Encoding device, decoding device, and bitstream transmitter

Abstract

To provide an encoding device capable of efficiently performing motion compensation using affine motion compensation.SOLUTION: An encoding device 100 includes a circuit 160 and a memory 162. The circuit 160 performs motion compensation of a target block while limiting the range in which motion search or motion compensation is performed in the affine motion compensation prediction processing for the inter prediction processing of the target block by using the memory 162. In the affine motion compensation prediction processing, the range for motion search or motion compensation is limited so that variation between the control point motion vectors in the upper left and upper right corners of the target block in the affine motion compensation prediction processing is within a specified range. The variation is a value based on the difference between the control point motion vectors in the upper left and upper right corners of the target block, in which the predetermined range changes depending on the type of picture being referenced.SELECTED DRAWING: Figure 18

Description

[Technical Field]

[0001] The present disclosure relates to an encoding device, a decoding device, and a bitstream transmission device. [Background technology]

[0002] Conventionally, H.265 exists as a standard for encoding moving images. H.265 is also known as HEVC (High Efficiency Video Coding). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] H.265(ISO / IEC 23008-2 HEVC(High Efficiency Coding)) Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the encoding and decoding of moving images, if affine motion compensation in inter-prediction processing is performed inefficiently, this may have a negative impact on processing efficiency, such as affine motion compensation not being selected and motion compensation being performed for the current block.

[0005] Therefore, the present disclosure provides an encoding device and the like that can efficiently perform motion compensation using affine motion compensation. [Means for solving the problem]

[0006] An encoding device according to one aspect of the present disclosure includes a circuit and a memory, and the circuit uses the memory to perform motion compensation for a target block by restricting the range of motion search or motion compensation in an affine motion compensation prediction process in inter-prediction processing of the target block, and in the affine motion compensation prediction process, the range of motion search or motion compensation is restricted so that the variation between the control point motion vector of the upper left corner and the control point motion vector of the upper right corner of the target block in the affine motion compensation prediction process falls within a predetermined range, the variation being a value based on the difference between the control point motion vector of the upper left corner and the control point motion vector of the upper right corner of the target block, and the predetermined range is changed depending on the type of picture to be referenced.

[0007] These comprehensive or specific aspects may be realized as a system, an apparatus, a method, an integrated circuit, a computer program, or a non-transitory recording medium such as a computer-readable CD-ROM, or may be realized as any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium. [Effects of the Invention]

[0008] A bitstream transmission device and the like according to one aspect of the present disclosure can efficiently perform motion compensation using affine motion compensation. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a block diagram showing a functional configuration of a coding device according to the first embodiment. [Figure 2] FIG. 2 is a diagram showing an example of block division according to the first embodiment. [Figure 3] FIG. 3 is a table showing the transformation basis functions corresponding to each transformation type. [Figure 4A] FIG. 4A is a diagram showing an example of the shape of a filter used in ALF. [Figure 4B] FIG. 4B is a diagram showing another example of the shape of the filter used in ALF. [Figure 4C] FIG. 4C is a diagram showing another example of the shape of the filter used in ALF. [Figure 5A] FIG. 5A is a diagram showing 67 intra prediction modes in intra prediction. [Figure 5B] FIG. 5B is a flowchart for explaining an outline of the predicted image correction process using the OBMC process. [Figure 5C] FIG. 5C is a conceptual diagram for explaining an outline of the predicted image correction process using the OBMC process. [Figure 5D] FIG. 5D is a diagram showing an example of FRUC. [Figure 6] FIG. 6 is a diagram for explaining pattern matching (bilateral matching) between two blocks along a motion trajectory. [Figure 7] FIG. 7 is a diagram for explaining pattern matching (template matching) between a template in a current picture and a block in a reference picture. [Figure 8] FIG. 8 is a diagram for explaining a model assuming uniform linear motion. [Figure 9A] FIG. 9A is a diagram for explaining derivation of a motion vector for each sub-block based on motion vectors of a plurality of adjacent blocks. [Figure 9B] FIG. 9B is a diagram for explaining an outline of the motion vector derivation process in the merge mode. [Figure 9C] FIG. 9C is a conceptual diagram for explaining an outline of the DMVR process. [Figure 9D] FIG. 9D is a diagram for explaining an outline of a predicted image generation method using luminance correction processing by LIC processing. [Figure 10] FIG. 10 is a block diagram showing a functional configuration of a decoding device according to the first embodiment. [Figure 11] FIG. 11 is a conceptual diagram illustrating the affine inter mode of affine motion compensation prediction. [Figure 12A]FIG. 12A is a conceptual diagram illustrating the affine merge mode of affine motion compensation prediction. [Figure 12B] FIG. 12B is a conceptual diagram illustrating the affine merge mode of affine motion compensation prediction. [Figure 13] FIG. 13 is a block diagram showing an internal configuration for performing affine motion compensation prediction processing in an inter prediction unit included in the encoding device in the first embodiment. [Figure 14] FIG. 14 is a flowchart showing a first processing procedure of the affine inter mode of affine motion compensation performed by the inter prediction unit of the encoding device according to the first embodiment. [Figure 15] FIG. 15 is a flowchart showing a second processing procedure of the affine inter mode of affine motion compensation performed by the inter prediction unit of the encoding device according to the first embodiment. [Figure 16] FIG. 16 is a flowchart showing a first processing procedure of the affine merge mode of affine motion compensation performed by the inter prediction unit of the encoding device according to the first embodiment. [Figure 17] FIG. 17 is a flowchart showing a second processing procedure in the affine merge mode of affine motion compensation performed by the inter prediction unit of the encoding device according to the first embodiment. [Figure 18] FIG. 18 is a block diagram showing an example of implementation of the encoding device according to the first embodiment. [Figure 19] FIG. 19 is a flowchart showing an example of the operation of the encoding device according to the first embodiment. [Figure 20] FIG. 20 is a block diagram showing an example of implementation of the decoding device according to the first embodiment. [Figure 21] FIG. 21 is a flowchart showing an example of operation of the decoding device according to the first embodiment. [Figure 22] FIG. 22 is a diagram showing the overall configuration of a content supply system that realizes a content distribution service. [Figure 23] FIG. 23 is a diagram showing an example of a coding structure for scalable coding. [Figure 24]FIG. 24 is a diagram showing an example of a coding structure for scalable coding. [Figure 25] FIG. 25 is a diagram showing an example of a display screen of a web page. [Figure 26] FIG. 26 is a diagram showing an example of a display screen of a web page. [Figure 27] FIG. 27 is a diagram illustrating an example of a smartphone. [Figure 28] FIG. 28 is a block diagram illustrating an example of the configuration of a smartphone. DETAILED DESCRIPTION OF THE INVENTION

[0010] For example, an encoding device according to one aspect of the present disclosure includes a circuit and a memory, and the circuit uses the memory to perform motion compensation for a target block by limiting the range of motion search or motion compensation in an affine motion compensation prediction process in an inter-prediction process for the target block.

[0011] This allows the encoding device to efficiently perform motion compensation using affine motion compensation. More specifically, by limiting the range in which motion search or motion compensation is performed in affine motion compensation prediction processing, it is possible to suppress variation in control point motion vectors in affine motion compensation prediction. This increases the likelihood that affine motion compensation prediction will be selected in inter prediction, allowing for efficient motion compensation using affine motion compensation. Furthermore, it is possible to limit the area of ​​reference images to be acquired, which may reduce the memory bandwidth required for external memory, which is a frame memory.

[0012] Here, for example, in the affine motion compensation prediction process, the range in which the motion search or motion compensation is performed is limited so that the variation between the control point motion vector of the upper left corner and the control point motion vector of the upper right corner of the target block in the affine motion compensation prediction process falls within a predetermined range.

[0013] This allows the encoding device to suppress variations in control point motion vectors in affine motion compensation prediction, increasing the likelihood that affine motion compensation prediction will be selected in inter prediction, thereby enabling efficient motion compensation using affine motion compensation.

[0014] Also, for example, in the affine motion compensation prediction process, the limits of the range in which the motion search or motion compensation is performed are determined anew for each picture to be processed, or a set of multiple motion search ranges or motion compensation ranges is determined in advance, and an appropriate set is selected for each picture to be processed.

[0015] This allows the range for motion search or motion compensation to be limited at a predetermined timing or using a predetermined set, thereby reducing the amount of processing, i.e., the memory band width required for external memory.

[0016] Furthermore, for example, in the affine motion compensation prediction process, the limitation of the range in which the motion search or motion compensation is performed is changed depending on the type of picture to be referenced.

[0017] This allows the range in which motion search or motion compensation is performed to be limited at a predetermined timing or using a predetermined set, thereby reducing the memory bandwidth required for external memory.

[0018] Furthermore, for example, in the affine motion compensation prediction process, the limitation of the range in which the motion search or the motion compensation is performed is determined for each predetermined profile and level.

[0019] This allows the limitation of the range in which motion search or motion compensation is performed to be determined for each predetermined profile and level, thereby reducing the memory bandwidth required for the external memory.

[0020] Also, for example, in the affine motion compensation prediction process, the range of motion search or motion compensation is limited depending on the motion search processing capability due to the computational processing capability or memory bandwidth on the encoding side.

[0021] This allows the limits on the range in which motion search or motion compensation is performed to be determined according to the search processing capacity, so not only can the amount of processing be reduced according to the search processing capacity, but motion compensation using affine motion compensation can also be performed efficiently.

[0022] Furthermore, for example, in the affine motion compensation prediction process, in order to restrict the range in which the motion search or motion compensation is performed, in addition to restricting the range of pixels that can be referenced, pictures that can be referenced are also restricted.

[0023] This not only reduces the memory bandwidth required for the external memory, but also makes it possible to efficiently perform motion compensation using affine motion compensation.

[0024] Also, for example, in the affine motion compensation prediction process, information regarding the limits on the range in which the motion search or motion compensation is performed is included in the header information of the VPS (Video Parameter Set), SPS (Sequence Parameter Set) or PPS (Picture Parameter Set) of the encoded bitstream.

[0025] This allows for efficient motion compensation using affine motion compensation.

[0026] Also, for example, in the affine motion compensation prediction process, information regarding limiting the range in which the motion search or motion compensation is performed includes information limiting the range of pixels that can be referenced, as well as information limiting the pictures to be referenced.

[0027] This not only reduces the memory bandwidth required for the external memory, but also makes it possible to efficiently perform motion compensation using affine motion compensation.

[0028] Also, for example, in the affine motion compensation prediction process, if the area referenced by the motion vector derived from the control point motion vector to be evaluated in the affine inter-mode motion search process is outside the range for motion search, the control point motion vector is excluded from the candidates for motion search.

[0029] This not only reduces the memory bandwidth required for the external memory, but also makes it possible to efficiently perform motion compensation using affine motion compensation.

[0030] Also, for example, in the affine motion compensation prediction process, in affine inter mode, if the area referenced by the motion vector derived from the control point predicted motion vector obtained from the processed block adjacent to the block to be processed is outside the range in which motion search is performed, encoding as affine inter mode is prohibited.

[0031] This not only reduces the memory bandwidth required for the external memory, but also makes it possible to efficiently perform motion compensation using affine motion compensation.

[0032] Also, for example, in the affine motion compensation prediction process, in affine merge mode, if the area referenced by the motion vector derived from the control point motion vector obtained from the processed block adjacent to the block to be processed is outside the range where motion compensation is performed, encoding in affine merge mode is prohibited.

[0033] This not only reduces the memory bandwidth required for the external memory, but also makes it possible to efficiently perform motion compensation using affine motion compensation.

[0034] Also, for example, a decoding device according to one aspect of the present disclosure includes a circuit and a memory, and the circuit decodes an encoded stream by using the memory to perform motion compensation for a target block in an affine motion compensation prediction process in an inter-prediction process of the target block by limiting the range in which motion search or motion compensation is performed.

[0035] This allows the decoding device to efficiently perform motion compensation using affine motion compensation. More specifically, by limiting the range in which motion search or motion compensation is performed in affine motion compensation prediction processing, it is possible to suppress variation in control point motion vectors in affine motion compensation prediction. This increases the likelihood that affine motion compensation prediction will be selected in inter prediction, allowing efficient motion compensation using affine motion compensation.

[0036] Here, for example, in the affine motion compensation prediction process, the range in which the motion search or motion compensation is performed is limited so that the variation between the control point motion vector of the upper left corner and the control point motion vector of the upper right corner of the target block in the affine motion compensation prediction process falls within a predetermined range.

[0037] This allows the decoding device to suppress variations in control point motion vectors in affine motion compensation prediction, increasing the likelihood that affine motion compensation prediction will be selected in inter prediction, thereby enabling efficient motion compensation using affine motion compensation.

[0038] Also, for example, in the affine motion compensation prediction process, the limits of the range in which the motion search or motion compensation is performed are determined anew for each picture to be processed, or a set of multiple motion search ranges or motion compensation ranges is determined in advance, and an appropriate set is selected for each picture to be processed.

[0039] This allows the range for motion search or motion compensation to be limited at a predetermined timing or using a predetermined set, thereby reducing the amount of processing, i.e., the memory band width required for external memory.

[0040] Furthermore, for example, in the affine motion compensation prediction process, the limitation of the range in which the motion search or motion compensation is performed is changed depending on the type of picture to be referenced.

[0041] This allows the range in which motion search or motion compensation is performed to be limited at a predetermined timing or using a predetermined set, thereby reducing the memory bandwidth required for external memory.

[0042] Furthermore, for example, in the affine motion compensation prediction process, the limitation of the range in which the motion search or the motion compensation is performed is determined for each predetermined profile and level.

[0043] This allows the limitation of the range in which motion search or motion compensation is performed to be determined for each predetermined profile and level, thereby reducing the memory bandwidth required for the external memory.

[0044] Also, for example, in the affine motion compensation prediction process, the range of motion search or motion compensation is limited depending on the motion search processing capability due to the computational processing capability or memory bandwidth on the encoding side.

[0045] This allows the limits on the range in which motion search or motion compensation is performed to be determined according to the search processing capacity, which not only reduces the memory band width required for external memory but also enables motion compensation using affine motion compensation to be performed efficiently.

[0046] Furthermore, for example, in the affine motion compensation prediction process, in order to restrict the range in which the motion search or motion compensation is performed, in addition to restricting the range of pixels that can be referenced, pictures that can be referenced are also restricted.

[0047] This not only reduces the memory bandwidth required for the external memory, but also makes it possible to efficiently perform motion compensation using affine motion compensation.

[0048] Also, for example, in the affine motion compensation prediction process, information regarding the limits on the range in which the motion search or motion compensation is performed is included in the header information of the VPS (Video Parameter Set), SPS (Sequence Parameter Set) or PPS (Picture Parameter Set) of the encoded bitstream.

[0049] This allows for efficient motion compensation using affine motion compensation.

[0050] Also, for example, in the affine motion compensation prediction process, information regarding limiting the range in which the motion search or motion compensation is performed includes information limiting the range of pixels that can be referenced, as well as information limiting the pictures to be referenced.

[0051] This not only reduces the memory bandwidth required for the external memory, but also makes it possible to efficiently perform motion compensation using affine motion compensation.

[0052] Also, for example, in the affine motion compensation prediction process, if the area referenced by the motion vector derived from the control point motion vector to be evaluated in the affine inter-mode motion search process is outside the range for motion search, the control point motion vector is excluded from the candidates for motion search.

[0053] This not only reduces the memory bandwidth required for the external memory, but also makes it possible to efficiently perform motion compensation using affine motion compensation.

[0054] Also, for example, the affine motion compensation prediction process prohibits encoding in affine inter mode if, in affine inter mode, the area referenced by the motion vector derived from the control point predicted motion vector obtained from the processed block adjacent to the block to be processed is outside the range in which motion search is performed.

[0055] This not only reduces the memory bandwidth required for the external memory, but also makes it possible to efficiently perform motion compensation using affine motion compensation.

[0056] Also, for example, in the affine motion compensation prediction process, in affine merge mode, if the area referenced by the motion vector derived from the control point motion vector obtained from the processed block adjacent to the block to be processed is outside the range where motion compensation is performed, encoding in affine merge mode is prohibited.

[0057] This not only reduces the memory bandwidth required for the external memory, but also makes it possible to efficiently perform motion compensation using affine motion compensation.

[0058] Furthermore, for example, in an encoding method according to an aspect of the present disclosure, in an affine motion compensation prediction process in inter prediction processing of a current block, a range in which motion search or motion compensation is performed is limited and motion compensation is performed on the current block.

[0059] This allows devices using this encoding method to efficiently perform motion compensation using affine motion compensation. More specifically, by limiting the range in which motion search or motion compensation is performed in affine motion compensation prediction processing, it is possible to suppress variation in control point motion vectors in affine motion compensation prediction. This increases the likelihood that affine motion compensation prediction will be selected in inter prediction, allowing for efficient motion compensation using affine motion compensation. Furthermore, it becomes possible to limit the area of ​​reference images to be acquired, potentially reducing the memory bandwidth required for external memory, which is a frame memory.

[0060] Also, for example, a decoding method according to one aspect of the present disclosure decodes an encoded stream by performing motion compensation on a target block by limiting the range of motion search or motion compensation in an affine motion compensation prediction process in an inter-prediction process of the target block.

[0061] As a result, devices using this decoding method can efficiently perform motion compensation using affine motion compensation. More specifically, by limiting the range in which motion search or motion compensation is performed in affine motion compensation prediction processing, it is possible to suppress variation in control point motion vectors in affine motion compensation prediction. This increases the likelihood that affine motion compensation prediction will be selected in inter prediction, allowing for efficient motion compensation using affine motion compensation. Furthermore, it becomes possible to limit the area of ​​reference images to be acquired, which may reduce the memory bandwidth required for external memory, which is a frame memory.

[0062] Furthermore, these comprehensive or specific aspects may be realized as a system, an apparatus, a method, an integrated circuit, a computer program, or a non-transitory recording medium such as a computer-readable CD-ROM, or may be realized as any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium.

[0063] Hereinafter, the embodiments will be specifically described with reference to the drawings.

[0064] The embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, component placement and connection configurations, steps, and step order shown in the following embodiments are merely examples and are not intended to limit the scope of the claims. Furthermore, among the components in the following embodiments, components that are not described in the independent claims that represent the highest concepts are described as optional components.

[0065] (Embodiment 1) First, an overview of the first embodiment will be described as an example of an encoding device and a decoding device to which the processes and / or configurations described in each aspect of the present disclosure can be applied. However, the first embodiment is merely an example of an encoding device and a decoding device to which the processes and / or configurations described in each aspect of the present disclosure can be applied, and the processes and / or configurations described in each aspect of the present disclosure can also be implemented in encoding devices and decoding devices different from the first embodiment.

[0066] When applying the processing and / or configurations described in each aspect of the present disclosure to the first embodiment, for example, any of the following may be performed.

[0067] (1) For the encoding device or decoding device of the first embodiment, among the multiple components constituting the encoding device or decoding device, components corresponding to the components described in each aspect of the present disclosure are replaced with the components described in each aspect of the present disclosure. (2) Any modification, such as addition, replacement, or deletion, of the functions or processes performed by some of the components constituting the encoding device or decoding device of the first embodiment may be made to the encoding device or decoding device, and then components corresponding to the components described in each aspect of the present disclosure may be replaced with the components described in each aspect of the present disclosure. (3) The method implemented by the encoding device or decoding device of the first embodiment may be modified by adding a process and / or replacing or deleting some of the processes included in the method, and then replacing the process described in each aspect of the present disclosure with the process described in each aspect of the present disclosure. (4) Some of the components constituting the encoding device or decoding device of the first embodiment may be implemented in combination with components described in each aspect of the present disclosure, components having some of the functions of the components described in each aspect of the present disclosure, or components performing some of the processing performed by the components described in each aspect of the present disclosure. (5) A component having some of the functions of some of the components constituting the encoding device or decoding device of the first embodiment, or a component that performs some of the processing performed by some of the components constituting the encoding device or decoding device of the first embodiment, is implemented in combination with a component described in each aspect of the present disclosure, a component having some of the functions of the components described in each aspect of the present disclosure, or a component that performs some of the processing performed by the components described in each aspect of the present disclosure. (6) In the method implemented by the encoding device or decoding device of the first embodiment, among the multiple processes included in the method, processes corresponding to the processes described in each aspect of the present disclosure are replaced with the processes described in each aspect of the present disclosure. (7) Some of the processes included in the method implemented by the encoding device or decoding device of the first embodiment may be implemented in combination with the processes described in each aspect of the present disclosure.

[0068] It should be noted that the manner of implementing the processes and / or configurations described in each aspect of the present disclosure is not limited to the above examples. For example, they may be implemented in a device used for a purpose different from the video / image encoding device or video / image decoding device disclosed in Embodiment 1, or the processes and / or configurations described in each aspect may be implemented independently. Furthermore, the processes and / or configurations described in different aspects may be implemented in combination.

[0069] [Outline of the encoding device] First, an overview of a coding device according to Embodiment 1 will be described. Fig. 1 is a block diagram showing a functional configuration of a coding device 100 according to Embodiment 1. The coding device 100 is a video / image coding device that codes a video / image on a block-by-block basis.

[0070] As shown in FIG. 1, the encoding device 100 is a device that encodes an image on a block-by-block basis, and includes a division unit 102, a subtraction unit 104, a transformation unit 106, a quantization unit 108, an entropy encoding unit 110, an inverse quantization unit 112, an inverse transformation unit 114, an addition unit 116, a block memory 118, a loop filter unit 120, a frame memory 122, an intra prediction unit 124, an inter prediction unit 126, and a prediction control unit 128.

[0071] The encoding device 100 is realized by, for example, a general-purpose processor and memory. In this case, when a software program stored in the memory is executed by the processor, the processor functions as the division unit 102, the subtraction unit 104, the transformation unit 106, the quantization unit 108, the entropy coding unit 110, the inverse quantization unit 112, the inverse transformation unit 114, the addition unit 116, the loop filter unit 120, the intra prediction unit 124, the inter prediction unit 126, and the prediction control unit 128. Alternatively, the encoding device 100 may be realized as one or more dedicated electronic circuits corresponding to the division unit 102, the subtraction unit 104, the transformation unit 106, the quantization unit 108, the entropy coding unit 110, the inverse quantization unit 112, the inverse transformation unit 114, the addition unit 116, the loop filter unit 120, the intra prediction unit 124, the inter prediction unit 126, and the prediction control unit 128.

[0072] Each component included in the encoding device 100 will be described below.

[0073] [Divided part] The division unit 102 divides each picture included in the input video into a plurality of blocks and outputs each block to the subtraction unit 104. For example, the division unit 102 first divides a picture into blocks of a fixed size (e.g., 128x128). These fixed-size blocks are sometimes called coding tree units (CTUs). The division unit 102 then divides each of the fixed-size blocks into blocks of a variable size (e.g., 64x64 or less) based on recursive quadtree and / or binary tree block division. These variable-size blocks are sometimes called coding units (CUs), prediction units (PUs), or transform units (TUs). Note that in this embodiment, there is no need to distinguish between CUs, PUs, and TUs, and some or all of the blocks in a picture may serve as the processing units of CUs, PUs, and TUs.

[0074] Fig. 2 is a diagram showing an example of block division according to embodiment 1. In Fig. 2, solid lines represent block boundaries based on quadtree block division, and dashed lines represent block boundaries based on binary tree block division.

[0075] Here, the block 10 is a square block of 128x128 pixels (128x128 block). This 128x128 block 10 is first divided into four square 64x64 blocks (quadtree block division).

[0076] The top-left 64x64 block is further divided vertically into two rectangular 32x64 blocks, and the left 32x64 block is further divided vertically into two rectangular 16x64 blocks (binary tree block division). As a result, the top-left 64x64 block is divided into two 16x64 blocks 11 and 12 and a 32x64 block 13.

[0077] The top right 64x64 block is divided horizontally into two rectangular 64x32 blocks 14 and 15 (binary tree block division).

[0078] The lower-left 64x64 block is divided into four square 32x32 blocks (quadtree block decomposition). Of the four 32x32 blocks, the upper-left and lower-right blocks are further divided. The upper-left 32x32 block is divided vertically into two rectangular 16x32 blocks, and the right 16x32 block is further divided horizontally into two 16x16 blocks (binary tree block decomposition). The lower-right 32x32 block is divided horizontally into two 32x16 blocks (binary tree block decomposition). As a result, the lower-left 64x64 block is divided into 16x32 block 16, two 16x16 blocks 17 and 18, two 32x32 blocks 19 and 20, and two 32x16 blocks 21 and 22.

[0079] The bottom right 64x64 block 23 is not split.

[0080] 2, block 10 is divided into 13 variable-sized blocks 11 to 23 based on recursive quad-tree and binary tree block division. This type of division is sometimes called QTBT (quad-tree plus binary tree) division.

[0081] In Fig. 2, one block is divided into four or two blocks (quadtree or binary tree block division), but the division is not limited to this. For example, one block may be divided into three blocks (ternary tree block division). Division including such ternary tree block division is sometimes called MBT (multi type tree) division.

[0082] [Subtraction section] The subtraction unit 104 subtracts a prediction signal (prediction sample) from an original signal (original sample) for each block divided by the division unit 102. That is, the subtraction unit 104 calculates a prediction error (also referred to as a residual) of a block to be coded (hereinafter referred to as a current block). Then, the subtraction unit 104 outputs the calculated prediction error to the conversion unit 106.

[0083] The original signal is an input signal to the encoding device 100, and is a signal representing an image of each picture constituting a moving image (for example, a luminance (luma) signal and two color difference (chroma) signals). Hereinafter, the signal representing an image may also be referred to as a sample.

[0084] [Conversion section] The transform unit 106 transforms the spatial domain prediction errors into frequency domain transform coefficients and outputs the transform coefficients to the quantization unit 108. Specifically, the transform unit 106 performs, for example, a predetermined discrete cosine transform (DCT) or discrete sine transform (DST) on the spatial domain prediction errors.

[0085] The transform unit 106 may adaptively select a transform type from among a plurality of transform types and transform the prediction errors into transform coefficients using a transform basis function corresponding to the selected transform type. Such a transform is sometimes called an explicit multiple core transform (EMT) or an adaptive multiple transform (AMT).

[0086] The multiple transform types include, for example, DCT-II, DCT-V, DCT-VIII, DST-I, and DST-VII. Fig. 3 is a table showing transform basis functions corresponding to each transform type. In Fig. 3, N represents the number of input pixels. Selection of a transform type from among these multiple transform types may depend, for example, on the type of prediction (intra prediction or inter prediction) or the intra prediction mode.

[0087] Information indicating whether EMT or AMT is applied (e.g., referred to as an AMT flag) and information indicating the selected transformation type are signaled at the CU level. Note that signaling of this information does not need to be limited to the CU level, and may be at other levels (e.g., sequence level, picture level, slice level, tile level, or CTU level).

[0088] Furthermore, the transform unit 106 may retransform the transform coefficients (transform results). Such retransformation may be referred to as an adaptive secondary transform (AST) or a non-separable secondary transform (NSST). For example, the transform unit 106 performs retransformation for each sub-block (e.g., 4x4 sub-block) included in a block of transform coefficients corresponding to intra-prediction errors. Information indicating whether or not to apply NSST and information regarding the transform matrix used for NSST are signaled at the CU level. Note that signaling of this information does not need to be limited to the CU level, and may be at other levels (e.g., the sequence level, picture level, slice level, tile level, or CTU level).

[0089] Here, a separable transformation is a method in which the transformation is performed multiple times by separating the input into directions equal to the number of dimensions, and a non-separable transformation is a method in which, when the input is multidimensional, two or more dimensions are treated as one dimension and the transformation is performed all at once.

[0090] For example, one example of a non-separable transformation is when the input is a 4x4 block, it is treated as a single array with 16 elements, and the transformation process is performed on that array using a 16x16 transformation matrix.

[0091] Similarly, a non-separable transformation is one that treats a 4x4 input block as a single array with 16 elements and then performs multiple Givens rotations on that array (Hypercube Givens Transform).

[0092] [Quantization section] The quantization unit 108 quantizes the transform coefficients output from the transform unit 106. Specifically, the quantization unit 108 scans the transform coefficients of the current block in a predetermined scanning order and quantizes the transform coefficients based on quantization parameters (QP) corresponding to the scanned transform coefficients. The quantization unit 108 then outputs the quantized transform coefficients of the current block (hereinafter referred to as quantized coefficients) to the entropy coding unit 110 and the inverse quantization unit 112.

[0093] The predetermined order is an order for quantizing / dequantizing the transform coefficients. For example, the predetermined scanning order is defined as an ascending order (low frequency to high frequency) or a descending order (high frequency to low frequency).

[0094] The quantization parameter is a parameter that defines the quantization step (quantization width). For example, as the value of the quantization parameter increases, the quantization step also increases. In other words, as the value of the quantization parameter increases, the quantization error also increases.

[0095] [Entropy coding section] The entropy coding unit 110 generates a coded signal (coded bit stream) by variable-length coding the quantized coefficients input from the quantization unit 108. Specifically, the entropy coding unit 110, for example, binarizes the quantized coefficients and arithmetically codes the binary signal.

[0096] [Dequantization section] The inverse quantization unit 112 inverse quantizes the quantized coefficients input from the quantization unit 108. Specifically, the inverse quantization unit 112 inverse quantizes the quantized coefficients of the current block in a predetermined scanning order. The inverse quantization unit 112 then outputs the inverse quantized transform coefficients of the current block to the inverse transform unit 114.

[0097] [Inverse conversion section] The inverse transform unit 114 restores the prediction error by inverse transforming the transform coefficients that are input from the inverse quantization unit 112. Specifically, the inverse transform unit 114 restores the prediction error of the current block by performing an inverse transform on the transform coefficients that corresponds to the transform performed by the transform unit 106. Then, the inverse transform unit 114 outputs the restored prediction error to the adder unit 116.

[0098] Note that the restored prediction error does not match the prediction error calculated by the subtraction unit 104 because information has been lost due to quantization. In other words, the restored prediction error includes a quantization error.

[0099] [Adder] The adder 116 reconstructs the current block by adding the prediction error input from the inverse transformer 114 and the prediction sample input from the prediction control unit 128. The adder 116 then outputs the reconstructed block to the block memory 118 and the loop filter unit 120. The reconstructed block is sometimes called a local decoded block.

[0100] [Block Memory] The block memory 118 is a storage unit for storing blocks that are referenced in intra prediction and are in a picture to be coded (hereinafter referred to as a current picture). Specifically, the block memory 118 stores the reconstructed blocks output from the adder 116.

[0101] [Loop filter section] The loop filter unit 120 applies a loop filter to the block reconstructed by the adder 116 and outputs the filtered reconstructed block to the frame memory 122. The loop filter is a filter (in-loop filter) used in the encoding loop, and includes, for example, a deblocking filter (DF), a sample adaptive offset (SAO), and an adaptive loop filter (ALF).

[0102] ALF applies a least squares error filter to remove coding artifacts, for example, for each 2x2 sub-block in the current block, one filter selected from multiple filters based on local gradient direction and activity.

[0103] Specifically, first, sub-blocks (e.g., 2x2 sub-blocks) are classified into a plurality of classes (e.g., 15 or 25 classes). The sub-blocks are classified based on the gradient direction and activity. For example, a classification value C (e.g., C=5D+A) is calculated using a gradient direction value D (e.g., 0 to 2 or 0 to 4) and a gradient activity value A (e.g., 0 to 4). Then, based on the classification value C, the sub-blocks are classified into a plurality of classes (e.g., 15 or 25 classes).

[0104] The gradient direction value D is derived by, for example, comparing gradients in multiple directions (e.g., horizontal, vertical, and two diagonal directions), and the gradient activity value A is derived by, for example, adding gradients in multiple directions and quantizing the sum.

[0105] Based on the result of such classification, a filter for the sub-block is determined from among a plurality of filters.

[0106] The filter shape used in ALF is, for example, a circularly symmetric shape. FIGS. 4A to 4C are diagrams showing several examples of filter shapes used in ALF. FIG. 4A shows a 5x5 diamond-shaped filter, FIG. 4B shows a 7x7 diamond-shaped filter, and FIG. 4C shows a 9x9 diamond-shaped filter. Information indicating the filter shape is signaled at the picture level. Note that signaling of the information indicating the filter shape does not need to be limited to the picture level, and may be at other levels (e.g., sequence level, slice level, tile level, CTU level, or CU level).

[0107] Whether ALF is turned on or off is determined, for example, at the picture level or the CU level. For example, whether ALF is applied to luminance is determined at the CU level, and whether ALF is applied to chrominance is determined at the picture level. Information indicating whether ALF is turned on or off is signaled at the picture level or the CU level. Note that signaling of information indicating whether ALF is turned on or off does not need to be limited to the picture level or the CU level, and may be at another level (for example, the sequence level, the slice level, the tile level, or the CTU level).

[0108] The coefficient sets of multiple selectable filters (e.g., up to 15 or 25 filters) are signaled at the picture level. Note that the signaling of the coefficient sets does not need to be limited to the picture level, but may also be at other levels (e.g., sequence level, slice level, tile level, CTU level, CU level, or sub-block level).

[0109] [Frame memory] The frame memory 122 is a storage unit for storing reference pictures used in inter prediction, and is sometimes called a frame buffer. Specifically, the frame memory 122 stores the reconstructed blocks filtered by the loop filter unit 120.

[0110] [Intra prediction section] The intra prediction unit 124 generates a prediction signal (intra prediction signal) by performing intra prediction (also referred to as intra-picture prediction) of the current block with reference to blocks in the current picture stored in the block memory 118. Specifically, the intra prediction unit 124 generates the intra prediction signal by performing intra prediction with reference to samples (e.g., luminance values, chrominance values) of blocks adjacent to the current block, and outputs the intra prediction signal to the prediction control unit 128.

[0111] For example, the intra prediction unit 124 performs intra prediction using one of a plurality of predefined intra prediction modes. The plurality of intra prediction modes includes one or more non-directional prediction modes and a plurality of directional prediction modes.

[0112] The one or more non-directional prediction modes include, for example, a planar prediction mode and a DC prediction mode defined in the H.265 / High-Efficiency Video Coding (HEVC) standard (Non-Patent Document 1).

[0113] The multiple directional prediction modes include, for example, the 33 prediction modes defined in the H.265 / HEVC standard. Note that the multiple directional prediction modes may also include 32 prediction modes in addition to the 33 directions (65 directional prediction modes in total). Fig. 5A is a diagram showing 67 intra prediction modes (2 non-directional prediction modes and 65 directional prediction modes) in intra prediction. Solid arrows represent the 33 directions defined in the H.265 / HEVC standard, and dashed arrows represent the additional 32 directions.

[0114] Note that a luminance block may be referenced in intra prediction of a chrominance block. That is, the chrominance component of the current block may be predicted based on the luminance component of the current block. This type of intra prediction is sometimes called CCLM (cross-component linear model) prediction. An intra prediction mode of a chrominance block that references such a luminance block (e.g., called a CCLM mode) may be added as one of the intra prediction modes for the chrominance block.

[0115] The intra prediction unit 124 may correct pixel values ​​after intra prediction based on gradients of reference pixels in the horizontal / vertical directions. Intra prediction involving such correction is sometimes called PDPC (position dependent intra prediction combination). Information indicating whether PDPC is applied (e.g., called a PDPC flag) is signaled, for example, at the CU level. Note that signaling of this information does not need to be limited to the CU level, and may be at other levels (e.g., sequence level, picture level, slice level, tile level, or CTU level).

[0116] [Inter prediction section] The inter prediction unit 126 generates a prediction signal (inter prediction signal) by performing inter prediction (also referred to as inter prediction) on the current block with reference to a reference picture stored in the frame memory 122 that is different from the current picture. The inter prediction is performed in units of the current block or sub-blocks (e.g., 4x4 blocks) within the current block. For example, the inter prediction unit 126 performs motion estimation on the current block or sub-block within the reference picture. The inter prediction unit 126 then generates an inter prediction signal for the current block or sub-block by performing motion compensation using motion information (e.g., a motion vector) obtained by the motion estimation. The inter prediction unit 126 then outputs the generated inter prediction signal to the prediction control unit 128.

[0117] The motion information used for motion compensation is signaled. For the signaling of the motion vector, a motion vector predictor may be used, i.e., the difference between the motion vector and the motion vector predictor may be signaled.

[0118] Note that an inter-prediction signal may be generated using not only the motion information of the current block obtained by motion estimation, but also the motion information of adjacent blocks. Specifically, an inter-prediction signal may be generated for each sub-block in the current block by weighting and adding a prediction signal based on the motion information obtained by motion estimation and a prediction signal based on the motion information of adjacent blocks. Such inter-prediction (motion compensation) may be called OBMC (overlapped block motion compensation).

[0119] In such an OBMC mode, information indicating the size of a sub-block for OBMC (e.g., called an OBMC block size) is signaled at the sequence level. Also, information indicating whether the OBMC mode is applied (e.g., called an OBMC flag) is signaled at the CU level. Note that the signaling level of this information is not limited to the sequence level and the CU level, and may be other levels (e.g., the picture level, slice level, tile level, CTU level, or sub-block level).

[0120] The OBMC mode will now be described in more detail. Figures 5B and 5C are a flowchart and a conceptual diagram for explaining an outline of the predictive image correction process using the OBMC process.

[0121] First, a predicted image (Pred) is obtained by normal motion compensation using a motion vector (MV) assigned to the block to be coded.

[0122] Next, the motion vector (MV_L) of the coded left adjacent block is applied to the block to be coded to obtain a predicted image (Pred_L), and the predicted image is weighted and superimposed with Pred_L to perform the first correction of the predicted image.

[0123] Similarly, the motion vector (MV_U) of the already coded upper adjacent block is applied to the block to be coded to obtain a predicted image (Pred_U), and the predicted image that has been corrected the first time is weighted and overlaid with Pred_U to perform a second correction of the predicted image, which is then used as the final predicted image.

[0124] Although a two-stage correction method using the left adjacent block and the upper adjacent block has been described here, it is also possible to configure a method in which correction is performed more than two times using the right adjacent block or the lower adjacent block.

[0125] The area to be superimposed does not have to be the pixel area of ​​the entire block, but may be only a part of the area near the block boundary.

[0126] Although the process of correcting a predicted image from one reference picture has been described here, the process is similar when correcting a predicted image from multiple reference pictures. After obtaining corrected predicted images from each reference picture, the obtained predicted images are further superimposed to form the final predicted image.

[0127] The target block to be processed may be a prediction block unit or a sub-block unit obtained by further dividing the prediction block.

[0128] As a method for determining whether to apply OBMC processing, for example, there is a method using obmc_flag, which is a signal indicating whether to apply OBMC processing. As a specific example, an encoding device determines whether a block to be encoded belongs to an area with complex motion, and if it belongs to an area with complex motion, sets the value of obmc_flag to 1 and performs encoding by applying OBMC processing, and if it does not belong to an area with complex motion, sets the value of obmc_flag to 0 and performs encoding without applying OBMC processing. On the other hand, a decoding device decodes obmc_flag described in a stream, and switches whether to apply OBMC processing depending on the value, and performs decoding.

[0129] Alternatively, the motion information may be derived on the decoding device side without being signaled. For example, a merge mode defined in the H.265 / HEVC standard may be used. Alternatively, the motion information may be derived by performing motion estimation on the decoding device side. In this case, the motion estimation is performed without using pixel values ​​of the current block.

[0130] Here, a mode in which motion estimation is performed on the decoding device side will be described. This mode in which motion estimation is performed on the decoding device side is sometimes called a pattern matched motion vector derivation (PMMVD) mode or a frame rate up-conversion (FRUC) mode.

[0131] An example of the FRUC process is shown in Figure 5D. First, a list of multiple candidates (which may be the same as the merge list) each having a predicted motion vector is generated by referring to the motion vectors of coded blocks spatially or temporally adjacent to the current block. Next, a best candidate MV is selected from the multiple candidate MVs registered in the candidate list. For example, an evaluation value of each candidate included in the candidate list is calculated, and one candidate is selected based on the evaluation value.

[0132] Then, a motion vector for the current block is derived based on the motion vector of the selected candidate. Specifically, for example, the motion vector of the selected candidate (best candidate MV) is derived as the motion vector for the current block as is. Also, for example, the motion vector for the current block may be derived by performing pattern matching in a peripheral area of ​​a position in a reference picture corresponding to the motion vector of the selected candidate. That is, a search is performed in a similar manner in a peripheral area of ​​the best candidate MV, and if an MV with a better evaluation value is found, the best candidate MV may be updated to the MV and used as the final MV for the current block. Note that a configuration may be adopted in which this process is not performed.

[0133] The same processing may be performed when processing is performed in sub-block units.

[0134] The evaluation value is calculated by finding the difference between the reconstructed image and a predetermined area by pattern matching between the area in the reference picture corresponding to the motion vector. The evaluation value may be calculated using other information in addition to the difference.

[0135] As the pattern matching, first pattern matching or second pattern matching is used. The first pattern matching and second pattern matching are sometimes called bilateral matching and template matching, respectively.

[0136] In the first pattern matching, pattern matching is performed between two blocks in two different reference pictures that are along the motion trajectory of the current block. Therefore, in the first pattern matching, an area in another reference picture that is along the motion trajectory of the current block is used as a predetermined area for calculating the evaluation value of the candidate.

[0137] FIG. 6 is a diagram illustrating an example of pattern matching (bilateral matching) between two blocks along a motion trajectory. As shown in FIG. 6, in the first pattern matching, two motion vectors (MV0, MV1) are derived by searching for the most closely matched pair of two blocks along the motion trajectory of a current block (Cur block) in two different reference pictures (Ref0, Ref1). Specifically, for the current block, a difference is derived between a reconstructed image at a specified position in a first coded reference picture (Ref0) specified by a candidate MV and a reconstructed image at a specified position in a second coded reference picture (Ref1) specified by a symmetric MV obtained by scaling the candidate MV by the display time interval, and an evaluation value is calculated using the obtained difference value. The candidate MV with the best evaluation value among multiple candidate MVs may be selected as the final MV.

[0138] Under the assumption of continuous motion trajectories, motion vectors (MV0, MV1) pointing to two reference blocks are proportional to the temporal distances (TD0, TD1) between a current picture (CurPic) and two reference pictures (Ref0, Ref1). For example, if the current picture is located between two reference pictures temporally and the temporal distances from the current picture to the two reference pictures are equal, the first pattern matching derives bidirectional motion vectors that are mirror-symmetric.

[0139] In the second pattern matching, pattern matching is performed between a template in the current picture (a block adjacent to the current block in the current picture (e.g., an upper and / or left adjacent block)) and a block in the reference picture. Therefore, in the second pattern matching, the block adjacent to the current block in the current picture is used as a predetermined area for calculating the evaluation value of the candidate.

[0140] 7 is a diagram illustrating an example of pattern matching (template matching) between a template in a current picture and a block in a reference picture. As shown in FIG. 7, in the second pattern matching, a motion vector of a current block is derived by searching a reference picture (Ref0) for a block that best matches a block adjacent to a current block (Cur block) in the current picture (Cur Pic). Specifically, a difference is derived between a reconstructed image of both or either of the coded areas adjacent to the left and / or above the current block and a reconstructed image at the same position in the coded reference picture (Ref0) specified by a candidate MV, an evaluation value is calculated using the obtained difference value, and the candidate MV with the best evaluation value among the multiple candidate MVs is selected as the best candidate MV.

[0141] Information indicating whether such a FRUC mode is applied (e.g., called an FRUC flag) is signaled at the CU level. Furthermore, when the FRUC mode is applied (e.g., when the FRUC flag is true), information indicating a pattern matching method (first pattern matching or second pattern matching) (e.g., called an FRUC mode flag) is signaled at the CU level. Note that signaling of this information does not need to be limited to the CU level, and may be at other levels (e.g., the sequence level, the picture level, the slice level, the tile level, the CTU level, or the sub-block level).

[0142] Here, we will explain a mode that derives a motion vector based on a model that assumes uniform linear motion. This mode is based on BIO (bi-directional optical This is sometimes called flow mode.

[0143] FIG. 8 is a diagram for explaining a model assuming uniform linear motion. In FIG. 8, (v x ,v y) denotes a velocity vector, and τ0 and τ1 denote the temporal distance between the current picture (Cur Pic) and two reference pictures (Ref0 and Ref1), respectively. (MVx0,MVy0) denotes a motion vector corresponding to reference picture Ref0, and (MVx1,MVy1) denotes a motion vector corresponding to reference picture Ref1.

[0144] At this time, the velocity vector (v x ,v y ), (MVx0,MVy0) and (MVx1,MVy1) are respectively (v x τ0,v y τ0) and (-v x τ1,-v y τ1), and the following optical flow equation (1) holds:

[0145]

number

[0146] Here, I (k) denotes the luminance value of reference image k (k=0,1) after motion compensation. This optical flow equation indicates that the sum of (i) the time derivative of the luminance value, (ii) the product of the horizontal velocity and the horizontal component of the spatial gradient of the reference image, and (iii) the product of the vertical velocity and the vertical component of the spatial gradient of the reference image is equal to zero. Based on a combination of this optical flow equation and Hermite interpolation, block-wise motion vectors obtained from a merge list or the like are corrected pixel by pixel.

[0147] Note that the decoding device may derive motion vectors using a method other than that based on a model assuming constant-velocity linear motion. For example, a motion vector may be derived for each sub-block based on the motion vectors of multiple adjacent blocks.

[0148] Here, a mode in which a motion vector is derived for each sub-block based on the motion vectors of multiple neighboring blocks will be described. This mode is sometimes called an affine motion compensation prediction mode.

[0149] FIG. 9A is a diagram for explaining the derivation of motion vectors for each sub-block based on the motion vectors of multiple adjacent blocks. In FIG. 9A, the current block includes 16 4x4 sub-blocks. Here, the motion vector v0 of the upper left corner control point of the current block is derived based on the motion vectors of the adjacent blocks, and the motion vector v1 of the upper right corner control point of the current block is derived based on the motion vectors of the adjacent sub-blocks. Then, using the two motion vectors v0 and v1, the motion vector (v x ,v y ) is derived.

[0150]

number

[0151] Here, x and y respectively indicate the horizontal and vertical positions of the sub-block, and w indicates a predetermined weighting coefficient.

[0152] Such an affine motion compensation prediction mode may include several modes in which the methods of deriving the motion vectors of the upper-left and upper-right corner control points are different. Information indicating such an affine motion compensation prediction mode (e.g., called an affine flag) is signaled at the CU level. Note that the signaling of the information indicating this affine motion compensation prediction mode does not need to be limited to the CU level, and may be at other levels (e.g., the sequence level, the picture level, the slice level, the tile level, the CTU level, or the sub-block level).

[0153] [Predictive control unit] The prediction control unit 128 selects either the intra-prediction signal or the inter-prediction signal, and outputs the selected signal to the subtraction unit 104 and the addition unit 116 as a prediction signal.

[0154] Here, an example of deriving a motion vector for a picture to be coded in merge mode will be described. Fig. 9B is a diagram for explaining an overview of the motion vector derivation process in merge mode.

[0155] First, a prediction MV list is generated in which prediction MV candidates are registered. The prediction MV candidates include spatially adjacent prediction MVs, which are MVs held by multiple coded blocks spatially located around the block to be coded, temporally adjacent prediction MVs, which are MVs held by blocks in the vicinity of the block to be coded projected onto the coded reference picture, joint prediction MVs, which are MVs generated by combining the MV values ​​of the spatially adjacent prediction MVs and the temporally adjacent prediction MVs, and zero prediction MVs, which are MVs with a value of zero.

[0156] Next, one prediction MV is selected from the plurality of prediction MVs registered in the prediction MV list, and is determined as the MV for the block to be coded.

[0157] Furthermore, the variable length coding unit encodes the stream by describing merge_idx, which is a signal indicating which predicted MV has been selected.

[0158] Note that the predicted MVs registered in the predicted MV list described in Figure 9B are just an example, and the number may be different from the number shown in the figure, the configuration may not include some of the types of predicted MVs shown in the figure, or the configuration may include predicted MVs other than the types of predicted MVs shown in the figure.

[0159] The final MV may be determined by performing the DMVR process, which will be described later, using the MV of the block to be coded derived in the merge mode.

[0160] Here, an example of determining the MV using the DMVR process will be described.

[0161] FIG. 9C is a conceptual diagram for explaining an outline of the DMVR process.

[0162] First, the optimal MVP set for the block to be processed is set as a candidate MV, and reference pixels are obtained from the first reference picture, which is a processed picture in the L0 direction, and the second reference picture, which is a processed picture in the L1 direction, according to the candidate MV, and a template is generated by averaging each reference pixel.

[0163] Next, the template is used to search the surrounding areas of the candidate MVs in the first and second reference pictures, and the MV with the smallest cost is determined as the final MV. The cost value is calculated using the difference between each pixel value of the template and each pixel value of the search area, the MV value, etc.

[0164] The outline of the processing described here is basically the same for the encoding device and the decoding device.

[0165] Note that other processing may be used instead of the processing described here, as long as it is processing that can search the vicinity of the candidate MV and derive the final MV.

[0166] Here, a mode for generating a predicted image using LIC processing will be described.

[0167] FIG. 9D is a diagram for explaining an outline of a predicted image generation method using luminance correction processing by LIC processing.

[0168] First, an MV for obtaining a reference image corresponding to a block to be coded is derived from a reference picture that is a coded picture.

[0169] Next, for the block to be coded, the luminance pixel values ​​of the coded surrounding reference areas adjacent to the left and above and the luminance pixel values ​​at the equivalent positions in the reference picture specified by the MV are used to extract information indicating how the luminance values ​​have changed between the reference picture and the picture to be coded, and a luminance correction parameter is calculated.

[0170] A predicted image for the block to be coded is generated by performing luminance correction processing on a reference image in a reference picture specified by the MV using the luminance correction parameters.

[0171] The shape of the peripheral reference region in FIG. 9D is an example, and other shapes may be used.

[0172] Although the process of generating a predicted image from one reference picture has been described here, the process is similar when generating a predicted image from multiple reference pictures, and a luminance correction process is performed in a similar manner on the reference images obtained from each reference picture before generating a predicted image.

[0173] As a method for determining whether to apply LIC processing, for example, there is a method using lic_flag, which is a signal indicating whether to apply LIC processing. As a specific example, an encoding device determines whether the encoding target block belongs to an area where a luminance change occurs, and if it belongs to an area where a luminance change occurs, sets the value of lic_flag to 1 and performs encoding by applying LIC processing, and if it does not belong to an area where a luminance change occurs, sets the value of lic_flag to 0 and performs encoding without applying LIC processing. On the other hand, a decoding device decodes lic_flag described in the stream, and switches whether to apply LIC processing depending on the value, and performs decoding.

[0174] As another method for determining whether to apply LIC processing, for example, there is also a method for determining whether LIC processing has been applied to surrounding blocks.As a specific example, when the block to be coded is in merge mode, it is determined whether the surrounding coded blocks selected when deriving MV in merge mode processing have been coded using LIC processing, and depending on the result, whether to apply LIC processing is switched and coded.In addition, in this example, the process in decoding is exactly the same.

[0175] [Overview of the decoding device] Next, an overview will be given of a decoding device capable of decoding the coded signal (coded bitstream) output from the above coding device 100. Fig. 10 is a block diagram showing the functional configuration of a decoding device 200 according to Embodiment 1. The decoding device 200 is a video / image decoding device that decodes video / images on a block-by-block basis.

[0176] As shown in FIG. 10, the decoding device 200 includes an entropy decoding unit 202, an inverse quantization unit 204, an inverse transform unit 206, an addition unit 208, a block memory 210, a loop filter unit 212, a frame memory 214, an intra prediction unit 216, an inter prediction unit 218, and a prediction control unit 220.

[0177] The decoding device 200 is realized by, for example, a general-purpose processor and memory. In this case, when a software program stored in the memory is executed by the processor, the processor functions as the entropy decoding unit 202, the inverse quantization unit 204, the inverse transform unit 206, the addition unit 208, the loop filter unit 212, the intra prediction unit 216, the inter prediction unit 218, and the prediction control unit 220. Alternatively, the decoding device 200 may be realized as one or more dedicated electronic circuits corresponding to the entropy decoding unit 202, the inverse quantization unit 204, the inverse transform unit 206, the addition unit 208, the loop filter unit 212, the intra prediction unit 216, the inter prediction unit 218, and the prediction control unit 220.

[0178] Each component included in the decoding device 200 will be described below.

[0179] [Entropy Decoding] The entropy decoding unit 202 entropy-decodes the coded bitstream. Specifically, the entropy decoding unit 202 arithmetically decodes the coded bitstream into a binary signal. The entropy decoding unit 202 then debinarizes the binary signal. As a result, the entropy decoding unit 202 outputs quantized coefficients to the inverse quantization unit 204 on a block-by-block basis.

[0180] [Dequantization section] The inverse quantization unit 204 inverse quantizes the quantized coefficients of a block to be decoded (hereinafter referred to as a current block) that is input from the entropy decoding unit 202. Specifically, the inverse quantization unit 204 inverse quantizes each quantized coefficient of the current block based on a quantization parameter corresponding to the quantized coefficient. The inverse quantization unit 204 then outputs the inverse quantized coefficients (i.e., transform coefficients) of the current block to the inverse transform unit 206.

[0181] [Inverse conversion section] The inverse transform unit 206 restores the prediction error by inverse transforming the transform coefficients input from the inverse quantization unit 204 .

[0182] For example, if the information interpreted from the encoded bitstream indicates that EMT or AMT is to be applied (e.g., the AMT flag is true), the inverse transform unit 206 inverse transforms the transform coefficients of the current block based on the interpreted information indicating the transform type.

[0183] Also, for example, if the information decoded from the coded bitstream indicates that NSST is to be applied, then inverse transform unit 206 applies an inverse re-transform to the transform coefficients.

[0184] [Adder] The adder 208 reconstructs the current block by adding the prediction error input from the inverse transformer 206 and the prediction sample input from the prediction control unit 220. The adder 208 then outputs the reconstructed block to the block memory 210 and the loop filter unit 212.

[0185] [Block Memory] The block memory 210 is a storage unit for storing blocks that are referenced in intra prediction and are in a picture to be decoded (hereinafter referred to as a current picture). Specifically, the block memory 210 stores the reconstructed blocks output from the adder 208.

[0186] [Loop filter section] The loop filter unit 212 applies a loop filter to the block reconstructed by the adder unit 208, and outputs the filtered reconstructed block to a frame memory 214, a display device, or the like.

[0187] If the information indicating ALF on / off read from the encoded bitstream indicates that ALF is on, one filter is selected from multiple filters based on the local gradient direction and activity, and the selected filter is applied to the reconstructed block.

[0188] [Frame memory] The frame memory 214 is a storage unit for storing reference pictures used in inter prediction, and is sometimes called a frame buffer. Specifically, the frame memory 214 stores the reconstructed blocks filtered by the loop filter unit 212.

[0189] [Intra prediction section] The intra prediction unit 216 generates a prediction signal (intra prediction signal) by performing intra prediction based on the intra prediction mode interpreted from the encoded bitstream, by referring to blocks in the current picture stored in the block memory 210. Specifically, the intra prediction unit 216 generates the intra prediction signal by performing intra prediction by referring to samples (e.g., luminance values, chrominance values) of blocks adjacent to the current block, and outputs the intra prediction signal to the prediction control unit 220.

[0190] Note that when an intra prediction mode that references a luminance block in intra prediction of a chrominance block is selected, the intra prediction unit 216 may predict the chrominance component of the current block based on the luminance component of the current block.

[0191] Furthermore, when information interpreted from the coded bitstream indicates the application of PDPC, the intra prediction unit 216 corrects pixel values ​​after intra prediction based on the gradients of reference pixels in the horizontal and vertical directions.

[0192] [Inter prediction section] The inter prediction unit 218 predicts the current block by referring to a reference picture stored in the frame memory 214. The prediction is performed in units of the current block or sub-blocks (e.g., 4x4 blocks) within the current block. For example, the inter prediction unit 218 generates an inter prediction signal for the current block or sub-block by performing motion compensation using motion information (e.g., motion vectors) interpreted from the coded bitstream, and outputs the inter prediction signal to the prediction control unit 220.

[0193] In addition, if the information interpreted from the encoded bitstream indicates that the OBMC mode is to be applied, the inter prediction unit 218 generates an inter prediction signal using not only the motion information of the current block obtained by motion search, but also the motion information of adjacent blocks.

[0194] Furthermore, if the information interpreted from the coded bitstream indicates that the FRUC mode is to be applied, the inter prediction unit 218 derives motion information by performing motion search according to the pattern matching method (bilateral matching or template matching) interpreted from the coded bitstream. Then, the inter prediction unit 218 performs motion compensation using the derived motion information.

[0195] Furthermore, when the BIO mode is applied, the inter prediction unit 218 derives a motion vector based on a model assuming constant-velocity linear motion. Furthermore, when information interpreted from the coded bitstream indicates that the affine motion compensation prediction mode is to be applied, the inter prediction unit 218 derives a motion vector for each sub-block based on the motion vectors of multiple adjacent blocks.

[0196] [Predictive control unit] The prediction control unit 220 selects either the intra-prediction signal or the inter-prediction signal, and outputs the selected signal to the addition unit 208 as a prediction signal.

[0197] [Explanation of Affine Inter Mode of Affine Motion Compensation Prediction] As described above, a mode in which a motion vector is derived for each sub-block based on the motion vectors of multiple neighboring blocks is called an affine motion compensation prediction mode. There are two affine motion compensation prediction modes: affine inter and affine merge. The two modes, affine inter and affine merge, will be explained below.

[0198] Fig. 11 is a conceptual diagram for explaining the affine inter-mode of affine motion compensation prediction. Fig. 11 shows a current block to be processed, a predicted motion vector v0 of the upper left corner control point of the current block to be processed, and a predicted motion vector v1 of the upper right corner control point.

[0199] In the affine inter mode, as shown in Fig. 11, the predicted motion vector v0 of the upper left corner control point is selected from the motion vectors of blocks A, B, and C, which are processed blocks adjacent to the current block to be processed. Similarly, the predicted motion vector v1 of the upper right corner control point is selected from the motion vectors of blocks D and E, which are processed blocks adjacent to the current block to be processed.

[0200] In the encoding process, a motion vector of a coded block adjacent to the current block to be processed is selected as a predicted motion vector of the control point in affine motion compensation prediction, using cost evaluation, etc. Then, a flag indicating which coded block's motion vector has been selected as the predicted motion vector of the control point is written in the bitstream.

[0201] In addition, in the encoding process, after the predicted motion vector of the control point of the currently processed block is determined, a motion search is performed to detect the motion vector of the control point. Using the detected motion vector of the control point, affine motion vectors of each sub-block in the currently processed block are calculated according to the above formula (2) to perform motion compensation. Then, while performing motion compensation, the difference between the detected motion vector of the control point and the predicted motion vector of the control point is written to the bitstream.

[0202] Although the encoding process has been described above, the decoding process also operates in the same manner.

[0203] [Explanation of Affine Merge Mode for Affine Motion Compensation Prediction] 12A and 12B are conceptual diagrams for explaining the affine merge mode of affine motion compensation prediction. Fig. 12A shows a current block to be processed and blocks A to D, which are processed blocks adjacent to the current block to be processed. Fig. 12B shows a processing example of the affine merge mode of affine motion compensation prediction. Fig. 12B also shows a current block to be processed, a predicted motion vector v0 of the upper left corner control point, a predicted motion vector v1 of the upper right corner control point, and block A, which is a processed block.

[0204] In the affine merge mode, as shown in Fig. 12A, processed blocks adjacent to the current block to be processed are examined in the order of processed blocks A (left), B (top), C (top right), D (bottom left), and E (top left).Then, from among the processed blocks A to D adjacent to the current block, the first valid processed block coded by affine motion compensation prediction is identified.

[0205] For example, referring to Figure 12B, if a processed block A adjacent to the left of the current block to be processed is coded using affine motion compensation prediction, motion vectors v2, v3, and v4 are derived for the upper left, upper right, and lower left corners of the processed blocks including block A. Next, motion vector v0 for the control point in the upper left corner of the current block to be processed is derived from the derived motion vectors v2, v3, and v4. Similarly, motion vector v1 for the control point in the upper right corner of the current block to be processed is calculated.

[0206] Next, using the calculated motion vector v0 of the control point in the upper left corner of the current processing target block and the motion vector v1 of the control point in the upper right corner, the affine motion vector of each sub-block in the current processing target block is calculated using equation (2) and motion compensation is performed.

[0207] Although the encoding process has been described above, the decoding process also operates in the same manner.

[0208] [Internal configuration of affine motion compensation prediction in the inter prediction unit of the encoding device] 13 is a block diagram showing an internal configuration for performing affine motion compensation prediction processing in the inter prediction unit 126 included in the encoding device 100 according to Embodiment 1. Note that, although the operation of the inter prediction unit 126 included in the encoding device 100 will be mainly described below, the operation of the inter prediction unit 218 included in the decoding device 200 is also similar.

[0209] As shown in FIG. 13, the inter prediction unit 126 in the first embodiment includes a range determination unit 1261, a control point MV derivation unit 1262, an affine MV calculation unit 1263, a motion compensation unit 1264, and a motion search unit 1265.

[0210] The range determination unit 1261 determines the range of motion search or motion compensation in the reference picture from the motion search or motion compensation range limitation information indicating a partial region in the reference picture in which motion search or motion compensation is permitted. The determined range of motion search or motion compensation limits the range in the reference picture in which motion search or motion compensation in affine motion compensation prediction is permitted. In this way, by limiting the range in the reference picture in which motion search or motion compensation is permitted, the range that a motion vector (MV) selected in affine motion compensation prediction can take is limited.

[0211] The control point MV derivation unit 1262 derives a motion vector of a control point (hereinafter referred to as a control point MV) using the MVs of processed blocks adjacent to the periphery in the affine inter mode or affine merge mode of affine motion compensation prediction.

[0212] The affine MV calculation unit 1263 uses the control point MV derived by the control point MV derivation unit 1262 to calculate an affine motion vector (hereinafter referred to as affine MV) for each sub-block according to equation (2).

[0213] The motion compensation unit 1264 performs motion compensation using the affine MV calculated for each sub-block by the affine MV calculation unit 1263, thereby generating a predicted image.

[0214] In the affine inter mode, the motion search unit 1265 performs motion search by evaluating costs using the predicted image input from the motion compensation unit 1264 and the current image. At this time, if the affine MV is outside the range of motion search and motion compensation for the reference picture, the affine inter mode and affine merge mode using the control point MV are prohibited.

[0215] [First step of affine intermode] FIG. 14 is a flowchart showing a first processing procedure for the affine inter mode of affine motion compensation performed by the inter prediction unit 126 of the encoding device 100 according to the first embodiment.

[0216] As shown in FIG. 14, the inter prediction unit 126 first determines the range of motion estimation in which motion estimation can be performed from motion estimation range limitation information indicating a partial area in a reference picture in which motion estimation can be performed (S101).

[0217] Next, the inter prediction unit 126 acquires motion vectors (MVs) of a plurality of processed blocks adjacent to the current block to be processed, and derives a predicted motion vector of a control point (referred to as a control point predicted MV) using the acquired plurality of MVs (S102). In the affine inter mode, as described with reference to FIG. 11, the motion vectors (MVs) of a plurality of processed blocks adjacent to the current block to be processed are acquired, and the control point predicted MV is derived using the acquired plurality of MVs. Here, a flag indicating which MV is used from the plurality of MVs is written in the bitstream.

[0218] Next, the inter prediction unit 126 updates the control point motion vector (hereinafter referred to as control point MV) (S103), and calculates an affine MV for each sub-block according to equation (2) (S104).

[0219] At this time, the inter prediction unit 126 determines whether the affine MV calculated in step S104 is within the range of motion search (S105). If it is determined to be outside the range (outside the range in S105), the inter prediction unit 126 excludes the control point MV to be evaluated from candidates for search.

[0220] On the other hand, if it is determined to be within the range (within the range in S105), the inter prediction unit 126 performs affine motion compensation (S106) and searches for a control point MV that minimizes the cost value (for example, the difference between the current image and the predicted image). Here, the difference between the obtained control point MV and the control point predicted MV updated in step S103 is written to the bitstream. Then, for example, by using the control point predicted MV as the control point MV at the start of the search, it becomes possible to set an initial value for the search that is closer to the optimal solution, thereby improving the accuracy of the search.

[0221] In addition, when performing processing using surrounding pixels of the block to be processed in processing after affine motion compensation prediction (such as OBMC), if the area including the surrounding pixels used in the processing after affine motion compensation prediction is outside the motion search range, it may be excluded from the search candidates.

[0222] In addition, the inter prediction unit 218 in the decoding device 200 performs decoding according to the bitstream information derived by the encoding device 100 in the above-mentioned manner, thereby enabling affine motion compensation processing using affine inter mode within the limited range of motion search.

[0223] [Second step of affine intermode] Fig. 15 is a flowchart showing a second processing procedure of the affine inter mode of affine motion compensation by the inter prediction unit 126 of the encoding device 100 according to Embodiment 1. The same elements as in Fig. 14 are denoted by the same reference numerals, and detailed description thereof will be omitted. The second processing procedure shown in Fig. 15 differs from the first processing procedure shown in Fig. 14 in that the determination of whether to exclude a control point MV to be evaluated from search candidates is made using a control point MV rather than an affine MV.

[0224] Specifically, in step S107, the inter prediction unit 126 determines whether the variation in the values ​​of the two control points MV at the upper left and upper right corners to be evaluated is within a limited range. If it is outside the range (out of range in S107), the inter prediction unit 126 excludes the control point MV to be evaluated from the search candidates. Here, for example, the variation in the values ​​of the two control points MV at the upper left and upper right corners refers to the size of the two control points MV, the difference in direction, the temporal distance to the reference picture, or the magnitude of the difference value. It is desirable that the positions in the reference picture indicated by the two control points MV at the upper left and upper right corners are within the limited range.

[0225] Since the affine MV for each sub-block is calculated from the control point MV in step S104 according to equation (2), if the variation between the two control point MVs is large, the variation in the calculated affine MV will also be large and will not fall within the range of motion search. Conversely, if the variation between the two control point MVs is within a specific range, the calculated affine MV will fall within the range of motion search. Therefore, by determining the specific range as a limit range in advance in step S101, it is possible to exclude the control point MV from search candidates when it is updated, thereby reducing the amount of processing.

[0226] In addition, when the inter prediction unit 126 derives the control point prediction MV in step S102, if it is determined that the variation in the control point prediction MV is no longer within the limited range, the inter prediction unit 126 may prohibit encoding as an affine inter mode.

[0227] In addition, when performing processing using surrounding pixels of the block to be processed in processing after affine motion compensation prediction (such as OBMC), if the area containing the surrounding pixels used in the processing after affine motion compensation prediction is outside the motion search range, it may be excluded from the search candidates.

[0228] In addition, the inter prediction unit 218 in the decoding device 200 performs decoding according to the bitstream information derived by the encoding device 100 in the above-mentioned manner, thereby enabling affine motion compensation processing using affine inter mode within the limited range of motion search.

[0229] [First step of affine merge mode] FIG. 16 is a flowchart showing a first processing procedure in the affine merge mode of affine motion compensation performed by the inter predictor 126 of the encoding device 100 according to the first embodiment.

[0230] As shown in FIG. 16, the inter prediction unit 126 first determines the range of motion compensation in which motion compensation can be performed from motion compensation range limitation information indicating a partial area in a reference picture in which motion compensation can be performed (S201).

[0231] Next, the inter prediction unit 126 checks processed blocks adjacent to the current block to be processed in a predetermined order. Then, the inter prediction unit 126 selects the MV of the first valid processed block coded by affine motion compensation prediction, and derives a control point MV using the selected MV (S202). In the affine merge mode, as described with reference to FIG. 12A, the processed blocks adjacent to the current block to be processed are checked in the order of block A (left), block B (top), C (top right), D (bottom left), and E (top left). Then, the MV of the first valid processed block coded by affine motion compensation prediction is selected from the processed blocks adjacent to the current block to be processed, and the selected MV is used to derive a control point MV.

[0232] Next, the inter prediction unit 126 calculates an affine MV for each sub-block from the control point MV derived in step S202 according to equation (2) (S203).

[0233] At this time, the inter prediction unit 126 determines whether the affine MV calculated in step S203 is within the range of motion estimation (S204). If it is determined to be outside the range (out of range in S204), the inter prediction unit 126 prohibits encoding in the affine merge mode (S205).

[0234] On the other hand, if it is determined that the value is within the range (within the range in S204), the inter prediction unit 126 performs affine motion compensation (S206) to obtain a predicted image.

[0235] In addition, when performing processing using surrounding pixels of the block to be processed in processing after affine motion compensation prediction (such as OBMC), if the area including the surrounding pixels used in the processing after affine motion compensation prediction is outside the motion compensation range, encoding in affine merge mode may be prohibited.

[0236] In addition, the inter prediction unit 218 in the decoding device 200 performs decoding according to the bitstream information derived by the encoding device 100 using the method described above, thereby enabling affine motion compensation processing using affine merge mode within the limited range of motion compensation.

[0237] [Second step of Affine Merge Mode] Fig. 17 is a flowchart showing a second processing procedure of the affine merge mode of affine motion compensation by the inter prediction unit 126 of the encoding device 100 according to Embodiment 1. The same elements as in Fig. 16 are denoted by the same reference numerals, and detailed description thereof will be omitted. The second processing procedure shown in Fig. 17 differs from the first processing procedure shown in Fig. 16 in that the determination of whether to exclude a control point MV to be evaluated from search candidates is made using a control point MV rather than an affine MV.

[0238] Specifically, in step S207, the inter prediction unit 126 determines whether the variation in the values ​​of the two control points MV at the upper left and upper right corners to be evaluated is within a limited range. If it is outside the range (out of range in S207), the process proceeds to step S205, where encoding as affine merge mode is prohibited. Here, for example, the variation in the values ​​of the two control points MV at the upper left and upper right corners refers to the size of the two control points MV, the difference in direction, the temporal distance to the reference picture, or the magnitude of the difference value. It is desirable that the positions in the reference picture indicated by the two control points MV at the upper left and upper right corners are within the limited range.

[0239] Since the affine MV for each subblock is calculated from the control point MV in step S203 according to equation (2), if the variation between the two control point MVs is large, the variation in the calculated affine MV will also be large and will not fall within the range of motion search. Conversely, if the variation between the two control point MVs is within a specific range, the calculated affine MV will fall within the range of motion search. Therefore, by determining the specific range as a limit range in advance in step S201, it becomes possible to prohibit coding in affine merge mode when the control point MV is derived, thereby reducing the amount of processing.

[0240] In addition, when performing processing using surrounding pixels of the block to be processed in processing after affine motion compensation prediction (such as OBMC), if the area including the surrounding pixels used in the processing after affine motion compensation prediction is outside the motion compensation range, encoding in affine merge mode may be prohibited.

[0241] In addition, the inter prediction unit 218 in the decoding device 200 performs decoding according to the bitstream information derived by the encoding device 100 using the above-mentioned method, making it possible to perform affine motion compensation processing using affine merge mode within a limited motion compensation range.

[0242] [Effects of the First Embodiment] According to the first embodiment, by limiting the range of motion vectors, it is possible to suppress the variation of control point motion vectors in affine motion compensation prediction, and it is more likely that affine motion compensation prediction will be selected in inter prediction. In addition, it is possible to limit the area of ​​reference images to be acquired, which may reduce the memory bandwidth required for external memory, which is a frame memory.

[0243] For example, if the motion search range is allowed to be wide without any restrictions, the magnitude and direction of the motion vectors of each block within a picture may vary over a wide range. Furthermore, affine motion compensation is intended for linear transformations and translations, such as scaling, shearing, and rotation, of objects within a picture. When affine motion compensation prediction is selected, the motion vectors of the two control points at the upper left and upper right corners are likely to point in the same direction. However, if the magnitude and direction of the motion vectors of each block within a picture vary over a wide range, the motion vectors selected from neighboring processed blocks may also vary. As a result, the magnitude and direction of the affine motion vectors may also vary, reducing the likelihood that affine motion compensation prediction will be selected. Furthermore, if the magnitude and direction of the motion vectors of each block within a picture vary over a wide range, the area within the picture to be acquired as a reference image will also be large, which may increase the memory bandwidth required for external frame memory.

[0244] Note that the following can be said by restricting the range of possible MVs in affine motion compensation prediction by the inter prediction unit 126 of the encoding device 100: In other words, the range of possible motion vectors in affine motion compensation prediction is also restricted in the inter prediction unit 218 of the decoding device 200 that decodes the coded bitstream generated by the encoding device 100, just like in the encoding device 100.

[0245] Furthermore, not all of the components described in embodiment 1 are always required, and only some of the components of embodiment 1 may be included. Furthermore, the processing contents of all the components described in embodiment 1 are not limited to this, and processing may be performed using components other than those in embodiment 1.

[0246] (Variation 1) In the affine motion compensation prediction process, a motion search range or a motion compensation range may be newly determined for each picture to be processed, or multiple sets of motion search ranges and motion compensation ranges may be determined in advance, and an appropriate set may be selected for each picture to be processed. This reduces the variation in control point motion vectors in affine motion compensation prediction, increasing the likelihood that affine motion compensation prediction will be selected in inter prediction. As a result, motion compensation using affine motion compensation can be performed efficiently.

[0247] In addition, in affine motion compensation prediction processing, the motion search range or motion compensation range may be changed depending on the type of picture being referenced. For example, when a P picture is referenced, the motion search range or motion compensation range may be larger than when a B picture is referenced. In addition, in affine motion compensation prediction processing, the motion search range or motion compensation range may be determined for each predetermined profile and level. This allows the range limits for motion search or motion compensation to be determined appropriately, thereby reducing the memory bandwidth required for external memory.

[0248] Furthermore, in affine motion compensation prediction processing, the motion search range or motion compensation range may be determined in accordance with the motion search processing capability, which is determined based on the computational processing capability on the encoding side, memory bandwidth, etc. This allows the range in which motion search or motion compensation is performed to be limited to be determined in accordance with the search processing capability, which not only reduces the amount of processing in accordance with the search processing capability, but also enables efficient motion compensation using affine motion compensation.

[0249] Furthermore, in affine motion compensation prediction processing, in addition to limiting the range of pixels that can be referenced for the motion search range or motion compensation range, the pictures to be referenced may also be limited. This not only reduces the memory bandwidth required for external memory, but also enables efficient motion compensation using affine motion compensation.

[0250] In addition, in the affine motion compensation prediction process, information regarding the limitation of the motion search range and the motion compensation range may be included in header information such as a video parameter set (VPS), a sequence parameter set (SPS), or a picture parameter set (PPS) of the coded bitstream, thereby enabling efficient motion compensation using affine motion compensation.

[0251] Furthermore, in affine motion compensation prediction processing, information regarding limiting the motion search range or motion compensation range may include information regarding limiting the reference picture in addition to information regarding limiting the range of pixels that can be referenced. This not only reduces the memory bandwidth required for external memory, but also enables efficient motion compensation using affine motion compensation.

[0252] Furthermore, in the affine motion compensation prediction process, the information relating to the limitation of the motion search range or motion compensation range may include only information indicating whether or not the motion search range and motion compensation range are to be limited.

[0253] In addition, if information regarding the limitation of the motion search range or motion compensation range is exchanged or predetermined between the transmitter and receiver in the higher-level system, it does not need to be included in the header information such as VPS, SPS, PPS, etc. of the coded bitstream.

[0254] Furthermore, when limiting the pictures to be referred to, the number of reference pictures may be specified, and the number of reference pictures may be limited to only the reference pictures specified in order from the reference picture with the smallest reference index.

[0255] (Variation 2) In addition, when limiting the pictures to be referenced, when performing temporal scalable encoding / decoding, the number of reference pictures can be specified for reference pictures in a hierarchy below the hierarchy of the picture currently being encoded and / or decoded, as indicated by the temporal identifier, and the number of reference pictures can be limited to only those specified in order from the reference picture with the smallest reference index.

[0256] In addition, when limiting the pictures to be referenced, the number of reference pictures may be specified, and the number of reference pictures may be limited to only those specified starting from the picture closest to the current picture to be coded in the order indicated by the information indicating the picture output order (POC: Picture Order Count).

[0257] Furthermore, when limiting the pictures to be referenced, when performing temporal scalable encoding, the number of reference pictures may be specified for reference pictures at a hierarchy below that of the picture currently to be encoded, as indicated by the temporal identifier, and the number of reference pictures may be limited to only those specified starting from those closest to the picture currently to be encoded / decoded in the order indicated by the information indicating the main order of pictures (POC: Picture Order Count).

[0258] [Example of an encoding device implementation] 18 is a block diagram showing an example implementation of the encoding device 100 according to Embodiment 1. The encoding device 100 includes a circuit 160 and a memory 162. For example, multiple components of the encoding device 100 shown in FIGS. 1 and 13 are implemented by the circuit 160 and memory 162 shown in FIG. 18.

[0259] The circuit 160 is a circuit that performs information processing and is a circuit that can access the memory 162. For example, the circuit 160 is a dedicated or general-purpose electronic circuit that encodes moving images. The circuit 160 may be a processor such as a CPU. The circuit 160 may also be a collection of multiple electronic circuits. For example, the circuit 160 may fulfill the roles of multiple components of the encoding device 100 shown in FIG. 1 and the like, excluding the components for storing information.

[0260] The memory 162 is a dedicated or general-purpose memory that stores information used by the circuit 160 to encode moving images. The memory 162 may be an electronic circuit and may be connected to the circuit 160. The memory 162 may also be included in the circuit 160. The memory 162 may also be a collection of multiple electronic circuits. The memory 162 may also be a magnetic disk, an optical disk, or the like, and may also be expressed as a storage or a recording medium. The memory 162 may also be a non-volatile memory or a volatile memory.

[0261] For example, the memory 162 may store a video to be encoded, or a bit string corresponding to the encoded video, or may store a program for the circuit 160 to encode the video.

[0262] Furthermore, for example, the memory 162 may serve as a component for storing information among the multiple components of the encoding device 100 shown in Fig. 1 etc. Specifically, the memory 162 may serve as the block memory 118 and the frame memory 122 shown in Fig. 1. More specifically, the memory 162 may store reconstructed blocks, reconstructed pictures, etc.

[0263] Note that not all of the components shown in Figure 1 and the like need to be implemented in the encoding device 100, and not all of the above-described processes need to be performed. Some of the components shown in Figure 1 and the like may be included in another device, and some of the above-described processes may be executed by another device. Then, in the encoding device 100, some of the components shown in Figure 1 and the like are implemented, and some of the above-described processes are performed, thereby efficiently performing motion compensation.

[0264] An example of the operation of the encoding device 100 shown in Fig. 18 is shown below. In the example of the operation below, the affine motion compensation prediction process is a process of deriving a motion vector for each sub-block based on the motion vectors of multiple adjacent blocks in the inter prediction process for the current block.

[0265] Fig. 19 is a flowchart showing an example of the operation of the encoding device 100 shown in Fig. 18. For example, the encoding device 100 shown in Fig. 18 performs the operation shown in Fig. 19 when encoding a moving image by performing motion compensation.

[0266] Specifically, the circuit 160 of the encoding device 100 uses the memory 162 to limit the range of motion search or motion compensation in the affine motion compensation prediction process in the inter prediction process of the target block, and performs motion compensation for the target block (S311).

[0267] This allows the encoding device 100 to efficiently perform motion compensation using affine motion compensation. More specifically, by limiting the range in which motion search or motion compensation is performed in the affine motion compensation prediction process, it is possible to suppress variation in control point motion vectors in affine motion compensation prediction. This increases the likelihood that affine motion compensation prediction will be selected in inter prediction, allowing for efficient motion compensation using affine motion compensation. Furthermore, it is possible to limit the area of ​​the reference image to be acquired, which may reduce the memory bandwidth required for the external memory, which is the frame memory.

[0268] [Example of implementation of a decryption device] 20 is a block diagram showing an example implementation of the decoding device 200 according to Embodiment 1. The decoding device 200 includes a circuit 260 and a memory 262. For example, multiple components of the decoding device 200 shown in FIG. 10 are implemented by the circuit 260 and the memory 262 shown in FIG.

[0269] The circuit 260 is a circuit that performs information processing and is a circuit that can access the memory 262. For example, the circuit 260 is a dedicated or general-purpose electronic circuit that decodes moving images. The circuit 260 may be a processor such as a CPU. The circuit 260 may also be a collection of multiple electronic circuits. For example, the circuit 260 may fulfill the roles of multiple components of the decoding device 200 shown in FIG. 10 and the like, excluding components for storing information.

[0270] The memory 262 is a dedicated or general-purpose memory that stores information for the circuit 260 to decode moving images. The memory 262 may be an electronic circuit and may be connected to the circuit 260. The memory 262 may also be included in the circuit 260. The memory 262 may also be a collection of multiple electronic circuits. The memory 262 may also be a magnetic disk, an optical disk, or the like, and may also be expressed as a storage, a recording medium, or the like. The memory 262 may also be a non-volatile memory or a volatile memory.

[0271] For example, the memory 262 may store a bit string corresponding to an encoded video, or a video corresponding to a decoded bit string, or may store a program for the circuit 260 to decode the video.

[0272] Furthermore, for example, the memory 262 may serve as a component for storing information among the multiple components of the decoding device 200 shown in Fig. 10 etc. Specifically, the memory 262 may serve as the block memory 210 and the frame memory 214 shown in Fig. 10. More specifically, the memory 262 may store reconstructed blocks, reconstructed pictures, etc.

[0273] Note that the decoding device 200 does not necessarily have to implement all of the components shown in Figure 10 and the like, and does not necessarily have to perform all of the above-described processes. Some of the components shown in Figure 10 and the like may be included in another device, and some of the above-described processes may be executed by another device. Then, the decoding device 200 implements some of the components shown in Figure 10 and the like, and performs some of the above-described processes, thereby efficiently performing motion compensation.

[0274] An example of the operation of the decoding device 200 shown in Fig. 20 is shown below. In the following example of the operation, the affine motion compensation prediction process is a process of deriving a motion vector for each sub-block based on the motion vectors of multiple adjacent blocks in the inter prediction process for the current block.

[0275] Fig. 21 is a flowchart showing an example of the operation of the decoding device 200 shown in Fig. 20. For example, the decoding device 200 shown in Fig. 20 performs the operation shown in Fig. 21 when performing motion compensation and decoding of moving images.

[0276] Specifically, the circuit 260 of the decoding device 200 performs motion compensation for the current block by limiting the range of motion search or motion compensation in the affine motion compensation prediction process in the inter prediction process for the current block using the memory 262 (S411), and then decodes the coded stream (S412).

[0277] This allows the decoding device 200 to efficiently perform motion compensation using affine motion compensation. More specifically, by limiting the range in which motion search or motion compensation is performed in the affine motion compensation prediction process, it is possible to suppress variations in control point motion vectors in affine motion compensation prediction. This increases the likelihood that affine motion compensation prediction will be selected in inter prediction, allowing for efficient motion compensation using affine motion compensation. Furthermore, it is possible to limit the area of ​​reference images to be acquired, which may reduce the memory bandwidth required for external memory, which is a frame memory.

[0278] [supplement] Furthermore, the encoding device 100 and the decoding device 200 in this embodiment may be used as an image encoding device and an image decoding device, or as a video encoding device and a video decoding device, respectively. Alternatively, the encoding device 100 and the decoding device 200 may be used as an inter prediction device (inter prediction device).

[0279] That is, the encoding device 100 and the decoding device 200 may correspond only to the inter prediction unit (inter prediction unit) 126 and the inter prediction unit (inter prediction unit) 218, respectively. Other components such as the transform unit 106 and the inverse transform unit 206 may be included in other devices.

[0280] In addition, in this embodiment, each component may be configured with dedicated hardware, or may be realized by executing a software program suitable for each component. Each component may be realized by a program execution unit such as a CPU or processor reading and executing a software program recorded on a recording medium such as a hard disk or semiconductor memory.

[0281] Specifically, each of the encoding device 100 and the decoding device 200 may include a processing circuitry and a storage device electrically connected to and accessible from the processing circuitry. For example, the processing circuitry corresponds to the circuit 160 or 260, and the storage device corresponds to the memory 162 or 262.

[0282] The processing circuit includes at least one of dedicated hardware and a program execution unit, and executes processing using a storage device. If the processing circuit includes a program execution unit, the storage device stores the software program executed by the program execution unit.

[0283] Here, the software for realizing the encoding device 100 or the decoding device 200 according to the present embodiment is the following program.

[0284] In other words, this program may cause a computer to execute an encoding method in which, in an affine motion compensation prediction process in an inter prediction process for a current block, the range in which motion search or motion compensation is performed is limited and motion compensation is performed for the current block.

[0285] Alternatively, the program may cause a computer to execute a decoding method for decoding an encoded stream by limiting the range of motion search or motion compensation in an affine motion compensation prediction process in an inter-prediction process for a target block and performing motion compensation for the target block.

[0286] Furthermore, each component may be a circuit, as described above. These circuits may form a single circuit as a whole, or may each be a separate circuit. Furthermore, each component may be realized by a general-purpose processor or a dedicated processor.

[0287] Furthermore, a process performed by a specific component may be performed by another component. The order in which the processes are performed may be changed, or multiple processes may be performed in parallel. Furthermore, the encoding / decoding device may include the encoding device 100 and the decoding device 200.

[0288] The ordinal numbers such as first and second used in the description may be changed as appropriate. Furthermore, new ordinal numbers may be assigned to components or removed.

[0289] Although aspects of the encoding device 100 and the decoding device 200 have been described above based on the embodiments, the aspects of the encoding device 100 and the decoding device 200 are not limited to these embodiments. As long as they do not deviate from the spirit of this disclosure, various modifications conceivable by those skilled in the art to the present embodiments and configurations constructed by combining components of different embodiments may also be included within the scope of the aspects of the encoding device 100 and the decoding device 200.

[0290] This aspect may be implemented in combination with at least a part of other aspects of the present disclosure. Also, some of the processes, some of the device configurations, and some of the syntax described in the flowcharts of this aspect may be implemented in combination with other aspects.

[0291] (Embodiment 2) In each of the above embodiments, each of the functional blocks can typically be realized by an MPU, memory, etc. Furthermore, the processing by each of the functional blocks is typically realized by a program execution unit such as a processor reading and executing software (programs) recorded on a recording medium such as a ROM. The software may be distributed by downloading, etc., or may be recorded on a recording medium such as a semiconductor memory and distributed. Of course, each functional block can also be realized by hardware (dedicated circuits).

[0292] Furthermore, the processing described in each embodiment may be realized by centralized processing using a single device (system), or may be realized by distributed processing using multiple devices. The processor that executes the program may be a single processor or multiple processors. That is, centralized processing or distributed processing may be performed.

[0293] The aspects of the present disclosure are not limited to the above examples, and various modifications are possible, and these modifications are also included within the scope of the aspects of the present disclosure.

[0294] Furthermore, here, we will explain application examples of the video coding method (image coding method) or video decoding method (image decoding method) shown in each of the above embodiments and a system using the same. The system is characterized by having an image coding device using the image coding method, an image decoding device using the image decoding method, and an image coding / decoding device that includes both. Other components of the system can be appropriately changed depending on the situation.

[0295] [Usage example] 22 is a diagram showing the overall configuration of a content supply system ex100 that provides a content distribution service. The area where communication services are provided is divided into cells of a desired size, and base stations ex106, ex107, ex108, ex109, and ex110, which are fixed wireless stations, are installed in each cell.

[0296] In this content supply system ex100, devices such as a computer ex111, a game console ex112, a camera ex113, a home appliance ex114, and a smartphone ex115 are connected to the Internet ex101 via an Internet service provider ex102 or a communication network ex104 and base stations ex106 to ex110. The content supply system ex100 may be configured to connect a combination of any of the above elements. The devices may be connected to each other directly or indirectly via a telephone network or short-range wireless communication, without using the base stations ex106 to ex110, which are fixed wireless stations. Furthermore, a streaming server ex103 is connected to devices such as the computer ex111, the game console ex112, the camera ex113, the home appliance ex114, and the smartphone ex115 via the Internet ex101, etc. Furthermore, the streaming server ex103 is connected to a terminal in a hotspot on an airplane ex117, etc., via a satellite ex116.

[0297] Note that wireless access points, hotspots, etc. may be used instead of the base stations ex106 to ex110. Furthermore, the streaming server ex103 may be directly connected to the communication network ex104 without going through the Internet ex101 or the Internet service provider ex102, or may be directly connected to an airplane ex117 without going through a satellite ex116.

[0298] The camera ex113 is a device capable of taking still images and videos, such as a digital camera. The smartphone ex115 is a smartphone, mobile phone, or PHS (Personal Handyphone System) that is compatible with mobile communication systems generally known as 2G, 3G, 3.9G, 4G, and 5G.

[0299] The home appliance ex118 is a refrigerator or an appliance included in a home fuel cell cogeneration system.

[0300] In the content supply system ex100, a terminal having a photographing function is connected to a streaming server ex103 via a base station ex106 or the like, thereby enabling live streaming and the like. In live streaming, a terminal (such as a computer ex111, a game console ex112, a camera ex113, a home appliance ex114, a smartphone ex115, or a terminal on an airplane ex117) performs the encoding process described in each of the above embodiments on still images or video content captured by a user using the terminal, multiplexes the video data obtained by encoding with audio data obtained by encoding audio corresponding to the video, and transmits the obtained data to the streaming server ex103. That is, each terminal functions as an image encoding device according to one aspect of the present disclosure.

[0301] Meanwhile, the streaming server ex103 streams the transmitted content data to the requesting client. The client is a computer ex111, a game console ex112, a camera ex113, a home appliance ex114, a smartphone ex115, a terminal on an airplane ex117, or the like, which is capable of decoding the encoded data. Each device that receives the distributed data decodes and plays back the received data. That is, each device functions as an image decoding device according to one aspect of the present disclosure.

[0302] [Distributed processing] The streaming server ex103 may also be multiple servers or multiple computers that process, record, and distribute data in a distributed manner. For example, the streaming server ex103 may be implemented as a CDN (Content Delivery Network), where content distribution is achieved through a network connecting numerous edge servers distributed around the world. In a CDN, a physically nearby edge server is dynamically assigned depending on the client. Content is then cached and distributed to that edge server, thereby reducing delays. Furthermore, if an error occurs or communication conditions change due to increased traffic, processing can be distributed among multiple edge servers, the distribution entity can be switched to another edge server, or distribution can be continued by bypassing the affected network portion, thereby achieving high-speed and stable distribution.

[0303] In addition to the distributed processing of the distribution itself, the encoding of captured data can be performed on each device, on the server side, or shared among devices. For example, encoding generally involves two processing loops. The first loop detects the image complexity or code size for each frame or scene. The second loop maintains image quality while improving encoding efficiency. For example, a device can perform the first encoding process, and the server that receives the content can perform the second encoding process, thereby improving content quality and efficiency while reducing the processing load on each device. In this case, if there is a request for near-real-time reception and decoding, the data encoded by a device can be received and played back on another device, enabling more flexible real-time distribution.

[0304] As another example, the camera ex113 or the like extracts features from an image, compresses the data related to the features as metadata, and transmits the data to the server. The server performs compression according to the meaning of the image, for example, by determining the importance of an object from the features and switching the quantization precision accordingly. The feature data is particularly effective in improving the accuracy and efficiency of motion vector prediction when the server recompresses the image. Alternatively, the terminal may perform simple encoding such as VLC (variable length coding), and the server may perform encoding with a heavy processing load such as CABAC (context-adaptive binary arithmetic coding).

[0305] As another example, in a stadium, shopping mall, factory, etc., there may be multiple pieces of video data that have been shot by multiple terminals of almost the same scene. In this case, using the multiple terminals that shot the video and, as necessary, other terminals and servers that did not shoot the video, encoding processes are assigned to each of them, for example, in units of GOPs (Group of Pictures), pictures, or tiles obtained by dividing a picture, for distributed processing. This reduces delays and achieves better real-time performance.

[0306] Furthermore, since multiple pieces of video data are of nearly the same scene, the server may manage and / or instruct the video data shot by each terminal to be mutually referenced. Alternatively, the server may receive encoded data from each terminal and change the reference relationships between multiple pieces of data, or correct or replace the pictures themselves and re-encode them. This allows for the generation of streams with improved quality and efficiency for each piece of data.

[0307] The server may also perform transcoding to change the encoding format of the video data before distributing it. For example, the server may convert MPEG-based encoding to VP-based encoding, or convert H.264 to H.265.

[0308] In this way, the encoding process can be performed by a terminal or one or more servers. Therefore, although the following uses terms such as "server" or "terminal" to refer to the entity performing the process, some or all of the processing performed by the server may be performed by the terminal, and some or all of the processing performed by the terminal may be performed by the server. The same applies to the decoding process.

[0309] [3D, multi-angle] In recent years, there has been an increasing trend to integrate and use images or videos of different scenes or the same scene taken from different angles by multiple devices such as cameras ex113 and / or smartphones ex115 that are nearly synchronized with each other. The videos taken by each device are integrated based on the relative positional relationship between the devices obtained separately, or on areas where feature points included in the videos match.

[0310] The server may not only encode 2D video, but also encode still images automatically or at a time specified by the user based on scene analysis of the video and transmit them to the receiving terminal. Furthermore, if the server can acquire the relative positional relationship between the capturing terminals, it can generate a 3D shape of the scene based on not only the 2D video but also images of the same scene captured from different angles. The server may also separately encode 3D data generated by point clouds, or may select or reconstruct images to be transmitted to the receiving terminal from images captured by multiple terminals based on the results of recognizing or tracking people or objects using the 3D data.

[0311] In this way, users can enjoy scenes by selecting any video corresponding to each camera device, or can enjoy content in which video from any viewpoint is extracted from 3D data reconstructed using multiple images or videos. Furthermore, like the video, sound may also be collected from multiple different angles, and the server may multiplex and transmit sound from a specific angle or space in accordance with the video.

[0312] In recent years, content that associates the real world with a virtual world, such as Virtual Reality (VR) and Augmented Reality (AR), has also become popular. In the case of VR images, the server creates viewpoint images for the right eye and left eye, and may perform encoding that allows reference between the viewpoint images using Multi-View Coding (MVC) or the like, or may encode them as separate streams without mutual reference. When decoding the separate streams, it is preferable to play them in synchronization with each other so that a virtual three-dimensional space is reproduced according to the user's viewpoint.

[0313] In the case of AR images, the server superimposes virtual object information in virtual space onto camera information in real space based on the 3D position or the user's viewpoint movement. The decoding device may acquire or store virtual object information and 3D data, generate a 2D image according to the user's viewpoint movement, and smoothly connect the images to create superimposed data. Alternatively, the decoding device may send the user's viewpoint movement to the server in addition to a request for virtual object information, and the server may create superimposed data based on the viewpoint movement received from the 3D data stored on the server, encode the superimposed data, and distribute it to the decoding device. Note that the superimposed data may also have an α value indicating transparency in addition to RGB, and the server may set the α value of parts other than the object created from the 3D data to 0, etc., to encode the parts in a transparent state. Alternatively, the server may generate data by setting a predetermined RGB value as the background, like a chromakey, and using the background color for parts other than the object.

[0314] Similarly, the decoding of distributed data may be performed by each client terminal, by the server, or by multiple terminals. For example, one terminal may first send a reception request to the server, and then other terminals may receive and decode content according to the request, after which the decoded signal is transmitted to a device with a display. By distributing the processing and selecting appropriate content regardless of the capabilities of the communication terminals themselves, high-quality data can be reproduced. As another example, large-sized image data may be received on a TV or other device, and only a portion of the picture, such as a tile into which the picture is divided, may be decoded and displayed on the viewer's personal device. This allows the viewer to share the overall picture while checking their own area of ​​responsibility or an area of ​​interest in more detail.

[0315] In the future, it is expected that content will be seamlessly received by switching the appropriate data for the current connection using delivery system standards such as MPEG-DASH in situations where multiple short-, medium-, or long-distance wireless communications are available, both indoors and outdoors. This will allow users to freely select and switch between decoding and display devices, such as their own devices, indoors and outdoors, in real time. Decoding can also be performed by switching between decoding and display devices based on user location information. This will enable users to display map information on the wall or ground of a neighboring building with an embedded display device while traveling to their destination. It is also possible to switch the bit rate of received data based on the accessibility of the encoded data on the network, such as if the encoded data is cached on a server that can be quickly accessed from the receiving device or copied to an edge server in a content delivery service.

[0316] [Scalable Coding] Regarding content switching, we will explain it using a scalable stream, as shown in Figure 23, compressed and encoded using the video encoding method described in each of the above embodiments. The server may have multiple streams with the same content but different qualities, but may also switch content by taking advantage of the characteristics of a temporally / spatially scalable stream, which is achieved by encoding the stream in layers as shown. In other words, the decoding side determines which layer to decode based on internal factors such as performance and external factors such as communication bandwidth, allowing the decoding side to freely switch between low-resolution and high-resolution content. For example, if a user wants to continue watching a video they were watching on their smartphone ex115 while on the go on a device such as an Internet TV after returning home, the device can simply decode the same stream up to different layers, thereby reducing the burden on the server.

[0317] Furthermore, in addition to the above-described scalability configuration in which pictures are coded for each layer and an enhancement layer exists above a base layer, the enhancement layer may include meta-information based on image statistics, etc., and the decoding side may generate high-quality content by super-resolving pictures in the base layer based on the meta-information. Super-resolution may mean either improving the signal-to-noise ratio at the same resolution or increasing the resolution. The meta-information may include information for specifying linear or nonlinear filter coefficients used in the super-resolution process, or information for specifying parameter values ​​in the filter process, machine learning, or least-squares calculation used in the super-resolution process.

[0318] Alternatively, a picture may be divided into tiles or the like according to the meaning of objects in the image, and the decoding side may select tiles to decode and decode only a portion of the area. Furthermore, by storing the object's attributes (such as a person, a car, or a ball) and its position in the video (such as a coordinate position in the same image) as meta information, the decoding side can identify the position of a desired object based on the meta information and determine the tile containing the object. For example, as shown in FIG. 24, the meta information is stored using a data storage structure different from that of pixel data, such as an SEI message in HEVC. This meta information indicates, for example, the position, size, or color of the main object.

[0319] Furthermore, meta information may be stored in units consisting of multiple pictures, such as streams, sequences, or random access units, which allows the decoding side to obtain the time when a specific person appears in the video, and by combining this with information in units of pictures, it is possible to identify the picture in which the object exists and the position of the object within the picture.

[0320] [Webpage optimization] FIG. 25 is a diagram showing an example of a web page display screen on a computer ex111 or the like. FIG. 26 is a diagram showing an example of a web page display screen on a smartphone ex115 or the like. As shown in FIGS. 25 and 26, a web page may include multiple link images that are links to image content, and the appearance of the web page may differ depending on the device used to view the page. When multiple link images are visible on the screen, the display device (decoding device) may display a still image or I-picture contained in each content as a link image, display a video such as a GIF animation using multiple still images or I-pictures, or receive only the base layer and decode and display the video until the user explicitly selects a link image, or until the link image approaches the center of the screen or until the entire link image is within the screen.

[0321] When a link image is selected by a user, the display device decodes the base layer with the highest priority. If the HTML constituting the web page contains information indicating that the content is scalable, the display device may decode up to the enhancement layer. To ensure real-time performance, before a selection is made or when the communication bandwidth is very limited, the display device decodes and displays only forward-referenced pictures (I-pictures, P-pictures, and forward-reference-only B-pictures), thereby reducing the delay between the decoding time of the first picture and the display time (the delay from the start of content decoding to the start of display). Alternatively, the display device may intentionally ignore the picture reference relationships and roughly decode all B-pictures and P-pictures using forward reference, and then perform normal decoding as the number of received pictures increases over time.

[0322] [Autonomous driving] Furthermore, when transmitting and receiving still image or video data such as 2D or 3D map information for automatic driving or driving assistance of a vehicle, the receiving terminal may receive weather or construction information as meta information in addition to image data belonging to one or more layers, and may associate and decode these. Note that the meta information may belong to a layer, or may simply be multiplexed with the image data.

[0323] In this case, since a vehicle, drone, airplane, etc. including a receiving terminal moves, the receiving terminal can realize seamless reception and decoding while switching between base stations ex106 to ex110 by transmitting the location information of the receiving terminal at the time of a reception request. Also, the receiving terminal can dynamically switch how much meta information to receive or how much to update map information depending on the user's selection, user situation, or communication bandwidth status.

[0324] In this way, in the content supply system ex100, the client can receive, decode, and play back the encoded information sent by the user in real time.

[0325] [Distribution of personal content] Furthermore, the content supply system ex100 allows not only high-quality, long-duration content from video distribution companies, but also unicast or multicast distribution of low-quality, short-duration content from individuals. It is expected that such personal content will continue to increase in the future. To improve the quality of personal content, the server may perform editing before encoding. This can be achieved, for example, with the following configuration.

[0326] During shooting, either in real time or after accumulating the footage, the server performs recognition processing such as detecting shooting errors, scene search, semantic analysis, and object detection from the original image or encoded data. Based on the recognition results, the server manually or automatically corrects out-of-focus or camera shake, deletes less important scenes (e.g., scenes with lower brightness or out-of-focus compared to other pictures), emphasizes object edges, changes color, and performs other editing. The server then encodes the edited data based on the editing results. It is also known that viewing rates decrease if the shooting time is too long. Therefore, the server may automatically clip not only less important scenes as described above but also scenes with little movement, based on the image processing results, so that the content falls within a specific time range depending on the shooting time. Alternatively, the server may generate and encode a digest based on the results of the semantic analysis of the scene.

[0327] In some cases, personal content may contain content that infringes copyright, moral rights, or portrait rights, or may cause the scope of sharing to exceed the intended scope, resulting in inconvenience to individuals. Therefore, for example, the server may intentionally defocus images of people's faces on the periphery of the screen or the interior of a house before encoding. The server may also recognize whether the image to be encoded contains the face of a person other than a pre-registered person, and if so, perform processing such as blurring the face. Alternatively, as pre- or post-processing before encoding, the user may specify a person or background area they wish to modify in the image for copyright or other reasons, and the server may replace the specified area with another image or blur the focus. For a person, the server may track the person in the video and replace the image of the face.

[0328] Furthermore, because viewing personal content with small data volumes requires real-time performance, the decoding device first receives the base layer as a top priority, and then decodes and plays it back, depending on the bandwidth. The decoding device may also receive an enhancement layer during this time, and if the content is played back more than twice, such as when playback is looped, it may play back high-quality video, including the enhancement layer. A stream that has undergone scalable encoding in this way can provide an experience in which the video appears rough when not selected or when viewing begins, but gradually becomes smoother and the image quality improves. In addition to scalable encoding, a similar experience can also be provided by configuring a single stream consisting of a rough stream played the first time and a second stream that is encoded with reference to the first video.

[0329] [Other use cases] Furthermore, these encoding or decoding processes are generally performed by the LSIex500 possessed by each terminal. The LSIex500 may be a single chip or may be configured with multiple chips. It is also possible to incorporate video encoding or decoding software into some kind of recording medium (such as a CD-ROM, flexible disk, or hard disk) that can be read by the computer ex111, and perform the encoding or decoding process using that software. Furthermore, if the smartphone ex115 is equipped with a camera, video data captured by the camera may be transmitted. This video data is data that has been encoded by the LSIex500 possessed by the smartphone ex115.

[0330] The LSIex500 may be configured to download and activate application software. In this case, the terminal first determines whether it supports the content encoding method or has the capability to execute a specific service. If the terminal does not support the content encoding method or does not have the capability to execute a specific service, the terminal downloads the codec or application software and then acquires and plays the content.

[0331] Furthermore, at least one of the video encoding device (image encoding device) or video decoding device (image decoding device) of each of the above embodiments can be incorporated into a digital broadcasting system, not limited to the content supply system ex100 via the Internet ex101. Since multiplexed data in which video and audio are multiplexed is transmitted and received over broadcast radio waves using a satellite or the like, the content supply system ex100 is more suited to multicast than the content supply system ex100, which is more suited to unicast, but similar applications are possible with regard to encoding and decoding processes.

[0332] [Hardware configuration] FIG. 27 is a diagram illustrating a smartphone ex115. FIG. 28 is a diagram illustrating an example configuration of the smartphone ex115. The smartphone ex115 includes an antenna ex450 for transmitting and receiving radio waves to and from the base station ex110, a camera unit ex465 capable of capturing video and still images, and a display unit ex458 for displaying video captured by the camera unit ex465 and decoded data of the video and other data received by the antenna ex450. The smartphone ex115 further includes an operation unit ex466 such as a touch panel, an audio output unit ex457 such as a speaker for outputting voice or sound, an audio input unit ex456 such as a microphone for inputting voice, a memory unit ex467 capable of storing encoded data or decoded data such as captured video or still images, recorded voice, received video or still images, and email, and a slot unit ex464 that serves as an interface with a SIM ex468 for identifying users and authenticating access to various data, including networks. In addition, an external memory may be used instead of the memory unit ex467.

[0333] In addition, a main control unit ex460 that comprehensively controls the display unit ex458 and operation unit ex466, etc., is connected to a power supply circuit unit ex461, an operation input control unit ex462, a video signal processing unit ex455, a camera interface unit ex463, a display control unit ex459, a modulation / demodulation unit ex452, a multiplexing / separation unit ex453, an audio signal processing unit ex454, a slot unit ex464, and a memory unit ex467 via a bus ex470.

[0334] When the power key is turned on by a user, the power supply circuit unit ex461 supplies power from the battery pack to each unit, thereby starting up the smartphone ex115 into an operational state.

[0335] The smartphone ex115 processes calls, data communications, and other communications under the control of a main control unit ex460, which includes a CPU, ROM, RAM, and the like. During calls, the audio signal collected by the audio input unit ex456 is converted into a digital audio signal by the audio signal processing unit ex454, which then undergoes spectrum spread processing by the modulation / demodulation unit ex452, digital-to-analog conversion processing and frequency conversion processing by the transmission / reception unit ex451, and then transmitted via the antenna ex450. The received data is amplified, frequency-converted, and analog-to-digital converted, then subjected to spectrum despreading processing by the modulation / demodulation unit ex452, and converted into an analog audio signal by the audio signal processing unit ex454, which then outputs the amplified data from the audio output unit ex457. During data communications mode, text, still images, or video data is sent to the main control unit ex460 via the operation input control unit ex462 by operating the operation unit ex466, etc., of the main unit, and similar transmission and reception processing is performed. When transmitting video, still images, or video and audio in the data communication mode, the video signal processing unit ex455 compression-encodes the video signal stored in the memory unit ex467 or the video signal input from the camera unit ex465 using the video encoding method described in each of the above embodiments, and sends the encoded video data to the multiplexing / demultiplexing unit ex453. The audio signal processing unit ex454 also encodes the audio signal picked up by the audio input unit ex456 while the camera unit ex465 is capturing video, still images, etc., and sends the encoded audio data to the multiplexing / demultiplexing unit ex453. The multiplexing / demultiplexing unit ex453 multiplexes the encoded video data and encoded audio data using a predetermined method, and modulates and converts the data in the modulation / demodulation unit (modulation / demodulation circuit unit) ex452 and the transmission / reception unit ex451 before transmitting the data via the antenna ex450.

[0336] When receiving video attached to an email or chat, or video linked to a web page, etc., the multiplexed data received via the antenna ex450 is decoded by the multiplexing / separation unit ex453, which separates the multiplexed data into a video data bitstream and an audio data bitstream. The multiplexing / separation unit ex453 then supplies the encoded video data to the video signal processing unit ex455 via the synchronization bus ex470, and supplies the encoded audio data to the audio signal processing unit ex454. The video signal processing unit ex455 decodes the video signal using a video decoding method corresponding to the video encoding method described in each of the above embodiments, and displays the video or still image included in the linked video file on the display unit ex458 via the display control unit ex459. The audio signal processing unit ex454 decodes the audio signal, and the audio is output from the audio output unit ex457. Note that with the widespread use of real-time streaming, audio playback may be socially inappropriate depending on the user's circumstances. Therefore, a configuration that initially plays only the video data without playing the audio signal is desirable. The audio may be played in synchronization only when the user performs an operation such as clicking on the video data.

[0337] Although the smartphone ex115 has been used as an example, three types of implementation are possible for the terminal: a transmitting / receiving terminal having both an encoder and a decoder, a transmitting terminal having only an encoder, and a receiving terminal having only a decoder. Furthermore, in the digital broadcasting system, multiplexed data in which audio data and the like are multiplexed onto video data is received or transmitted, but the multiplexed data may also include text data related to the video in addition to audio data, or the video data itself may be received or transmitted instead of the multiplexed data.

[0338] While the main control unit ex460, which includes a CPU, controls the encoding and decoding processes, devices often also include a GPU. Therefore, a configuration is possible in which a memory shared by the CPU and GPU, or a memory with addresses managed for common use, is used to take advantage of the GPU's performance and process a large area at once. This shortens encoding time, ensures real-time performance, and achieves low latency. It is particularly efficient to perform motion estimation, deblocking filtering, SAO (Sample Adaptive Offset), and transformation and quantization processes at a picture level or other unit in the GPU rather than the CPU. [Industrial Applicability]

[0339] The present disclosure is applicable to, for example, television receivers, digital video recorders, car navigation systems, mobile phones, digital cameras, digital video cameras, video conference systems, electronic mirrors, and the like. [Explanation of symbols]

[0340] 100 Encoding device 102 Division 104 Subtraction section 106 Conversion unit 108 Quantization section 110 Entropy coding unit 112, 204 Inverse quantization section 114, 206 Inverse conversion unit 116, 208 Addition section 118, 210 block memory 120, 212 Loop filter section 122, 214 frame memory 124, 216 Intra prediction unit (intra-screen prediction unit) 126, 218 Inter prediction unit (inter-frame prediction unit) 128, 220 Predictive control unit 160, 260 circuits 162, 262 memory 200 Decryption Device 202 Entropy Decoding Unit 1261 Range determination unit 1262 Control Point MV Derivation Unit 1263 Affine MV calculation unit 1264 Motion Compensation Unit 1265 Motion Search Unit

Claims

1. The circuit and a memory; The circuit uses the memory to: In an affine motion compensation prediction process in an inter prediction process of a current block, a range in which motion search or motion compensation is performed is limited and motion compensation of the current block is performed; In the affine motion compensation prediction process, limiting the range in which the motion estimation or the motion compensation is performed so that a variation between the control point motion vector at the upper left corner and the control point motion vector at the upper right corner of the target block in the affine motion compensation prediction process falls within a predetermined range; the variation is a value based on a difference between a control point motion vector at an upper left corner of the target block and a control point motion vector at an upper right corner of the target block, The predetermined range is changed depending on the type of picture to be referenced. Encoding device.

2. The circuit and a memory; The circuit uses the memory to: In an affine motion compensation prediction process in an inter prediction process of a current block, a range in which motion search or motion compensation is performed is limited and motion compensation is performed on the current block, thereby decoding the coded stream; In the affine motion compensation prediction process, limiting the range in which the motion estimation or the motion compensation is performed so that a variation between the control point motion vector at the upper left corner and the control point motion vector at the upper right corner of the target block in the affine motion compensation prediction process falls within a predetermined range; the variation is a value based on a difference between a control point motion vector at an upper left corner of the target block and a control point motion vector at an upper right corner of the target block, The predetermined range is changed depending on the type of picture to be referenced. Decryption device.

3. The circuit and a memory; The circuit uses the memory to: In an affine motion compensation prediction process in an inter prediction process of a current block, a range in which motion search or motion compensation is performed is limited and motion compensation of the current block is performed; In the affine motion compensation prediction process, limiting the range in which the motion estimation or the motion compensation is performed so that a variation between the control point motion vector at the upper left corner and the control point motion vector at the upper right corner of the target block in the affine motion compensation prediction process falls within a predetermined range; the variation is a value based on a difference between a control point motion vector at an upper left corner of the target block and a control point motion vector at an upper right corner of the target block, The predetermined range is changed depending on the type of picture to be referenced; transmitting a bitstream including parameters relating to the predetermined range restriction; Bitstream transmitter.

Images