KR20220065740A - Method and apparatus for encoding and decoding video using picture partition information - Google Patents

Abstract

Disclosed are a method and device for encoding and decoding video using picture segmentation information. Each picture of pictures of video is divided into tiles or slices based on picture division information. Each picture is divided in one of at least two different ways based on picture segmentation information. The picture segmentation information may indicate two or more picture segmentation ways. The picture segmentation method may change periodically or according to a specified rule. The picture segmentation information may describe such periodic change or specified rule.

Description

Method and apparatus for encoding and decoding video using picture segmentation information

The following embodiments relate to a video decoding method, a decoding apparatus, an encoding method, and an encoding apparatus, and more particularly, to a method and apparatus for encoding and decoding a moving picture using picture segmentation information.

With the continuous development of the information and communication industry, a broadcasting service having a high definition (HD) resolution has spread worldwide. Through this proliferation, many users have become accustomed to high-resolution and high-definition images and/or videos.

In order to satisfy users' demand for high picture quality, many organizations are spurring the development of next-generation imaging devices. User interest in High Definition TV (HDTV) and Full HD (FHD) TV, as well as Ultra High Definition (UHD) TV, which has a resolution four times higher than that of FHD TV has increased, and with this increase in interest, image encoding/decoding technology for an image having higher resolution and image quality is required.

An image encoding/decoding apparatus and method for encoding/decoding high-resolution and high-definition images, such as inter prediction technology, intra prediction technology, entropy encoding technology, etc. can be used The inter prediction technique may be a technique of predicting a value of a pixel included in a current picture using a temporally previous picture and/or a temporally later picture. The intra prediction technique may be a technique of predicting the value of a pixel included in the current picture by using information on the pixel in the current picture. The entropy encoding technique may be a technique of allocating a short code to a symbol having a high frequency of occurrence and a technique of assigning a long code to a symbol having a low frequency of occurrence.

In encoding and decoding of an image, prediction may mean generating a prediction signal similar to an original signal. Prediction may be largely classified into prediction referring to a spatially reconstructed image, prediction referring to a temporally reconstructed image, and prediction of other symbols. That is, temporal reference may mean referring to a temporally reconstructed image, and spatial reference may mean referring to a spatially reconstructed image.

The current block may be a block currently being encoded or decoded. The current block may be called a target block or a target unit. In encoding, the current block may be referred to as an encoding object block or an encoding object unit. In decoding, the current block may be referred to as a decoding object block or a decoding object unit.

Inter prediction may be a technique for predicting a current block using a temporal reference and a spatial reference. Intra prediction may be a technique for predicting a current block using only spatial reference.

In encoding pictures constituting a video, the picture may be divided into a plurality of parts, and the plurality of parts may be encoded. In this case, in order for the decoder to decode the divided picture, information related to picture division may be required.

An embodiment may provide a method and apparatus for improving encoding efficiency and decoding efficiency through a technique for performing adaptive encoding and decoding using picture partition information.

An embodiment may provide a method and apparatus for improving encoding efficiency and decoding efficiency through a technique for performing encoding and decoding for determining picture division for a plurality of pictures based on one picture division information.

An embodiment may provide a method and apparatus for deriving another picture partitioning information from one picture partitioning information with respect to a bitstream encoded using two or more different picture partitioning information.

An embodiment may provide a method and apparatus for omitting transmission or reception of picture division information for at least some of pictures of a moving picture.

In one aspect, the method comprising: encoding a plurality of pictures; and generating data including picture division information and the encoded plurality of pictures, wherein each picture of the plurality of pictures is divided in one of at least two different methods corresponding to the picture division information. A video encoding method is provided.

In the other side, the control unit for obtaining picture division information; and a decoding unit configured to decode a plurality of pictures, wherein each picture of the plurality of pictures is divided by one of at least two different methods based on the picture division information.

In another aspect, the method comprising: decoding picture division information; and performing decoding of a plurality of pictures based on the picture division information, wherein each picture of the plurality of pictures is divided by one of at least two different methods.

A first picture among the plurality of pictures may be divided based on the picture division information.

A second picture among the plurality of pictures may be divided based on other picture division information derived based on the picture division information.

The plurality of pictures may be divided by a periodically changing picture division method defined by the picture division information.

The plurality of pictures may be divided by a picture division method that changes according to a rule defined by the picture division information.

The picture division information may indicate that the same picture division method is applied to pictures having a second predefined value remaining when a picture order among the plurality of pictures is divided by a first predefined value.

The picture division information may indicate how many tiles each picture of the plurality of pictures is divided into.

Each picture of the plurality of pictures may be divided into a number of tiles determined based on the picture division information.

Each picture of the plurality of pictures may be divided into a number of slices determined based on the picture division information.

The picture division information may be included in a picture parameter set (PPS).

The PPS may include an integrated division indication flag indicating whether the picture referring to the PPS is divided by one of at least two or more different methods.

The picture division information may indicate a picture division method of a picture of a specified level.

The level may be a temporal level.

The picture division information may include reduction indication information for reducing the number of tiles generated by picture division.

The reduction indication information may control the number of horizontal tiles when the horizontal picture length is greater than the vertical picture length, and control the number of vertical tiles when the picture vertical length is greater than the picture horizontal length.

The horizontal length of the picture may be the horizontal length of the picture.

The vertical length of the picture may be the vertical length of the picture.

The number of horizontal tiles may be the number of tiles in a horizontal direction of the picture.

The number of vertical tiles may be the number of tiles in a vertical direction of the picture.

The picture division information may include level n reduction indication information for reducing the number of tiles generated by picture division for a level n picture.

The picture division information may include reduction indication information for reducing the number of slices generated by picture division.

The picture division information may include level n reduction indication information for reducing the number of slices generated by picture division for a level n picture.

The at least two different methods may be different from each other with respect to the number of slices generated for picture division.

A method and apparatus for improving encoding efficiency and decoding efficiency through a technique for performing adaptive encoding and decoding using picture segmentation information are provided.

A method and apparatus for improving encoding efficiency and decoding efficiency through a technique for performing encoding and decoding for determining picture division for a plurality of pictures based on one picture division information are provided.

A method and apparatus are provided for deriving different picture partitioning information from one picture partitioning information with respect to a bitstream encoded using two or more different picture partitioning information.

A method and apparatus for omitting transmission or reception of picture division information for at least some of pictures of a moving picture are provided.

1 is a block diagram illustrating a configuration of an encoding apparatus to which the present invention is applied according to an embodiment.
2 is a block diagram illustrating a configuration of a decoding apparatus to which the present invention is applied according to an embodiment.
3 is a diagram schematically illustrating a structure of an image segmentation when an image is encoded and decoded.
4 is a diagram illustrating a form of a prediction unit (PU) that a coding unit (CU) may include.
5 is a diagram illustrating a form of a transform unit (TU) that may be included in a coding unit (CU).
6 is a diagram for explaining an embodiment of an intra prediction process.
7 is a diagram for explaining an embodiment of an inter prediction process.
8 illustrates division of a picture using tiles according to an example.
9 illustrates a reference structure of encoding to which a GOP level is applied according to an example.
10 shows an encoding order of pictures of a GOP according to an example.
11 illustrates parallel encoding of pictures of a GOP according to an example.
12 illustrates division of a picture using a slice according to an example.
13 is a structural diagram of an encoding apparatus for encoding a video according to an embodiment.
14 is a flowchart of an encoding method for encoding a video according to an example.
15 is a structural diagram of a decoding apparatus that decodes a video according to an embodiment.
16 is a flowchart of a decoding method for decoding a video according to an example.
17 is a structural diagram of an electronic device implementing an encoding apparatus and/or a decoding apparatus according to an embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0010] Reference is made to the accompanying drawings, which illustrate specific embodiments by way of example.

Like reference numerals in the drawings refer to the same or similar functions throughout the various aspects. The shapes and sizes of elements in the drawings may be exaggerated for clearer description.

When a component is referred to as being “connected” or “connected” to another component, the two components may be directly connected or connected to each other, but in the above 2 It should be understood that other components may exist in the middle of the components. In addition, the description of "including" a specific configuration in the exemplary embodiments does not exclude components other than the above specific configuration, and additional configuration is the implementation of the exemplary embodiments or the technical spirit of the exemplary embodiments. It means that it can be included in the scope.

Each component is listed as a respective component for convenience of description. For example, at least two components among the components may be combined into one component. Also, one component may be divided into a plurality of components. Integrated embodiments and separate embodiments of each of these components are also included in the scope of rights without departing from the essence.

Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings in order to enable those of ordinary skill in the art to easily implement the embodiments. In describing the embodiments, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present specification, the detailed description thereof will be omitted.

Hereinafter, an image may mean one picture constituting a video, or may indicate a video itself. For example, "encoding and/or decoding of an image" may mean "encoding and/or decoding of a video", and may mean "encoding and/or decoding of one image among images constituting a video". may be

Hereinafter, "video" and "motion picture" may be used as the same meaning, and may be used interchangeably.

Hereinafter, the terms “image”, “picture”, “frame” and “screen” may be used interchangeably and may be used interchangeably.

In embodiments, each of the specified information, data, flags and elements, attributes, etc. may have a value. A value "0" of information, data, flags and elements, attributes, etc. may represent logical false or a first predefined value. In other words, the value “0”, logical false and the first predefined value may be used interchangeably. A value “1” of information, data, flags and elements, attributes, etc. may represent logical true or a second predefined value. In other words, the value “1”, logical true and the second predefined value may be used interchangeably.

When a variable such as i or j is used to indicate a row, column, or index, the value of i may be an integer of 0 or more, or an integer of 1 or more. That is, in embodiments, a row, column, index, etc. may be counted from 0, and may be counted from 1.

In the following, terms used in the embodiments are described.

Unit: A “unit” may indicate a unit of encoding and decoding of an image. The meanings of unit and block may be the same. Also, the terms “unit” and “block” may be used interchangeably.

- A unit (or block) may be an MxN array of samples. M and N may each be a positive integer. A unit can often mean an array of two-dimensional samples. A sample may be a pixel or a pixel value.

- The terms "pixel" and "sample" may be used interchangeably and may be used interchangeably.

- In image encoding and decoding, a unit may be an area generated by segmentation of one image. One image may be divided into a plurality of units. In encoding and decoding of an image, a predefined process for the unit may be performed according to the type of the unit. According to the function, the type of the unit may be classified into a macro unit, a coding unit (CU), a prediction unit (PU), a transform unit (TU), and the like. One unit may be further divided into sub-units having a smaller size compared to the unit.

- The unit division information may include information about the depth of the unit. The depth information may indicate the number and/or degree to which a unit is divided.

- One unit may be hierarchically divided into a plurality of sub-units while having depth information based on a tree structure. In other words, a unit and a sub-unit generated by division of the unit may correspond to a node and a child node of the node, respectively. Each divided sub-unit may have depth information. Since the depth information of the unit indicates the number and/or degree of division of the unit, the division information of the sub-unit may include information about the size of the sub-unit.

- In the tree structure, the highest node may correspond to the first undivided unit. The uppermost node may be referred to as a root node. Also, the highest node may have a minimum depth value. In this case, the highest node may have a depth of level 0.

- A node with a depth of level 1 may represent a unit created as the original unit is split once. A node with a depth of level 2 may represent a unit generated as the original unit is split twice.

- A node having a depth of level n may represent a unit generated as the original unit is divided n times.

- A leaf node may be the lowest node, and may be a node that cannot be further divided. The depth of the leaf node may be the maximum level. For example, the predefined value of the maximum level may be three.

Transform Unit: A transform unit may be a basic unit in residual signal encoding and/or residual signal decoding such as transform, inverse transform, quantization, inverse quantization, transform coefficient encoding, and transform coefficient decoding. . One transform unit may be divided into multiple transform units having a smaller size.

Prediction Unit: A prediction unit may be a basic unit in performing prediction or compensation. A prediction unit may be divided into multiple partitions. Multiple partitions may also be a basic unit in the performance of prediction or compensation. A partition generated by division of a prediction unit may also be a prediction unit.

Reconstructed Neighbor Unit: The reconstructed neighboring unit may be a reconstructed unit that has already been encoded or decoded near the encoding object unit or the decoding object unit. The reconstructed neighboring unit may be a spatial (spatial) neighboring unit or a temporal (temporal) neighboring unit with respect to the target unit.

Prediction unit partition: A prediction unit partition may mean a form in which a prediction unit is divided.

Parameter Set: A parameter set may correspond to header information among structures in a bitstream. For example, the parameter set may include a sequence parameter set, a picture parameter set, an adaptation parameter set, and the like.

Rate-distortion optimization: The encoding apparatus uses a combination of a size of a coding unit, a prediction mode, a size of a prediction unit, motion information, and a size of a transform unit to provide high encoding efficiency. Distortion optimization can be used.

- The rate-distortion optimization method may calculate a rate-distortion cost of each combination in order to select an optimal combination from among the above combinations. The rate-distortion cost can be calculated using Equation 1 below. In general, the combination in which the rate-distortion cost is minimized may be selected as the optimal combination in the rate-distortion optimization method.

[Formula 1]

D may represent distortion. D may be a mean square error of squares of difference values between original transform coefficients and reconstructed transform coefficients in a transform block.

R may represent a rate. R may represent a bit rate using related context information.

λ may represent a Lagrangian multiplier. R may include not only encoding parameter information such as prediction mode, motion information, and a coded block flag, but also bits generated by encoding a transform coefficient.

The encoding apparatus performs processes such as inter prediction and/or intra prediction, transformation, quantization, entropy encoding, inverse quantization, and inverse transformation to calculate accurate D and R. These processes may significantly increase the complexity of the encoding apparatus. there is.

Reference picture: The reference picture may be an image used for inter prediction or motion compensation. The reference picture may be a picture including the reference unit referenced by the target unit for inter prediction or motion compensation. The meanings of the picture and the image may be the same. Also, the terms “picture” and “image” may be used interchangeably.

Reference picture list: The reference picture list may be a list including reference pictures used for inter prediction or motion compensation. The type of the reference picture list may include a list combination (LC), a list 0 (List 0; L0), and a list 1 (List 1; L1).

Motion Vector (MV): The motion vector may be a two-dimensional vector used in inter prediction. For example, the MV may be expressed in the form (mv _x , mv _y ). mv _x may represent a horizontal component, and mv _y may represent a vertical component.

- MV may indicate an offset between the target picture and the reference picture.

Search range: The search range may be a two-dimensional area in which an MV is searched during inter prediction. For example, the size of the search area may be MxN. M and N may each be a positive integer.

1 is a block diagram illustrating a configuration of an encoding apparatus to which the present invention is applied according to an embodiment.

The encoding apparatus 100 may be a video encoding apparatus or an image encoding apparatus. A video may include one or more images. The encoding apparatus 100 may sequentially encode one or more images of a video according to time.

Referring to FIG. 1 , the encoding apparatus 100 includes an inter prediction unit 110 , an intra prediction unit 120 , a switch 115 , a subtractor 125 , a transform unit 130 , a quantization unit 140 , and entropy encoding. It may include a unit 150 , an inverse quantizer 160 , an inverse transform unit 170 , an adder 175 , a filter unit 180 , and a reference picture buffer 190 .

The encoding apparatus 100 may encode an input image in an intra mode and/or an inter mode. The input image may be referred to as a current image that is a current encoding target.

Also, the encoding apparatus 100 may generate a bitstream including encoding information through encoding of an input image, and may output the generated bitstream.

When the intra mode is used, the switch 115 may be switched to intra. When the inter mode is used, the switch 115 may be switched to the inter mode.

The encoding apparatus 100 may generate a prediction block for the input block of the input image. Also, after the prediction block is generated, the encoding apparatus 100 may encode a residual between the input block and the prediction block. The input block may be referred to as a current block that is a current encoding target.

When the prediction mode is the intra mode, the intra prediction unit 120 may use a pixel value of an already encoded block adjacent to the current block as a reference pixel. The intra prediction unit 120 may perform spatial prediction on the current block by using the reference pixel, and may generate prediction samples for the current block through spatial prediction.

The inter prediction unit 110 may include a motion prediction unit and a motion compensator.

When the prediction mode is the inter mode, the motion prediction unit may search for a region that best matches the current block from the reference image in the motion prediction process, and may derive a motion vector for the current block and the searched region. The reference picture may be stored in the reference picture buffer 190 , and may be stored in the reference picture buffer 190 when encoding and/or decoding of the reference picture is processed.

The motion compensator may generate a prediction block by performing motion compensation using a motion vector. Here, the motion vector may be a two-dimensional vector used for inter prediction. Also, the motion vector may indicate an offset between the current image and the reference image.

The subtractor 125 may generate a residual block that is a difference between the input block and the prediction block. The residual block may be referred to as a residual signal.

The transform unit 130 may generate a transform coefficient by performing a transform on the residual block, and may output the generated transform coefficient. Here, the transform coefficient may be a coefficient value generated by performing transform on the residual block. When a transform skip mode is applied, the transform unit 130 may skip transform on the residual block.

A quantized transform coefficient level may be generated by applying quantization to the transform coefficient. Hereinafter, in embodiments, a quantized transform coefficient level may also be referred to as a transform coefficient.

The quantizer 140 may generate a quantized transform coefficient level by quantizing the transform coefficient according to the quantization parameter. The quantization unit 140 may output the generated quantized transform coefficient level. In this case, the quantization unit 140 may quantize the transform coefficients using a quantization matrix.

The entropy encoding unit 150 may generate a bitstream by performing entropy encoding according to a probability distribution based on the values calculated by the quantization unit 140 and/or encoding parameter values calculated during the encoding process. . The entropy encoder 150 may output the generated bitstream.

The entropy encoding unit 150 may perform entropy encoding on information for decoding an image in addition to information on pixels of the image. For example, information for decoding an image may include a syntax element or the like.

The encoding parameter may be information required for encoding and/or decoding. The encoding parameter may include information encoded by the encoding apparatus and transmitted to the decoding apparatus, and may include information that can be inferred during encoding or decoding. For example, as information transmitted to the decoding apparatus, there is a syntax element.

For example, the coding parameters include a prediction mode, a motion vector, a reference picture index, a coding block pattern, presence or absence of a residual signal, a transform coefficient, a quantized transform coefficient, a quantization parameter, a block size, and a block partition. It may include values or statistics such as information. The prediction mode may indicate an intra prediction mode or an inter prediction mode.

The residual signal may mean a difference between the original signal and the predicted signal. Alternatively, the residual signal may be a signal generated by transforming a difference between the original signal and the predicted signal. Alternatively, the residual signal may be a signal generated by transforming and quantizing a difference between the original signal and the predicted signal. The residual block may be a residual signal in units of blocks.

When entropy encoding is applied, a small number of bits may be allocated to a symbol having a high probability of occurrence, and a large number of bits may be allocated to a symbol having a low probability of occurrence. As a symbol is expressed through this allocation, the size of a bitstring for symbols to be encoded may be reduced. Accordingly, compression performance of image encoding may be improved through entropy encoding.

In addition, for entropy encoding, such as exponential golomb, context-adaptive variable length coding (CAVLC) and context-adaptive binary arithmetic coding (CABAC), etc. A coding method may be used. For example, the entropy encoding unit 150 may perform entropy encoding using a Variable Length Coding/Code (VLC) table. For example, the entropy encoder 150 may derive a binarization method for a target symbol. Also, the entropy encoder 150 may derive a probability model of a target symbol/bin. The entropy encoding unit 150 may perform entropy encoding using the derived binarization method or a probability model.

Since encoding is performed through inter prediction by the encoding apparatus 100, the encoded current image may be used as a reference image for other image(s) to be processed later. Accordingly, the encoding apparatus 100 may decode the encoded current image again and store the decoded image as a reference image. Inverse quantization and inverse transformation of the encoded current image for decoding may be processed.

The quantized coefficient may be inversely quantized by the inverse quantization unit 160 and may be inversely transformed by the inverse transform unit 170 . The inverse quantized and inverse transformed coefficients may be summed with the prediction block through the adder 175. A reconstructed block may be generated by summing the inverse quantized and inverse transformed coefficients and the prediction block.

The reconstructed block may pass through the filter unit 180 . The filter unit 180 may apply at least one of a deblocking filter, a sample adaptive offset (SAO), and an adaptive loop filter (ALF) to a reconstructed block or a reconstructed picture. there is. The filter unit 180 may be referred to as an adaptive in-loop filter.

The deblocking filter may remove block distortion occurring at the boundary between blocks. The SAO may add an appropriate offset value to the pixel value to compensate for the coding error. The ALF may perform filtering based on a value obtained by comparing the reconstructed image and the original image. The reconstructed block passing through the filter unit 180 may be stored in the reference picture buffer 190 .

2 is a block diagram illustrating a configuration of a decoding apparatus to which the present invention is applied according to an embodiment.

The decoding apparatus 200 may be a video decoding apparatus or an image decoding apparatus.

Referring to FIG. 2 , the decoding apparatus 200 includes an entropy decoding unit 210 , an inverse quantization unit 220 , an inverse transform unit 230 , an intra prediction unit 240 , an inter prediction unit 250 , and an adder 255 . , a filter unit 260 and a reference picture buffer 270 may be included.

The decoding apparatus 200 may receive the bitstream output from the encoding apparatus 100 . The decoding apparatus 200 may perform intra-mode and/or inter-mode decoding on the bitstream. Also, the decoding apparatus 200 may generate a reconstructed image through decoding and may output the generated reconstructed image.

For example, switching to an intra mode or an inter mode according to a prediction mode used for decoding may be performed by a switch. When the prediction mode used for decoding is the intra mode, the switch may be switched to the intra mode. When the prediction mode used for decoding is the inter mode, the switch may be switched to the inter mode.

The decoding apparatus 200 may obtain a reconstructed residual block from the input bitstream and generate a prediction block. When the reconstructed residual block and the prediction block are obtained, the decoding apparatus 200 may generate a reconstructed block by adding the reconstructed residual block and the prediction block.

The entropy decoding unit 210 may generate symbols by performing entropy decoding on the bitstream based on the probability distribution. The generated symbols may include symbols in the form of quantized coefficients. Here, the entropy decoding method may be similar to the entropy encoding method described above. For example, the entropy decoding method may be a reverse process of the entropy encoding method described above.

The quantized coefficient may be inverse quantized by the inverse quantizer 220 . Also, the inverse quantized coefficient may be inversely transformed by the inverse transform unit 230 . As a result of inverse quantization and inverse transformation of the quantized coefficient, a reconstructed residual block may be generated. In this case, the inverse quantizer 220 may apply a quantization matrix to the quantized coefficients.

When the intra mode is used, the intra prediction unit 240 may generate a prediction block by performing spatial prediction using pixel values of an already decoded block around the current block.

The inter prediction unit 250 may include a motion compensator. When the inter mode is used, the motion compensator may generate a prediction block by performing motion compensation using a motion vector and a reference image. The reference image may be stored in the reference picture buffer 270 .

The reconstructed residual block and the prediction block may be added through an adder 255 . The adder 255 may generate a reconstructed block by adding the reconstructed residual block and the prediction block.

The reconstructed block may pass through the filter unit 260 . The filter unit 260 may apply at least one of the deblocking filter, SAO, and ALF to the reconstructed block or the reconstructed picture. The filter unit 260 may output a reconstructed image. The reconstructed image may be stored in the reference picture buffer 270 and used for inter prediction.

3 is a diagram schematically illustrating a structure of an image segmentation when an image is encoded and decoded.

In order to efficiently segment an image, a coding unit (CU) may be used in encoding and decoding. A unit may be a term that collectively refers to 1) a block including image samples and 2) a syntax element. For example, "division of a unit" may mean "division of a block corresponding to a unit".

Referring to FIG. 3 , an image 300 may be sequentially divided in units of a Largest Coding Unit (LCU), and the division structure of the image 300 may be determined according to the LCU. Here, LCU may be used in the same meaning as a Coding Tree Unit (CTU).

The division structure may mean a distribution of coding units (CUs) for efficiently encoding an image in the LCU 310 . This distribution may be determined according to whether one CU is divided into four CUs. The horizontal size and vertical size of the CU generated by division may be half of the horizontal size and half of the vertical size of the CU before division, respectively. The divided CU may be recursively divided into four CUs whose horizontal size and vertical size are reduced by half in the same manner.

In this case, the division of the CU may be performed recursively to a predefined depth. The depth information may be information indicating the size of a CU. Depth information may be stored for each CU. For example, the depth of the LCU may be 0, and the depth of a Smallest Coding Unit (SCU) may be a predefined maximum depth. Here, the LCU may be a CU having the largest coding unit size as described above, and the SCU may be a CU having the smallest coding unit size.

The division may start from the LCU 310, and whenever the horizontal size and the vertical size of the CU are halved by the division, the depth of the CU may increase by one. For each depth, an undivided CU may have a size of 2Nx2N. In addition, in the case of a divided CU, a CU having a size of 2Nx2N may be divided into four CUs having a size of NxN. The size of N can be halved for each increase in depth by 1.

Referring to FIG. 3 , an LCU having a depth of 0 may be 64x64 pixels. 0 may be the minimum depth. An SCU of depth 3 may be 8x8 pixels. 3 may be the maximum depth. In this case, a CU of 64x64 pixels, which is an LCU, may be expressed as depth 0. A CU of 32x32 pixels may be expressed as depth 1. A CU of 16x16 pixels may be represented with depth 2. A CU of 8x8 pixels, which is an SCU, may be expressed as depth 3 .

Also, information on whether a CU is split may be expressed through split information of the CU. The division information may be 1-bit information. All CUs except for the SCU may include partition information. For example, if the CU is not split, the value of the split information of the CU may be 0, and if the CU is split, the value of the split information of the CU may be 1.

4 is a diagram illustrating a form of a prediction unit (PU) that a coding unit (CU) may include.

A CU that is no longer split among CUs split from an LCU may be split into one or more prediction units (PUs). This partition may also be referred to as a partition.

A PU may be a basic unit for prediction. The PU may be encoded and decoded in any one of a skip mode, an inter mode, and an intra mode. The PU may be divided into various forms according to each mode.

In skip mode, there may not be a split in a CU. In the skip mode, the 2Nx2N mode 410 in which PU and CU sizes are the same without division may be supported.

In the inter mode, 8 types of divided types within a CU may be supported. For example, in the inter mode, 2Nx2N mode 410, 2NxN mode 415, Nx2N mode 420, NxN mode 425, 2NxnU mode 430, 2NxnD mode 435, nLx2N mode 440, and nRx2N mode Mode 445 may be supported.

In the intra mode, the 2Nx2N mode 410 and the NxN mode 425 may be supported.

In the 2Nx2N mode 410, a PU having a size of 2Nx2N may be encoded. A PU having a size of 2Nx2N may mean a PU having the same size as that of a CU. For example, a PU having a size of 2Nx2N may have a size of 64x64, 32x32, 16x16, or 8x8.

In the NxN mode 425 , a PU having a size of NxN may be encoded.

For example, in intra prediction, when the size of a PU is 8x8, four divided PUs may be coded. The size of the divided PU may be 4x4.

When a PU is encoded by an intra mode, the PU may be encoded using one intra prediction mode among a plurality of intra prediction modes. For example, a High Efficiency Video Coding (HEVC) technique may provide 35 intra prediction modes, and a PU may be encoded in one intra prediction mode among 35 intra prediction modes.

Which mode of the 2Nx2N mode 410 and the NxN mode 425 the PU is coded by may be determined by rate-distortion cost.

The encoding apparatus 100 may perform an encoding operation on a PU having a size of 2Nx2N. Here, the encoding operation may be encoding the PU using each of a plurality of intra prediction modes that the encoding apparatus 100 can use. An optimal intra prediction mode for a PU having a size of 2Nx2N may be derived through an encoding operation. The optimal intra prediction mode may be an intra prediction mode that generates a minimum rate-distortion cost for encoding a PU having a size of 2Nx2N among a plurality of intra prediction modes that can be used by the encoding apparatus 100 .

Also, the encoding apparatus 100 may sequentially perform an encoding operation on each PU of the PUs divided into NxN. Here, the encoding operation may be encoding the PU using each of a plurality of intra prediction modes that the encoding apparatus 100 can use. An optimal intra prediction mode for an NxN-sized PU may be derived through an encoding operation. The optimal intra-prediction mode may be an intra-prediction mode that generates a minimum rate-distortion cost for encoding an NxN-sized PU among a plurality of intra prediction modes that can be used by the encoding apparatus 100 .

The encoding apparatus 100 may determine which of the 2Nx2N PU and the NxN PUs to be encoded based on a comparison of the rate-distortion cost of the 2Nx2N PU and the rate-distortion costs of the NxN PUs.

5 is a diagram illustrating a form of a transform unit (TU) that may be included in a coding unit (CU).

A transform unit (TU) may be a basic unit used for transform, quantization, inverse transform, inverse quantization, entropy encoding, and entropy decoding processes within a CU. A TU may have a square shape or a rectangular shape.

Among CUs split from an LCU, a CU that is no longer split into CUs may be split into one or more TUs. In this case, the partition structure of the TU may be a quad-tree structure. For example, as shown in FIG. 5 , one CU 510 may be divided one or more times according to a quad-tree structure. Through division, one CU 510 may be configured with TUs of various sizes.

In the encoding apparatus 100 , a 64x64 coding tree unit (CTU) may be divided into a plurality of smaller CUs by a recursive quad-tree structure. One CU may be divided into 4 CUs having the same sizes. CUs may be recursively partitioned, and each CU may have a quad tree structure.

A CU may have depth. When a CU is split, CUs generated by splitting may have a depth increased by 1 from the depth of the split CU.

For example, the depth of the CU may have a value of 0 to 3. The size of the CU may range from 64x64 to 8x8 according to the depth of the CU.

Through recursive segmentation for CUs, an optimal segmentation method that produces the minimum rate-distortion ratio can be selected.

6 is a diagram for explaining an embodiment of an intra prediction process.

Arrows outward from the center of the graph of FIG. 6 may indicate prediction directions of intra prediction modes. Also, a number indicated adjacent to the arrow may indicate an example of an intra prediction mode or a mode value assigned to a prediction direction of the intra prediction mode.

Intra encoding and/or decoding may be performed using reference samples of units adjacent to the target unit. The neighboring units may be neighboring restored units. For example, intra encoding and/or decoding may be performed using a value of a reference sample included in a neighboring reconstructed unit or an encoding parameter.

The encoding apparatus 100 and/or the decoding apparatus 200 may generate a prediction block by performing intra prediction on a target unit based on information on a sample in the current picture. When performing intra prediction, the encoding apparatus 100 and/or the decoding apparatus 200 may generate a prediction block for a target unit by performing intra prediction based on information on a sample in the current picture. When performing intra prediction, the encoding apparatus 100 and/or the decoding apparatus 200 may perform directional prediction and/or non-directional prediction based on at least one reconstructed reference sample.

The prediction block may mean a block generated as a result of performing intra prediction. The prediction block may correspond to at least one of a CU, a PU, and a TU.

The unit of the prediction block may be the size of at least one of CU, PU, and TU. The prediction block may have a square shape having a size of 2Nx2N or NxN. The size of NxN may include 4x4, 8x8, 16x16, 32x32 and 64x64.

Alternatively, the prediction block may be a square-shaped block having a size such as 2x2, 4x4, 16x16, 32x32 or 64x64, or a rectangular block having a size such as 2x8, 4x8, 2x16, 4x16 and 8x16.

Intra prediction may be performed according to an intra prediction mode for a target unit. The number of intra prediction modes that the target unit can have may be a predefined fixed value, or a value determined differently according to the properties of the prediction block. For example, the properties of the prediction block may include the size of the prediction block and the type of the prediction block.

For example, the number of intra prediction modes may be fixed to 35 regardless of the size of the prediction unit. Or, for example, the number of intra prediction modes may be 3, 5, 9, 17, 34, 35, or 36.

The intra prediction mode may include two non-directional modes and 33 directional modes as shown in FIG. 6 . The two non-directional modes may include a DC mode and a planar mode.

For example, in the case of a vertical mode having a mode value of 26, prediction may be performed in a vertical direction based on a pixel value of a reference sample. For example, in the case of a horizontal mode having a mode value of 10, prediction may be performed in a horizontal direction based on a pixel value of a reference sample.

Even in a directional mode other than the above-described mode, the encoding apparatus 100 and the decoding apparatus 200 may perform intra prediction on a target unit by using a reference sample according to an angle corresponding to the directional mode.

The intra prediction mode located to the right of the vertical mode may be referred to as a vertical-right mode. The intra prediction mode located at the bottom of the horizontal mode may be called a horizontal-below mode. For example, in FIG. 6 , intra prediction modes whose mode value is one of 27, 28, 29, 30, 31, 32, 33, and 34 may be vertical right modes 613 . Intra prediction modes in which the mode value is one of 2, 3, 4, 5, 6, 7, 8, and 9 may be horizontal bottom modes 616 .

The non-directional mode may include a DC mode and a planar mode. For example, the mode value of the DC mode may be 1. The mode value of the planner mode may be 0.

The directional mode may include an angular mode. Modes other than the DC mode and the planar mode among the plurality of intra prediction modes may be a directional mode.

In the DC mode, a prediction block may be generated based on an average of pixel values of a plurality of reference samples. For example, a value of a pixel of the prediction block may be determined based on an average of pixel values of a plurality of reference samples.

The number of intra prediction modes and the mode value of each intra prediction mode described above may be merely exemplary. The number of the above-described intra prediction modes and a mode value of each intra prediction mode may be defined differently according to an embodiment, implementation, and/or need.

The number of intra prediction modes may be different depending on the type of color component. For example, the number of prediction modes may be different depending on whether the color component is a luma signal or a chroma signal.

7 is a diagram for explaining an embodiment of an inter prediction process.

The rectangle shown in FIG. 7 may represent an image (or a picture). Also, an arrow in FIG. 7 may indicate a prediction direction. That is, the image may be encoded and/or decoded according to the prediction direction.

Each image (or picture) may be classified into an I picture (intra picture), a P picture (uni-prediction picture), and a B picture (bi-prediction picture) according to an encoding type. Each picture may be encoded according to the encoding type of each picture.

When an image to be encoded is an I picture, the image may be encoded with respect to the image itself without inter prediction. When an image to be encoded is a P picture, the image may be encoded through inter prediction using reference pictures only in the forward direction. When an image to be encoded is a B picture, it may be encoded through inter prediction using reference pictures in both forward and backward directions, and may be encoded through inter prediction using reference pictures in one of the forward and backward directions.

P-pictures and B-pictures that are encoded and/or decoded using a reference picture may be regarded as images for which inter prediction is used.

Hereinafter, inter prediction in inter mode according to an embodiment will be described in detail.

In the inter mode, the encoding apparatus 100 and the decoding apparatus 200 may perform prediction and/or motion compensation on the encoding object unit and the decoding object unit. For example, the encoding apparatus 100 or the decoding apparatus 200 may perform prediction and/or motion compensation by using the motion information of the reconstructed neighboring unit as the motion information of the encoding object unit or the decoding object unit. Here, the to-be-encoded unit or the to-be-decoded unit may mean a prediction unit and/or a prediction unit partition.

Inter prediction may be performed using a reference picture and motion information. In addition, inter prediction may use the skip mode described above.

The reference picture may be at least one of a picture before the current picture or a picture after the current picture. In this case, the inter prediction may perform prediction on the block of the current picture based on the reference picture. Here, the reference picture may mean an image used for prediction of a block.

In this case, the region in the reference picture may be specified by using a reference picture index refIdx indicating the reference picture and a motion vector to be described later.

Inter prediction may select a reference picture and a reference block corresponding to the current block within the reference picture, and may generate a prediction block for the current block using the selected reference block. The current block may be a block to be currently encoded or decoded among blocks of the current picture.

Motion information may be derived during inter prediction by each of the encoding apparatus 100 and the decoding apparatus 200 . In addition, the derived motion information may be used to perform inter prediction.

In this case, the encoding apparatus 100 and the decoding apparatus 200 use the reconstructed motion information of a neighboring block and/or motion information of a collocated block to achieve encoding efficiency and/or decoding efficiency. can improve The collocated block may be a block corresponding to a current block in an already reconstructed collocated picture (col picture).

The reconstructed neighboring block may be a block within the current picture and already reconstructed through encoding and/or decoding. The reconstructed block may be a neighboring block adjacent to the current block and/or a block located at an outer corner of the current block. Here, the block located at the outer corner of the current block may be a block vertically adjacent to a neighboring block horizontally adjacent to the current block or a block horizontally adjacent to a neighboring block vertically adjacent to the current block.

For example, the restored peripheral unit may be a unit located on the left side of the target unit, a unit located on the top of the target unit, a unit located on the lower left corner of the target unit, a unit located on the upper right corner of the target unit, or the upper left corner of the target unit. It may be a unit located in a corner.

Each of the encoding apparatus 100 and the decoding apparatus 200 may determine a block existing at a position spatially corresponding to the current block in the collocated picture, and may determine a predefined relative position based on the determined block. The predefined relative position may be a position inside and/or outside a block that exists spatially at a position corresponding to the current block. Also, each of the encoding apparatus 100 and the decoding apparatus 200 may derive a collocated block based on the determined and predefined relative positions. Here, the collocated picture may be one picture from among at least one reference picture included in the reference picture list.

A block in the reference picture may exist in a position spatially corresponding to the position of the current block in the reconstructed reference picture. That is, the position of the current block in the current picture and the position of the block in the reference picture may correspond to each other. Hereinafter, motion information of a block included in a reference picture may be referred to as temporal motion information.

A method of deriving motion information may change according to a prediction mode of the current block. For example, as a prediction mode applied for inter prediction, there may be an advanced motion vector predictor (AMVP) and a merge.

For example, when AMVP is applied as a prediction mode, each of the encoding apparatus 100 and the decoding apparatus 200 uses a motion vector of a reconstructed neighboring block and/or a motion vector of a collocated block as a prediction motion vector candidate. You can create a list. A motion vector of a reconstructed neighboring block and/or a motion vector of a collocated block may be used as a prediction motion vector candidate.

The bitstream generated by the encoding apparatus 100 may include a prediction motion vector index. The prediction motion vector index may indicate an optimal prediction motion vector selected from prediction motion vector candidates included in the prediction motion vector candidate list. The prediction motion vector index may be transmitted from the encoding apparatus 100 to the decoding apparatus 200 through the bitstream.

The decoding apparatus 200 may select the prediction motion vector of the current block from among the prediction motion vector candidates included in the prediction motion vector candidate list by using the prediction motion vector index.

The encoding apparatus 100 may calculate a motion vector difference (MVD) between the motion vector of the current block and the predicted motion vector, and may encode the MVD. The bitstream may include an encoded MVD. The MVD may be transmitted from the encoding apparatus 100 to the decoding apparatus 200 through a bitstream. In this case, the decoding apparatus 200 may decode the received MVD. The decoding apparatus 200 may derive the motion vector of the current block through the sum of the decoded MVD and the predicted motion vector.

The bitstream may include a reference picture index indicating a reference picture, and the like. The reference picture index may be transmitted from the encoding apparatus 100 to the decoding apparatus 200 through a bitstream. The decoding apparatus 200 may predict the motion vector of the current block using motion information of the neighboring block, and may derive the motion vector of the current block using the predicted motion vector and the motion vector difference. The decoding apparatus 200 may generate a prediction block for the current block based on the derived motion vector and reference picture index information.

Since motion information of the reconstructed neighboring unit may be used for the encoding object unit and the decoding object unit, the encoding apparatus 100 may not separately encode the motion information on the object unit in a specific inter prediction mode. If the motion information of the target unit is not encoded, the amount of bits transmitted to the decoding apparatus 200 may be reduced, and encoding efficiency may be improved. For example, as an inter prediction mode in which the motion information of the target unit is not encoded, there may be a skip mode and/or a merge mode. In this case, the encoding apparatus 100 and the decoding apparatus 200 may use an identifier and/or an index indicating which of the reconstructed neighboring units motion information is used as the motion information of the target unit.

Another example of a method of deriving motion information is a merge. Merge may refer to merging of motions for a plurality of blocks. Merge may mean applying motion information of one block to another block as well. When merge is applied, each of the encoding apparatus 100 and the decoding apparatus 200 may generate a merge candidate list using motion information of a reconstructed neighboring block and/or motion information of a collocated block. there is. The motion information may include at least one of 1) a motion vector, 2) an index to a reference image, and 3) a prediction direction. The prediction direction may be unidirectional or bidirectional.

In this case, the merge may be applied in units of CUs or units of PUs. When the merge is performed in units of CUs or PUs, the encoding apparatus 100 may transmit predefined information to the decoding apparatus 200 through a bitstream. The bitstream may include predefined information. The predefined information may include 1) information indicating whether to perform a merge for each block partition, and 2) information on which block to be merged with among neighboring blocks adjacent to the current block. For example, the neighboring blocks of the current block may include a left neighboring block of the current block, an upper neighboring block of the current block, and a temporal neighboring block of the current block.

The merge candidate list may indicate a list in which motion information is stored. Also, the merge candidate list may be generated before merging is performed. The motion information stored in the merge candidate list may be 1) motion information of a neighboring block adjacent to the current block or 2) motion information of a collocated block corresponding to the current block in a reference image. Also, the motion information stored in the merge candidate list may be new motion information generated by a combination of motion information already existing in the merge candidate list.

The skip mode may be a mode in which information of a neighboring block is applied to the current block as it is. The skip mode may be one of modes used for inter prediction. When the skip mode is used, the encoding apparatus 100 may transmit only information about which block of motion information to use as the motion information of the current block to the decoding apparatus 200 through the bitstream. The encoding apparatus 100 may not transmit other information to the decoding apparatus 200 . For example, the other information may be syntax information. The syntax information may include motion vector difference information.

Picture division using picture division information

In encoding pictures constituting a video, the picture may be divided into a plurality of parts, and each of the plurality of parts may be encoded. In this case, in order for the decoding apparatus to decode the divided picture, information related to picture division may be required.

The encoding apparatus may transmit picture division information indicating picture division to the decoding apparatus. The decoding apparatus may decode the picture by using the picture division information.

The header information of the picture may include picture division information. Alternatively, picture division information may be included in header information of a picture. The header information of the picture may be information applied to each of one or more pictures.

In one or more consecutive pictures, when picture division is changed, picture division information indicating how the picture is divided may be changed. When the picture division information is changed in processing a plurality of pictures, the encoding apparatus may transmit new picture division information according to the change to the decoding apparatus.

For example, a picture parameter set (PPS) may include picture division information, and the encoding apparatus may transmit the PPS to the decoding apparatus. The PPS may include a PPS ID that is an identifier (ID) of the PPS. The encoding apparatus may inform the decoding apparatus which PPS is used for a picture through the PPS ID. A picture may be divided according to picture division information of the PPS.

In encoding of a moving picture, picture division information for pictures constituting a moving picture may be frequently and repeatedly changed. If the encoding apparatus has to transmit new picture division information to the decoding apparatus every time the picture division information is changed, encoding efficiency and decoding efficiency may decrease. Accordingly, if encoding, transmission, and decoding of picture partition information can be omitted even when picture partition information applied to a picture is changed, encoding efficiency and decoding efficiency can be improved.

In the following embodiments, with respect to a bitstream of a moving picture encoded using two or more pieces of picture division information, a method of deriving another picture division information using one picture division information is described.

As other picture partitioning information is derived based on one piece of picture partitioning information, at least two different picture partitioning schemes may be provided by different information including one picture partitioning information.

8 illustrates division of a picture using tiles according to an example.

In Fig. 8, pictures are shown with solid lines, and tiles are shown with dotted lines. As shown, the picture may be divided into a plurality of tiles.

A tile may be one of entities used as a unit of division of a picture. A tile may be a unit of picture division. Alternatively, a tile may be a unit of picture division coding.

Tile-related information may be signaled through the PPS. The PPS may include information on tiles of a picture or information for dividing a picture into a plurality of tiles.

Table 1 below shows an example of the structure of pic_parameter_set_rbsp. The picture division information may be pic_parameter_set_rbsp or may include pic_parameter_set_rbsp.

pic_parameter_set_rbsp may include the following elements.

- tiles_enabled_flag: tiles_enabled_flag may be a tile existence indication flag indicating whether one or more tiles exist in a picture referring to the PPS.

For example, a value of "0" of tiles_enabled_flag may indicate that a tile does not exist in a picture referring to the PPS. A value of “1” of tiles_enabled_flag may indicate that one or more tiles exist in a picture referring to the PPS.

Values of tile_enabled_flags of all activated PPSs in one Coded Video Sequence (CVS) may be the same.

- num_tile_columns_minus1: num_tile_columns_minus1 may be column tile number information corresponding to the number of tiles in the horizontal direction of the divided picture. For example, a value of “num_tile_columns_minus1 + 1” may indicate the number of tiles in the horizontal direction in the divided picture. Alternatively, a value of “num_tile_columns_minus1 + 1” may indicate the number of tiles in one row.

- num_tile_rows_minus1: num_tile_rows_minus1 may be information on the number of row tiles corresponding to the number of tiles in the vertical direction of the divided picture. For example, a value of “num_tile_rows_minus1 + 1” may indicate the number of tiles in the vertical direction in the divided picture. Alternatively, a value of “num_tile_row_minus1 + 1” may indicate the number of tiles in one column.

- uniform_spacing_flag: uniform_spacing_flag may be an even division indication flag indicating whether a picture is equally divided into tiles in a horizontal direction and a vertical direction. For example, uniform_spacing_flag may be a flag indicating whether sizes of tiles of a picture are all the same. For example, a value of "0" of uniform_spacing_flag may indicate that the picture is not evenly divided in the horizontal direction and/or the vertical direction. A value of uniform_spacing_flag of “1” may indicate that the picture is equally divided in the horizontal direction and the vertical direction. When the value of uniform_spacing_flag is “0”, an element that more specifically defines division, such as column_width_minus1[ i ] and row_height_minus1[ i ], which will be described later, may be additionally required for picture division.

- column_width_minus1[ i ]: column_width_minus1[ i ] may be tile width information corresponding to the width of the tile in the i-th column. i may be an integer greater than or equal to 0 and less than the number n of columns of tiles. For example, "column_width_minus1[ i ] + 1" may indicate the width of a tile in the i+1th column. The area may be expressed in a predefined unit. For example, the unit of the area may be a Coding Tree Block (CTB).

- row_height_minus1[ i ]: row_height_minus1[ i ] may be tile height information corresponding to the height of the tile in the i-th row. i may be an integer greater than or equal to 0 and less than the number n of rows of tiles. For example, "row_height_minus1[i] + 1" may indicate the height of the tile in the i+1th row. The height may be expressed in a predefined unit. For example, the unit of height may be CTB.

In one example, the picture division information may be included in the PPS, and may be transmitted as part of the PPS when the PPS is transmitted. The decoding apparatus may obtain picture division information required for picture division by referring to the PPS for the picture.

In order for the encoding apparatus to signal different picture division information from previously transmitted, the encoding apparatus may first transmit a new PPS including new picture division information and a new PPS ID to the decoding apparatus. Next, the encoding apparatus may transmit the slice header including the PPS ID to the decoding apparatus.

Proposal of a method for signaling picture segmentation information based on tiles that change according to a specified rule

As described above, in a series of pictures, picture division information applied to the pictures may change, and it may be required to retransmit a new PPS each time the picture division information changes.

In a series of pictures, picture division information applied to the pictures may change according to a specified rule. For example, the picture division information may change periodically according to the number of pictures.

When the picture division information changes according to a specified rule, transmission of the picture division information may be omitted using this rule. For example, the decoding apparatus may derive picture division information of another picture from the previously transmitted picture division information.

In general, the picture division information may not change for each picture and may be repeated according to a certain period and rule.

For example, pictures may be divided according to a parallel encoding policy. In order to perform parallel encoding on pictures, the encoding apparatus may divide the picture into tiles. The decoding apparatus may obtain a rule of periodic change of picture division information by using the information of the parallel encoding policy.

For example, when a tile is used as a picture division tool, a periodically changing rule for a method of dividing one picture into a plurality of tiles according to information on a parallel encoding policy of an encoding apparatus This can be derived.

9 illustrates a reference structure of encoding to which a GOP level is applied according to an example.

9 shows pictures constituting a group of pictures (GOP) and a reference relationship between the pictures.

In encoding a sequence of pictures, GOP may be applied. Random access to the encoded video may be enabled through the GOP.

9 shows that the size of the GOP is 8. For example, one GOP may be a group of 8 pictures.

In Fig. 9, the picture is shown as a rectangle. I, B, or b in the picture may indicate the type of the picture. The horizontal position of the picture may indicate the temporal order of the picture. The vertical position of the picture may indicate the level of the picture. Here, the level may be a temporal level. For example, the GOP level of the picture may correspond to the temporal level of the picture. Alternatively, the GOP level of the picture may be the same as the temporal level of the picture.

The GOP level of a picture may be determined by a picture order count (POC) of the picture. The GOP level of the picture may be determined by a residual value obtained by dividing the POC of the picture by the size of the GOP. That is, when the POC of the picture is (8k) which is a multiple of 8, the GOP level of the picture may be 0. k may be an integer greater than or equal to 0. When the POC of the picture is (8k+4), the GOP level of the picture may be 1. When the POC of the picture is (8k+2) or (8k+6), the GOP level may be 2. When the POC of the picture is (8k+1), (8k+3), (8k+5), or (8k+7), the GOP level may be 3.

In FIG. 9, pictures are divided by GOP levels from GOP level 0 to GOP level 3. Arrows between pictures may indicate a reference relationship between pictures. For example, an arrow from the picture of the first I to the picture of the second b may indicate that the picture of the first I is referenced by the picture of the second b.

10 shows an encoding order of pictures of a GOP according to an example.

In FIG. 10 , a sequence of pictures, an Instantaneous Decoder Refresh (IDR) period in the sequence, and a GOP are shown. Also, the coding order of the pictures of the GOP is shown.

In FIG. 10 , a picture with an empty interior may be a GOP level 0 or GOP level 1 picture. The picture in which the inside is lightly painted may be a picture of GOP level 2. The picture in which the inside is darkly colored may be a picture of GOP level 3 .

As illustrated, the encoding order of the pictures of the GOP may be determined by preferentially applying the picture type rather than the temporal order of the pictures.

11 illustrates parallel encoding of pictures of a GOP according to an example.

In an example, for pictures having GOP levels as shown in FIG. 9 , the encoding apparatus may encode the pictures using a combination of picture-level parallelization and tile-level parallelization.

Since the pictures do not refer to each other, the picture-level parallelization may mean that pictures that can be independently encoded are encoded in parallel.

The tile-level parallelization may be parallelism for picture division. The tile-level parallelization may mean dividing one picture into a plurality of tiles and encoding the plurality of divided tiles in parallel.

In parallelization of pictures, the picture-level parallelization and the tile-level parallelization may be simultaneously applied. Alternatively, picture-level parallelism and tile-level parallelism may be combined.

For such parallelization, as shown in FIG. 9 , pictures having the same GOP level except for pictures having a GOP level of 0 among the pictures of the GOP may be designed not to refer to each other. That is, in FIG. 9 , pictures of B having a GOP level of 2 may not refer to each other, and pictures of B having a GOP level of 3 may not refer to each other.

Under this design, a devise may be devised so that pictures of the GOP, except for pictures having a GOP level of 0, can be encoded in parallel. Since two pictures having a GOP level of 2 do not refer to each other, two pictures having a GOP level of 2 may be coded in parallel. In addition, since four pictures having a GOP level of 3 do not refer to each other, the four pictures having a GOP level of 3 may be coded in parallel.

Under the coding scenario as described above, the number of picture divisions and picture division types of pictures may be allocated differently according to GOP levels of the pictures. The number of picture divisions of a picture may indicate how many tiles or how many slices the picture is divided into. The picture division type may indicate respective sizes and/or positions of tiles or slices.

That is, the number of picture divisions and the picture division type of a picture may be determined based on the GOP level of the picture. A picture may be divided into a number of parts specified by the GOP level of the picture.

The GOP level of a picture and the division of a picture may have a specified relationship. Pictures of the same GOP levels may have the same picture division information.

For example, when parallelization as shown in FIG. 11 is devised, if a picture having a GOP level of 0 and a picture having a GOP level of 1 are divided into 4N parts, the picture having a GOP level of 2 can be divided into 2N parts. and a picture having a GOP level of 3 may be divided into N parts. Here, N may be an integer of 1 or more. According to this design, the number of threads for parts to be coded in parallel when frame-level parallelism and picture division parallelism are simultaneously used can be determined. In other words, when there is another picture that can be encoded or decoded in parallel with the specified picture, picture-level parallelization is preferentially performed, and tile-level parallelization for one picture is performed to an extent that is inversely proportional to picture-level parallelism. can

In the embodiment, picture division information that changes periodically or changes according to a specified rule is not transmitted by multiple PPSs, but changed picture division information of another picture is derived using picture division information included in one PPS. A method may be suggested. Alternatively, one picture division information may indicate a plurality of picture division types in which a picture is divided into different types.

For example, the picture division information may indicate the number of pictures processed in parallel at each of the specified GOP levels. The number of picture divisions of a picture may be obtained using picture division information.

In the above-described embodiments, the description of the GOP level in relation to picture division may also be applied to a temporal identifier (Temporal ID) or a temporal level. That is to say, in embodiments, “GOP level” may be replaced with “temporal level” or “temporal identifier”.

The temporal identifier may indicate a level within a hierarchical temporal prediction structure.

The temporal identifier may be included in a Network Abstraction Layer (NAL) unit header.

12 illustrates division of a picture using a slice according to an example.

In FIG. 12 , a picture is illustrated by a solid line, a slice is illustrated by a thick dotted line, and a Coding Tree Unit (CTU) is illustrated by a thin dotted line. As shown, a picture may be divided into a plurality of slices. One slice may be sequential one or more CTUs.

A slice may be one of entities used as a unit of division of a picture. A slice may be a unit of picture division. Alternatively, a slice may be a unit of picture division coding.

Slice-related information may be signaled through a slice segment header. The slice segment header may include information on slices.

When a slice is a unit of picture division coding, picture division information may define a start address of each slice of one or more slices.

The unit of the start address of the slice may be a CTU. The picture partition information may define a start CTU address of each slice of one or more slices. A picture division type may be defined by start addresses of slices.

Table 2 below shows an example of the structure of slice_segment_header. The picture segmentation information may be slice_segment_header or may include slice_segment_header.

slice_segment_header may include the following elements.

- first_slice_segment_in_pic_flag: first_slice_segment_in_pic_flag may be a first slice indication flag indicating whether the slice indicated by slice_segment_header is the first slice of the picture.

For example, a value of "0" of first_slice_segment_in_pic_flag may indicate that the slice is not the first slice of the picture. A value of "1" of first_slice_segment_in_pic_flag may indicate that the slice is the first slice of the picture.

- dependent_slice_segment_flag: dependent_slice_segment_flag may be a dependent slice segment indication flag indicating whether the slice indicated by slice_segment_header is a dependent slice.

For example, a value of "0" of dependent_slice_segment_flag may indicate that the slice is not a dependent slice. A value of "1" of dependent_slice_segment_flag may indicate that the slice is a dependent slice.

For example, a slice of a substream of Wavefront Parallel Processing (WPP) may be a dependent slice. Independent corresponding to the dependent slice may exist. When the slice indicated by slice_segment_header is a dependent slice, at least one element of slice_segment_header may not exist. In other words, the value of an element in slice_segment_header may not be defined. For an element for which the value of the dependent slice is not defined, the value of the element of the independent slice corresponding to the dependent slice may be used. In other words, a value of a specified element that does not exist in slice_segment_header of a dependent slice may be the same as a value of a specified element of slice_segment_header of an independent slice corresponding to the dependent slice. For example, a dependent slice may inherit values of elements of a corresponding independent slice, and may redefine values of elements of at least some of the independent slices.

- slice_segment_address: slice_segment_address may be start address information indicating the start address of the slice indicated by slice_segment_header. The unit of the start address information may be CTB.

A method of dividing a picture into one or more slices may include the following methods 1) to 3).

Method 1) A first method may be to divide a picture into a maximum size of a bitstream that one slice can include.

Method 2) The second method may be to divide a picture into the maximum number of CTUs that one slice can contain.

Method 3) A third method may be to divide a picture by the maximum number of tiles that one slice can include.

When the encoding apparatus performs parallel encoding in units of slides, the second method and the third method among the above three methods may be generally used.

In the case of the first scheme, since the size of the bitstream can be known after encoding is completed, it may be difficult to define slices to be processed in parallel before the start of encoding. Accordingly, the picture partitioning method enabling parallel encoding of slide units may be a second method using a unit of the maximum number of CTUs and a third method using a unit of the maximum number of tiles.

When the second method and the third method are used, a size to divide a picture may be predetermined before the pictures are encoded in parallel. Also, slice_segment_address may be calculated according to a predetermined size. When the encoding apparatus uses a slice as a unit of parallel encoding, slice_segment_address does not usually change for every picture, but tends to be repeated according to a certain period and/or a specified rule.

Accordingly, in the embodiment, a method in which picture division information is not signaled for every slice, and picture division information is signaled through a parameter commonly applied to pictures may be used.

13 is a structural diagram of an encoding apparatus for encoding a video according to an embodiment.

The encoding apparatus 1300 may include a control unit 1310 , an encoding unit 1320 , and a communication unit 1330 .

The controller 1310 may perform control for encoding a video.

The encoder 1320 may encode a video.

The encoder 1320 includes the inter prediction unit 110 , the intra prediction unit 120 , the switch 115 , the subtractor 125 , the transform unit 130 , the quantization unit 140 , and entropy described above with reference to FIG. 1 . It may include an encoder 150 , an inverse quantizer 160 , an inverse transform unit 170 , an adder 175 , a filter unit 180 , and a reference picture buffer 190 .

The communication unit 1330 may transmit encoded video data to another device.

Detailed functions and operations of the control unit 1310 , the encoder 1320 , and the communication unit 1330 will be described in more detail below.

14 is a flowchart of an encoding method for encoding a video according to an example.

In operation 1410, the controller 1310 may generate picture division information for a plurality of pictures of a moving picture. The picture division information may indicate a picture division method for each picture of a plurality of pictures of a moving picture.

For example, the picture division information may indicate how each picture of a plurality of pictures will be divided. The picture division information may be applied to a plurality of pictures. Also, when a plurality of pictures are divided based on the picture division information, methods of dividing the plurality of pictures may not be the same. The manner of division may indicate the number of parts produced by the division, the shapes of the parts, the sizes of the parts, the widths of the parts, the heights of the parts and/or the lengths of the parts.

For example, the picture partitioning information may indicate at least two different ways of partitioning a picture. At least two different ways of partitioning a picture may be specified by the picture partitioning information. Also, the picture division information may indicate in which method each picture of the plurality of pictures will be divided among at least two different methods.

For example, the plurality of pictures may be pictures of one GOP or pictures constituting one GOP.

In operation 1420 , the controller 1310 may divide each picture of the plurality of pictures by one of at least two different methods. At least two different ways may correspond to picture division information. In other words, the picture division information may specify at least two different ways of dividing a plurality of pictures.

Here, the different methods may mean that the number, shape, or size of parts generated by division are different from each other. Here, the portions may be tiles or slices.

For example, the controller 1310 may determine in which method each picture of the plurality of pictures is to be divided among at least two different methods based on the picture division information. The controller 1310 may generate parts of the picture by dividing the picture.

In operation 1430, the decoder 1320 may perform encoding of a plurality of divided pictures based on picture division information. The decoder 1320 may encode each picture divided by one of at least two different methods.

Portions of the picture may be coded respectively. The decoder 1320 may perform encoding on a plurality of parts generated by picture division in parallel.

In operation 1440, the decoder 1320 may generate data including picture division information and a plurality of encoded pictures. The data may be a bitstream.

In operation 1450, the communication unit 1330 may transmit the generated data to the decoding device.

The picture division information and the picture portion will be described in more detail with reference to other embodiments. The picture division information and the picture part described in other embodiments may also be applied to the present embodiment. A duplicate description is omitted.

15 is a structural diagram of a decoding apparatus for decoding a video according to an embodiment.

The decoding apparatus 1500 may include a control unit 1510 , a decoding unit 1520 , and a communication unit 1530 .

The controller 1510 may perform a control for decoding a video. For example, the controller 1510 may obtain picture division information in data or a bitstream. Alternatively, the controller 1510 may decode picture division information in data or a bitstream. Also, the controller 1510 may control the decoder 1520 to decode a video according to the picture division information.

The decoder 1520 may decode the video.

The decoder 1520 includes the entropy decoder 210 , the inverse quantizer 220 , the inverse transform 230 , the intra predictor 240 , the inter predictor 250 , and the adder 255 described above with reference to FIG. 2 . ), a filter unit 260 and a reference picture buffer 270 .

The communication unit 1530 may receive encoded video data from another device.

Detailed functions and operations of the control unit 1510 , the decoding unit 1520 , and the communication unit 1530 will be described in more detail below.

16 is a flowchart of a decoding method for decoding a video according to an example.

In operation 1610 , the communication unit 1530 may receive encoded video data from the encoding apparatus 1300 . The data may be a bitstream.

In operation 1620, the controller 1510 may obtain picture division information in data. The controller 1510 may decode picture division information in data, and may obtain picture division information through decoding.

The picture division information may indicate a picture division method for each picture of a plurality of pictures of a moving picture.

For example, the picture division information may indicate how each picture of a plurality of pictures will be divided. Also, when a plurality of pictures are divided based on the picture division information, methods of dividing the plurality of pictures may not be the same.

The manner of division may indicate the number of parts produced by the division, the shapes of the parts, the sizes of the parts, the widths of the parts, the heights of the parts and/or the lengths of the parts.

For example, the picture partitioning information may indicate at least two different ways of partitioning a picture. At least two different ways of partitioning a picture may be specified by the picture partitioning information. Also, the picture division information may indicate in which method each picture of the plurality of pictures will be divided among at least two different methods based on a characteristic or attribute of the picture.

For example, the attribute of a picture may be a GOP level, a temporal identifier, or a temporal level of the picture.

For example, the plurality of pictures may be pictures of one GOP or pictures constituting one GOP.

In operation 1630 , the controller 1510 may divide each picture of the plurality of pictures by one of at least two different methods based on the picture division information. The controller 1510 may determine in which method each picture of the plurality of pictures will be divided among at least two different methods based on the picture division information. The controller 1510 may generate parts of the picture by dividing the picture.

A portion generated by division may be a tile or a slice.

For example, the controller 1510 may divide a first picture among a plurality of pictures based on picture division information. The controller 1510 may divide the first picture according to the first picture division method indicated by the picture division information. The controller 1510 may divide the second picture among the plurality of pictures based on other picture division information derived based on the picture division information. The first picture and the second picture may be different pictures. For example, the GOP level of the first picture and the GOP level of the second picture may be different from each other. At least some elements of the one or more elements of the picture partitioning information may be used to derive other picture partitioning information from the picture partitioning information.

Alternatively, the controller 1510 may divide the second picture according to the second picture division method induced by the picture division information. At least some of the one or more elements of the picture division information may indicate the first picture division method. Other elements of at least some of the one or more elements of the picture partitioning information may be used to derive the second picture partitioning scheme from the picture partitioning information or the first picture partitioning scheme.

The picture division information may define a picture division method that is changed periodically. The control unit 1510 may divide a plurality of pictures using a periodically changing picture division method defined by picture division information. In other words, the specified picture division methods may be repeatedly applied to a series of pictures. When the specified picture division methods are applied to the specified number of pictures, the specified picture division methods may be repeatedly applied to the next specified number of pictures again.

The picture division information may define a picture division method that changes according to a rule. The controller 1510 may divide the plurality of pictures in a picture division method that changes according to a rule defined by the picture division information. In other words, the picture division methods specified by the rule may be applied to a series of pictures.

In operation 1640 , the decoder 1520 may decode a plurality of divided pictures based on the picture division information. The decoder 1520 may decode each picture divided by one of at least two different methods.

Portions of the picture may be decoded respectively. The decoder 1520 may perform decoding on a plurality of parts generated by picture division in parallel.

In operation 1650 , the decoder 1520 may generate a video including a plurality of decoded pictures.

As described above, the picture division information may be defined by the PPS or at least some elements of the PPS.

In an embodiment, the PPS may include picture division information. In other words, the PPS may include an element corresponding to the picture division information and an element independent of the picture division information. The picture division information may correspond to at least some elements of the PPS.

Alternatively, according to an embodiment, the picture division information may include a PPS. In other words, picture division information can be defined by PPS and other information.

In an embodiment, picture division information used for a plurality of pictures may be defined by a single PPS instead of multiple PPSs. In other words, picture division information defined by one PPS may be used for at least two different types of divisions for a plurality of pictures.

That is, according to an embodiment, picture division information for one picture may be used for division of another picture which is divided in a picture division method different from that of the above picture. The picture division information may include information for inducing another picture division method, in addition to information for dividing a picture of the PPS.

In this case, it may be understood that one picture division information indicates a plurality of picture division methods applied to a plurality of pictures. For example, at least some elements of the picture division information may define the first picture division method. The first picture division method may be applied to a first picture among a plurality of pictures. Other at least some elements of the picture partitioning information may be used to derive the second picture partitioning scheme from the first picture partitioning scheme. The derived second picture division method may be applied to a second picture among a plurality of pictures. The picture division information may include information defining which picture division method is to be applied to which picture. That is, the picture division information may include information for specifying a picture division method corresponding to each picture of a plurality of pictures.

Alternatively, according to an embodiment, one PPS may include a plurality of picture division information. The plurality of picture division information may be used for division of the plurality of pictures. That is, according to an embodiment, the PPS for one picture may include picture division information for dividing another picture as well as picture division information for dividing the above picture.

In this case, it may be understood that the number of picture division information indicates a plurality of different picture division methods, respectively, and the plurality of picture division information is transmitted from the encoding apparatus to the decoding apparatus through one PPS. For example, at least some elements of the PPS may define picture division information. The defined picture division information may be applied to a first picture among a plurality of pictures. Other at least some elements of the PPS may be used to derive other picture division information from the defined picture division information. The derived other picture division information may be applied to a second picture among a plurality of pictures. The PPS may include information defining which picture division information is to be applied to which picture. In other words, the PPS may include information for specifying picture division information corresponding to each picture of the plurality of pictures.

Picture division information for dividing a picture into tiles

As described above, portions of a picture generated by division may be tiles. A picture may be divided into a plurality of tiles.

The PPS may define parameters applied to a specified picture. At least some of the parameters may be used to determine a picture division method as picture division information.

In an embodiment, picture division information included in one PPS may be applied to a plurality of pictures. Here, the plurality of pictures may be divided in one of at least two different ways. That is, to define at least two different picture division schemes, one PPS may be used instead of several PPSs.

Even if two pictures are divided by different picture division methods, a PPS is not signaled for each picture, and a changing picture division method can be induced by one PPS or one picture division information. For example, the PPS may include picture division information to be applied to one picture, and picture division information to be applied to another picture may be derived by the PPS. Alternatively, for example, the PPS may include picture division information to be applied to one picture, and picture division methods to be applied to a plurality of pictures may be defined by the picture division information.

For example, the PPS may define the number of pictures to be processed in parallel for each GOP level. When the number of pictures to be processed in parallel for each GOP level is defined, a picture division method of a picture of the specified GOP level may be determined. Alternatively, if the number of pictures to be processed in parallel for each GOP level is defined, it may be determined how many tiles the picture of the specified GOP level is divided into.

For example, the PPS may define the number of pictures to be processed in parallel for each temporal identifier. When the number of pictures to be processed in parallel for each temporal identifier is defined, a picture division method of a picture having a specified temporal identifier may be determined. Alternatively, if the number of pictures to be processed in parallel for each temporal identifier is defined, it may be determined how many tiles a picture having a specified temporal identifier is divided into.

The decoding apparatus may derive the size of the GOP through the configuration of the reference picture, and may derive the GOP level from the size of the GOP. Alternatively, the decoding apparatus may derive the GOP level from the temporal level. The GOP level and the temporal level may be used for segmentation of a picture as will be described below.

An embodiment in which a picture is divided into tiles according to the GOP level

Table 3 below shows an example of a structure of pic_parameter_set_rbsp indicating a PPS for signaling picture split information. The picture division information may be pic_parameter_set_rbsp or may include pic_parameter_set_rbsp. A picture may be divided into a plurality of tiles by pic_parameter_set_rbsp.

pic_parameter_set_rbsp may include the following elements.

- parallel_frame_by_gop_level_enable_flag: parallel_frame_by_gop_level_enable_flag may be a GOP level parallel processing flag indicating whether a picture referring to the PPS is encoded or decoded in parallel with other pictures having the same GOP level.

For example, a value of “0” of parallel_frame_by_gop_level_enable_flag may indicate that a picture referring to the PPS is not encoded or decoded in parallel with another picture having the same GOP level. A value of “1” of parallel_frame_by_gop_level_enable_flag may indicate that a picture referring to the PPS is encoded or decoded in parallel with another picture having the same GOP level.

When a picture is processed in parallel with other pictures, it can be seen that the need for dividing one picture into parts and processing the parts in parallel is reduced. Accordingly, it can be seen that parallel processing of pictures and parallel processing of parts of one picture have a correlation with each other.

The picture division information may include parallel processing picture number information for GOP level n. The information on the number of parallel processing pictures for the specified GOP level n may correspond to the number of pictures having a GOP level of n to which parallel processing may be applied. n may be an integer of 2 or more. Parallel processing picture number information may include the following num_frame_in_parallel_gop_level3_minus1 and num_frame_in_parallel_gop_level2_minus1.

- num_frame_in_parallel_gop_level3_minus1: num_frame_in_parallel_gop_level3_minus1 may be information on the number of parallel processing pictures for GOP level 3. Information on the number of parallel processing pictures for GOP level 3 may correspond to the number of pictures having a GOP level of 3 that can be encoded or decoded in parallel.

For example, a value of “num_frame_in_parallel_gop_level3_minus1 + 1” may indicate the number of pictures having a GOP level of 3 that can be encoded or decoded in parallel.

- num_frame_in_parallel_gop_level2_minus1: num_frame_in_parallel_gop_level2_minus1 may be information on the number of parallel processing pictures for GOP level 2. Information on the number of parallel processing pictures for GOP level 2 may correspond to the number of pictures having a GOP level of 2 that can be encoded or decoded in parallel.

For example, a value of “num_frame_in_parallel_gop_level2_minus1 + 1” may indicate the number of pictures having a GOP level of 2 that can be encoded or decoded in parallel.

A plurality of encoded pictures may be decoded through the following process by using the signaling of picture division information using the above-described pic_parameter_set_rbsp.

For example, when the value of “parallel_frame_by_gop_level_enable_flag” of the PPS of the current picture is “1” and the GOP level of the current picture is 2, num_tile_columns_minus1 and num_tile_rows_minus1 to be applied to the current picture are expressed in Equation 2 and Equation 3 below. can be redefined.

[Equation 2]

new_num_tile_columns = (num_tile_columns_minus1 + 1) / (num_frame_in_parallel_gop_level2_minus1 + 1)

[Equation 3]

new_num_tile_rows = (num_tile_rows_minus1 + 1) / (num_frame_in_parallel_gop_level2_minus1 + 1)

Here, new_num_tile_columns may indicate the number of tiles in the horizontal direction of the divided picture (that is, the number of columns of tiles). new_num_tile_rows may indicate the number of tiles (that is, the number of rows of tiles) in a vertical direction of the divided picture. The current picture may be divided into new_num_tile_columns * new_num_tile_rows tiles.

For example, when the "parallel_frame_by_gop_level_enable_flag" value of the PPS of the current picture is "1" and the GOP level of the current picture is 3, num_tile_columns_minus1 and/or num_tile_rows_minus1 to be applied to the current picture are Equations 5 and 4 and Equations 5 and below. can be redefined together.

[Equation 4]

new_num_tile_columns = (num_tile_columns_minus1 + 1) / (num_frame_in_parallel_gop_level3_minus1 + 1)

[Equation 5]

new_num_tile_rows = (num_tile_rows_minus1 + 1) / (num_frame_in_parallel_gop_level3_minus1 + 1)

The above redefinition may be applied to one of new_num_tile_columns and new_num_tile_rows, or may be applied to both.

According to Equations 2 to 5, as the value of num_frame_in_parallel_gop_level2_minus1 increases, the value of new_num_tile_columns may decrease. That is, as the value of num_frame_in_parallel_gop_level2_minus1 or num_frame_in_parallel_gop_level3_minus1 increases, the number of tiles generated by division may decrease. Accordingly, num_frame_in_parallel_gop_level2_minus1 and num_frame_in_parallel_gop_level3_minus1 may be reduction indication information for reducing the number of tiles generated by picture division. As the number of pictures having the same GOP level to be encoded or decoded in parallel increases, each picture may be divided into a smaller number of tiles.

The picture division information may include reduction indication information for reducing the number of tiles generated by picture division. In addition, the reduction indication information may indicate a degree to which the number of tiles generated by dividing a picture in relation to encoding or decoding processed in parallel is reduced.

The picture division information may include GOP level n reduction indication information for reducing the number of tiles generated by picture division for a picture having a GOP level of n. n may be an integer of 2 or more. For example, num_frame_in_parallel_gop_level2_minus1 may be GOP level 2 reduction indication information. num_frame_in_parallel_gop_level3_minus1 may be GOP level 3 reduction indication information.

For example, if the “parallel_frame_by_gop_level_enable_flag” value of the PPS of the current picture is “0”, the current picture can be divided into S tiles using the value of num_tile_columns_minus1 and/or num_tile_columns_minus1 of the PPS of the current picture. there is.

For example, S may be calculated according to Equation 6 below.

[Equation 6]

S = (num_tile_columns_minus1 + 1) * (num_tile_rows_minus1 + 1)

As described above in relation to Equations 2 to 6, the picture division information may include GOP level n reduction indication information for a picture having a GOP level n. When the number of columns of tiles generated by division of a picture having a GOP level of 0 or 1 is w, and the number of columns of tiles generated by division of a picture having a GOP level of n is w/m, GOP level n reduction indication The information may correspond to m. Alternatively, when the number of rows of tiles generated by division of a picture having a GOP level of 0 or 1 is w, and the number of rows of tiles generated by division of a picture having a GOP level of n is w/m, the GOP Level n reduction indication information may correspond to m.

As described above in relation to Equations 2 to 6, the picture division type applied to picture division may be determined based on the GOP level of the picture. Also, as described above with reference to FIG. 10 , the GOP level of the picture may be determined based on the picture order of the picture.

The GOP level of the picture may be determined according to a value remaining when the picture order of the picture is divided by a predefined value. For example, a picture having a GOP level of 3 among a plurality of pictures of the GOP may be a picture having a remainder of 1 when the picture order of the picture is divided by 2. For example, a picture having a GOP level of 2 among a plurality of pictures of a GOP may be a picture having a remainder of 2 when the picture order of the picture is divided by 4.

Also, as described above, the same picture division method may be applied to pictures having the same GOP level among a plurality of pictures of the GOP. The parsing information may indicate that the same picture division method is applied to pictures having a second predefined value remaining when a picture order is divided by a first predefined value among a plurality of pictures.

The picture division information may indicate a picture division method of a picture with respect to pictures whose GOP level is a specified value. Also, the picture division information may define picture division methods for one or more pictures corresponding to one GOP level among two or more GOP levels.

In an implementation in which a picture is divided into tiles according to a temporal level, etc.

Table 4 below shows an example of the structure of pic_parameter_set_rbsp indicating a PPS for signaling picture split information. The picture division information may be pic_parameter_set_rbsp or may include pic_parameter_set_rbsp. A picture may be divided into a plurality of tiles by pic_parameter_set_rbsp.

pic_parameter_set_rbsp may include the following elements.

- drive_num_tile_enable_flag: drive_num_tile_enable_flag may be a unified division indication flag indicating whether a picture referring to the PPS is divided by one of at least two or more different methods. Alternatively, drive_num_tile_enable_flag may indicate whether the number of tiles generated by division is the same when a picture referring to the PPS is divided into tiles.

For example, a value of "0" of drive_num_tile_enable_flag may indicate that a picture referring to the PPS is divided in a single manner. Alternatively, a value of “0” of drive_num_tile_enable_flag may indicate that a picture referring to the PPS is always divided into the same number of tiles when divided.

A value of "1" of drive_num_tile_enable_flag may indicate that a plurality of partition types are defined by one PPS. Alternatively, the value of drive_num_tile_enable_flag of “1” may indicate that the picture referring to the PPS is divided by one of at least two or more different methods. Alternatively, the value of drive_num_tile_enable_flag of “1” may indicate that the number of tiles generated by dividing a picture referring to the PPS is not constant.

When temporal scalability is applied to a moving picture or picture, it can be seen that the need to divide a picture into parts and process the parts in parallel is related to a temporal identifier. Accordingly, it can be seen that the processing of pictures providing temporal scalability and the division into parts of one picture have a correlation with each other.

The picture division information may include information on the number of tiles for the temporal identifier n. The tile number information for the specified temporal identifier n may indicate how many tiles a picture having a temporal level n is divided into. n may be an integer of 1 or more.

The tile number information may include the following num_tile_level1_minus1 and num_tile_level2_minus1. Also, the tile number information may include num_tile_levelN_minus1 for one or more values.

The picture division information or PPS may selectively include at least one of num_tile_level1_minus1, num_tile_level2_minus1, and num_tile_levelN_minus1 when the value of drive_num_tile_enable_flag is “1”.

- num_tile_level1_minus1: num_tile_level1_minus1 may be information on the number of level 1 tiles for a picture having a level of 1. The level may be a temporal level.

The level 1 tile number information may correspond to the number of tiles generated by division of a level 1 picture. The level 1 tile number information may be inversely proportional to the number of tiles generated by division of a level 1 picture.

For example, a picture having a level of 1 may be divided into m / (num_tile_level1_minus1 + 1) tiles. The value of m may be (num_tile_columns_minus1 + 1) x (num_tile_rows_minus1 + 1). Accordingly, as the value of the level 1 tile number information increases, the number of tiles generated by division of the level 1 picture may become smaller.

- num_tile_level2_minus1: num_tile_level2_minus1 may be information on the number of level 2 tiles for a picture having a level of 2. The level may be a temporal level.

The level 2 tile number information may correspond to the number of tiles generated by division of a level 2 picture. The level 2 tile number information may be inversely proportional to the number of tiles generated by division of a level 2 picture.

For example, a picture having a level of 2 may be divided into m / (num_tile_level2_minus1 + 1) tiles. The value of m may be (num_tile_columns_minus1 + 1) x (num_tile_rows_minus1 + 1). Accordingly, as the value of the level 2 tile number information becomes larger, the number of tiles generated by dividing the level 2 picture may be smaller.

- num_tile_levelN_minus1: num_tile_levelN_minus1 may be information on the number of level N tiles for a picture having a level of N. The level may be a temporal level.

The level N tile number information may correspond to the number of tiles generated by division of a level N picture. The level N tile number information may be inversely proportional to the number of tiles generated by division of a level N picture.

For example, a picture having a level of N may be divided into m / (num_tile_levelN_minus1 + 1) tiles. The value of m may be (num_tile_columns_minus1 + 1) x (num_tile_rows_minus1 + 1). Accordingly, as the value of the level N tile number information increases, the number of tiles generated by dividing the level N picture may be smaller.

num_tile_levelN_minus1 may be reduction indication information for reducing the number of tiles generated by picture division.

The picture division information may include level N reduction indication information for reducing the number of tiles generated by picture division for a level N picture. N may be an integer of 2 or more. For example, num_tile_level2_minus1 may be level 2 reduction indication information. num_tile_level3_minus1 may be level 3 reduction indication information.

A plurality of encoded pictures may be decoded through the following process by using the signaling of picture division information using the above-described pic_parameter_set_rbsp.

As described above, the number of tiles generated by dividing a picture may vary according to the level of the picture. The encoding apparatus and the decoding apparatus may divide the picture in the same way.

For example, when the value of drive_num_tile_enable_flag of the PPS of the current picture is “0”, the current picture may be divided into (num_tile_columns_minus1 + 1) x (num_tile_rows_minus1 + 1) tiles. Hereinafter, a partition when the value of drive_num_tile_enable_flag is “0” is referred to as a basic partition.

For example, when the value of drive_num_tile_enable_flag of the PPS is “1” and the value of num_tile_levelN_minus1 + 1 is P, the picture of level N is to be divided into (num_tile_columns_minus1 + 1) x (num_tile_rows_minus1 + 1) / P tiles. can In other words, for a picture having a level of N, the number of tiles generated by division may be 1/P times the number of tiles of the basic division. In this case, a picture having a level of N may be divided according to one of the following methods 1) to 5).

Here, P may be the GOP level of the picture.

The number of N-level horizontal tiles may indicate the number of tiles (that is, the number of columns of tiles) in the horizontal direction of the picture of the level N picture.

The number of N-level vertical tiles may indicate the number of tiles (that is, the number of rows of tiles) in a vertical direction of a picture having a level of N.

The basic number of horizontal tiles may be (num_tile_columns_minus1 + 1).

The basic number of vertical tiles may be (num_tile_rows_minus1 + 1).

The picture horizontal length may indicate the horizontal length of the picture.

The picture vertical length may indicate the vertical length of the picture.

Method 1)

The reduction indication information may adjust the number of horizontal tiles by picture division.

The number of N-level horizontal tiles may be 1/P times the number of basic horizontal tiles, and the number of N-level vertical tiles may be equal to the number of basic vertical tiles.

Method 2)

The reduction indication information may adjust the number of vertical tiles by division of a picture.

The number of N-level vertical tiles may be 1/P times the number of basic vertical tiles, and the number of N-level horizontal tiles may be equal to the number of basic horizontal tiles.

Method 3)

The reduction indication information may control the number of horizontal tiles when the horizontal picture length is greater than the vertical picture length, and control the number of vertical tiles when the picture vertical length is greater than the picture horizontal length.

Based on the comparison between the picture horizontal length and the picture vertical length, it may be determined that 1/P of the number of N-level horizontal tiles and the number of N-level vertical tiles is applied.

For example, when the picture horizontal length is greater than the picture vertical length, the number of N-level horizontal tiles may be 1/P times the number of basic horizontal tiles, and the number of N-level vertical tiles may be equal to the number of basic vertical tiles. When the picture vertical length is greater than the picture horizontal length, the number of N-level vertical tiles may be 1/P times the number of basic vertical tiles, and the number of N-level horizontal tiles may be equal to the number of basic horizontal tiles.

When the picture horizontal length and the picture vertical length are the same, the number of N-level horizontal tiles may be 1/P times the number of basic horizontal tiles, and the number of N-level vertical tiles may be equal to the number of basic vertical tiles. Conversely, when the picture horizontal length and the picture vertical length are the same, the number of N-level vertical tiles may be 1/P times the number of basic vertical tiles, and the number of N-level horizontal tiles may be equal to the number of basic horizontal tiles.

For example, if the picture horizontal length is greater than the picture vertical length, the number of N-level horizontal tiles may be "(num_tile_columns_minus1 + 1) / P", and the number of N-level vertical tiles may be "(num_tile_rows_minus1 + 1)" there is. When the picture vertical length is greater than the picture horizontal length, the number of N-level horizontal tiles may be “(num_tile_columns_minus1 + 1)”, and the number of N-level vertical tiles may be “(num_tile_rows_minus1 + 1) / P”.

Method 4)

The reduction indication information may adjust the number of horizontal tiles when the number of basic horizontal tiles is greater than the number of basic vertical tiles, and may adjust the number of vertical tiles when the number of basic vertical tiles is greater than the number of basic horizontal tiles.

Based on the comparison between the basic number of horizontal tiles and the number of basic vertical tiles, it may be determined to which of the number of N-level horizontal tiles and the number of N-level vertical tiles a reduction of 1/P times is to be applied.

For example, when the number of basic horizontal tiles is greater than the number of basic vertical tiles, the number of N-level horizontal tiles may be 1/P times the number of basic horizontal tiles, and the number of N-level vertical tiles may be equal to the number of basic vertical tiles. When the number of basic vertical tiles is greater than the number of basic horizontal tiles, the number of N-level vertical tiles may be 1/P times the number of basic vertical tiles, and the number of N-level horizontal tiles may be equal to the number of basic horizontal tiles.

When the number of basic horizontal tiles and the number of basic vertical tiles are the same, the number of N-level horizontal tiles may be 1/P times the number of basic horizontal tiles, and the number of N-level vertical tiles may be equal to the number of basic vertical tiles. Conversely, when the number of basic horizontal tiles and the number of basic vertical tiles are the same, the number of N-level vertical tiles may be 1/P times the number of basic vertical tiles, and the number of N-level horizontal tiles may be equal to the number of basic horizontal tiles.

For example, when the basic number of horizontal tiles is greater than the number of basic vertical tiles, the number of N-level horizontal tiles may be "(num_tile_columns_minus1 + 1) / P", and the number of N-level vertical tiles is "(num_tile_rows_minus1 + 1)" can be When the basic number of vertical tiles is greater than the number of basic horizontal tiles, the number of N-level horizontal tiles may be “(num_tile_columns_minus1 + 1)”, and the number of N-level vertical tiles may be “(num_tile_rows_minus1 + 1) / P”.

Method 5)

When “P=QR”, the number of N-level horizontal tiles may be “the number of basic horizontal tiles / Q”, and the number of N-level vertical tiles may be “the number of basic vertical tiles / R”.

For example, (P, Q, R) is (P, P, 1), (P, 1, P), (T ² , T, T), (6, 3, 2), (6, 2, 3), (8, 4, 2), and (8, 2, 4), and the like, and each of P, Q, R and T may be an integer of 1 or more.

Picture division information for dividing a picture into slices

As described above, portions of a picture generated by division may be slices. A picture may be divided into a plurality of slices.

In the above-described embodiments, picture segmentation information may be signaled by slice_segment_header. slice_segment_address of slice_segment_header may be used for picture segmentation.

In the following embodiment, slice_segment_address may be included in the PPS rather than the slice_segment_header. In other words, a PPS including slice_segment_address may be used to divide a picture into a plurality of slices.

The PPS may define parameters applied to a specified picture. Here, at least some of the parameters may be used to determine a picture division method as picture division information.

In an embodiment, picture division information included in one PPS may be applied to a plurality of pictures. Here, the plurality of pictures may be divided in one of at least two different ways. That is, to define at least two different picture division schemes, one PPS may be used instead of several PPSs. Even if two pictures are divided by different picture division methods, a PPS is not signaled for each picture, and a changing picture division method may be induced by picture division information of one PPS. For example, the PPS may include picture division information to be applied to one picture, and picture division information to be applied to another picture may be derived by the PPS. Alternatively, for example, the PPS may include picture division information to be applied to one picture, and picture division methods to be applied to a plurality of pictures may be defined by the picture division information.

For example, the PPS may define the number of pictures to be processed in parallel for each GOP level. When the number of pictures to be processed in parallel for each GOP level is defined, a picture division method of a picture of the specified GOP level may be determined. Alternatively, if the number of pictures to be processed in parallel for each GOP level is defined, it may be determined how many slices the picture of the specified GOP level is divided into.

An embodiment in which a picture is divided into slices according to the GOP level

Table 5 below shows an example of a structure of pic_parameter_set_rbsp indicating a PPS for signaling picture split information. The picture division information may be pic_parameter_set_rbsp or may include pic_parameter_set_rbsp. A picture may be divided into a plurality of slices by pic_parameter_set_rbsp. The shape of the plurality of slices may change periodically.

Table 6 below shows an example of the structure of slice_segment_header when the PPS of Table 5 is used.

Referring to Table 5, pic_parameter_set_rbsp may include the following elements.

- parallel_slice_enabled_flag: parallel_slice_enabled_flag may be a slice division information flag. The slice division information flag may indicate whether the PPS includes slice division information applied to a picture referring to the PPS.

For example, a value of “1” of parallel_slice_enabled_flag may indicate that the PPS includes slice division information to be applied to a picture referring to the PPS. A value of "0" of parallel_slice_enabled_flag may indicate that the PPS does not include slice division information to be applied to a picture referring to the PPS.

For example, a value of "0" of parallel_slice_enabled_flag may indicate that slice segmentation information of a picture referring to the PPS exists in slice_segment_header. Here, the slice segmentation information may include slice_segment_address.

- num_parallel_slice_minus1: num_parallel_slice_minus1 may be slice number information corresponding to the number of slices of a divided picture.

For example, a value of “num_parallel_slice_minus1 + 1” may indicate the number of slices in the divided picture.

- slice_uniform_spacing_flag: slice_uniform_spacing_flag may be a uniform spacing flag indicating whether all slices have the same size.

For example, when the value of slice_uniform_spacing_flag is “0”, the sizes of slices cannot all be considered to be the same, and other information for determining the sizes of slices may be required.

For example, when the value of slice_uniform_spacing_flag is “1”, the sizes of slices may all be the same. In addition, when the value of slice_uniform_spacing_flag is “1”, since sizes of slices are all the same, slice division information for slices may be derived by the total size of a picture and the number of slices.

- parallel_slice_segment_address_minus1[i]: parallel_slice_segment_address_minus1 may indicate sizes of slices generated by picture division. For example, a value of “parallel_slice_segment_address_minus1[i] + 1” may indicate the size of the i-th slice. The unit of the size of the slice may be CTB. i may be an integer greater than or equal to 0 and less than n. n may be the number of slices.

- parallel_frame_by_gop_level_enable_flag: parallel_frame_by_gop_level_enable_flag may be a GOP level parallel processing flag indicating whether a picture referring to the PPS is encoded or decoded in parallel with other pictures having the same GOP level.

For example, a value of “0” of parallel_frame_by_gop_level_enable_flag may indicate that a picture referring to the PPS is not encoded or decoded in parallel with another picture having the same GOP level. A value of “1” of parallel_frame_by_gop_level_enable_flag may indicate that a picture referring to the PPS is encoded or decoded in parallel with another picture having the same GOP level.

When the value of parallel_frame_by_gop_level_enable_flag is “1”, the degree of picture division needs to be adjusted according to picture level parallelization.

The picture division information may include parallel processing picture number information for GOP level n. The information on the number of parallel processing pictures for the specified GOP level n may correspond to the number of pictures having a GOP level n to which parallel processing may be applied. n may be an integer of 2 or more.

Parallel processing picture number information may include the following num_frame_in_parallel_gop_level3_minus1 and num_frame_in_parallel_gop_level2_minus1.

- num_frame_in_parallel_gop_level3_minus1: num_frame_in_parallel_gop_level3_minus1 may be information on the number of parallel processing pictures for GOP level 3. Information on the number of parallel processing pictures for GOP level 3 may correspond to the number of pictures having a GOP level of 3 that can be encoded or decoded in parallel.

For example, a value of “num_frame_in_parallel_gop_level3_minus1 + 1” may indicate the number of pictures having a GOP level of 3 that can be encoded or decoded in parallel.

- num_frame_in_parallel_gop_level2_minus1: num_frame_in_parallel_gop_level2_minus1 may be information on the number of parallel processing pictures for GOP level 2. Information on the number of parallel processing pictures for GOP level 2 may correspond to the number of pictures having a GOP level of 2 that can be encoded or decoded in parallel.

For example, a value of “num_frame_in_parallel_gop_level2_minus1 + 1” may indicate the number of pictures having a GOP level of 2 that can be encoded or decoded in parallel.

A plurality of encoded pictures may be decoded through the following process by using the signaling of picture division information using the above-described pic_parameter_set_rbsp.

For example, if the value of “parallel_slice_enabled_flag” of the PPS of the current picture is “1”, the picture may be divided into one or more slices. In order to divide a picture into slices, slice_segment_address, which is slice segmentation information, may need to be calculated. After the PPS is received, slice_segment_address may be calculated based on the elements of the PPS.

If the value of “slice_uniform_spacing_flag” is “1”, the sizes of all slices may be the same. That is, the size of the unit slice may be calculated according to the size of the picture and the number of slices, and sizes of all slices may be the same as the calculated size of the unit slice. Also, slice_segment_addresses of all slices may be calculated using the size of the unit slice. When the value of “slice_uniform_spacing_flag” is “1”, the size of a unit slice and slice_segment_addresses of slices may be calculated according to the code of Table 7 below.

num_CTB_in_slice = the number of CTBs in the picture / (num_parallel_slice_minus1 + 1)
slice_segment_address[0] = 0;
for( i = 1; i < num_parallel_slice_minus1 + 1; i++ ){
slice_segment_address[i] = slice_segment_address[i - 1] + num_CTB_in_slice;
}

When the value of "slice_uniform_spacing_flag" is "0", slice_segment_address[i] may be parsed in the PPS. That is, when the value of "slice_uniform_spacing_flag" is "0", the PPS may include slice_segment_address[i]. i may be an integer greater than or equal to 0 and less than n. n may be the number of slices. For example, if the value of “parallel_frame_by_gop_level_enable_flag” of the PPS of the current picture is “1”, num_parallel_slice_minus1 and slice_segment_address[i] may be redefined.

When the value of “parallel_frame_by_gop_level_enable_flag” of the PPS of the current picture is “1” and the GOP Level of the current picture is 2, num_parallel_slice_minus1 to be applied to the current picture may be redefined as in Equation 7 below.

[Equation 7]

new_num_parallel_slice_minus1 = (num_parallel_slice_minus1) / (num_frame_in_parallel_gop_level2_minus1 + 1)

Here, new_num_parallel_slice_minus1 may correspond to the number of slices of a current picture having a GOP level of 2. For example, a value of “new_num_parallel_slice_minus1 + 1” may indicate the number of slices in the divided current picture.

When the value of “parallel_frame_by_gop_level_enable_flag” of the PPS of the current picture is “1” and the GOP Level of the current picture is 3, num_parallel_slice_minus1 to be applied to the current picture may be redefined as in Equation 8 below.

[Equation 8]

new_num_parallel_slice_minus1 = (num_parallel_slice_minus1) / (num_frame_in_parallel_gop_level3_minus1 + 1)

Here, new_num_parallel_slice_minus1 may correspond to the number of slices of a current picture having a GOP level of 3. For example, a value of “new_num_parallel_slice_minus1 + 1” may indicate the number of slices in the divided current picture.

According to Equations 7 and 8, as the value of num_frame_in_parallel_gop_level2_minus1 or num_frame_in_parallel_gop_level3_minus1 increases, the value of new_num_parallel_slice_minus1 may decrease. That is, as the value of num_frame_in_parallel_gop_level2_minus1 or num_frame_in_parallel_gop_level3_minus1 increases, the number of slices generated by division may decrease. Accordingly, num_frame_in_parallel_gop_level2_minus1 and num_frame_in_parallel_gop_level3_minus1 may be reduction indication information for reducing the number of slices generated by picture division. As the number of pictures having the same GOP level to be encoded or decoded in parallel increases, each picture may be divided into a smaller number of slices.

The picture division information may include reduction indication information for reducing the number of tiles generated by picture division. In addition, the reduction indication information may indicate a degree to which the number of slices generated by picture division in relation to encoding or decoding processed in parallel is reduced. The picture division information may include GOP level n reduction indication information for reducing the number of tiles generated by picture division for a picture having a GOP level of n. n may be an integer of 2 or more. For example, num_frame_in_parallel_gop_level2_minus1 may be GOP level 2 reduction indication information. num_frame_in_parallel_gop_level3_minus1 may be GOP level 3 reduction indication information.

As described above in relation to Equations 7 and 8, the picture division information may include GOP level n reduction indication information for a picture having a GOP level n. When the number of slices generated by division of a picture having a GOP level of 0 or 1 is w, and the number of slices generated by division of a picture having a GOP level of n is w/m, the GOP level n reduction indication information is can correspond to m.

By redefining Equations 7 and 8, slice_segment_addresses of slices of the current picture can be calculated by the code of Table 8 below.

new_num_CTB_in_slice = the number of CTBs in the picture / (new_num_parallel_slice_minus1 + 1)
slice_segment_address[0] = 0;
for( i = 1; i <new_num_parallel_slice_minus1+1; i++ ){
slice_segment_address[i] = slice_segment_address[i - 1] + new_num_CTB_in_slice;
}

An embodiment in which a picture is divided into slices according to a GOP level or a temporal level Table 9 below shows an example of a structure of a pic_parameter_set_rbsp indicating a PPS for signaling picture division information. The picture division information may be pic_parameter_set_rbsp or may include pic_parameter_set_rbsp. A picture may be divided into a plurality of slices by pic_parameter_set_rbsp. The shape of the plurality of slices may change periodically.

Table 10 below shows an example of the structure of slice_segment_header when the PPS of Table 9 is used.

Referring to Table 9, pic_parameter_set_rbsp may include the following elements.

- unified_slice_segment_enabled_flag: unified_slice_segment_enabled_flag may be a slice segmentation information flag. The slice division information flag may indicate whether the PPS includes slice division information applied to a picture referring to the PPS.

For example, a value of “1” of unified_slice_segment_enabled_flag may indicate that the PPS includes slice division information to be applied to a picture referring to the PPS. A value of "0" of unified_slice_segment_enabled_flag may indicate that the PPS does not include slice segmentation information to be applied to a picture referring to the PPS.

For example, a value of “0” of unified_slice_segment_enabled_flag may indicate that slice segmentation information of a picture referring to the PPS exists in slice_segment_header. Here, the slice segmentation information may include slice_segment_address.

- num_slice_minus1: num_slice_minus1 may be slice number information corresponding to the number of slices of a divided picture. For example, a value of “num_slice_minus1 + 1” may indicate the number of slices in the divided picture.

- slice_uniform_spacing_flag: slice_uniform_spacing_flag may be a uniform spacing flag indicating whether all slices have the same size.

For example, when the value of slice_uniform_spacing_flag is “0”, the sizes of slices cannot all be considered to be the same, and other information for determining the sizes of slices may be required. For example, when the value of slice_uniform_spacing_flag is “1”, the sizes of slices may all be the same.

In addition, when the value of slice_uniform_spacing_flag is “1”, since sizes of slices are all the same, slice division information for slices may be derived by the total size of a picture and the number of slices.

- unified_slice_segment_address_minus1[i]: unified_slice_segment_address_minus1 may indicate sizes of slices created by picture division.

For example, a value of “unified_slice_segment_address_minus1[i] + 1” may indicate the size of the i-th slice. The unit of the size of the slice may be CTB. i may be an integer greater than or equal to 0 and less than n. n may be the number of slices.

- unified_slice_segment_by_gop_level_enable_flag: unified_slice_segment_by_gop_level_enable_flag may be a division method indication flag indicating whether a picture referring to the PPS is divided in one of at least two or more different methods.

Alternatively, unified_slice_segment_by_gop_level_enable_flag may indicate whether the number and shapes of slices generated by division are the same when a picture referring to the PPS is divided into slices. The shape of the slice may include one or more of a start position of the slice, a length of the slice, and an end position of the slice.

For example, a value of "0" of unified_slice_segment_by_gop_level_enable_flag may indicate that a picture referring to the PPS is divided in a single method. Alternatively, the value of unified_slice_segment_by_gop_level_enable_flag of “0” may indicate that the number of slices created when a picture referring to the PPS is divided is always the same and the shapes of the slices are always constant.

For example, a value of “1” of unified_slice_segment_by_gop_level_enable_flag may indicate that a plurality of division types are defined by one PPS. Alternatively, the value of unified_slice_segment_by_gop_level_enable_flag of “1” may indicate that the picture referring to the PPS is divided by one of at least two or more different methods. That the picture is divided in different ways may mean that the number of slices and/or shapes of slices generated by the picture being divided are different.

For example, a value of “1” of unified_slice_segment_by_gop_level_enable_flag may indicate that the number of slices or shapes of slices generated by splitting a picture referring to the PPS is not constant.

Alternatively, unified_slice_segment_by_gop_level_enable_flag may be a GOP level parallel processing flag indicating whether a picture referring to the PPS is encoded or decoded in parallel with other pictures having the same GOP level.

For example, a value of "0" of unified_slice_segment_by_gop_level_enable_flag may indicate that a picture referring to the PPS is not encoded or decoded in parallel with another picture having the same GOP level. A value of unified_slice_segment_by_gop_level_enable_flag of “1” may indicate that a picture referring to the PPS is encoded or decoded in parallel with another picture having the same GOP level. When the value of unified_slice_segment_by_gop_level_enable_flag is "1", the degree of picture division needs to be adjusted according to picture level parallelization.

The picture division information may include frame number indication information for GOP level n. The frame number indication information for the specified GOP level n may correspond to the number of pictures having a GOP level of n to which parallel processing may be applied. n may be an integer of 2 or more.

The frame number indication information may include the following num_frame_by_gop_level2_minus1 and num_frame_by_gop_level3_minus1. Also, the frame number indication information may include num_frame_by_gop_levelN_minus1 for one or more values.

The picture segmentation information or PPS may optionally include at least one of num_frame_by_gop_level2_minus1, num_frame_by_gop_level3_minus1, and num_frame_by_gop_levelN_minus1 when the value of unified_slice_segment_by_gop_level_enable_flag is “1”.

- num_frame_by_gop_level3_minus1: num_frame_by_gop_level3_minus1 may be frame number information for GOP level 3. The frame number information for the GOP level 3 may correspond to the number of pictures having the GOP level 3 that can be encoded or decoded in parallel.

For example, a value of “num_frame_by_gop_level3_minus1 + 1” may indicate the number of pictures having a GOP level of 3 that can be encoded or decoded in parallel.

- num_frame_by_gop_level2_minus1: num_frame_by_gop_level2_minus1 may be frame number information for GOP level 2. The frame number information for GOP level 2 may correspond to the number of pictures having a GOP level of 2 that can be encoded or decoded in parallel.

For example, a value of “num_frame_by_gop_level3_minus1 + 1” may indicate the number of pictures having a GOP level of 2 that can be encoded or decoded in parallel.

The above description can also be applied to the temporal level. That is, in the embodiment, "GOP" may be replaced with "temporal identifier", and "GOP level" may be replaced with "temporal level".

A plurality of encoded pictures may be decoded through the following process by using the signaling of picture division information using the above-described pic_parameter_set_rbsp.

First, if the value of “unified_slice_segment_enabled_flag” of the PPS of the current picture is “1”, the picture may be divided into one or more slices.

In addition, if the value of “unified_slice_segment_by_gop_level_enable_flag” of the PPS of the current picture is “1”, the picture referring to the PPS may be divided by one of at least two or more different schemes.

In order to divide a picture into slices, slice_segment_address, which is slice segmentation information, may need to be calculated. After the PPS is received, slice_segment_address may be calculated based on the elements of the PPS.

If the value of “slice_uniform_spacing_flag” is “1”, the sizes of all slices may be the same. That is, the size of the unit slice may be calculated, and sizes of all slices may be equal to the calculated size of the unit slice. slice_segment_addresses of all slices may be calculated using the size of the unit slice. When the value of “slice_uniform_spacing_flag” is “1”, the size of the unit slice and unified_slice_segment_addresses of the slices may be calculated according to the code of Table 11 below.

num_CTB_in_slice = the number of CTBs in the picture / (num_slice_minus1 + 1)
unified_slice_segment_address[0] = 0;
for( i = 1; i < num_slice_minus1 + 1; i++){
unified_slice_segment_address[i] = unified_slice_segment_address[i - 1] + num_CTB_in_slice;
}

If the value of "slice_uniform_spacing_flag" is "0", unified_slice_segment_address[i] may be parsed in PPS. That is, when the value of "slice_uniform_spacing_flag" is "0", the PPS may include unified_slice_segment_address[i]. i may be an integer greater than or equal to 0 and less than n. n may be the number of slices. For example, if the value of “unified_slice_segment_by_gop_level_enable_flag” of the PPS of the current picture is “1”, num_slice_minus1 and unified_slice_segment_address[i] may be redefined.

When the value of “parallel_frame_by_gop_level_enable_flag” of the PPS of the current picture is “1” and the GOP Level of the current picture is 2, num_slice_minus1 to be applied to the current picture may be redefined as in Equation 9 below.

[Equation 9]

num_slice_minus1 = (num_slice_minus1) / (num_frame_by_gop_level2_minus1 + 1)

Here, the redefined num_slice_minus1 may correspond to the number of slices of a current picture having a GOP level of 2. For example, a value of “num_slice_minus1 + 1” may indicate the number of slices in the divided current picture.

When the value of “parallel_frame_by_gop_level_enable_flag” of the PPS of the current picture is “1” and the GOP Level of the current picture is 3, num_parallel_slice_minus1 to be applied to the current picture may be redefined as in Equation 10 below.

[Equation 10]

num_slice_minus1 = (num_slice_minus1) / (num_frame_by_gop_level3_minus1 + 1)

Here, the redefined num_slice_minus1 may correspond to the number of slices of a current picture having a GOP level of 3. For example, a value of “num_slice_minus1 + 1” may indicate the number of slices in the divided current picture.

According to Equations 9 and 10, as the value of num_frame_by_gop_level2_minus1 or num_frame_by_gop_level3_minus1 increases, the value of num_slice_minus1 may decrease. That is, as the value of num_frame_by_gop_level2_minus1 or num_frame_by_gop_level3_minus1 increases, the number of slices generated by division may decrease. Accordingly, num_frame_by_gop_level2_minus1 and num_frame_by_gop_level3_minus1 may be reduction indication information for reducing the number of slices generated by picture division. As the number of pictures having the same GOP level to be encoded or decoded in parallel increases, each picture may be divided into a smaller number of slices.

The picture division information may include reduction indication information for reducing the number of slices generated by picture division. In addition, the reduction indication information may indicate a degree to which the number of slices generated by picture division in relation to encoding or decoding processed in parallel is reduced. The picture division information may include GOP level n reduction indication information for reducing the number of slices generated by picture division for a picture having a GOP level of n. n may be an integer of 2 or more. For example, num_frame_by_gop_level2_minus1 may be GOP level 2 reduction indication information. num_frame_by_gop_level3_minus1 may be GOP level 3 reduction indication information.

As described above with respect to Equations 9 and 10, the picture division information may include GOP level n reduction indication information for a picture having a GOP level of n. When the number of slices generated by division of a picture having a GOP level of 0 or 1 is w, and the number of slices generated by division of a picture having a GOP level of n is w/m, the GOP level n reduction indication information is can correspond to m.

By redefining Equations 9 and 10, unified_slice_segment_addresses of slices of the current picture may be calculated by the codes of Table 12 below.

new_num_CTB_in_slice = the number of CTBs in the picture / (num_slice_minus1 + 1)
unified_slice_segment_address[0] = 0;
for( i = 1; i < num_slice_minus1 + 1; i++ ){
unified_slice_segment_address[i] = unified_slice_segment_address[i - 1] + num_CTB_in_slice;
}

Table 13 below shows an example of a syntax of a PPS for signaling picture splitting information when a picture splitting method applied to a plurality of pictures is changed according to a picture.

Table 14 below shows an example of a syntax of a slice segment header for signaling picture splitting information when a picture splitting method applied to a plurality of pictures is changed according to a picture.

Table 15 below shows another example of syntax of a PPS for signaling picture splitting information when a picture splitting method applied to a plurality of pictures is changed according to a picture.

Table 16 below shows another example of a syntax of a slice segment header for signaling picture splitting information when a picture splitting method applied to a plurality of pictures is changed according to a picture.

According to the above-described embodiments, picture division information in a bitstream may be transmitted from the encoding apparatus 1300 to the decoding apparatus 1500 .

According to embodiments, even when a plurality of pictures are divided in different ways, picture division information may not be signaled for each picture or for each picture division.

According to embodiments, even when a plurality of pictures are divided in different ways, the picture division information may not be coded for each picture or for each picture part each time. As encoding and signaling are efficiently performed, the size of the encoded bitstream may be reduced, encoding efficiency may be improved, and implementation complexity of the decoding apparatus 1500 may be reduced.

17 is a structural diagram of an electronic device implementing an encoding apparatus and/or a decoding apparatus according to an embodiment.

According to an embodiment, at least some of the control unit 1310 , the encoder 1320 , and the communication unit 1330 of the encoding apparatus 1300 may be program modules, and may communicate with an external device or system. The program modules may be included in the encoding apparatus 1300 in the form of an operating system, an application program module, and other program modules.

Also, according to an embodiment, at least some of the control unit 1510 , the decryption unit 1520 , and the communication unit 1530 of the decryption apparatus 1500 may be program modules, and may communicate with an external device or system. The program modules may be included in the decryption apparatus 1500 in the form of an operating system, an application program module, and other program modules.

Program modules may be physically stored on various known storage devices. Also, at least some of these program modules may be stored in a remote storage device capable of communicating with the encoding device 1300 or a remote storage device capable of communicating with the decoding device 1500 .

Program modules include routines, subroutines, programs, objects, components, and data that perform functions or operations according to an embodiment or implement abstract data types according to an embodiment. It may include, but is not limited to, a data structure and the like.

The program modules may include instructions or codes executed by at least one processor of the encoding apparatus 1300 or at least one processor of the decoding apparatus 1500 .

The encoding apparatus 1300 and/or the decoding apparatus 1500 may be implemented as the electronic apparatus 1700 illustrated in FIG. 17 . The electronic device 1700 may be a general-purpose computer system operating as the encoding device 1300 and/or the decoding device 1500 .

As shown in FIG. 17 , the electronic device 1700 includes at least one processor 1710 , a memory 1730 , a user interface (UI) input device 1750 that communicate with each other through a bus 1790 , It may include a UI output device 1760 and storage 1740 . Also, the electronic device 1700 may further include a communication unit 1720 connected to the network 1799 . The processor 1710 may be a semiconductor device that executes processing instructions stored in a central processing unit (CPU), the memory 1730 , or the storage 1740 . Memory 1730 and storage 1740 may be various types of volatile or non-volatile storage media. For example, the memory may include at least one of a ROM 1731 and a RAM 1732 .

The encoding apparatus 1300 and/or the decoding apparatus 1500 may be implemented in a computer system including a recording medium that can be read by a computer.

The recording medium may store at least one module required for the electronic device 1700 to operate as the encoding apparatus 1300 and/or the decoding apparatus 1500 . The memory 1730 may store at least one module and may be configured to be executed by at least one processor 1710 .

A function related to communication of data or information of the encoding apparatus 1300 and/or the decoding apparatus 1500 may be performed through the communication unit 1720 . For example, the control unit 1310 and the encoder 1320 of the encoding unit 1300 may correspond to the processor 1710 , and the communication unit 1330 may correspond to the communication unit 1720 . For example, the control unit 1510 and the decryption unit 1520 of the decryption unit 1500 may correspond to the processor 1710 , and the communication unit 1530 may correspond to the communication unit 1720 .

In the above-described embodiments, the methods are described on the basis of a flowchart as a series of steps or units, but the present invention is not limited to the order of steps, and some steps may occur in a different order or at the same time as other steps as described above. can In addition, those of ordinary skill in the art will recognize that the steps shown in the flowchart are not exclusive, other steps may be included, or that one or more steps in the flowchart may be deleted without affecting the scope of the present invention. you will understand

The embodiments according to the present invention described above may be implemented in the form of program instructions that can be executed through various computer components and recorded in a computer-readable recording medium. The computer-readable recording medium may include program instructions, data files, data structures, etc. alone or in combination. The program instructions recorded on the computer-readable recording medium may be specially designed and configured for the present invention, or may be known and available to those skilled in the computer software field. Examples of the computer-readable recording medium include hard disks, magnetic media such as floppy disks and magnetic tapes, optical recording media such as CD-ROMs and DVDs, and magneto-optical media such as floppy disks. tical media), and hardware devices specially configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine language codes such as those generated by a compiler, but also high-level language codes that can be executed by a computer using an interpreter or the like. The hardware device may be configured to operate as one or more software modules for carrying out the processing according to the present invention, and vice versa.

In the above, the present invention has been described with specific matters such as specific components and limited embodiments and drawings, but these are provided to help a more general understanding of the present invention, and the present invention is not limited to the above embodiments. , various modifications and variations can be devised from these descriptions by those of ordinary skill in the art to which the present invention pertains.

Therefore, the spirit of the present invention should not be limited to the above-described embodiments, and not only the claims described below but also all modifications equivalently or equivalently to the claims described below belong to the scope of the spirit of the present invention. will do it

Claims (20)

obtaining picture division information; and
performing division on the plurality of pictures based on the picture division information
including,
Each of the plurality of pictures is divided using a plurality of division methods,
Each picture of the plurality of pictures is partitioned using one of the plurality of partitioning methods,
Each division method of the plurality of division methods divides a picture into one or more parts,
and each part of the one or more parts has one or more tiles. The method of claim 1,
The picture division information is included in a parameter set for the plurality of pictures. The method of claim 1,
The picture division information is transmitted once through a bitstream and decoded once for the plurality of pictures. The method of claim 1,
The picture division information determines the number and shape of the plurality of pictures. The method of claim 1,
The plurality of pictures each have different identifiers. According to claim 1,
The picture parameter sets of the plurality of pictures are different from each other. The method of claim 1,
and information indicating whether the division into the one or more parts is performed is used. generating picture division information indicating a division method applied to a plurality of pictures; and
generating a bitstream including the picture division information
including,
Each of the plurality of pictures is divided using a plurality of division methods,
Each picture of the plurality of pictures is partitioned using one of the plurality of partitioning methods,
Each division method of the plurality of division methods divides a picture into one or more parts,
and each part of the one or more parts comprises one or more tiles. 9. The method of claim 8,
The picture division information is included in a parameter set for the plurality of pictures. 9. The method of claim 8,
The picture division information is encoded once in a bitstream with respect to the plurality of pictures. 9. The method of claim 8,
The picture division information determines the number and shape of the plurality of pictures. 9. The method of claim 8,
The plurality of pictures each have different identifiers. 9. The method of claim 8,
and picture parameter sets of the plurality of pictures are different from each other. 9. The method of claim 8,
and information indicating whether division into the one or more parts is performed is generated. A recording medium for recording the bitstream generated by the encoding method according to claim 8. A computer-readable recording medium for storing a bitstream, comprising:
The bitstream is
Picture division information
including,
A plurality of pictures are divided based on the picture division information,
Each of the plurality of pictures is divided using a plurality of division methods,
Each picture of the plurality of pictures is partitioned using one of the plurality of partitioning methods,
Each division method of the plurality of division methods divides a picture into one or more parts,
wherein each portion of the one or more portions comprises one or more tiles. 17. The method of claim 16,
The picture division information is included in a parameter set for the plurality of pictures. 17. The method of claim 16,
The picture division information is transmitted once through the bitstream and decoded once for the plurality of pictures. 17. The method of claim 16,
The picture division information determines the number and shape of the plurality of pictures. 17. The method of claim 16,
The picture parameter sets of the plurality of pictures are different from each other.

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