Transmission device and method for transmission

Abstract

To provide a further improved transmission device.SOLUTION: The transmission device prohibits a second sub-block from being divided into two partitions in a first direction, prohibits the second sub-block from being divided into three partitions in the first direction, codes a first sub-block to a third sub-block, generates a bit stream including a coded coding target block, and sends the generated bit stream.SELECTED DRAWING: Figure 27

Description

Technical Field

[0001] The present disclosure relates to a transmission device and a transmission method.

Background Art

[0002] A video coding standard called HEVC (High-Efficiency Video Coding) has been standardized by JCT-VC (Joint Collaborative Team on Video Coding).

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In such encoding and decoding technologies, further improvement is required.

[0005] Therefore, an object of the present disclosure is to provide a transmission device and a transmission method capable of realizing further improvement.

Means for Solving the Problems

[0006] A transmission device according to one aspect of the present disclosure includes a circuit and a memory. The circuit divides an encoding target block into a first sub-block, a second sub-block, and a third sub-block in a first direction using the memory. The second sub-block is located between the first sub-block and the third sub-block. Dividing the second sub-block into two partitions in the first direction is prohibited, and dividing the second sub-block into three partitions in the first direction is not prohibited. The first sub-block, the second sub-block, and the third sub-block are encoded to generate a bit stream including the encoded processing target block, and the generated bit stream is transmitted.

[0007] Note that these general or specific aspects may be implemented in a system, a method, an integrated circuit, a computer program, or a recording medium such as a computer-readable CD-ROM, or may be implemented in any combination of a system, a method, an integrated circuit, a computer program, and a recording medium.

Effect of the Invention

[0008] The present disclosure can provide a transmission device and a transmission method capable of achieving further improvement.

Brief Description of the Drawings

[0009]

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Best Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments will be specifically described with reference to the drawings.

[0011] It should be noted that all of the embodiments described below show comprehensive or specific examples. The numerical values, shapes, materials, components, arrangement positions and connection forms of components, steps, order of steps, etc. shown in the following embodiments are merely examples and are not intended to limit the scope of the claims. In addition, among the components in the following embodiments, the components not described in the independent claims indicating the most general concept are described as optional components.

[0012] (Embodiment 1) First, 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 to be described later are applicable, an outline of Embodiment 1 will be described. However, Embodiment 1 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 are applicable, 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 Embodiment 1.

[0013] When applying the processes and / or configurations described in each aspect of the present disclosure to Embodiment 1, for example, any of the following may be performed.

[0014] (1) For the encoding device or the decoding device of Embodiment 1, among the plurality of components constituting the encoding device or the decoding device, the component corresponding to the component described in each aspect of the present disclosure is replaced with the component described in each aspect of the present disclosure. (2) For the encoding device or the decoding device of Embodiment 1, after performing arbitrary changes such as addition, replacement, deletion, etc. of functions or processes performed on some of the plurality of components constituting the encoding device or the decoding device, the component corresponding to the component described in each aspect of the present disclosure is replaced with the component described in each aspect of the present disclosure. (3) For the method performed by the encoding device or the decoding device of Embodiment 1, after performing arbitrary changes such as addition of processes and / or replacement, deletion, etc. of some of the plurality of processes included in the method, the process corresponding to the process described in each aspect of the present disclosure is replaced with the process described in each aspect of the present disclosure. (4) Some of the plurality of components constituting the encoding device or the decoding device of Embodiment 1 are combined and implemented with the component described in each aspect of the present disclosure, a component having a part of the functions provided by the component described in each aspect of the present disclosure, or a component that performs a part of the processes performed by the component described in each aspect of the present disclosure. (5) A component that has a part of the functions of some of the components that make up the encoding device or decoding device of Embodiment 1, or a component that performs a part of the processes performed by some of the components that make up the encoding device or decoding device of Embodiment 1, is combined with the components described in each aspect of the present disclosure, a component that has a part of the functions of the components described in each aspect of the present disclosure, or a component that performs a part of the processes performed by the components described in each aspect of the present disclosure for implementation. (6) For the method performed by the encoding device or decoding device of Embodiment 1, among the plurality of processes included in the method, the process corresponding to the process described in each aspect of the present disclosure is replaced with the process described in each aspect of the present disclosure. (7) A part of the processes included in the method performed by the encoding device or decoding device of Embodiment 1 is implemented in combination with the processes described in each aspect of the present disclosure.

[0015] Note that the implementation manners of the processes and / or configurations described in each aspect of the present disclosure are not limited to the above examples. For example, they may be implemented in a device used for a purpose different from the moving image / image encoding device or moving image / image decoding device disclosed in Embodiment 1, or the processes and / or configurations described in each aspect may be implemented alone. Also, the processes and / or configurations described in different aspects may be implemented in combination.

[0016] [Outline of Encoding Device] First, the outline of the encoding device according to Embodiment 1 will be described. FIG. 1 is a block diagram showing the functional configuration of an encoding device 100 according to Embodiment 1. The encoding device 100 is a moving image / image encoding device that encodes moving images / images in block units.

[0017] As shown in FIG. 1, the encoding device 100 is a device that encodes an image in block units, and includes a division unit 102, a subtraction unit 104, a conversion unit 106, a quantization unit 108, an entropy encoding unit 110, an inverse quantization unit 112, an inverse conversion 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.

[0018] The encoding device 100 is realized by, for example, a general-purpose processor and a 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 conversion unit 106, the quantization unit 108, the entropy encoding unit 110, the inverse quantization unit 112, the inverse conversion 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. Also, 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 conversion unit 106, the quantization unit 108, the entropy encoding unit 110, the inverse quantization unit 112, the inverse conversion 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.

[0019] Each component included in the encoding device 100 will be described below.

[0020] [Division Unit] The splitting unit 102 splits each picture included in the input moving image into a plurality of blocks and outputs each block to the subtraction unit 104. For example, the splitting unit 102 first splits the picture into blocks of a fixed size (e.g., 128x128). Such blocks of a fixed size are sometimes called Coding Tree Units (CTUs). Then, the splitting unit 102 splits each of the blocks of a fixed size into blocks of a variable size (e.g., 64x64 or less) based on recursive quadtree and / or binary tree block splitting. Such blocks of a variable size are sometimes called Coding Units (CUs), Prediction Units (PUs), or Transformation Units (TUs). Note that in this embodiment, it is not necessary to distinguish between CUs, PUs, and TUs, and some or all of the blocks in the picture may serve as the processing units for CUs, PUs, and TUs.

[0021] FIG. 2 is a diagram showing an example of block splitting in Embodiment 1. In FIG. 2, solid lines represent block boundaries by quadtree block splitting, and dashed lines represent block boundaries by binary tree block splitting.

[0022] Here, block 10 is a square block of 128x128 pixels (128x128 block). This 128x128 block 10 is first split into four square 64x64 blocks (quadtree block splitting).

[0023] The upper-left 64x64 block is further vertically split into two rectangular 32x64 blocks, and the left 32x64 block is further vertically split into two rectangular 16x64 blocks (binary tree block splitting). As a result, the upper-left 64x64 block is split into two 16x64 blocks 11 and 12 and a 32x64 block 13.

[0024] The upper-right 64x64 block is horizontally split into two rectangular 64x32 blocks 14 and 15 (binary tree block splitting).

[0025] The bottom - left 64x64 block is divided into four square 32x32 blocks (quadtree block division). Among the four 32x32 blocks, the upper - left block and the lower - right block are further divided. The upper - left 32x32 block is vertically divided into two rectangular 16x32 blocks, and the right 16x32 block is further horizontally divided into two 16x16 blocks (binary - tree block division). The lower - right 32x32 block is horizontally divided into two 32x16 blocks (binary - tree block division). As a result, the bottom - left 64x64 block is divided into 16 16x32 blocks, two 16x16 blocks 17, 18, two 32x32 blocks 19, 20, and two 32x16 blocks 21, 22.

[0026] The bottom - right 64x64 block 23 is not divided.

[0027] As described above, in FIG. 2, block 10 is divided into 13 variable - size blocks 11 - 23 based on recursive quadtree and binary - tree block division. Such a division is sometimes called QTBT (quad - tree plus binary tree) division.

[0028] Note that 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). A division including such a ternary - tree block division is sometimes called MBT (multi - type tree) division.

[0029] [Subtraction unit] The subtraction unit 104 subtracts the predicted signal (predicted sample) from the original signal (original sample) in block units divided by the division unit 102. That is, the subtraction unit 104 calculates the prediction error (also called the residual) of the block to be encoded (hereinafter referred to as the current block). Then, the subtraction unit 104 outputs the calculated prediction error to the conversion unit 106.

[0030] The original signal is the input signal of the encoding device 100, and is a signal representing the image of each picture constituting the moving image (for example, a luminance signal and two chroma signals). Hereinafter, the signal representing the image may also be referred to as a sample.

[0031] [Transformation unit] The transformation unit 106 transforms the prediction error in the spatial domain into transformation coefficients in the frequency domain and outputs the transformation coefficients to the quantization unit 108. Specifically, the transformation unit 106 performs, for example, a predetermined discrete cosine transform (DCT) or discrete sine transform (DST) on the prediction error in the spatial domain.

[0032] Note that the transformation unit 106 may adaptively select a transformation type from a plurality of transformation types and transform the prediction error into transformation coefficients using a transformation basis function corresponding to the selected transformation type. Such a transformation may be called an EMT (explicit multiple core transform) or an AMT (adaptive multiple transform).

[0033] The plurality of transformation types include, for example, DCT-II, DCT-V, DCT-VIII, DST-I, and DST-VII. FIG. 3 is a table showing the transformation basis functions corresponding to each transformation type. In FIG. 3, N indicates the number of input pixels. The selection of the transformation type from these plurality of transformation types may depend on, for example, the type of prediction (intra prediction and inter prediction), or may depend on the intra prediction mode.

[0034] Information indicating whether to apply such an EMT or AMT (for example, called an AMT flag) and information indicating the selected transformation type are signaled at the CU level. Note that the signaling of these information does not necessarily have to be limited to the CU level, and may be at other levels (for example, sequence level, picture level, slice level, tile level, or CTU level).

[0035] Further, the conversion unit 106 may re-convert the conversion coefficient (conversion result). Such re-conversion may be referred to as AST (adaptive secondary transform) or NSST (non-separable secondary transform). For example, the conversion unit 106 performs re-conversion for each sub-block (e.g., 4x4 sub-block) included in the block of conversion coefficients corresponding to the intra prediction error. Information indicating whether to apply NSST and information regarding the conversion matrix used for NSST are signaled at the CU level. Note that the signaling of these pieces of information is not necessarily limited to the CU level and may be at other levels (e.g., sequence level, picture level, slice level, tile level, or CTU level).

[0036] Here, separable conversion is a method in which conversion is performed multiple times by separating for each direction by the number of dimensions of the input, and non-separable conversion is a method in which when the input is multi-dimensional, two or more dimensions are regarded as one dimension and conversion is performed collectively.

[0037] For example, as an example of non-separable conversion, when the input is a 4×4 block, it is regarded as an array having 16 elements, and a conversion process is performed on the array with a 16×16 conversion matrix.

[0038] Also, after similarly regarding a 4×4 input block as an array having 16 elements, performing Givens rotation multiple times on the array (Hypercube Givens Transform) is also an example of non-separable conversion.

[0039] [Quantization unit] The quantization unit 108 quantizes the conversion coefficients output from the conversion unit 106. Specifically, the quantization unit 108 scans the conversion coefficients of the current block in a predetermined scanning order, and quantizes the conversion coefficients based on the quantization parameter (QP) corresponding to the scanned conversion coefficients. Then, the quantization unit 108 outputs the quantized conversion coefficients (hereinafter referred to as quantization coefficients) of the current block to the entropy encoding unit 110 and the inverse quantization unit 112.

[0040] The predetermined order is the order for quantization / inverse quantization of the conversion coefficients. For example, the predetermined scanning order is defined in ascending order of frequency (from low frequency to high frequency) or descending order of frequency (from high frequency to low frequency).

[0041] 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. That is, as the value of the quantization parameter increases, the quantization error increases.

[0042] [Entropy Encoding Unit] The entropy encoding unit 110 generates an encoded signal (encoded bit stream) by performing variable-length encoding on the quantization coefficients that are the input from the quantization unit 108. Specifically, the entropy encoding unit 110, for example, binarizes the quantization coefficients and performs arithmetic encoding on the binary signal.

[0043] [Inverse Quantization Unit] The inverse quantization unit 112 inverse-quantizes the quantization coefficients that are the input from the quantization unit 108. Specifically, the inverse quantization unit 112 inverse-quantizes the quantization coefficients of the current block in a predetermined scanning order. Then, the inverse quantization unit 112 outputs the inverse-quantized conversion coefficients of the current block to the inverse conversion unit 114.

[0044] [Inverse Conversion Unit] The inverse transform unit 114 restores the prediction error by inversely transforming the transform coefficients which are the input from the inverse quantization unit 112. Specifically, the inverse transform unit 114 inversely transforms the transform coefficients corresponding to the transform by the transform unit 106 to restore the prediction error of the current block. Then, the inverse transform unit 114 outputs the restored prediction error to the addition unit 116.

[0045] Note that since information is lost due to quantization, the restored prediction error does not match the prediction error calculated by the subtraction unit 104. That is, the restored prediction error includes quantization error.

[0046] [Addition unit] The addition unit 116 reconstructs the current block by adding the prediction error which is the input from the inverse transform unit 114 and the prediction sample which is the input from the prediction control unit 128. Then, the addition unit 116 outputs the reconstructed block to the block memory 118 and the loop filter unit 120. The reconstructed block may also be called a local decoding block.

[0047] [Block memory] The block memory 118 is a storage unit for storing blocks within the coded picture (hereinafter referred to as the current picture) which are blocks referred to in intra prediction. Specifically, the block memory 118 stores the reconstructed block output from the addition unit 116.

[0048] [Loop filter unit] The loop filter unit 120 applies a loop filter to the block reconstructed by the addition unit 116 and outputs the filtered reconstructed block to the frame memory 122. The loop filter is a filter (in-loop filter) used within the coding loop and includes, for example, a deblocking filter (DF), a sample adaptive offset (SAO), and an adaptive loop filter (ALF).

[0049] In ALF, a least-squares error filter for removing encoding distortion is applied, and for example, for each 2x2 sub-block within a current block, one filter selected from a plurality of filters is applied based on the direction and activity of the local gradient.

[0050] Specifically, first, a sub-block (e.g., a 2x2 sub-block) is classified into a plurality of classes (e.g., 15 or 25 classes). The classification of the sub-block is performed based on the direction and activity of the gradient. For example, a classification value C (e.g., C = 5D + A) is calculated using the gradient direction value D (e.g., 0 to 2 or 0 to 4) and the gradient activity value A (e.g., 0 to 4). Then, based on the classification value C, the sub-block is classified into a plurality of classes (e.g., 15 or 25 classes).

[0051] The gradient direction value D is derived, for example, by comparing the gradients in a plurality of directions (e.g., horizontal, vertical, and two diagonal directions). Also, the gradient activity value A is derived, for example, by adding the gradients in a plurality of directions and quantizing the addition result.

[0052] Based on the result of such classification, a filter for the sub-block is determined from among a plurality of filters.

[0053] As the shape of the filter used in ALF, for example, a circularly symmetric shape is utilized. FIGS. 4A to 4C are diagrams showing a plurality of examples of the shape of the filter 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. The information indicating the shape of the filter is signaled at the picture level. Note that the signaling of the information indicating the shape of the filter is not necessarily limited to the picture level and may be at other levels (e.g., sequence level, slice level, tile level, CTU level, or CU level).

[0054] The on / off of ALF is determined at, for example, the picture level or CU level. For example, for luminance, it is determined whether to apply ALF at the CU level, and for chrominance difference, it is determined whether to apply ALF at the picture level. The information indicating the on / off of ALF is signaled at the picture level or CU level. Note that the signaling of the information indicating the on / off of ALF does not have to be limited to the picture level or CU level, and it may be at other levels (e.g., sequence level, slice level, tile level, or CTU level).

[0055] The coefficient sets of a plurality of selectable filters (e.g., filters up to 15 or 25) are signaled at the picture level. Note that the signaling of the coefficient sets does not have to be limited to the picture level, and it may be at other levels (e.g., sequence level, slice level, tile level, CTU level, CU level, or sub-block level).

[0056] [Frame memory] The frame memory 122 is a storage unit for storing reference pictures used for 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.

[0057] [Intra prediction unit] The intra prediction unit 124 generates a prediction signal (intra prediction signal) by performing intra prediction (also called in-picture prediction) of the current block with reference to the blocks in the current picture stored in the block memory 118. Specifically, the intra prediction unit 124 generates an intra prediction signal by performing intra prediction with reference to the samples (e.g., luminance values, chrominance difference values) of the blocks adjacent to the current block, and outputs the intra prediction signal to the prediction control unit 128.

[0058] 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.

[0059] The one or more non-directional prediction modes include, for example, the Planar prediction mode and the DC prediction mode defined in the H.265 / HEVC (High-Efficiency Video Coding) standard (Non-Patent Document 1).

[0060] The plurality of directional prediction modes includes, for example, the 33-direction prediction mode defined in the H.265 / HEVC standard. Note that the plurality of directional prediction modes may further include a 32-direction prediction mode (a total of 65 directional prediction modes) in addition to the 33 directions. FIG. 5A is a diagram showing 67 intra prediction modes (2 non-directional prediction modes and 65 directional prediction modes) in intra prediction. The solid arrows represent the 33 directions defined in the H.265 / HEVC standard, and the dashed arrows represent the additional 32 directions.

[0061] In the intra prediction of the chrominance blocks, a luminance block may be referred to. That is, based on the luminance component of the current block, the chrominance components of the current block may be predicted. Such intra prediction is sometimes called CCLM (cross-component linear model) prediction. An intra prediction mode of a chrominance block that refers to such a luminance block (for example, called the CCLM mode) may be added as one of the intra prediction modes of the chrominance block.

[0062] The intra prediction unit 124 may correct the pixel value after intra prediction based on the gradient of reference pixels in the horizontal / vertical direction. Such intra prediction with such correction is sometimes called PDPC (position dependent intra prediction combination). Information indicating the presence or absence of the application of PDPC (for example, called a PDPC flag) is signaled at, for example, the CU level. Note that the signaling of this information does not have to be limited to the CU level and may be at other levels (for example, sequence level, picture level, slice level, tile level, or CTU level).

[0063] [Inter prediction unit] The inter prediction unit 126 generates a prediction signal (inter prediction signal) by performing inter prediction (also called inter-picture prediction) of 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 (for example, 4x4 blocks) within the current block. For example, the inter prediction unit 126 performs motion estimation within the reference picture for the current block or sub-block. Then, the inter prediction unit 126 generates an inter prediction signal for the current block or sub-block by performing motion compensation using the motion information (for example, motion vector) obtained by the motion estimation. Then, the inter prediction unit 126 outputs the generated inter prediction signal to the prediction control unit 128.

[0064] The motion information used for motion compensation is signaled. A motion vector predictor may be used for the signaling of the motion vector. That is, the difference between the motion vector and the predicted motion vector may be signaled.

[0065] In addition to the motion information of the current block obtained by motion search, the motion information of adjacent blocks may also be used to generate an inter prediction signal. Specifically, an inter prediction signal may be generated for each sub-block in the current block by weighted addition of a prediction signal based on the motion information obtained by motion search and a prediction signal based on the motion information of adjacent blocks. Such inter prediction (motion compensation) is sometimes called OBMC (overlapped block motion compensation).

[0066] In such an OBMC mode, information indicating the size of sub-blocks for OBMC (for example, called OBMC block size) is signaled at the sequence level. Also, information indicating whether or not to apply the OBMC mode (for example, called OBMC flag) is signaled at the CU level. Note that the signaling levels of these pieces of information do not necessarily have to be limited to the sequence level and the CU level, and may be other levels (for example, picture level, slice level, tile level, CTU level, or sub-block level).

[0067] The OBMC mode will be described in more detail. FIGS. 5B and 5C are a flowchart and a conceptual diagram for explaining the outline of the prediction image correction process by OBMC processing.

[0068] First, a prediction image (Pred) by normal motion compensation is obtained using the motion vector (MV) assigned to the block to be coded.

[0069] Next, the motion vector (MV_L) of the coded left adjacent block is applied to the block to be coded to obtain a prediction image (Pred_L), and the first correction of the prediction image is performed by weighting and superimposing the prediction image and Pred_L.

[0070] Similarly, the motion vector (MV_U) of the encoded upper adjacent block is applied to the block to be encoded to obtain a predicted image (Pred_U). The predicted image after the first correction and Pred_U are weighted and superimposed to perform the second correction on the predicted image, and this is used as the final predicted image.

[0071] Here, a two-stage correction method using the left adjacent block and the upper adjacent block has been described. However, it is also possible to adopt a configuration in which corrections are performed more times than two stages using the right adjacent block or the lower adjacent block.

[0072] Note that the area for superimposition may be only a partial area near the block boundary, rather than the pixel area of the entire block.

[0073] Here, the predicted image correction process from a single reference picture has been described. However, the same applies to the case of correcting the predicted image from a plurality of reference pictures. After obtaining the predicted images corrected from each reference picture, the obtained predicted images are further superimposed to obtain the final predicted image.

[0074] Note that the block to be processed may be in units of prediction blocks or in units of sub-blocks obtained by further dividing the prediction blocks.

[0075] As a method for determining whether to apply OBMC processing, for example, there is a method using an obmc_flag which is a signal indicating whether to apply OBMC processing. As a specific example, in an encoding device, it is determined whether the block to be encoded belongs to a region with complex motion. If it belongs to a region with complex motion, the value 1 is set as the obmc_flag and encoding is performed by applying OBMC processing. If it does not belong to a region with complex motion, the value 0 is set as the obmc_flag and encoding is performed without applying OBMC processing. On the other hand, in a decoding device, the obmc_flag described in the stream is decoded, and decoding is performed by switching whether to apply OBMC processing according to the value.

[0076] Note that the motion information may be derived on the decoder side without being signaled. For example, the merge mode defined in the H.265 / HEVC standard may be used. Also for example, the motion information may be derived by performing motion search on the decoder side. In this case, the motion search is performed without using the pixel values of the current block.

[0077] Here, a mode in which motion search is performed on the decoder side will be described. This mode in which motion search is performed on the decoder side may be called the PMMVD (pattern matched motion vector derivation) mode or the FRUC (frame rate up-conversion) mode.

[0078] An example of the FRUC process is shown in FIG. 5D. First, with reference to the motion vectors of the encoded blocks spatially or temporally adjacent to the current block, a list of a plurality of candidates (which may be common to the merge list) each having a predicted motion vector is generated. Next, the best candidate MV is selected from among the plurality of candidate MVs registered in the candidate list. For example, an evaluation value for each candidate included in the candidate list is calculated, and one candidate is selected based on the evaluation value.

[0079] Then, based on the motion vector of the selected candidate, a motion vector for the current block is derived. Specifically, for example, the motion vector of the selected candidate (best candidate MV) is directly derived as the motion vector for the current block. Also for example, in the peripheral region of the position in the reference picture corresponding to the motion vector of the selected candidate, by performing pattern matching, a motion vector for the current block may be derived. That is, search is performed in the same manner for the region around the best candidate MV, and if there is an MV for which the evaluation value is a good value, the best candidate MV may be updated to the MV and used as the final MV of the current block. Note that it is also possible to adopt a configuration in which the said process is not performed.

[0080] The same processing may be performed in units of sub-blocks as well.

[0081] Note that the evaluation value is calculated by obtaining the difference value of the reconstructed image through pattern matching between the region in the reference picture corresponding to the motion vector and a predetermined region. Note that the evaluation value may be calculated using information other than the difference value.

[0082] As the pattern matching, the first pattern matching or the second pattern matching is used. The first pattern matching and the second pattern matching may be called bilateral matching and template matching, respectively.

[0083] In the first pattern matching, pattern matching is performed between two blocks in two different reference pictures, which are two blocks along the motion trajectory of the current block. Therefore, in the first pattern matching, as the predetermined region for calculating the evaluation value of the candidate described above, the region in another reference picture along the motion trajectory of the current block is used.

[0084] FIG. 6 is a diagram for explaining 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 matching pair among pairs of two blocks in two different reference pictures (Ref0, Ref1) that are two blocks along the motion trajectory of the current block (Cur block). Specifically, for the current block, the difference between the reconstructed image at the specified position in the first encoded reference picture (Ref0) specified by the candidate MV and the reconstructed image at the specified position in the second encoded reference picture (Ref1) specified by the symmetric MV obtained by scaling the candidate MV by the display time interval is derived, and an evaluation value is calculated using the obtained difference value. It is preferable to select the candidate MV with the best evaluation value among a plurality of candidate MVs as the final MV.

[0085] Under the assumption of a continuous motion trajectory, the motion vectors (MV0, MV1) indicating the two reference blocks are proportional to the temporal distances (TD0, TD1) between the current picture (Cur Pic) and the two reference pictures (Ref0, Ref1). For example, when the current picture is temporally located between the two reference pictures and the temporal distances from the current picture to the two reference pictures are equal, in the first pattern matching, mirror-symmetric bidirectional motion vectors are derived.

[0086] 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., the upper and / or left adjacent block)) and a block in the reference picture. Therefore, in the second pattern matching, a block adjacent to the current block in the current picture is used as a predetermined region for calculating the evaluation value of the above-described candidate.

[0087] FIG. 7 is a diagram for explaining 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, the motion vector of the current block is derived by searching for the block that most closely matches the block adjacent to the current block (Cur block) in the current picture (Cur Pic) within the reference picture (Ref0). Specifically, for the current block, the difference between the reconstructed image of the encoded region of both or either one of the left adjacent and upper adjacent blocks and the reconstructed image at the equivalent position within the encoded reference picture (Ref0) specified by the candidate MV is derived, an evaluation value is calculated using the obtained difference value, and the candidate MV with the best evaluation value among the plurality of candidate MVs may be selected as the best candidate MV.

[0088] Information indicating whether or not to apply such a FRUC mode (for example, called a FRUC flag) is signaled at the CU level. Also, when the FRUC mode is applied (for example, when the FRUC flag is true), information indicating the pattern matching method (the first pattern matching or the second pattern matching) (for example, called a FRUC mode flag) is signaled at the CU level. Note that the signaling of this information does not necessarily have to be limited to the CU level and may be at other levels (for example, sequence level, picture level, slice level, tile level, CTU level, or sub-block level).

[0089] Here, a mode for deriving a motion vector based on a model assuming uniform linear motion will be described. This mode may be called the BIO (bi - directional optical flow) mode.

[0090] FIG. 8 is a diagram for explaining a model assuming uniform linear motion. In FIG. 8, (vx, vy) represents the velocity vector, and τ0 and τ1 represent the temporal distances between the current picture (Cur Pic) and two reference pictures (Ref0, Ref1), respectively. (MVx0, MVy0) represents the motion vector corresponding to the reference picture Ref0, and (MVx1, MVy1) represents the motion vector corresponding to the reference picture Ref1.

[0091] At this time, under the assumption of uniform linear motion of the velocity vector (vx, vy), (MVx0, MVy0) and (MVx1, MVy1) are represented as (vxτ0, vyτ0) and (-vxτ1, -vyτ1), respectively, and the following optical flow equation (1) holds.

[0092]

Equation

[0093] Here, I(k) represents the luminance value of the reference image k (k = 0, 1) after motion compensation. This optical flow equation indicates that the sum of (i) the temporal 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 the combination of this optical flow equation and Hermite interpolation, the motion vectors in block units obtained from the merge list, etc., are corrected in pixel units.

[0094] Note that the motion vector may be derived on the decoder side by a method different from the derivation of the motion vector based on the model assuming uniform linear motion. For example, the motion vector may be derived in sub-block units based on the motion vectors of a plurality of adjacent blocks.

[0095] Here, a mode of deriving a motion vector in units of sub-blocks based on the motion vectors of a plurality of adjacent blocks will be described. This mode may be called an affine motion compensation prediction mode.

[0096] FIG. 9A is a diagram for explaining the derivation of a motion vector in units of sub-blocks based on the motion vectors of a plurality of adjacent blocks. In FIG. 9A, a current block includes 16 4×4 sub-blocks. Here, based on the motion vectors of the adjacent blocks, the motion vector v0 of the upper left control point of the current block is derived, and based on the motion vectors of the adjacent sub-blocks, the motion vector v1 of the upper right control point of the current block is derived. Then, using the two motion vectors v0 and v1, the motion vector (vx, vy) of each sub-block within the current block is derived by the following equation (2).

[0097]

Equation

[0098] Here, x and y indicate the horizontal position and vertical position of the sub-block, respectively, and w indicates a predetermined weight coefficient.

[0099] Such an affine motion compensation prediction mode may include several modes in which the methods for deriving the motion vectors of the upper left and upper right control points are different. Information indicating such an affine motion compensation prediction mode (for example, called an affine flag) is signaled at the CU level. Note that the signaling of the information indicating this affine motion compensation prediction mode is not necessarily limited to the CU level, and it may be at other levels (for example, sequence level, picture level, slice level, tile level, CTU level, or sub-block level).

[0100] [Prediction control unit] The prediction control unit 128 selects either an intra prediction signal or an inter prediction signal, and outputs the selected signal as a prediction signal to the subtraction unit 104 and the addition unit 116.

[0101] Here, an example of deriving the motion vector of the picture to be coded in the merge mode will be described. FIG. 9B is a diagram for explaining the outline of the motion vector derivation process in the merge mode.

[0102] First, a prediction MV list in which candidates for the prediction MV are registered is generated. As candidates for the prediction MV, a spatial adjacent prediction MV which is an MV possessed by a plurality of coded blocks located spatially adjacent to the block to be coded, a temporal adjacent prediction MV which is an MV possessed by a neighboring block obtained by projecting the position of the block to be coded in the coded reference picture, a combined prediction MV which is an MV generated by combining the MV values of the spatial adjacent prediction MV and the temporal adjacent prediction MV, and a zero prediction MV which is an MV having a value of zero, etc. are available.

[0103] Next, one prediction MV is selected from among the plurality of prediction MVs registered in the prediction MV list, and is determined as the MV of the block to be coded.

[0104] Furthermore, in the variable length coding unit, a merge_idx which is a signal indicating which prediction MV has been selected is described in the stream and coded.

[0105] Note that the prediction MVs registered in the prediction MV list described in FIG. 9B are just an example, and the number may be different from that in the figure, or the configuration may not include some of the types of prediction MVs in the figure, or the configuration may be such that prediction MVs other than the types of prediction MVs in the figure are added.

[0106] Note that the final MV may be determined by performing the DMVR process described later using the MV of the block to be coded derived in the merge mode.

[0107] Here, an example of determining the MV using the DMVR process will be described.

[0108] FIG. 9C is a conceptual diagram for explaining the outline of DMVR processing.

[0109] First, using the optimal MVP set for the processing target block as a candidate MV, according to the candidate MV, reference pixels are respectively obtained from a first reference picture which is a processed picture in the L0 direction and a second reference picture which is a processed picture in the L1 direction, and a template is generated by taking the average of each reference pixel.

[0110] Next, using the template, the peripheral regions of the candidate MVs of the first reference picture and the second reference picture are respectively searched, and the MV with the minimum cost is determined as the final MV. Note that the cost value is calculated using the difference value between each pixel value of the template and each pixel value of the search region, the MV value, etc.

[0111] Note that in the encoding device and the decoding device, the outline of the processing described here is basically common.

[0112] Note that even if it is not the processing itself described here, other processing may be used as long as it is a process capable of searching the periphery of the candidate MV to derive the final MV.

[0113] Here, a mode of generating a predicted image using the LIC process will be described.

[0114] FIG. 9D is a diagram for explaining the outline of a predicted image generation method using the luminance correction process by the LIC process.

[0115] First, an MV for obtaining a reference image corresponding to the encoding target block is derived from a reference picture which is an encoded picture.

[0116] Next, for the encoding target block, using the luminance pixel values of the left adjacent and upper adjacent encoded peripheral reference regions and the luminance pixel values at the equivalent positions in the reference picture specified by the MV, information indicating how the luminance values change between the reference picture and the encoding target picture is extracted to calculate the luminance correction parameter.

[0117] By performing a luminance correction process on the reference image in the reference picture specified by MV using the luminance correction parameter, a predicted image for the block to be encoded is generated.

[0118] Note that the shape of the peripheral reference region in FIG. 9D is an example, and other shapes may be used.

[0119] Also, although the process of generating a predicted image from one reference picture has been described here, the same applies when generating a predicted image from a plurality of reference pictures. After performing a luminance correction process on the reference images obtained from each reference picture in the same manner, a predicted image is generated.

[0120] As a method for determining whether to apply the LIC process, for example, there is a method using a lic_flag which is a signal indicating whether to apply the LIC process. As a specific example, in an encoding apparatus, it is determined whether the block to be encoded belongs to a region where a luminance change has occurred. If it belongs to a region where a luminance change has occurred, a value 1 is set as the lic_flag and encoding is performed by applying the LIC process. If it does not belong to a region where a luminance change has occurred, a value 0 is set as the lic_flag and encoding is performed without applying the LIC process. On the other hand, in a decoding apparatus, by decoding the lic_flag described in the stream, decoding is performed by switching whether to apply the LIC process according to the value.

[0121] As another method for determining whether to apply the LIC process, for example, there is also a method of determining according to whether the LIC process has been applied to peripheral blocks. As a specific example, when the block to be encoded is in the merge mode, it is determined whether the peripheral encoded blocks selected at the time of deriving the MV in the merge mode process have been encoded by applying the LIC process, and encoding is performed by switching whether to apply the LIC process according to the result. Note that in this example, the process in decoding is exactly the same.

[0122] [Overview of the Decoder] Next, an overview of a decoder capable of decoding the encoded signal (encoded bit stream) output from the above-described encoder 100 will be described. FIG. 10 is a block diagram showing the functional configuration of a decoder 200 according to Embodiment 1. The decoder 200 is a moving image / image decoder that decodes moving images / images in block units.

[0123] As shown in FIG. 10, the decoder 200 includes an entropy decoder 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.

[0124] The decoder 200 is realized by, for example, a general-purpose processor and a memory. In this case, when a software program stored in the memory is executed by the processor, the processor functions as the entropy decoder 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. Further, the decoder 200 may be realized as one or more dedicated electronic circuits corresponding to the entropy decoder 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.

[0125] Hereinafter, each component included in the decoder 200 will be described.

[0126] [Entropy Decoder] The entropy decoder 202 entropy-decodes the encoded bit stream. Specifically, the entropy decoder 202, for example, arithmetically decodes the encoded bit stream into a binary signal. Then, the entropy decoder 202 de-binarizes the binary signal. Thereby, the entropy decoder 202 outputs quantization coefficients to the inverse quantization unit 204 in block units.

[0127] [Inverse quantization unit] The inverse quantization unit 204 inverse quantizes the quantization coefficients of the block to be decoded (hereinafter referred to as the current block), which is the input from the entropy decoding unit 202. Specifically, for each of the quantization coefficients of the current block, the inverse quantization unit 204 inverse quantizes the quantization coefficient based on the quantization parameter corresponding to the quantization coefficient. Then, the inverse quantization unit 204 outputs the inverse quantized quantization coefficients (i.e., transform coefficients) of the current block to the inverse transform unit 206.

[0128] [Inverse transform unit] The inverse transform unit 206 restores the prediction error by inverse-transforming the transform coefficients that are the input from the inverse quantization unit 204.

[0129] For example, when the information read 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 information indicating the read transform type.

[0130] Also, for example, when the information read from the encoded bitstream indicates that NSST is to be applied, the inverse transform unit 206 applies inverse reconversion to the transform coefficients.

[0131] [Addition unit] The addition unit 208 reconstructs the current block by adding the prediction error that is the input from the inverse transform unit 206 and the prediction sample that is the input from the prediction control unit 220. Then, the addition unit 208 outputs the reconstructed block to the block memory 210 and the loop filter unit 212.

[0132] [Block memory] The block memory 210 is a storage unit for storing blocks within the decoded target picture (hereinafter referred to as the current picture), which are blocks referred to in intra prediction. Specifically, the block memory 210 stores the reconstructed blocks output from the addition unit 208.

[0133] [Loop Filter Section] The loop filter section 212 applies a loop filter to the block reconstructed by the addition section 208, and outputs the filtered reconstructed block to the frame memory 214, a display device, and the like.

[0134] When the information indicating the on / off of the ALF read from the encoded bitstream indicates that the ALF is on, one filter is selected from a plurality of filters based on the direction and activity of the local gradient, and the selected filter is applied to the reconstructed block.

[0135] [Frame Memory] The frame memory 214 is a storage unit for storing reference pictures used for inter prediction, and may also be called a frame buffer. Specifically, the frame memory 214 stores the reconstructed block filtered by the loop filter section 212.

[0136] [Intra Prediction Section] The intra prediction section 216 generates a prediction signal (intra prediction signal) by performing intra prediction with reference to a block in the current picture stored in the block memory 210 based on the intra prediction mode read from the encoded bitstream. Specifically, the intra prediction section 216 generates an intra prediction signal by performing intra prediction with reference to samples (for example, luminance values, chrominance difference values) of blocks adjacent to the current block, and outputs the intra prediction signal to the prediction control section 220.

[0137] In addition, when an intra prediction mode that refers to a luminance block in the intra prediction of a chrominance difference block is selected, the intra prediction section 216 may predict the chrominance component of the current block based on the luminance component of the current block.

[0138] Also, when the information read from the encoded bitstream indicates the application of PDPC, the intra prediction section 216 corrects the pixel value after intra prediction based on the gradient of the reference pixels in the horizontal / vertical direction.

[0139] [Inter Prediction Unit] The inter prediction unit 218 predicts the current block by referring to the 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 performs motion compensation using motion information (e.g., motion vectors) decoded from the encoded bitstream to generate an inter prediction signal for the current block or sub-block, and outputs the inter prediction signal to the prediction control unit 220.

[0140] Note that when the information decoded 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.

[0141] Also, when the information decoded from the encoded 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) decoded from the encoded stream. Then, the inter prediction unit 218 performs motion compensation using the derived motion information.

[0142] In addition, the inter prediction unit 218 derives a motion vector based on a model assuming uniform linear motion when the BIO mode is applied. Also, when the information decoded from the encoded bitstream indicates that the affine motion compensation prediction mode is to be applied, the inter prediction unit 218 derives a motion vector in units of sub-blocks based on the motion vectors of a plurality of adjacent blocks.

[0143] [Prediction Control Unit] The prediction control unit 220 selects either the intra prediction signal or the inter prediction signal, and outputs the selected signal as a prediction signal to the addition unit 208.

[0144] Next, each aspect of block division in such an encoding device 100 and decoding device 200 will be specifically described with reference to the drawings. In the following, an encoding target block or a decoding target block is simply referred to as a block.

[0145] (First Aspect) FIG. 11 shows the encoding process performed by the encoding method and encoding device according to the first aspect.

[0146] In step S1001, a first cost is calculated from the first block encoding process. Here, the first block encoding process does not include dividing the block into a plurality of partitions, and the cost includes distortion. For example, the cost can be obtained by adding a value indicating encoding distortion and a value obtained by multiplying a value indicating the generated code amount by a Lagrange undetermined multiplier. The encoding distortion can be obtained based on, for example, the sum of absolute differences between the locally decoded image and the original image.

[0147] In step S1002, a second cost is calculated from the second block encoding process. Here, the second block encoding process includes a step of first dividing the block into two smaller partitions.

[0148] In step S1003, it is determined whether the first cost is lower than the second cost.

[0149] In step S1004, when it is determined that the first cost is lower than the second cost, the block encoding process is selected from the second set of block encoding processes. Here, the second set of block encoding processes does not include the third block encoding process, and the third block encoding process includes a step of first dividing the block into three smaller partitions.

[0150] FIG. 12 shows that when it is determined that the first cost is lower than all second costs, the second block encoding process set excludes a third block encoding process that includes a step of first dividing a block into three smaller partitions. The second block splitting process set is a subset of the first block splitting process set.

[0151] Specifically, in FIG. 12, when it is determined that the first cost is not lower than any second cost, block encoding processing is selected from a first block encoding processing set that includes third block encoding processing. On the other hand, when it is determined that the first cost is lower than all second costs, block encoding processing is selected from a second block encoding processing set obtained by excluding the third block encoding processing from the first block encoding processing set.

[0152] FIG. 13 shows other examples of the first cost having different binary tree depths. In the upper example, cost calculation is performed for the left partition obtained by vertically dividing the block into two partitions. In the lower example, cost calculation is performed for the upper sub-partition obtained by horizontally dividing the block into two partitions and then horizontally dividing the upper partition into two sub-partitions. In any example, when it is determined that the first cost is lower than all second costs, the second block encoding process set excludes a third block encoding process that has a step of first dividing the block into three smaller partitions. The second block splitting process set is a subset of the first block splitting process set.

[0153] In step S1005, when it is determined that the first cost is not lower than the second cost, block encoding processing is selected from the first block encoding processing set. Here, the first block encoding processing set includes at least the third block encoding processing.

[0154] In step S1006, the block is encoded using the selected block encoding processing.

[0155] [Effect of the First Aspect] This aspect reduces the total number of candidates for the partition structure on the encoding side and reduces the encoding complexity.

[0156] [Combination with Other Aspects] This aspect may be implemented in combination with at least a part of other aspects in this disclosure. Also, a part of the processing described in the flowchart of this aspect, a part of the configuration of the device, a part of the syntax, etc. may be implemented in combination with other aspects.

[0157] (Second Aspect) FIG. 14 shows the encoding process performed by the encoding method and encoding device according to the second aspect.

[0158] In step S2001, a first cost is calculated from the first block encoding process. Here, the first block encoding process includes dividing a block into only two smaller partitions. That is, in the first block encoding process, the block is divided into two partitions, and each partition is not further divided.

[0159] In step S2002, a second cost is calculated from the second block encoding process. Here, the second block encoding process includes a step of first dividing a block into two smaller partitions and a subsequent step of dividing it into three or more partitions.

[0160] Step S2003 is the same as step S1003.

[0161] Step S2004 is the same as step S1004.

[0162] FIG. 15 shows that when it is determined that any of the first costs is lower than all of the second costs, block encoding processing is selected from the second block encoding processing set. The second block encoding processing set excludes a third block encoding processing having a step of first dividing a block into three smaller partitions.

[0163] The second block encoding processing set is a subset of the first block encoding processing set. That is, the second block encoding processing set is obtained by excluding a predetermined encoding processing from the first block encoding processing set. At this time, the predetermined encoding processing includes at least the third block encoding processing.

[0164] Step S2005 is the same as step S1005.

[0165] Step S2006 is the same as step S1006.

[0166] [Effect of the second aspect] This aspect reduces the total number of candidates for the partition structure on the encoding side and reduces the encoding complexity.

[0167] [Combination with other aspects] This aspect may be implemented in combination with at least a part of other aspects in the present disclosure. Also, a part of the processing described in the flowchart of this aspect, a part of the configuration of the apparatus, a part of the syntax, etc. may be implemented in combination with other aspects.

[0168] (Third aspect) FIG. 16 shows the encoding processing performed by the encoding method and the encoding apparatus according to the third aspect.

[0169] In step S3001, at least a first gradient of a rectangular block is calculated in a first direction parallel to the long side of the rectangular block. Here, the calculation of the gradient includes at least a change having a directionality of intensity or color.

[0170] In step S3002, at least the second gradient of the rectangular block is calculated in the second direction. Here, the second direction is different from the first direction.

[0171] In step S3003, it is determined whether the first gradient is greater than the second gradient.

[0172] In step S3004, when it is determined that the first gradient is greater than the second gradient, block encoding processing is selected from the second block encoding processing set. Here, the second block encoding processing set does not include at least the first block encoding processing, and the first block encoding processing includes the step of first dividing a block into three smaller partitions in the first direction.

[0173] The second block encoding processing set is a subset of the first block encoding processing set. That is, the second block encoding processing set is obtained by excluding a predetermined encoding processing from the first block encoding processing set. At this time, the predetermined encoding processing includes at least the first block encoding processing.

[0174] FIG. 17 shows that when the vertical gradient of a rectangular block whose height is greater than its width is greater than the horizontal or diagonal gradient, the second block encoding processing set excludes the first block encoding processing that includes the step of first dividing the block into three smaller partitions in the vertical direction. That is, when the vertical gradient is greater than the horizontal or diagonal gradient, block encoding processing is selected from the second block encoding processing set from which the first block encoding processing has been excluded. Conversely, when the vertical gradient is not greater than the horizontal or diagonal gradient, block encoding processing is selected from the first block encoding processing set that includes the first block encoding processing.

[0175] FIG. 18 shows that when the horizontal gradient of a rectangular block whose width is greater than its height is greater than the vertical or diagonal gradient, the second block encoding process set excludes the first block encoding process that first horizontally divides the block into three smaller partitions. That is, when the horizontal gradient is greater than the vertical or diagonal gradient, the block encoding process is selected from the second block encoding process set excluding the first block encoding process. Conversely, when the horizontal gradient is not greater than the vertical or diagonal gradient, the block encoding process is selected from the first block encoding process set including the first block encoding process.

[0176] FIGS. 19A and 19B show examples of calculating the change in pixel intensity in the horizontal direction. The horizontal gradient is a calculation related to the change in intensity or color in the horizontal direction. Similarly, the vertical gradient can be calculated based on the change in intensity or color in the vertical direction. Similarly, the diagonal gradient can be calculated based on the change in intensity or color in the diagonal direction.

[0177] Specifically, in the example of FIG. 19A, first, the absolute value of the difference between two adjacent pixels in a horizontal pixel row is calculated. For example, in the first row, the absolute values of the differences h1_12 = abs(p1, p2), h1_23, h1_34 are calculated. Then, in each pixel row, the average of the absolute values of the differences (for example, the average of the absolute values of the differences in the first row H1 = average(h1_12 + h1_23 + h1_34)) is calculated. The horizontal gradient is calculated by calculating the average of the averages of the absolute values of the differences in a plurality of pixel columns calculated in this way (average(H1 + H2 + H3 + H4)).

[0178] Also, in the example of FIG. 19B, first, a one-dimensional filter is applied to three adjacent pixels in a horizontal pixel row. For example, using filter coefficients (-1, 2, -1), h1_123 (= 2×p2 - p1 - p3) and h1_234 are calculated. Then, in each pixel row, the average of the filtered values (for example, in the first row, H1 = average(h1_123 + h1_234)) is calculated. Further, a horizontal gradient is calculated by calculating the average (average(H1 + H2 + H3 + H4)) in a plurality of pixel rows.

[0179] The first gradient and the second gradient are not limited to only vertical / horizontal gradients. It can include gradients in other directions such as diagonals, or gradients in even other directions. The gradient calculations described in FIGS. 19A and 19B are merely examples, and other methods for gradient calculation may be applied.

[0180] In step S3005, when it is determined that the first gradient is not greater than the second gradient, block encoding processing is selected from the first set of block encoding processing. Here, the first set of block encoding processing includes the first block encoding processing.

[0181] In step S3006, the block is encoded using the selected block encoding processing.

[0182] [Effect of the Third Aspect] This aspect reduces the total number of candidates for the partition structure on the encoding side and reduces the complexity of encoding.

[0183] [Combination with Other Aspects] This aspect may be implemented in combination with at least a part of other aspects in the present disclosure. Also, a part of the processing described in the flowchart of this aspect, a part of the configuration of the device, a part of the syntax, etc. may be implemented in combination with other aspects.

[0184] (Fourth Aspect) FIG. 20 shows the encoding process performed by the encoding method and encoding device according to the fourth aspect.

[0185] In step S4001, it is determined whether the step of dividing the block in the first block encoding process generates a partition of half the size of the block.

[0186] In step S4002, when it is determined that the step of dividing the block in the first block encoding process generates a partition of half the size of the block, at least the gradient of the block is calculated.

[0187] In step S4003, a second block encoding process set is generated from the first block encoding process set by excluding at least the block encoding process that uses gradient information. The block encoding process excluded here includes at least the step of first dividing the block into three smaller partitions.

[0188] In step S4004, a block encoding process is selected from the second block encoding process set.

[0189] Figure 21(a) shows that when the block encoding process generates a sub-partition area that is half the area of the block and the horizontal gradient is larger than the vertical gradient, a block encoding process is selected from the second block encoding process set. The second encoding process set excludes the process of encoding a block having a plurality of partitions and the step of first dividing the block into three smaller partitions in the horizontal direction.

[0190] Figure 21(b) shows that when the block encoding process generates a sub-partition area that is half the area of the block and the vertical gradient is larger than the horizontal gradient, a block encoding process is selected from the second block encoding process set. The second encoding process set excludes the process of encoding a block having a plurality of partitions and the step of first dividing the block into three smaller partitions in the vertical direction.

[0191] In step S4005, when it is determined that the step of dividing the block in the first block encoding process does not generate a partition of half the size of the block, block encoding processing is selected from the first block encoding processing set.

[0192] In step S4006, the block is encoded using the selected block encoding processing.

[0193] [Effect of the Fourth Aspect] This aspect reduces the total number of candidates for the partition structure on the encoding side and reduces the complexity of encoding.

[0194] [Combination with Other Aspects] This aspect may be implemented in combination with at least a part of other aspects in the present disclosure. Also, a part of the processing described in the flowchart of this aspect, a part of the configuration of the apparatus, a part of the syntax, etc. may be implemented in combination with other aspects.

[0195] (Fifth Aspect) FIG. 22 shows the encoding processing performed by the encoding method and the encoding apparatus according to the fifth aspect.

[0196] In step S5001, the first side of the block is identified as the longer side of the two sides, and the second side of the block is identified as the side that is not the long side of the block.

[0197] In step S5002, when the block is divided into three or more smaller partitions, it is determined whether the block division in the direction parallel to the first side generates a partition of a size that is not supported in at least the prediction processing or the conversion processing.

[0198] In step S5003, when it is determined that block partitioning in a direction parallel to the first side generates partitions of a size that is not supported, at least, in the prediction process or the transformation process, the block is divided into smaller partitions in a direction parallel to the second side. FIG. 23A shows an example of dividing a 16×8 block into three smaller partitions in a direction parallel to the height of the 16×8 block (vertical direction) when the transformation for 16×2 is not implemented. FIG. 23B shows an example of dividing a 16×8 block into four smaller partitions in a direction parallel to the height of the 16×8 block (vertical direction) when the transformation for 16×2 is not implemented. Here, the size 16×2 is obtained by dividing the block in a direction parallel to the width of the block (horizontal direction). That is, in FIGS. 23A and 23B, dividing the block into three or four parts in the horizontal direction parallel to the first side (long side) is not permitted.

[0199] In step S5004, when it is not determined that block partitioning in a direction parallel to the first side generates partitions of a size that is not supported, at least, in the prediction process or the transformation process, the division direction parameter is written into the bit stream. Here, the division direction parameter indicates the division direction of the block and may indicate the horizontal or vertical direction. The position of the division direction parameter is shown in FIG. 31.

[0200] In step S5005, the block is divided into smaller partitions in the direction indicated by the division direction parameter.

[0201] In step S5006, the partition or the sub - partition of the partition is encoded.

[0202] Note that, for the terms "write" and "to (bitstream)" in step S5004 of the encoding process performed by the encoding method and the encoding apparatus, and the term "encode" in step S5006, they may be replaced with the terms "decode", "from (bitstream)", and "decode" for the decoding process performed by the decoding method and the image decoding apparatus.

[0203] [Effect of the Fifth Aspect] In this aspect, it is not necessary to encode the splitting direction with some specific block sizes, which improves the encoding efficiency. The present disclosure also reduces the total number of candidates for the splitting direction on the encoding side and reduces the complexity of encoding.

[0204] [Combination with Other Aspects] This aspect may be implemented in combination with at least a part of other aspects in the present disclosure. Also, a part of the processing described in the flowchart of this aspect, a part of the configuration of the apparatus, a part of the syntax, etc. may be implemented in combination with other aspects.

[0205] (Sixth Aspect) FIG. 24 shows the encoding process performed by the encoding method and the encoding apparatus according to the sixth aspect.

[0206] In step S6001, in each of a plurality of directions, it is determined whether block splitting into three smaller partitions generates partitions of sizes that are not supported in at least the prediction process or the transform process.

[0207] In step S6002, if it is determined in each of a plurality of directions that block splitting into three smaller partitions generates partitions of sizes that are not supported in at least the prediction process or the transform process, the block is split in one direction into two smaller partitions.

[0208] In step S6003, when it is determined that block splitting into three smaller partitions in at least one of a plurality of directions does not generate partitions of a size that is not supported in at least prediction processing or transformation processing, a parameter is written to the bitstream. Here, the parameter indicates the number of small partitions by splitting the block. Here, the parameter may be a split mode parameter. Here, the split mode parameter may indicate the number of sub-blocks having a predetermined split ratio for splitting the block. Also, the split mode parameter may indicate at least the number of splits of the block. The position of the split mode parameter is shown in FIG. 31.

[0209] In step S6004, the block is split in one direction into several partitions according to the parameter. The number can be 2 or 3.

[0210] Step S6005 is the same as step S5006.

[0211] FIG. 25A shows an example of candidates for partition structures for splitting a 16×16 block. FIG. 25B shows an example of candidates for partition structures for splitting an 8×8 block. As shown in FIG. 25A, there are four candidates for partition structures for splitting a 16×16 block. On the other hand, as shown in FIG. 25B, there are two candidates for partition structures for splitting an 8×8 block. In this example, since 8×2 and 2×8 are not supported in the transformation process, the partition structure that splits the 8×8 block into three smaller partitions along the horizontal and vertical directions is excluded from the candidates for the partition structure. That is, since the 8×2 and 2×8 sizes are not supported in the transformation process, splitting the 8×8 block into three 3 sub-blocks is not permitted.

[0212] Note that the terms "write" and "to (bitstream)" in step S6003 of the encoding process performed by the encoding method and the encoding apparatus, and the term "encode" in step S6005 may be replaced with the terms "decode", "from (bitstream)", and "decode" for the decoding process performed by the decoding method and the image decoding apparatus.

[0213] [Effect of the Sixth Aspect] In this aspect, it is not necessary to encode the splitting direction for some specific block sizes, improving the encoding efficiency. The present disclosure also reduces the total number of candidates for the splitting direction on the encoding side, reducing the complexity of encoding.

[0214] [Combination with Other Aspects] This aspect may be implemented in combination with at least a part of other aspects in the present disclosure. Also, some of the processes described in the flowchart of this aspect, some of the configurations of the apparatus, some of the syntax, etc. may be implemented in combination with other aspects.

[0215] (Seventh Aspect) FIG. 26 shows the encoding process performed by the encoding method and the encoding apparatus according to the seventh aspect.

[0216] In step S7001, the block is split into first to third sub-blocks in a first direction. In this aspect, as shown in FIG. 30, the splitting ratio for the three-way split is 1:2:1. Therefore, the second sub-block located between the first and third sub-blocks is larger in size than the first and third sub-blocks. Note that index values from 0 to 2 may be sequentially assigned to the first to third sub-blocks.

[0217] In step S7002, when the second sub-block is divided into a plurality of partitions, a division mode parameter is written into the bit stream to indicate the number of partitions. Here, as shown in FIG. 30, the division mode parameter may indicate the number of sub-blocks having a predetermined division ratio by dividing the block. Also, the division mode parameter may indicate only the number of sub-blocks. Further, the division mode parameter may indicate information different from the division ratio together with the number of sub-blocks. The position of the division mode parameter is shown in FIG. 31.

[0218] In step S7003, it is determined whether the division mode parameter indicates that the number of partitions is 2.

[0219] In step S7004, when it is determined that the division mode parameter indicates that the number of partitions is 2, the second sub-block is divided into two partitions in a second direction different from the first direction. That is, it is prohibited to divide the second sub-block into two partitions in the first direction. Therefore, the division direction parameter is not written into the bit stream. That is, writing of the division direction parameter into the bit stream is omitted (i.e., skipped).

[0220] FIG. 27 shows an example of a method for dividing a 32×32 block. In (a), the 32×32 block is first divided vertically into two sub-blocks, and then all the sub-blocks are divided vertically into two partitions. In (b), the 32×32 block is first divided vertically into three sub-blocks, and then the largest sub-block is divided into two partitions. Here, the division direction for dividing the largest sub-block is set to be parallel to the short side of the 16×32 block. That is, in (b), in the largest sub-block, horizontal division into two partitions is permitted, but vertical division is not permitted. Here, the largest sub-block corresponds to the second sub-block. This suppresses the occurrence of the same partition structure (also referred to as a repetitive partition structure) in the different division methods of (a) and (b).

[0221] In step S7005, when it is not determined that the division mode parameter indicates that the number of partitions is 2, the division direction parameter is written into the bit stream. Here, the division direction parameter indicates the division direction of the block, and as shown in FIG. 30, it may indicate the horizontal or vertical direction. The position of the division direction parameter is shown in FIG. 31.

[0222] In step S7006, the second sub-block is divided in the direction indicated by the division direction parameter into three or more partitions.

[0223] Step S7007 is the same as step S5006.

[0224] Note that the terms “write” and “into (the bit stream)” in steps S7002 and S7005 of the encoding process performed by the encoding method and the encoding apparatus, and the term “encode” in step S7007 may be replaced with the terms “decode”, “from (the bit stream)”, and “decode” for the decoding process performed by the decoding method and the image decoding apparatus.

[0225] Note that, as described above, the steps and the order of the steps are merely examples and are not limited thereto. Without departing from the spirit of the present disclosure, those skilled in the art may change the order of the steps as they can think of. For example, in FIG. 26, the division direction parameter may be written into the bit stream before the division mode parameter. That is, in FIG. 31, the positions of the division mode parameter and the division direction parameter in the bit stream may be interchanged. Also, in FIG. 26, the order of step S7002 and step S7005 may be interchanged.

[0226] In this case, when the second sub-block is divided into a plurality of partitions, first, the division direction parameter is written into the bit stream. Then, it is determined whether or not the division direction parameter indicates the first direction. Here, when the division direction parameter indicates the first direction, the second sub-block is divided into three partitions in the first direction. That is, it is prohibited to divide the second block into two partitions in the first direction. Therefore, the division mode parameter is not written into the bit stream. That is, the writing of the division mode parameter into the bit stream is omitted or skipped. On the other hand, when the division direction parameter indicates the second direction different from the first direction, the division mode parameter indicating the number of divisions of the second sub-block is written into the bit stream, and the second sub-block is divided into the number of partitions indicated by the division mode parameter in the second direction. Here, the division direction parameter is an example of a first parameter indicating the division direction of the second sub-block, and the division mode parameter is an example of a second parameter indicating the number of divisions of the second sub-block.

[0227] [Effect of the Seventh Aspect] This aspect does not require encoding the division direction or the number of divisions for some specific block sizes, improving the encoding efficiency. The present disclosure also reduces the total number of candidates for the division direction on the encoding side, reducing the complexity of encoding.

[0228] [Combination with Other Aspects] This aspect may be implemented in combination with at least a part of other aspects in the present disclosure. Also, some processes described in the flowchart of this aspect, some configurations of the apparatus, some syntax, etc. may be implemented in combination with other aspects.

[0229] (Eighth aspect) FIG. 28 shows the encoding process performed by the encoding method and encoding apparatus according to the eighth aspect.

[0230] In step S8001, the block is divided into first to third sub-blocks in a first direction.

[0231] In step S8002, it is determined whether each of the first and second sub-blocks is further divided into two smaller partitions in a second direction different from the first direction.

[0232] In step S8003, when it is determined that each of the first and second sub-blocks is further divided into two smaller partitions in a second direction different from the first direction, the third sub-block is divided into smaller partitions. When the third sub-block is divided into two partitions, the third sub-block is divided in the same direction as the first direction.

[0233] In step S8004, when it is not determined that each of the first and second sub-blocks is further divided into two smaller partitions in a second direction different from the first direction, a division direction parameter is written into the bit stream. Here, as shown in FIG. 30, the division direction parameter may indicate a horizontal or vertical direction. The position of the division direction parameter is shown in FIG. 31.

[0234] In step S8005, the first sub-block is divided in the direction indicated by the division direction parameter into smaller partitions.

[0235] Step S8006 is the same as step S5006.

[0236] Figure 29 shows an example of a method for dividing a 64×64 block. In (a), the 64×64 block is first divided vertically into two sub-blocks, and then all the sub-blocks are divided horizontally into three partitions. In (b), the 64×64 block is first divided horizontally into three sub-blocks, and then all the sub-blocks are divided into two partitions.

[0237] In (b), the direction for dividing the 64×64 block into the first to third sub-blocks is horizontal, and the direction for dividing the first two sub-blocks (i.e., the first and second sub-blocks) is vertical. The direction for dividing the third sub-block is horizontal in the same direction as the direction used for dividing the 64×64 block. That is, in (b), it is prohibited to divide the third sub-block vertically into two partitions. This suppresses the occurrence of the same partition structure in the different division methods of (a) and (b).

[0238] In step S8005, the first sub-block is divided into two partitions in the direction indicated by the division direction parameter.

[0239] Note that the terms "write" and "(to the bitstream)" in step S8004 of the encoding process performed by the encoding method and the encoding device, and the term "encode" in step S8006 may be replaced with the terms "decode", "(from the bitstream)", and "decode" for the decoding process performed by the decoding method and the image decoding device.

[0240] [Effect of the Eighth Aspect] This aspect does not require encoding the division direction for some specific block sizes, improving the encoding efficiency. The present disclosure also reduces the total number of candidates for the division direction on the encoding side, reducing the complexity of encoding.

[0241] [Combination with Other Aspects] This aspect may be implemented in combination with at least a part of other aspects in the present disclosure. Also, some processes described in the flowchart of this aspect, some configurations of the apparatus, some syntax, etc. may be implemented in combination with other aspects.

[0242] (Variant example) In all of the above aspects, one or more threshold values can be used to determine the number of smaller partitions and the partitioning direction for dividing the blocks. The threshold value can be adaptively changed according to the picture type, time layer, quantization parameter, pixel value activity within the slice, or according to a combination of partitioning patterns such as a combination of quadtree, binary tree, and other partitions, or according to a combination of other coding tools such as triangular partitioning. The threshold value can also be adaptively changed according to the block size such as block width, block height, or according to the multiplication of block width and block height. The threshold value can also be adaptively changed according to the block shape and / or partitioning depth.

[0243] Note that the positions of the partitioning mode parameter and the partitioning direction parameter are not limited to the positions in FIG. 31. That is, the signaling of the partitioning mode parameter and the partitioning direction parameter does not necessarily have to be limited to the CTU level and may be at other levels (for example, picture level, slice level, tile group level, or tile level).

[0244] Note that a parameter indicating whether to divide a block into two or three sub-blocks or partitions may be written into the bitstream. In this case, when the parameter indicates that the block is divided into two or three sub-blocks or partitions, the encoding method or decoding method according to each of the above aspects may be applied.

[0245] (Other aspects) In each of the above embodiments, each of the functional blocks can usually be realized by an MPU, a memory, etc. Further, the processing by each of the functional blocks is usually realized by a program execution unit such as a processor reading and executing software (program) recorded on a recording medium such as a ROM. The software may be distributed by download or the like, or may be recorded on a recording medium such as a semiconductor memory and distributed. Of course, it is also possible to realize each functional block by hardware (a dedicated circuit).

[0246] Also, 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 a plurality of devices. Further, the processor that executes the above program may be singular or plural. That is, centralized processing may be performed, or distributed processing may be performed.

[0247] Aspects of the present disclosure are not limited to the above examples, and various modifications are possible, and these are also included within the scope of the aspects of the present disclosure.

[0248] Furthermore, here, an application example of the moving image encoding method (image encoding method) or the moving image decoding method (image decoding method) shown in each of the above embodiments and a system using the same will be described. The system is characterized by having an image encoding device using an image encoding method, an image decoding device using an image decoding method, and an image encoding / decoding device having both. Other configurations in the system can be appropriately changed as the case may be.

[0249] [Usage Example] FIG. 32 is a diagram showing the overall configuration of a content supply system ex100 that realizes a content distribution service. The communication service providing area is divided into a desired size, and base stations ex106, ex107, ex108, ex109, ex110, which are fixed radio stations, are installed in each cell.

[0250] In this content supply system ex100, devices such as computer ex111, game console ex112, camera ex113, home appliances ex114, and smartphone ex115 are connected to the Internet ex101 via Internet service provider ex102 or communication network ex104, and base stations ex106 - ex110. The content supply system ex100 may be connected by combining any of the above elements. The devices may be directly or indirectly connected to each other via a telephone network or short - range wireless, etc., without passing through base stations ex106 - ex110 which are fixed radio stations. Also, streaming server ex103 is connected to devices such as computer ex111, game console ex112, camera ex113, home appliances ex114, and smartphone ex115 via Internet ex101, etc. Further, streaming server ex103 is connected to terminals, etc. within a hotspot in airplane ex117 via satellite ex116.

[0251] Note that a wireless access point or hotspot, etc. may be used instead of base stations ex106 - ex110. Also, streaming server ex103 may be directly connected to communication network ex104 without passing through Internet ex101 or Internet service provider ex102, or may be directly connected to airplane ex117 without passing through satellite ex116.

[0252] Camera ex113 is a device capable of taking still pictures and videos such as a digital camera. Also, smartphone ex115 is a smartphone device, mobile phone, or PHS (Personal Handyphone System), etc. that generally supports the mobile communication system methods called 2G, 3G, 3.9G, 4G, and in the future 5G.

[0253] Home appliances ex118 are devices such as refrigerators or devices included in a household fuel cell cogeneration system.

[0254] In the content supply system ex100, a terminal having a photographing function is connected to a streaming server ex103 through a base station ex106 or the like, enabling live distribution and the like. In live distribution, terminals (such as a computer ex111, a game machine ex112, a camera ex113, a household appliance ex114, a smartphone ex115, and a terminal in an airplane ex117) perform the encoding process described in each of the above embodiments on still image or moving image content photographed by a user using the terminal, multiplex the video data obtained by encoding with audio data obtained by encoding the sound corresponding to the video, and transmit 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.

[0255] On the other hand, the streaming server ex103 stream-distributes the content data transmitted to a requested client. The client is a computer ex111, a game machine ex112, a camera ex113, a household appliance ex114, a smartphone ex115, or a terminal in an airplane ex117 that can decode the encoded data. Each device that has received the distributed data decodes and reproduces the received data. That is, each device functions as an image decoding device according to one aspect of the present disclosure.

[0256] [Distributed Processing] In addition, the streaming server ex103 may be a plurality of servers or a plurality of computers that distribute, process, record, and deliver data. For example, the streaming server ex103 may be implemented by a CDN (Content Delivery Network), and content delivery may be realized by a network connecting a large number of edge servers distributed around the world and the edge servers. In a CDN, a physically closer edge server is dynamically assigned according to the client. Then, by caching and delivering the content to the edge server, the delay can be reduced. Also, when some error occurs or the communication state changes due to an increase in traffic, etc., the processing can be distributed among multiple edge servers, the delivery entity can be switched to another edge server, or the part of the network with a failure can be bypassed to continue the delivery, so high-speed and stable delivery can be realized.

[0257] Moreover, not only the distributed processing of the delivery itself, but also the encoding process of the captured data may be performed on each terminal, on the server side, or shared between them. As an example, generally in the encoding process, the processing loop is performed twice. In the first loop, the complexity of the image in units of frames or scenes, or the amount of code is detected. Also, in the second loop, a process of improving the encoding efficiency while maintaining the image quality is performed. For example, by having the terminal perform the first encoding process and the server side that receives the content perform the second encoding process, it is possible to improve the quality and efficiency of the content while reducing the processing load on each terminal. In this case, if there is a requirement to receive and decode in almost real time, since the first encoded data performed by the terminal can be received and played back by other terminals, more flexible real-time delivery becomes possible.

[0258] As another example, cameras such as ex113 perform feature extraction from images, compress data related to the features as metadata, and transmit it to the server. The server performs compression according to the meaning of the image, for example, determines the importance of the object from the features and switches the quantization accuracy. Feature data is particularly effective in improving the accuracy and efficiency of motion vector prediction during re-compression on the server. Also, simple encoding such as VLC (Variable Length Coding) may be performed on the terminal, and encoding with a large processing load such as CABAC (Context Adaptive Binary Arithmetic Coding) may be performed on the server.

[0259] As yet another example, in a stadium, shopping mall, factory, etc., there may be a plurality of video data in which substantially the same scene is captured by a plurality of terminals. In this case, using the plurality of terminals that have performed the shooting, and other terminals and servers that have not performed the shooting as necessary, encoding processing is respectively assigned and distributed processing is performed, for example, in units of GOP (Group of Picture), picture units, or tile units obtained by dividing the picture. This can reduce the delay and achieve more real-time performance.

[0260] Also, since the plurality of video data are of substantially the same scene, the server may manage and / or give instructions so that the video data captured by each terminal can refer to each other. Alternatively, the encoded data from each terminal may be received by the server, and the reference relationship may be changed between the plurality of data, or the picture itself may be corrected or replaced and re-encoded. This can generate a stream with improved quality and efficiency for each piece of data.

[0261] Also, the server may perform transcoding to change the encoding method of the video data and then distribute the video data. For example, the server may convert an MPEG-based encoding method to a VP-based method, or convert H.264 to H.265.

[0262] In this way, the encoding process can be performed by a terminal or one or more servers. Therefore, hereinafter, descriptions such as "server" or "terminal" will be used as the entity performing the process, but part or all of the processes performed by the server may be performed by the terminal, or part or all of the processes performed by the terminal may be performed by the server. Also, regarding these, the same applies to the decoding process.

[0263] [3D, Multi-angle] In recent years, it has also become increasingly common to integrate and utilize different scenes photographed by terminals such as a plurality of cameras ex113 and / or smartphones ex115 that are substantially synchronized with each other, or images or videos of the same scene photographed from different angles. The videos photographed by each terminal are integrated based on the relative positional relationship between the terminals obtained separately, or the regions where the feature points included in the videos match.

[0264] The server may not only encode a two-dimensional moving image, but also automatically or at a time specified by the user, encode a still image based on scene analysis of the moving image, etc., and transmit it to the receiving terminal. When the server can further obtain the relative positional relationship between the photographing terminals, it can generate the three-dimensional shape of the scene based on not only the two-dimensional moving image but also the videos of the same scene photographed from different angles. Note that the server may separately encode the three-dimensional data generated by a point cloud or the like, or select or reconstruct the video to be transmitted to the receiving terminal from the videos photographed by a plurality of terminals based on the results of recognizing or tracking a person or an object using the three-dimensional data.

[0265] In this way, the user can arbitrarily select each video corresponding to each photographing terminal to enjoy the scene, or can also enjoy the content obtained by cutting out a video from an arbitrary viewpoint from the three-dimensional data reconstructed using a plurality of images or videos. Furthermore, similar to the video, sound is also collected from a plurality of different angles, and the server may multiplex and transmit the sound from a specific angle or space together with the video according to the video.

[0266] In recent years, content that associates the real world with the virtual world, such as Virtual Reality (VR) and Augmented Reality (AR), has also become popular. In the case of VR images, the server may create viewpoint images for the right eye and the left eye respectively, and perform encoding that allows reference between each viewpoint video by means of Multi-View Coding (MVC) or the like, or may perform encoding as separate streams without referring to each other. At the time of decoding the separate streams, they may be reproduced in synchronization with each other so that a virtual three-dimensional space is reproduced according to the user's viewpoint.

[0267] In the case of AR images, the server superimposes virtual object information in the virtual space on the camera information of the real space based on the three-dimensional position or the movement of the user's viewpoint. The decoding device may acquire or hold the virtual object information and the three-dimensional data, generate a two-dimensional image according to the movement of the user's viewpoint, and create superimposed data by smoothly connecting them. Alternatively, in addition to requesting the virtual object information, the decoding device may transmit the movement of the user's viewpoint to the server, and the server may create superimposed data according to the received movement of the viewpoint from the three-dimensional data held by the server, encode the superimposed data, and distribute it to the decoding device. Note that the superimposed data has an α value indicating transparency in addition to RGB, and the server may set the α value of the portion other than the object created from the three-dimensional data to 0 or the like and perform encoding in a state where the portion is transparent. Or, the server may set an RGB value of a predetermined value as the background like chroma key and generate data with the portion other than the object being the background color.

[0268] The decoding process of the data delivered in the same way may be performed on each client terminal, on the server side, or may be shared between them. As an example, a certain terminal may once send a reception request to the server, and the content corresponding to the request may be received by another terminal and decoded, and the decoded signal may be transmitted to a device having a display. By dispersing the processing regardless of the performance of the communicable terminals themselves and selecting appropriate content, it is possible to reproduce high-quality data. As another example, while receiving large-size image data on a TV or the like, only a part of the area such as tiles in which the picture is divided may be decoded and displayed on the viewer's personal terminal. Thereby, while sharing the overall image, it is possible to check at hand the area of one's own field of responsibility or the area that one wants to check in more detail.

[0269] In the future, regardless of indoors or outdoors, in a situation where multiple short-range, medium-range, or long-range wireless communications can be used, it is expected to receive content seamlessly while switching appropriate data for the ongoing communication using a delivery system standard such as MPEG-DASH. As a result, the user can switch in real time while freely selecting not only their own terminal but also a decoding device or a display device such as a display installed indoors and outdoors. Also, based on their own location information or the like, decoding can be performed while switching the terminal to be decoded and the terminal to be displayed. Thereby, it becomes possible to move while displaying map information on a part of the wall surface or the ground of the adjacent building in which a displayable device is embedded during the movement to the destination. Also, based on the ease of access to the encoded data on the network, such as the encoded data being cached in a server that can be accessed from the receiving terminal in a short time, or being copied to an edge server in a content delivery service, it is also possible to switch the bit rate of the received data.

[0270] [Scalable Encoding] Regarding content switching, an explanation will be given using a scalable stream that is compression-encoded by applying the moving image encoding method shown in each of the above embodiments and shown in FIG. 33. The server may have a plurality of streams with the same content but different qualities as individual streams, but it may also be configured to switch content by taking advantage of the characteristics of a temporally / spatially scalable stream realized by encoding in layers as shown in the figure. That is, by the decoder determining up to which layer to decode according to internal factors such as performance and external factors such as the state of the communication bandwidth, the decoder can freely switch between low-resolution content and high-resolution content for decoding. For example, when you want to watch the continuation of a video that you were watching on smartphone ex115 while moving on a device such as an Internet TV after returning home, the device only needs to decode the same stream to a different layer, thus reducing the burden on the server side.

[0271] Furthermore, as described above, in addition to the configuration that realizes scalability in which pictures are encoded layer by layer and an enhancement layer exists above the base layer, the enhancement layer may include meta information based on statistical information of the image, and the decoder may generate high-quality content by super-resolving the pictures of the base layer based on the meta information. Super-resolution may be either an improvement in the signal-to-noise ratio at the same resolution or an increase in resolution. The meta information includes information for specifying linear or non-linear filter coefficients used in super-resolution processing, or information for specifying parameter values in filter processing, machine learning, or least-squares operations used in super-resolution processing.

[0272] Alternatively, the picture may be divided into tiles or the like according to the meaning of objects or the like in the image, and the decoding side may decode only a part of the area by selecting the tile to be decoded. Also, by storing the attributes of the object (such as a person, a car, a ball, etc.) and the position in the video (such as the coordinate position in the same image) as meta information, the decoding side can identify the position of the desired object based on the meta information and determine the tile including the object. For example, as shown in FIG. 34, the meta information is stored using a data storage structure different from pixel data such as the SEI message in HEVC. This meta information indicates, for example, the position, size, or color of the main object.

[0273] Also, the meta information may be stored in units composed of a plurality of pictures, such as a stream, a sequence, or a random access unit. Thereby, the decoding side can obtain the time when a specific person appears in the video, etc., and by combining with the information in picture units, identify the picture in which the object exists and the position of the object in the picture.

[0274] [Optimization of Web Page] FIG. 35 is a diagram showing an example of a display screen of a web page on a computer ex111 or the like. FIG. 36 is a diagram showing an example of a display screen of a web page on a smartphone ex115 or the like. As shown in FIGS. 35 and 36, the web page may include a plurality of link images that are links to image contents, and the appearance thereof varies depending on the device for viewing. When a plurality of link images are visible on the screen, until the user explicitly selects a link image, or until the link image approaches the vicinity of the center of the screen or the entire link image enters the screen, the display device (decoding device) displays a still image or an I picture that each content has as a link image, displays a video like a gif animation with a plurality of still images or I pictures, etc., or receives only the base layer and decodes and displays the video.

[0275] When a user selects a linked image, the display device decodes the base layer with the highest priority. If there is information indicating that the HTML constituting the web page is scalable content, the display device may decode up to the enhancement layer. Also, in order to ensure real-time performance, before selection or when the communication bandwidth is very strict, the display device can reduce the delay (the delay from the start of content decoding to the start of display) between the decoding time and the display time of the leading picture by decoding and displaying only forward reference pictures (I pictures, P pictures, B pictures with only forward reference). Further, the display device may deliberately ignore the reference relationship of pictures, coarsely decode all B pictures and P pictures as forward references, and perform normal decoding as the received pictures increase over time.

[0276] [Autonomous Driving] Also, when transmitting and receiving still image or video data such as two-dimensional or three-dimensional map information for the autonomous driving or driving support of a vehicle, in addition to the image data belonging to one or more layers, the receiving terminal may also receive weather or construction information, etc. as meta information, and decode them in association with each other. Note that the meta information may belong to a layer or may simply be multiplexed with the image data.

[0277] In this case, since a vehicle, drone, airplane, etc. including the receiving terminal moves, the receiving terminal can achieve seamless reception and decoding by transmitting the position information of the receiving terminal at the time of a reception request while switching between base stations ex106 to ex110. Also, the receiving terminal can dynamically switch how much meta information to receive or how much to update the map information according to the user's selection, the user's situation, or the state of the communication bandwidth.

[0278] As described above, in the content supply system ex100, the client can receive, decode, and play back the encoded information transmitted by the user in real time.

[0279] [Delivery of Personal Content] In addition, in the content supply system ex100, not only high-quality and long-duration content by video distributors but also unicast or multicast distribution of low-quality and short-duration content by individuals is possible. Also, it is considered that such individual content will increase in the future. In order to make individual content into better content, the server may perform encoding processing after performing editing processing. This can be realized, for example, in the following configuration.

[0280] At the time of shooting in real time or accumulating and after shooting, the server performs recognition processing such as shooting error, scene search, semantic analysis, and object detection from the original image or encoded data. Then, based on the recognition result, the server manually or automatically corrects out-of-focus or camera shake, deletes less important scenes such as a scene with lower brightness or out-of-focus compared to other pictures, emphasizes the edges of the object, or changes the color tone. The server encodes the edited data based on the editing result. Also, it is known that the viewing rate decreases if the shooting time is too long. The server may automatically clip not only less important scenes but also scenes with little movement within a specific time range according to the shooting time so as to be content within that range, based on the image processing result. Alternatively, the server may generate and encode a digest based on the result of semantic analysis of the scene.

[0281] Note that there are cases where personal content contains elements that, as they are, would infringe on copyright, moral rights of the author, or portrait rights, etc., and there may be inconveniences for individuals, such as the sharing scope exceeding the intended scope. Therefore, for example, the server may deliberately change and encode an image so that the face of a person in the peripheral part of the screen or the inside of a house is out of focus. Also, the server may recognize whether a face of a person different from the pre-registered person appears in the image to be encoded, and if it does, perform processing such as applying a mosaic to the face part. Or, as pre-processing or post-processing of encoding, from the perspective of copyright, etc., the user designates a person or background area that the user wants to process the image, and the server can perform processing such as replacing the designated area with another video or blurring the focus. In the case of a person, the video of the face part can be replaced while tracking the person in the moving image.

[0282] Also, since the viewing of personal content with a small data volume has a strong requirement for real-time performance, depending on the bandwidth, the decoding device first receives the base layer with the highest priority and decodes and plays it. During this time, the decoding device receives the enhancement layer, and when the playback is looped or played two or more times, it may play a high-quality video including the enhancement layer. For a stream with scalable encoding like this, it provides an experience where the video is rough when not selected or at the beginning of viewing, but gradually becomes smarter and the image quality improves. In addition to scalable encoding, a similar experience can be provided even if a rough stream played for the first time and a second stream encoded with reference to the first video are configured as one stream.

[0283] [Other usage examples] Also, these encoding or decoding processes are generally processed in the LSIex500 possessed by each terminal. The LSIex500 may be a one-chip configuration or a configuration consisting of multiple chips. In addition, software for moving image encoding or decoding may be incorporated into some recording medium (such as a CD-ROM, flexible disk, or hard disk) readable by a computer ex111 or the like, and encoding or decoding processing may be performed using the software. Further, when the smartphone ex115 has a camera, video data acquired by the camera may be transmitted. The video data at this time is data encoded by the LSIex500 possessed by the smartphone ex115.

[0284] Note that the LSIex500 may be configured to download and activate application software. In this case, the terminal first determines whether the terminal supports the encoding method of the content or has the ability to execute a specific service. If the terminal does not support the encoding method of the content or does not have the ability to execute a specific service, the terminal downloads the codec or application software and then acquires and plays the content.

[0285] Also, not limited to the content supply system ex100 via the Internet ex101, at least one of the moving image encoding device (image encoding device) or the moving image decoding device (image decoding device) of the above-described embodiments can be incorporated into a digital broadcast system. Since multiplexed data in which video and audio are multiplexed is carried on broadcast radio waves using a satellite or the like for transmission and reception, there is a difference in that it is more suitable for multicast compared to the unicast-friendly configuration of the content supply system ex100, but the same application is possible for encoding and decoding processing.

[0286] [Hardware Configuration] FIG. 37 is a diagram showing a smartphone ex115. Further, FIG. 38 is a diagram showing a configuration example of the smartphone ex115. The smartphone ex115 includes an antenna ex450 for transmitting and receiving radio waves to and from a base station ex110, a camera unit ex465 capable of capturing video and still images, and a display unit ex458 for displaying data obtained by decoding video captured by the camera unit ex465, video received by the antenna ex450, and the like. 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 audio or sound, an audio input unit ex456 such as a microphone for inputting audio, a memory unit ex467 capable of storing captured video or still images, recorded audio, received video or still images, encoded data such as emails, or decoded data, and a slot unit ex464 which is an interface unit with a SIM ex468 for identifying the user and authenticating access to various data including the network. Note that an external memory may be used instead of the memory unit ex467.

[0287] Also, a main control unit ex460 that comprehensively controls the display unit ex458, the operation unit ex466, and the like, 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 / demultiplexing unit ex453, an audio signal processing unit ex454, a slot unit ex464, and a memory unit ex467 are connected via a bus ex470.

[0288] When the power key is turned on by a user operation, the power supply circuit unit ex461 starts the smartphone ex115 in an operable state by supplying power from a battery pack to each unit.

[0289] The smartphone ex115 performs processes such as calls and data communication based on the control of the main control unit ex460 having a CPU, ROM, RAM, etc. During a call, the voice signal picked up by the voice input unit ex456 is converted into a digital voice signal by the voice signal processing unit ex454, spectrally spread by the modulation / demodulation unit ex452, and after performing digital-to-analog conversion processing and frequency conversion processing by the transmission / reception unit ex451, it is transmitted via the antenna ex450. Also, the received data is amplified, frequency conversion processing and analog-to-digital conversion processing are performed, inverse spectral spreading processing is performed by the modulation / demodulation unit ex452, and after being converted into an analog voice signal by the voice signal processing unit ex454, it is output from the voice output unit ex457. In the data communication 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 of the main body unit, and the same 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 compresses and encodes the video signal stored in the memory unit ex467 or the video signal input from the camera unit ex465 by the moving image encoding method shown in each of the above embodiments, and sends the encoded video data to the multiplexing / demultiplexing unit ex453. Also, the voice signal processing unit ex454 encodes the voice signal picked up by the voice input unit ex456 while a video or still image is being captured by the camera unit ex465, and sends the encoded voice data to the multiplexing / demultiplexing unit ex453. The multiplexing / demultiplexing unit ex453 multiplexes the encoded video data and the encoded voice data in a predetermined manner, performs modulation processing and conversion processing by the modulation / demodulation unit (modulation / demodulation circuit unit) ex452 and the transmission / reception unit ex451, and transmits it via the antenna ex450.

[0290] When receiving a video attached to an email or chat, or a video linked to a web page or the like, in order to decode the multiplexed data received via the antenna ex450, the multiplexing / demultiplexing unit ex453 separates the multiplexed data into a bit stream of video data and a bit stream of audio data by separating the multiplexed data, 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 by a moving image decoding method corresponding to the moving image encoding method shown in each of the above embodiments, and a video or a still image included in the linked moving image file is displayed from the display unit ex458 via the display control unit ex459. Also, the audio signal processing unit ex454 decodes the audio signal, and audio is output from the audio output unit ex457. Since real-time streaming has become widespread, depending on the user's situation, there may be a situation where it is not socially appropriate to play audio. Therefore, as an initial value, it is desirable to have a configuration that plays only video data without playing the audio signal. The audio may be played synchronously only when the user performs an operation such as clicking on the video data.

[0291] Also, although the smartphone ex115 has been described as an example here, as the terminal, in addition to the transceiver type terminal having both an encoder and a decoder, there are three possible implementation forms: a transmitting terminal having only an encoder and a receiving terminal having only a decoder. Furthermore, in the digital broadcast system, although it has been described as receiving or transmitting multiplexed data in which audio data and the like are multiplexed in video data, in the multiplexed data, character data related to the video or the like may be multiplexed in addition to the audio data, or the video data itself may be received or transmitted instead of the multiplexed data.

[0292] Although the main control unit ex460 including the CPU has been described as controlling the encoding or decoding process, many terminals also have a GPU. Therefore, a configuration in which a wide area is processed in a batch by taking advantage of the performance of the GPU using a memory shared by the CPU and the GPU or a memory whose address is managed so as to be commonly used may be adopted. As a result, the encoding time can be shortened, real-time performance can be ensured, and low latency can be achieved. In particular, it is efficient to perform the processes of motion search, deblocking filter, SAO (Sample Adaptive Offset), and transform / quantization in units such as pictures using the GPU instead of the CPU.

Industrial Applicability

[0293] The present disclosure can be applied to, for example, a television receiver, a digital video recorder, a car navigation system, a mobile phone, a digital camera, or a digital video camera.

Explanation of Signs

[0294] 100 Encoding device 102 Division unit 104 Subtraction unit 106 Transformation unit 108 Quantization unit 110 Entropy encoding unit 112, 204 Inverse quantization unit 114, 206 Inverse transformation unit 116, 208 Addition unit 118, 210 Block memory 120, 212 Loop filter unit 122, 214 Frame memory 124, 216 Intra prediction unit 126, 218 Inter prediction unit 128, 220 Prediction control unit 200 Decoding device 202 Entropy decoding unit

Claims

**Claim 1** A circuit and a memory, wherein the circuit uses the memory to divide an encoding target block into a first sub-block, a second sub-block, and a third sub-block in a first direction, and the second sub-block is located between the first sub-block and the third sub-block; prohibit dividing the second sub-block into two partitions in the first direction, and do not prohibit dividing the second sub-block into three partitions in the first direction; encode the first sub-block, the second sub-block, and the third sub-block; generate a bit stream including the encoded encoding target block; transmit the generated bit stream. A transmitting device. **Claim 2** Divide an encoding target block into a first sub-block, a second sub-block, and a third sub-block in a first direction, and the second sub-block is located between the first sub-block and the third sub-block; Prohibit dividing the second sub-block into two partitions in the first direction, and do not prohibit dividing the second sub-block into three partitions in the first direction; Encode the first sub-block, the second sub-block, and the third sub-block; Generate a bit stream including the encoded encoding target block; Transmit the generated bit stream. A transmitting method.

Images