the method of generating and encoding a prediction candidate identification flag have been described with reference to FIGS. 2 to 11, Is omitted. The order of steps shown in Fig. 12 is only an example, and the present invention is not necessarily limited to this order, and the order may be selectively changed, and in some cases, some or all of the steps may be performed in parallel It is possible.

13 is a flowchart illustrating an image encoding method according to an embodiment of the present invention.

The image coding apparatus 100 determines a current motion vector of the current block and generates a prediction block using the determined current motion vector (S1310). The current block and the prediction block are subtracted to generate a residual block, and the residual block is transformed Quantized and encoded (S1320). The image encoding apparatus 100 determines one of the motion vector prediction candidates as a predicted motion vector as a predicted motion vector (S1330) and encodes a difference vector obtained by subtracting the predicted motion vector determined in step S1330 from the current motion vector (S1340). At this time, the image encoding apparatus 100 can generate and encode a prediction candidate identification flag. The image encoding apparatus 100 generates and outputs a bitstream including the residual block encoded in step S1320 and the difference vector encoded in step S1340 (S1350). The image encoding apparatus 100 may further include a prediction candidate identification flag encoded in the bitstream when the prediction candidate identification flag is encoded. Also, the order of steps shown in Fig. 13 is only an example, and the present invention is not necessarily limited to this order, and the order may be selectively changed, and in some cases, some or all steps may be performed in parallel It is possible.

As described above, the image encoded with the bit stream by the image encoding apparatus 100 can be transmitted through a wired / wireless communication network such as the Internet, a local area wireless communication network, a wireless LAN network, a WiBro network, a mobile communication network, , A universal serial bus (USB), or the like, to be transmitted to a video decoding apparatus to be described later, decoded by the video decoding apparatus, and restored and reproduced as an image.

FIG. 14 is a block diagram schematically illustrating an image decoding apparatus according to an embodiment of the present invention.

An image decoding apparatus 1400 according to an embodiment of the present invention includes a decoder 1410, an inverse quantizer 1420, an inverse transformer 1430, a predictor 1440, an adder 1450, and a memory 1460 . The video decoding apparatus 1400 may be a personal computer (PC), a notebook computer, a personal digital assistant (PDA), a portable multimedia player (PMP), a PlayStation Portable ), A mobile communication terminal, and the like, and may be a communication device such as a communication modem for performing communication with various devices or wired / wireless communication networks, a memory for storing various programs and data for decrypting video, a program And a microprocessor for calculating and controlling the microprocessor.

The decoder 1410 extracts the residual block coded from the bitstream and the coded difference vector to reconstruct the residual block and the difference vector, and selects one of the motion vector prediction candidates as the predicted motion vector And restores the current motion vector of the current block by adding the predicted motion vector and the reconstructed difference vector.

Here, the decoder 1410 further extracts and decodes the encoded predictive candidate identification flag from the bitstream to further recover the predictive candidate identification flag, and identifies it by the restored predictive candidate identification flag among the at least one motion vector predictive candidate Can be determined as a predicted motion vector.

Also, the decoder 1410 decodes the predicted candidate identification flag and the encoded partial predicted candidate identification flag from the bitstream to restore the predicted candidate identification flag and the partial predicted candidate identification flag, and restores one or more motion vector prediction candidates The motion vector prediction candidate identified by the reconstructed prediction candidate identification flag among the motion vector prediction candidates identified by some of the prediction candidate identification flags can be determined as the predictive motion vector.

In addition, the decoder 1410 further extracts and decodes the encoded prediction candidate identification flag from the bitstream to further recover the prediction candidate identification flag, and the absolute value of the x-component of the reconstructed differential vector and the absolute value of the y- Component x-component of the motion vector prediction candidate identified by the reconstructed prediction candidate identification flag, if at least one of the absolute values is less than or equal to at least one of the predetermined x-component threshold and the predetermined y- And y-components as one or more of the x-component and the y-component of the predicted motion vector.

The inverse quantizer 1420 dequantizes the residual block reconstructed by the decoder 1410 and the inverse transformer 1430 inversely transforms the inverse quantized residual block by the inverse quantizer 1420. The inverse quantizer 1420 inversely quantizes the residual block reconstructed by the predictor 1440 ) Generates a prediction block using the current motion vector reconstructed by the decoder 1410 and the adder 1450 generates the prediction block generated by the inverse transformed residual block by the inverse transformer 1430 and the predicted block generated by the predictor 1440 The blocks are added to restore the current block. The memory 1460 stores the reconstructed current block output from the adder 1450 as a reference frame on a frame-by-frame basis so that the predictor 1440 can use the reference frame.

Although not shown in FIG. 14, the video decoding apparatus 1400 according to an embodiment of the present invention described above may be configured to perform an intra predictor for intra prediction, a deblocking filtering Deblocking Filtering), and the like.

15 is a block diagram schematically showing a motion vector decoding apparatus according to an embodiment of the present invention.

The motion vector decoding apparatus according to an embodiment of the present invention may be implemented as a decoder 1410 in the video decoding apparatus according to an embodiment of the present invention described above with reference to FIG. Hereinafter, a motion vector decoding apparatus according to an embodiment of the present invention will be referred to as a decoder 1410 for convenience of explanation.

The decoder 1410 according to an embodiment of the present invention may include a difference vector decoder 1530 and a motion vector restorer 1540. In addition, the decoder 1410 may further include a prediction candidate selection flag decoder 1510 and a prediction candidate identification flag decoder 1520, as the case may be. In addition, the decoder 1410 may further include an image decoder for decoding the encoded residual block, but the image decoder is obvious to a person skilled in the art, and a detailed description thereof will be omitted.

The difference vector decoder 1530 decodes the coded difference vector to recover the difference vector. The motion vector restorer 1540 determines one of the motion vector prediction candidates as a predicted motion vector, and adds the determined predicted motion vector and the restored difference vector to restore the current motion vector of the current block .

The prediction candidate selection flag decoder 1510 restores the encoded prediction candidate selection flag from the header of the bitstream, and the candidate identification flag decoder 1530 extracts one or more of the encoded prediction candidate identification flags from the bitstream, . The motion vector reconstructor 1540 may determine the motion vector prediction candidate identified by the prediction candidate selection flag restored by the candidate selection flag decoder 1510 as one or more motion vector prediction candidates, The motion vector prediction candidate identified by the prediction candidate identification flag reconstructed by the motion vector estimation unit 1520 can be determined as a predicted motion vector.

Here, if the candidate selection flag decoder 1510 is not present or the prediction candidate selection flag is not restored by the candidate selection flag decoder 1510, the motion vector reconstructor 1530 may generate a motion vector of the current block A motion vector of a neighboring block, a motion vector of a col block at the same position as the current block in the reference frame, a motion vector of a neighboring block of the col block, and an indicator vector indicating a specific block of the reference frame in the current block It can be selected as one or more motion vector prediction candidates. Here, the specific block may be a block having a motion vector which is horizontal to the indicating vector or whose difference between the indicating vector is smaller than a preset threshold value. This has been described above with reference to FIGS. 5 to 7, and thus a detailed description thereof will be omitted.

If the selected one or more motion vector prediction candidates are all the same, the same motion vector prediction candidate is assumed to be one motion vector prediction candidate, and the candidate identification flag decoder 1520 determines the predicted motion vector, Thereby restoring the current motion vector.

In addition, the motion vector restorer 1540 restores the absolute value of the x-component and the absolute value of the y-component of the differential vector reconstructed by the difference vector decoder 1530 to the predetermined x- The candidate identification flag may not be decoded and a motion vector prediction candidate in which the restored current motion vector is minimized using each of the one or more motion vector prediction candidates may be determined as a predicted motion vector.

8 and 9, if the difference vector is greater than the threshold value, the motion vector reconstructor 1540 determines that any motion vector prediction candidate among the motion vector prediction candidates selected without the prediction candidate identification flag is a predictive motion vector , The current motion vector is '7' (10-3 = 7) if the current motion vector is restored to the x-component of the first motion vector prediction candidate. However, since the x-component of the second motion vector prediction candidate is '7', it can be discriminated that it is not encoded using the x-component of the first motion vector prediction candidate. When the current motion vector is restored using the x-component of the second motion vector prediction candidate, the current motion vector is '4' (7-3 = 4). Therefore, if the current motion vector is '4' It is possible to identify that the prediction with the third motion vector prediction candidate is more optimal than the prediction with the x-component of the prediction candidate. Therefore, it can be seen that the motion vector is not encoded using the x-component of the second motion vector prediction candidate. In this way, since the x-component of the third motion vector prediction candidate is found to be optimal, the image coding apparatus 100 determines the x-component of the predicted motion vector with the x-component of the third motion vector prediction candidate Can be identified.

If the decoder 1410 does not need to decode the prediction candidate identification flag because the absolute value of each component of the difference vector is larger than the corresponding component threshold value, the motion vector prediction candidates are separately decoded for each component, You can decide. For example, as described in the description of the encoder 150, when the absolute values of the two components of the difference vector are all greater than the threshold value of each component, the optimal predicted motion vector for the x- , And the optimal predicted motion vector of the y-component is determined as 'B', and the predicted motion vector may be determined as a different motion vector prediction candidate for each component.

Also, if the absolute value of each component of the difference vector is smaller than the corresponding component threshold value or only one of the two components is small, the decoder 1410 must decode the prediction candidate identification flag. The motion vector reconstructor 1540 can determine the motion vector prediction candidate identified by the prediction candidate identification flag restored by the prediction candidate identification flag decoder 1520 as a motion vector prediction candidate. If the x-component and the y-component of the difference vector are both smaller than the threshold value, the motion vector prediction candidate identified by decoding the prediction candidate identification flag of each of the x-component and the y- It is also possible to decode one prediction candidate identification flag to determine a motion vector prediction candidate satisfying both components at the same time as a prediction motion vector. If only one of the absolute values of the two components of the difference vector is larger than the threshold value of the corresponding component, the prediction candidate identification flag is decoded only for the component smaller than the threshold of the component. The motion vector reconstructor 1540 may be configured such that at least one of the absolute value of the x-component and the absolute value of the y-component of the differential vector restored by the difference vector decoder 1530 is set to a predetermined x- component and y-component of the motion vector prediction candidate identified by the prediction candidate identification flag reconstructed by the prediction candidate identification flag decoder 1520, if one or more of the y- Of the predicted motion vector as one or more of the x-component and the y-component of the predicted motion vector. At this time, when the prediction candidate selection flag decoder 1510 restores the prediction candidate selection flag, the motion vector reconstructor 1540 generates the prediction candidate selection flag by using the restored prediction candidate identification flag among the motion vector prediction candidates identified by the prediction candidate selection flag It is of course possible to determine at least one of the x-component and the y-component of the identified motion vector prediction candidate as at least one of the x-component and the y-component of the predicted motion vector.

For example, in the case where only one component is smaller than the threshold value, the prediction candidate identification flag encoder 240 described above with reference to FIG. 2 uses a prediction value that identifies which motion vector prediction candidate is used as one component larger than a threshold value If both components are not larger than the threshold value, a prediction candidate identification flag that identifies which motion vector prediction candidate is used as the two components is generated and encoded, Two prediction candidate identification flags for identifying whether the motion vector prediction candidates are used can be generated and encoded.

Accordingly, when the predictive candidate identification flag decoder 1520 extracts and decodes the two encoded predictive candidate identification flags from the bitstream, the motion vector reconstructor 1540 obtains the motion vector prediction candidates identified by the two predictive candidate identification flags And the y-component of the predicted motion vector as the x-component and the y-component of the predicted motion vector. If the candidate identification flag decoder 1520 extracts and decodes one encoded prediction candidate identification flag, the motion vector reconstructor 1540 obtains the x-direction of the motion vector prediction candidate identified by one prediction candidate identification flag, Component or y-component of the predicted motion vector or a x-component or y-component of the motion vector prediction candidate identified by one predictive candidate identification flag to the x-component of the predicted motion vector Or a y-component.

At this time, the motion vector restorer 1540 determines which of the x-component and the y-component of the motion vector prediction candidate identified by the one prediction candidate identification flag is the corresponding component of the predicted motion vector, (Or preset) with the predictive candidate identification flag encoder 240 of FIG. In addition, when a component of the x-component and the y-component of the motion vector prediction candidate identified by one prediction candidate identification flag is determined as a corresponding component of the predicted motion vector, The remaining components can determine the corresponding component of the motion vector prediction candidate in which the restored current motion vector is minimized by using each of the corresponding components of the one or more motion vector prediction candidates as a corresponding component of the predicted motion vector.

If the number of prediction candidates selected as shown in Equation (7) in the description of the encoder 150 is N using the motion vector prediction candidates selected by the decoder 1510, the decoder 1410 decodes , The N-1 threshold values are calculated and the length of the prediction candidate identification flag to be decoded is changed according to the size of the difference vector as shown in FIG. 8 and FIG. The prediction candidate identification flag decoder 1520 generates and decodes the prediction candidate identification flag differently according to the magnitude of the absolute value of each component of the difference vector and each component threshold value. That is, if the absolute value of each component of the difference vector is smaller than or equal to the smallest threshold value of the corresponding component, the prediction candidate identification flag decoder 1520 arranges N-1 threshold values in descending order, A prediction candidate identification flag that identifies which motion vector prediction candidate has been determined as a prediction motion vector among the prediction candidates is decoded and if the absolute value of each component of the difference vector is smaller than or equal to a second smallest threshold value of the component, It is assumed that there is no current motion vector between two motion vector prediction candidates having the smallest threshold value of the corresponding component and it is discriminated whether any motion vector prediction candidate among N-1 selected motion vector prediction candidates is determined as a predicted motion vector And decodes the prediction candidate identification flag. If the absolute value of each component of the difference vector is less than or equal to the third smallest threshold value of the component, it is assumed that there is no current motion vector between the two motion vector prediction candidates having the smallest threshold value of the component , It is assumed that there is no current motion vector between two motion vector prediction candidates having the second smallest threshold value of the corresponding component, and any motion vector prediction candidate among N-2 selected motion vector prediction candidates is determined as a predicted motion vector And decodes the predictive candidate identification flag for identifying whether or not the received signal has been received.

The length of the candidate prediction candidate identification flag to be decoded is one bit read when the value calculated by Equation (9) is an integer as described above in the encoder as shown in FIG. 11, and when it is '1', the highest probability motion vector prediction candidate Is determined. '0', the motion vector prediction candidate is determined by reading the maximum length of the prediction candidate identification flag as shown in Equation (8). If the value calculated by Equation (9) is not an integer, the motion vector prediction candidate MVp_cand [i] is determined by reading a maximum length of the prediction candidate identification flag as shown in Equation (8).

Referring to FIG. 8 and FIG. 10, for example, the number of motion vector prediction candidates is 4, and the threshold values are '1', '3', and '5', respectively. 10 is a diagram obtained by dividing a section according to three threshold values. The interval indicated by (1) represents the x-component of the motion vector prediction candidates, and the interval indicated by (2) represents the current motion vector when the absolute value of the x-component of the difference vector is smaller than or equal to the smallest threshold value of the x- component, and the interval indicated by (3) indicates that the x-component of the current motion vector when the absolute value of the x-component of the difference vector is smaller than or equal to the second smallest threshold value of the x- Component, and the section indicated by (4) represents a section where the x-component of the current motion vector is located when the absolute value of the x-component of the difference vector is smaller than or equal to the largest threshold value of the x-component , The interval indicated by (5) indicates that the x-component of the current motion vector in the case where the absolute value of the x-component of the difference vector is larger than the largest threshold value of the x- A shows a section in which location.

The predictive candidate identification flag decoder 1520 decodes a prediction candidate identification flag that identifies which of the four motion vector prediction candidates has been determined as a predictive motion vector in the section indicated by 2, A prediction candidate identification flag that identifies which of the three motion vector prediction candidates the motion vector prediction candidate is determined as a prediction motion vector is decoded. In a section indicated by 4, any motion vector prediction candidate is predicted Decodes the prediction candidate identification flag that identifies whether the vector is determined as the vector, and does not decode the prediction candidate identification flag in the period indicated by (5).

If the difference vector is '+4', it is larger than the second-largest threshold value and smaller than the largest threshold value. Therefore, as described in the description of the encoder 150, have. A prediction candidate identification flag indicating which motion vector prediction candidate is used in the encoder 150 among the prediction candidates '4' and '14' may be decoded. At this time, since the number of motion vector prediction candidates to be decoded by Equation (8) is two, only one bit can be decoded. The motion vector prediction candidates '-4', '2' and '14' are used as prediction candidates indicating which prediction candidates are used by the encoder 150. In this case, The identification flag can be decoded. Since the number of prediction candidates to be decoded is 3, the calculated value according to Equation (9) is an integer. Thus, if MVp_cand [0] is a value read first by one bit as shown in FIG. 11, MVp_cand [ Decoded by the length of the predictive candidate identification flag to be decoded calculated by Equation (8) in case of '0'.

In the case where the decoder 1410 further includes the prediction candidate identification flag decoder 1520, the motion vector restorer 1540 reads only one bit of the prediction candidate identification flag, 1 &quot;, it is discriminated whether the motion vector prediction candidate having the highest probability is determined as the prediction motion vector, and only when the motion vector prediction candidate having the highest probability is not determined as the prediction motion vector, It is further possible to identify which motion vector prediction candidate has been determined as a predicted motion vector.

At this time, the motion vector reconstructor 1540 may calculate a probability that the current motion vector is determined for each of the one or more motion vector prediction candidates by coding one or more regions of the current frame using one or more motion vector prediction candidates, The motion vector prediction candidate set according to the probability of being designated or set or set arbitrarily can be selected as the motion vector prediction candidate having the highest probability.

16 is a flowchart for explaining a motion vector decoding method according to an embodiment of the present invention.

The decoder 1410 reads and decodes the encoded prediction candidate identification flag from the bit stream to restore the prediction candidate identification flag (S1610), reads and decodes the encoded difference vector from the bit stream to restore the difference vector (S1620) (Step S1630). A motion vector prediction candidate identified by the prediction candidate identification flag reconstructed in step S1630 of the one or more motion vector prediction candidates is predicted by decoding the predicted candidate identification flag And determines the current motion vector of the current block by adding the determined predicted motion vector and the restored difference vector in step S1620 (S1640). Here, the decoder 1410 may not necessarily perform steps S1610 and S1630. In this case, when the predictive motion vector is determined in step S1640, the decoder 1410 decodes the prediction candidate identification If there is no flag, the predicted motion vector can be determined according to the method of determining the predicted motion vector. Also, the order of the steps shown in FIG. 16 is only an example, and the present invention is not necessarily limited to this order, and the order may be selectively changed.

17 is a flowchart illustrating an image decoding method according to an embodiment of the present invention.

The image decoding apparatus 1400 reconstructs the prediction candidate identification flag by extracting and decoding the encoded prediction candidate identification flag from the bit stream (S1710), extracts and decodes the encoded difference vector from the bit stream to restore the difference vector ( S1720), the predicted candidate identification flag is extracted and decoded from the bitstream to decode the predicted candidate identification flag (S1730), and among the one or more motion vector prediction candidates, the motion vector prediction candidate As a predicted motion vector, and adds the determined predicted motion vector and the reconstructed difference vector in step S1720 to reconstruct the current motion vector (S1740).

The image decoding apparatus 1400 estimates and compensates for the motion of the current block using the restored current motion vector in step S1740 to generate a predicted block and generates a predicted block (S1750), and extracts the encoded residual block from the bitstream And decodes the coded residual block by inverse-quantizing and inverse-transforming the decoded residual block to restore the residual block, and restores the current block by adding the restored residual block to the prediction block (S1760).

Here, the image decoding apparatus 1400 may not necessarily perform steps S1710 and S1730. In this case, when determining the predicted motion vector in step S1740, the image decoding apparatus 1400 decodes the prediction If there is no candidate identification flag, a predicted motion vector may be determined according to a method of determining a predicted motion vector. In addition, the steps shown and described in Fig. 17 are not necessarily limited to the order shown and described, and the order may be selectively changed.

For example, instead of performing the respective steps in the order shown in FIG. 17, the image decoding apparatus 1400 extracts and decodes the encoded residual block from the bitstream, restores the residual block, and outputs the encoded difference vector from the bitstream Extracts and decodes the motion vectors to restore a differential vector, selects one of the motion vector prediction candidates as a prediction motion vector, restores the current motion vector of the current block using the selected prediction vector and the reconstructed differential vector Quantizes the reconstructed residual block, inversely transforms the inversely quantized residual block, generates a prediction block using the reconstructed current motion vector, and adds the inverse transformed residual block and the generated prediction block to reconstruct the current block And then perform each step in the order.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments. That is, within the scope of the present invention, all of the components may be selectively coupled to one or more of them. In addition, although all of the components may be implemented as one independent hardware, some or all of the components may be selectively combined to perform a part or all of the functions in one or a plurality of hardware. As shown in FIG. The codes and code segments constituting the computer program may be easily deduced by those skilled in the art. Such a computer program can be stored in a computer-readable storage medium, readable and executed by a computer, thereby realizing an embodiment of the present invention. As the storage medium of the computer program, a magnetic recording medium, an optical recording medium, a carrier wave medium, or the like may be included.

Furthermore, the terms "comprises", "comprising", or "having" described above mean that a component can be implanted unless otherwise specifically stated, But should be construed as including other elements. All terms, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, unless otherwise defined. Commonly used terms, such as predefined terms, should be interpreted to be consistent with the contextual meanings of the related art, and are not to be construed as ideal or overly formal, unless expressly defined to the contrary.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

As described above, according to the present invention, inter prediction is performed using pixels that have been coded, decoded and reconstructed before a current block to be encoded, motion vectors used for inter prediction are efficiently encoded or decoded, The present invention is applied to an image processing field for encoding or decoding data of a moving picture so as to improve a compression efficiency by reducing a bit amount for coding information on a predictive motion vector while coding a motion vector using a more accurately predicted predictive motion vector It is a very useful invention that produces an effect.

Claims (18)

An apparatus for coding a current motion vector, which is a motion vector of a current block,
A prediction candidate selector for selecting a motion vector prediction candidate for predicting the current motion vector;
A predicted motion vector determiner for determining a predicted motion vector from the motion vector prediction candidate; And
And a difference vector encoder for calculating and coding a difference vector by subtracting the predicted motion vector from the current motion vector,
Wherein the prediction candidate selector comprises:
A module for selecting at least one first motion vector prediction candidate based on a neighboring block of the current block in the current frame and a module for selecting a second motion vector prediction candidate based on a reference block in the reference frame, And a motion vector coding unit. 2. The apparatus of claim 1, wherein the prediction candidate selector comprises:
And determines the position of the reference block in the reference frame based on the position of the current block in the current frame. 2. The apparatus of claim 1, wherein the prediction candidate selector comprises:
Wherein the selecting unit selects the at least one first motion vector prediction candidate in at least one of an upper left block, an upper block, and an upper right block of the current block. 2. The apparatus of claim 1, wherein the prediction candidate selector comprises:
And selects only one of the two candidates as a motion vector prediction candidate if the distance between the two motion vector prediction candidates does not satisfy a predetermined criterion. 2. The apparatus of claim 1, wherein the prediction candidate selector comprises:
Selecting all of the motion vector prediction candidates for determining the predicted motion vector from the at least one first motion vector prediction candidate,
And selects the motion vector prediction candidate for determining the predicted motion vector in each of the at least one first motion vector prediction candidate and the second motion vector prediction candidate. A method for coding a current motion vector, which is a motion vector of a current block,
Selecting a motion vector prediction candidate for predicting the current motion vector;
Determining a predicted motion vector from the motion vector prediction candidate; And
And subtracting the predicted motion vector from the current motion vector to calculate and encode a difference vector,
Wherein the motion vector prediction candidate selection step comprises:
Selecting a first motion vector prediction candidate based on a neighboring block of the current block in a current frame; and selecting a second motion vector prediction candidate based on a reference block in the reference frame. Vector encoding method. The method according to claim 6,
Wherein the position of the reference block in the reference frame is determined based on the position of the current block in the current frame. The method according to claim 6,
Wherein the first motion vector prediction candidate is selected from at least one of an upper left block, an upper block, and an upper right block of the current block. The method according to claim 6,
Wherein the step of selecting the motion vector prediction candidates selects only one of the two motion vector prediction candidates if the distance between the two motion vector prediction candidates does not satisfy a predetermined reference. An apparatus for decoding a current motion vector of a current block,
A difference vector decoder for decoding a difference vector from a bitstream; And
A motion vector prediction unit for selecting a motion vector prediction candidate for predicting the current motion vector, determining a predicted motion vector from the motion vector prediction candidates, and adding the predicted motion vector and the difference vector to recover a current motion vector of the current block, A reconstructor,
Wherein the motion vector reconstructor comprises:
A module for selecting at least one first motion vector prediction candidate based on a neighboring block of the current block in the current frame and a module for selecting a second motion vector prediction candidate based on a reference block in the reference frame, The motion vector decoding apparatus comprising: 11. The apparatus of claim 10,
And determines the position of the reference block in the reference frame based on the position of the current block in the current frame. 11. The apparatus of claim 10,
Wherein the motion vector decoding unit selects the at least one first motion vector prediction candidate in at least one of an upper left block, an upper block, and an upper right block of the current block. 11. The apparatus of claim 10,
And selects only one of the two candidates as a motion vector prediction candidate if the distance between the two motion vector prediction candidates does not satisfy a predetermined criterion. 11. The apparatus of claim 10,
Selecting all of the motion vector prediction candidates for determining the predicted motion vector from the at least one first motion vector prediction candidate,
And selects the motion vector prediction candidate for determining the predicted motion vector in each of the at least one first motion vector prediction candidate and the second motion vector prediction candidate. A method for decoding a current motion vector of a current block,
Reconstructing a differential vector from the bitstream;
Selecting a motion vector prediction candidate for predicting the current motion vector;
Determining a predicted motion vector from the motion vector prediction candidates; And
And restoring a current motion vector of a current block by adding the predictive motion vector and the difference vector,
Wherein the motion vector prediction candidate selection step comprises:
Selecting a first motion vector prediction candidate based on a neighboring block of the current block in a current frame; and selecting a second motion vector prediction candidate based on a reference block in the reference frame. Vector decoding method. 16. The method of claim 15,
Wherein a position of the reference block in the reference frame is determined based on a position of the current block in the current frame. 16. The method of claim 15,
Wherein the first motion vector prediction candidate is selected from at least one of an upper left block, an upper block, and an upper right block of the current block. 16. The method of claim 15,
Wherein the step of selecting the motion vector prediction candidates selects only one of the two candidates as a motion vector prediction candidate if the distance between the two motion vector prediction candidates does not satisfy a predetermined criterion.

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