Image encoding device, encoding method, image decoding device, decoding method, bitstream transmission device, and bitstream transmission method

Abstract

To provide an image encoding device capable of improving compression efficiency in coding block division information.SOLUTION: An image encoding device is configured to acquire a block from a coding tree unit (CTU), divide the block into multiple subblocks in a first direction by using a first partition mode, and encode the multiple subblocks, and in the block division using the first partition mode, on the basis of partition mode parameters written to the bitstream, when the size of a block is Nx2N pixels, the first direction is along 2N pixels, and N is an integer, select block division into multiple subblocks including at least one subblock of N / 4x2N pixel size, and not select block division into two subblocks of N / 4x2N pixel size.SELECTED DRAWING: Figure 15

Description

[Technical Field]

[0001] The present disclosure relates to methods and apparatus for encoding and decoding video and images using block partitioning. [Background technology]

[0002] In traditional image and video coding methods, images are typically divided into blocks, and encoding and decoding processes are performed at the block level. Recent video standard developments allow encoding and decoding processes with various block sizes in addition to the typical 8x8 or 16x16 sizes. A range of sizes from 4x4 to 256x256 can be used for image encoding and decoding processes. [Prior art documents] [Non-patent literature]

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

[0004] To represent a range of sizes from 4x4 to 256x256, block partition information such as block partition mode (e.g., quadtree, binary tree, and ternary tree) and partition flag (e.g., split flag) is determined and signaled for the block. The signaling overhead increases as the partition depth increases, and the increased overhead reduces video compression efficiency.

[0005] Therefore, an encoding device according to one aspect of the present disclosure provides an encoding device or the like that can improve compression efficiency in encoding block division information. [Means for solving the problem]

[0006] An image encoding device according to an aspect of the present disclosure includes: a memory coupled to a circuit; and the circuit, in operation, obtains a block from a coding tree unit (CTU), divides the block into a plurality of sub-blocks in a first direction using a first partition mode, encodes the plurality of sub-blocks, and writes the sub-blocks into a bitstream in the division of the block using the first partition mode. , arranged in the coding tree unit Based on the parameters, if the size of the block is Nx2N pixels, the first direction is along 2N pixels, and N is an integer, select to divide the block into a plurality of sub-blocks including at least one sub-block of size N / 4x2N pixels, and do not select to divide the block into two sub-blocks of size N / 2x2N pixels; if the size of the block is 2NxN pixels, the first direction is along 2N pixels, and N is an integer, select to divide the block into a plurality of sub-blocks including at least one sub-block of size 2NxN / 4 pixels, and do not select to divide the block into two sub-blocks of size 2NxN / 2 pixels.

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

[0008] According to the present disclosure, it is possible to improve compression efficiency in encoding block division information. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a block diagram showing a functional configuration of a coding device according to the first embodiment. [Figure 2] FIG. 2 is a diagram showing an example of block division according to the first embodiment. [Figure 3]FIG. 3 is a table showing the transformation basis functions corresponding to each transformation type. [Figure 4A] FIG. 4A is a diagram showing an example of the shape of a filter used in ALF. [Figure 4B] FIG. 4B is a diagram showing another example of the shape of the filter used in ALF. [Figure 4C] FIG. 4C is a diagram showing another example of the shape of the filter used in ALF. [Figure 5A] FIG. 5A is a diagram showing 67 intra prediction modes in intra prediction. [Figure 5B] FIG. 5B is a flowchart for explaining an outline of the predicted image correction process using the OBMC process. [Figure 5C] FIG. 5C is a conceptual diagram for explaining an outline of the predicted image correction process using the OBMC process. [Figure 5D] FIG. 5D is a diagram showing an example of FRUC. [Figure 6] FIG. 6 is a diagram for explaining pattern matching (bilateral matching) between two blocks along a motion trajectory. [Figure 7] FIG. 7 is a diagram for explaining pattern matching (template matching) between a template in a current picture and a block in a reference picture. [Figure 8] FIG. 8 is a diagram for explaining a model assuming uniform linear motion. [Figure 9A] FIG. 9A is a diagram for explaining derivation of a motion vector for each sub-block based on motion vectors of a plurality of adjacent blocks. [Figure 9B] FIG. 9B is a diagram for explaining an outline of the motion vector derivation process in the merge mode. [Figure 9C] FIG. 9C is a conceptual diagram for explaining an outline of the DMVR process. [Figure 9D] FIG. 9D is a diagram for explaining an outline of a predicted image generation method using luminance correction processing by LIC processing. [Figure 10]FIG. 10 is a block diagram showing a functional configuration of a decoding device according to the first embodiment. [Figure 11] FIG. 11 is a flowchart showing a video encoding process according to the second embodiment. [Figure 12] FIG. 12 is a flowchart showing a video decoding process according to the second embodiment. [Figure 13] FIG. 13 is a flowchart showing a video encoding process according to the third embodiment. [Figure 14] FIG. 14 is a flowchart showing a video decoding process according to the third embodiment. [Figure 15] FIG. 15 is a block diagram showing a structure of a video / image coding device according to the second or third embodiment. [Figure 16] FIG. 16 is a block diagram showing a structure of a video / image decoding device according to the second or third embodiment. [Figure 17] FIG. 17 shows examples of possible locations of the first parameter in a compressed video stream according to the second or third embodiment. [Figure 18] FIG. 18 shows examples of possible locations of the second parameter in the compressed video stream according to the second or third embodiment. [Figure 19] FIG. 19 is a diagram showing an example of a second parameter following a first parameter in the second or third embodiment. [Figure 20] FIG. 20 is a diagram showing an example in which the second partition mode is not selected for division into blocks of 2NxN pixels as shown in step (2c) in the second embodiment. [Figure 21] FIG. 21 is a diagram showing an example in which the second partition mode is not selected for division into blocks of Nx2N pixels as shown in step (2c) in the second embodiment. [Figure 22] FIG. 22 is a diagram showing an example in which the second partition mode is not selected for division into blocks of NxN pixels as shown in step (2c) in the second embodiment. [Figure 23]FIG. 23 is a diagram showing an example in which the second partition mode is not selected for division into blocks of NxN pixels as shown in step (2c) in the second embodiment. [Figure 24] FIG. 24 is a diagram showing an example of dividing a block of 2NxN pixels using the partition mode selected when the second partition mode is not selected, as shown in step (3) in the second embodiment. [Figure 25] FIG. 25 is a diagram showing an example of dividing a block of Nx2N pixels using the partition mode selected when the second partition mode is not selected, as shown in step (3) in the second embodiment. [Figure 26] FIG. 26 is a diagram showing an example of dividing a block of N×N pixels using the partition mode selected when the second partition mode is not selected, as shown in step (3) in the second embodiment. [Figure 27] FIG. 27 is a diagram showing an example of dividing a block of NxN pixels using the partition mode selected when the second partition mode is not selected, as shown in step (3) in the second embodiment. [Figure 28] 28A to 28H are diagrams showing examples of partition modes for dividing a block of NxN pixels in Embodiment 2. (a) to (h) show different partition modes. [Figure 29] 29 is a diagram showing an example of partition types and partition directions for dividing an NxN pixel block in embodiment 3. (1), (2), (3), and (4) are different partition types, (1a), (2a), (3a), and (4a) are partition modes with different partition types in the vertical partition direction, and (1b), (2b), (3b), and (4b) are partition modes with different partition types in the horizontal partition direction. [Figure 30]FIG. 30 is a diagram showing an advantage of encoding the partition type before the partition direction compared to encoding the partition direction before the partition type in the third embodiment. [Figure 31A] FIG. 31A is a diagram showing an example of dividing a block into sub-blocks using a partition mode set with a smaller number of bins in partition mode encoding. [Figure 31B] FIG. 31B is a diagram showing an example of dividing a block into sub-blocks using a partition mode set with a smaller number of bins in partition mode encoding. [Figure 32A] FIG. 32A is a diagram showing an example of dividing a block into sub-blocks using a partition mode set that appears first in a predetermined order among a plurality of partition mode sets. [Figure 32B] FIG. 32B is a diagram showing an example of dividing a block into sub-blocks using the partition mode set that appears first in a predetermined order among a plurality of partition mode sets. [Figure 32C] FIG. 32C is a diagram showing an example of dividing a block into sub-blocks using the partition mode set that appears first in a predetermined order among a plurality of partition mode sets. [Figure 33] FIG. 33 is a diagram showing the overall configuration of a content supply system that realizes a content distribution service. [Figure 34] FIG. 34 is a diagram showing an example of a coding structure for scalable coding. [Figure 35] FIG. 35 is a diagram showing an example of a coding structure for scalable coding. [Figure 36] FIG. 36 is a diagram showing an example of a display screen of a web page. [Figure 37] FIG. 37 is a diagram showing an example of a display screen of a web page. [Figure 38] FIG. 38 is a diagram illustrating an example of a smartphone. [Figure 39] FIG. 39 is a block diagram showing an example of the configuration of a smartphone. DETAILED DESCRIPTION OF THE INVENTION

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

[0011] The embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, component placement and connection configurations, steps, and step order shown in the following embodiments are merely examples and are not intended to limit the scope of the claims. Furthermore, among the components in the following embodiments, components that are not described in the independent claims that represent the highest concepts are described as optional components.

[0012] (Embodiment 1) First, an overview of the first embodiment will be described as an example of an encoding device and a decoding device to which the processes and / or configurations described in each aspect of the present disclosure can be applied. However, the first embodiment is merely an example of an encoding device and a decoding device to which the processes and / or configurations described in each aspect of the present disclosure can be applied, and the processes and / or configurations described in each aspect of the present disclosure can also be implemented in encoding devices and decoding devices different from the first embodiment.

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

[0014] (1) For the encoding device or decoding device of the first embodiment, among the multiple components constituting the encoding device or decoding device, components corresponding to the components described in each aspect of the present disclosure are replaced with the components described in each aspect of the present disclosure. (2) Any modification, such as addition, replacement, or deletion, of the functions or processes performed by some of the components constituting the encoding device or decoding device of the first embodiment may be made to the encoding device or decoding device, and then components corresponding to the components described in each aspect of the present disclosure may be replaced with the components described in each aspect of the present disclosure. (3) The method implemented by the encoding device or decoding device of the first embodiment may be modified by adding a process and / or replacing or deleting some of the processes included in the method, and then replacing the process described in each aspect of the present disclosure with the process described in each aspect of the present disclosure. (4) Some of the components constituting the encoding device or decoding device of the first embodiment may be implemented in combination with components described in each aspect of the present disclosure, components having some of the functions of the components described in each aspect of the present disclosure, or components performing some of the processing performed by the components described in each aspect of the present disclosure. (5) A component having some of the functions of some of the components constituting the encoding device or decoding device of the first embodiment, or a component that performs some of the processing performed by some of the components constituting the encoding device or decoding device of the first embodiment, is implemented in combination with a component described in each aspect of the present disclosure, a component having some of the functions of the components described in each aspect of the present disclosure, or a component that performs some of the processing performed by the components described in each aspect of the present disclosure. (6) In the method implemented by the encoding device or decoding device of the first embodiment, among the multiple processes included in the method, processes corresponding to the processes described in each aspect of the present disclosure are replaced with the processes described in each aspect of the present disclosure. (7) Some of the processes included in the method implemented by the encoding device or decoding device of the first embodiment may be implemented in combination with the processes described in each aspect of the present disclosure.

[0015] It should be noted that the manner of implementing the processes and / or configurations described in each aspect of the present disclosure is not limited to the above examples. For example, they may be implemented in a device used for a purpose different from the video / image encoding device or video / image decoding device disclosed in Embodiment 1, or the processes and / or configurations described in each aspect may be implemented independently. Furthermore, the processes and / or configurations described in different aspects may be implemented in combination.

[0016] [Outline of the encoding device] First, an overview of a coding device according to Embodiment 1 will be described. Fig. 1 is a block diagram showing a functional configuration of a coding device 100 according to Embodiment 1. The coding device 100 is a video / image coding device that codes a video / image on a block-by-block basis.

[0017] As shown in FIG. 1, the encoding device 100 is a device that encodes an image on a block-by-block basis, and includes a division unit 102, a subtraction unit 104, a transformation unit 106, a quantization unit 108, an entropy encoding unit 110, an inverse quantization unit 112, an inverse transformation unit 114, an addition unit 116, a block memory 118, a loop filter unit 120, a frame memory 122, an intra prediction unit 124, an inter prediction unit 126, and a prediction control unit 128.

[0018] The encoding device 100 is realized by, for example, a general-purpose processor and memory. In this case, when a software program stored in the memory is executed by the processor, the processor functions as the division unit 102, the subtraction unit 104, the transformation unit 106, the quantization unit 108, the entropy coding unit 110, the inverse quantization unit 112, the inverse transformation unit 114, the addition unit 116, the loop filter unit 120, the intra prediction unit 124, the inter prediction unit 126, and the prediction control unit 128. Alternatively, the encoding device 100 may be realized as one or more dedicated electronic circuits corresponding to the division unit 102, the subtraction unit 104, the transformation unit 106, the quantization unit 108, the entropy coding unit 110, the inverse quantization unit 112, the inverse transformation unit 114, the addition unit 116, the loop filter unit 120, the intra prediction unit 124, the inter prediction unit 126, and the prediction control unit 128.

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

[0020] [Divided part] The division unit 102 divides each picture included in the input video into a plurality of blocks and outputs each block to the subtraction unit 104. For example, the division unit 102 first divides a picture into blocks of a fixed size (e.g., 128x128). These fixed-size blocks are sometimes called coding tree units (CTUs). The division unit 102 then divides each of the fixed-size blocks into blocks of a variable size (e.g., 64x64 or less) based on recursive quadtree and / or binary tree block division. These variable-size blocks are sometimes called coding units (CUs), prediction units (PUs), or transform units (TUs). Note that in this embodiment, there is no need to distinguish between CUs, PUs, and TUs, and some or all of the blocks in a picture may serve as the processing units of CUs, PUs, and TUs.

[0021] Fig. 2 is a diagram showing an example of block division according to embodiment 1. In Fig. 2, solid lines represent block boundaries based on quadtree block division, and dashed lines represent block boundaries based on binary tree block division.

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

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

[0024] The top right 64x64 block is divided horizontally into two rectangular 64x32 blocks 14 and 15 (binary tree block division).

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

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

[0027] 2, block 10 is divided into 13 variable-sized blocks 11 to 23 based on recursive quad-tree and binary tree block division. This type of division is sometimes called QTBT (quad-tree plus binary tree) division.

[0028] In Fig. 2, one block is divided into four or two blocks (quadtree or binary tree block division), but the division is not limited to this. For example, one block may be divided into three blocks (ternary tree block division). Division including such ternary tree block division is sometimes called MBT (multi type tree) division.

[0029] [Subtraction section] The subtraction unit 104 subtracts a prediction signal (prediction sample) from an original signal (original sample) for each block divided by the division unit 102. That is, the subtraction unit 104 calculates a prediction error (also referred to as a residual) of a block to be coded (hereinafter referred to as a current block). Then, the subtraction unit 104 outputs the calculated prediction error to the conversion unit 106.

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

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

[0032] The transform unit 106 may adaptively select a transform type from among a plurality of transform types and transform the prediction errors into transform coefficients using a transform basis function corresponding to the selected transform type. Such a transform is sometimes called an explicit multiple core transform (EMT) or an adaptive multiple transform (AMT).

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

[0034] Information indicating whether EMT or AMT is applied (e.g., referred to as an AMT flag) and information indicating the selected transformation type are signaled at the CU level. Note that signaling of this information does not need to be limited to the CU level, and may be at other levels (e.g., sequence level, picture level, slice level, tile level, or CTU level).

[0035] Furthermore, the transform unit 106 may retransform the transform coefficients (transform results). Such retransformation may be referred to as an adaptive secondary transform (AST) or a non-separable secondary transform (NSST). For example, the transform unit 106 performs retransformation for each sub-block (e.g., 4x4 sub-block) included in a block of transform coefficients corresponding to intra-prediction errors. Information indicating whether or not to apply NSST and information regarding the transform matrix used for NSST are signaled at the CU level. Note that signaling of this information does not need to be limited to the CU level, and may be at other levels (e.g., the sequence level, picture level, slice level, tile level, or CTU level).

[0036] Here, a separable transformation is a method in which the transformation is performed multiple times by separating the input into directions equal to the number of dimensions, and a non-separable transformation is a method in which, when the input is multidimensional, two or more dimensions are treated as one dimension and the transformation is performed all at once.

[0037] For example, one example of a non-separable transformation is when the input is a 4x4 block, it is treated as a single array with 16 elements, and the transformation process is performed on that array using a 16x16 transformation matrix.

[0038] Similarly, a non-separable transformation is one that treats a 4x4 input block as a single array with 16 elements and then performs multiple Givens rotations on that array (Hypercube Givens Transform).

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

[0040] The predetermined order is an order for quantizing / dequantizing the transform coefficients. For example, the predetermined scanning order is defined as an ascending order (low frequency to high frequency) or a descending order (high frequency to low frequency).

[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. In other words, as the value of the quantization parameter increases, the quantization error also increases.

[0042] [Entropy coding section] The entropy coding unit 110 generates a coded signal (coded bit stream) by variable-length coding the quantized coefficients input from the quantization unit 108. Specifically, the entropy coding unit 110, for example, binarizes the quantized coefficients and arithmetically codes the binary signal.

[0043] [Dequantization section] The inverse quantization unit 112 inverse quantizes the quantized coefficients input from the quantization unit 108. Specifically, the inverse quantization unit 112 inverse quantizes the quantized coefficients of the current block in a predetermined scanning order. The inverse quantization unit 112 then outputs the inverse quantized transform coefficients of the current block to the inverse transform unit 114.

[0044] [Inverse conversion section] The inverse transform unit 114 restores the prediction error by inverse transforming the transform coefficients that are input from the inverse quantization unit 112. Specifically, the inverse transform unit 114 restores the prediction error of the current block by performing an inverse transform on the transform coefficients that corresponds to the transform performed by the transform unit 106. Then, the inverse transform unit 114 outputs the restored prediction error to the adder unit 116.

[0045] Note that the restored prediction error does not match the prediction error calculated by the subtraction unit 104 because information has been lost due to quantization. In other words, the restored prediction error includes a quantization error.

[0046] [Addition section] The adder 116 reconstructs the current block by adding the prediction error input from the inverse transformer 114 and the prediction sample input from the prediction control unit 128. The adder 116 then outputs the reconstructed block to the block memory 118 and the loop filter unit 120. The reconstructed block is sometimes called a local decoded block.

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

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

[0049] ALF applies a least squares error filter to remove coding artifacts, for example, for each 2x2 sub-block in the current block, one filter selected from multiple filters based on local gradient direction and activity.

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

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

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

[0053] The filter shape used in ALF is, for example, a circularly symmetric shape. FIGS. 4A to 4C are diagrams showing several examples of filter shapes used in ALF. FIG. 4A shows a 5x5 diamond-shaped filter, FIG. 4B shows a 7x7 diamond-shaped filter, and FIG. 4C shows a 9x9 diamond-shaped filter. Information indicating the filter shape is signaled at the picture level. Note that signaling of the information indicating the filter shape does not need to be limited to the picture level, and may be at other levels (e.g., sequence level, slice level, tile level, CTU level, or CU level).

[0054] Whether ALF is turned on or off is determined, for example, at the picture level or the CU level. For example, whether ALF is applied to luminance is determined at the CU level, and whether ALF is applied to chrominance is determined at the picture level. Information indicating whether ALF is turned on or off is signaled at the picture level or the CU level. Note that signaling of information indicating whether ALF is turned on or off does not need to be limited to the picture level or the CU level, and may be at another level (for example, the sequence level, the slice level, the tile level, or the CTU level).

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

[0056] [Frame memory] The frame memory 122 is a storage unit for storing reference pictures used in inter prediction, and is sometimes called a frame buffer. Specifically, the frame memory 122 stores the reconstructed blocks filtered by the loop filter unit 120.

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

[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, a planar prediction mode and a DC prediction mode defined in the H.265 / High-Efficiency Video Coding (HEVC) standard (Non-Patent Document 1).

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

[0061] Note that a luminance block may be referenced in intra prediction of a chrominance block. That is, the chrominance component of the current block may be predicted based on the luminance component of the current block. This type of intra prediction is sometimes called CCLM (cross-component linear model) prediction. An intra prediction mode of a chrominance block that references such a luminance block (e.g., called a CCLM mode) may be added as one of the intra prediction modes for the chrominance block.

[0062] The intra prediction unit 124 may correct pixel values ​​after intra prediction based on gradients of reference pixels in the horizontal / vertical directions. Intra prediction involving such correction is sometimes called PDPC (position dependent intra prediction combination). Information indicating whether PDPC is applied (e.g., called a PDPC flag) is signaled, for example, at the CU level. Note that signaling of this information does not need to be limited to the CU level, and may be at other levels (e.g., sequence level, picture level, slice level, tile level, or CTU level).

[0063] [Inter prediction section] The inter prediction unit 126 generates a prediction signal (inter prediction signal) by performing inter prediction (also referred to as inter prediction) on the current block with reference to a reference picture stored in the frame memory 122 that is different from the current picture. The inter prediction is performed in units of the current block or sub-blocks (e.g., 4x4 blocks) within the current block. For example, the inter prediction unit 126 performs motion estimation on the current block or sub-block within the reference picture. The inter prediction unit 126 then generates an inter prediction signal for the current block or sub-block by performing motion compensation using motion information (e.g., a motion vector) obtained by the motion estimation. The inter prediction unit 126 then outputs the generated inter prediction signal to the prediction control unit 128.

[0064] The motion information used for motion compensation is signaled. For the signaling of the motion vector, a motion vector predictor may be used, i.e., the difference between the motion vector and the motion vector predictor may be signaled.

[0065] Note that an inter-prediction signal may be generated using not only the motion information of the current block obtained by motion estimation, but also the motion information of adjacent blocks. Specifically, an inter-prediction signal may be generated for each sub-block in the current block by weighting and adding a prediction signal based on the motion information obtained by motion estimation and a prediction signal based on the motion information of adjacent blocks. Such inter-prediction (motion compensation) may be called OBMC (overlapped block motion compensation).

[0066] In such an OBMC mode, information indicating the size of a sub-block for OBMC (e.g., called an OBMC block size) is signaled at the sequence level. Also, information indicating whether the OBMC mode is applied (e.g., called an OBMC flag) is signaled at the CU level. Note that the signaling level of this information is not limited to the sequence level and the CU level, and may be other levels (e.g., the picture level, slice level, tile level, CTU level, or sub-block level).

[0067] The OBMC mode will now be described in more detail. Figures 5B and 5C are a flowchart and a conceptual diagram for explaining an outline of the predictive image correction process using the OBMC process.

[0068] First, a predicted image (Pred) is obtained by normal motion compensation using a 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 predicted image (Pred_L), and the predicted image is weighted and superimposed with Pred_L to perform the first correction of the predicted image.

[0070] Similarly, the motion vector (MV_U) of the already coded upper adjacent block is applied to the block to be coded to obtain a predicted image (Pred_U), and the predicted image that has been corrected the first time is weighted and overlaid with Pred_U to perform a second correction of the predicted image, which is then used as the final predicted image.

[0071] Although a two-stage correction method using the left adjacent block and the upper adjacent block has been described here, it is also possible to configure a method in which correction is performed more than two times using the right adjacent block or the lower adjacent block.

[0072] The area to be superimposed does not have to be the pixel area of ​​the entire block, but may be only a part of the area near the block boundary.

[0073] Although the process of correcting a predicted image from one reference picture has been described here, the process is similar when correcting a predicted image from multiple reference pictures. After obtaining corrected predicted images from each reference picture, the obtained predicted images are further superimposed to form the final predicted image.

[0074] The target block to be processed may be a prediction block unit or a sub-block unit obtained by further dividing the prediction block.

[0075] As a method for determining whether to apply OBMC processing, for example, there is a method using obmc_flag, which is a signal indicating whether to apply OBMC processing. As a specific example, an encoding device determines whether a block to be encoded belongs to an area with complex motion, and if it belongs to an area with complex motion, sets the value of obmc_flag to 1 and performs encoding using OBMC processing, and if it does not belong to an area with complex motion, sets the value of obmc_flag to 0 and performs encoding without applying OBMC processing. On the other hand, a decoding device decodes obmc_flag described in a stream, and switches whether to apply OBMC processing depending on the value, and performs decoding.

[0076] Alternatively, the motion information may be derived on the decoding device side without being signaled. For example, a merge mode defined in the H.265 / HEVC standard may be used. Alternatively, the motion information may be derived by performing motion estimation on the decoding device side. In this case, the motion estimation is performed without using pixel values ​​of the current block.

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

[0078] An example of the FRUC process is shown in Figure 5D. First, a list of multiple candidates (which may be the same as the merge list) each having a predicted motion vector is generated by referring to the motion vectors of coded blocks spatially or temporally adjacent to the current block. Next, a best candidate MV is selected from the multiple candidate MVs registered in the candidate list. For example, an evaluation value of each candidate included in the candidate list is calculated, and one candidate is selected based on the evaluation value.

[0079] Then, a motion vector for the current block is derived based on the motion vector of the selected candidate. Specifically, for example, the motion vector of the selected candidate (best candidate MV) is derived as the motion vector for the current block as is. Also, for example, the motion vector for the current block may be derived by performing pattern matching in a peripheral area of ​​a position in a reference picture corresponding to the motion vector of the selected candidate. That is, a search is performed in a similar manner in a peripheral area of ​​the best candidate MV, and if an MV with a better evaluation value is found, the best candidate MV may be updated to the MV and used as the final MV for the current block. Note that a configuration may be adopted in which this process is not performed.

[0080] The same processing may be performed when processing is performed in sub-block units.

[0081] The evaluation value is calculated by finding the difference between the reconstructed image and a predetermined area by pattern matching between the area in the reference picture corresponding to the motion vector. The evaluation value may be calculated using other information in addition to the difference.

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

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

[0084] FIG. 6 is a diagram illustrating an example of pattern matching (bilateral matching) between two blocks along a motion trajectory. As shown in FIG. 6, in the first pattern matching, two motion vectors (MV0, MV1) are derived by searching for the most closely matched pair of two blocks along the motion trajectory of a current block (Cur block) in two different reference pictures (Ref0, Ref1). Specifically, for the current block, a difference is derived between a reconstructed image at a specified position in a first coded reference picture (Ref0) specified by a candidate MV and a reconstructed image at a specified position in a second coded reference picture (Ref1) specified by a symmetric MV obtained by scaling the candidate MV by the display time interval, and an evaluation value is calculated using the obtained difference value. The candidate MV with the best evaluation value among multiple candidate MVs may be selected as the final MV.

[0085] Under the assumption of continuous motion trajectories, motion vectors (MV0, MV1) pointing to two reference blocks are proportional to the temporal distances (TD0, TD1) between a current picture (CurPic) and two reference pictures (Ref0, Ref1). For example, if the current picture is located between two reference pictures temporally and the temporal distances from the current picture to the two reference pictures are equal, the first pattern matching derives bidirectional motion vectors that are mirror-symmetric.

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

[0087] 7 is a diagram illustrating an example of pattern matching (template matching) between a template in a current picture and a block in a reference picture. As shown in FIG. 7, in the second pattern matching, a motion vector of a current block is derived by searching a reference picture (Ref0) for a block that best matches a block adjacent to a current block (Cur block) in the current picture (Cur Pic). Specifically, a difference is derived between a reconstructed image of both or either of the coded areas adjacent to the left and / or above the current block and a reconstructed image at the same position in the coded reference picture (Ref0) specified by a candidate MV, an evaluation value is calculated using the obtained difference value, and the candidate MV with the best evaluation value among the multiple candidate MVs is selected as the best candidate MV.

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

[0089] Here, we will explain a mode that derives a motion vector based on a model that assumes uniform linear motion. This mode is based on BIO (bi-directional optical This is sometimes called flow mode.

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

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

[0092]

number

[0093] Here, I(k) denotes the luminance value of reference image k (k=0,1) after motion compensation. This optical flow equation indicates that the sum of (i) the time derivative of the luminance value, (ii) the product of the horizontal velocity and the horizontal component of the spatial gradient of the reference image, and (iii) the product of the vertical velocity and the vertical component of the spatial gradient of the reference image is equal to zero. Based on a combination of this optical flow equation and Hermite interpolation, block-wise motion vectors obtained from a merge list or the like are corrected pixel by pixel.

[0094] Note that the decoding device may derive motion vectors using a method other than that based on a model assuming constant-velocity linear motion. For example, a motion vector may be derived for each sub-block based on the motion vectors of multiple adjacent blocks.

[0095] Here, a mode in which a motion vector is derived for each sub-block based on the motion vectors of multiple neighboring blocks will be described. This mode is sometimes called an affine motion compensation prediction mode.

[0096] 9A is a diagram illustrating the derivation of motion vectors for each sub-block based on the motion vectors of multiple adjacent blocks. In FIG. 9A, the current block includes 16 4x4 sub-blocks. Here, a motion vector v0 for the upper left corner control point of the current block is derived based on the motion vectors of the adjacent blocks, and a motion vector v1 for the upper right corner control point of the current block is derived based on the motion vectors of the adjacent sub-blocks. Then, using the two motion vectors v0 and v1, the motion vectors (vx, vy) of each sub-block within the current block are derived according to the following equation (2):

[0097]

number

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

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

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

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

[0102] First, a prediction MV list is generated in which prediction MV candidates are registered. The prediction MV candidates include spatially adjacent prediction MVs, which are MVs held by multiple coded blocks spatially located around the block to be coded, temporally adjacent prediction MVs, which are MVs held by blocks in the vicinity of the block to be coded projected onto the coded reference picture, joint prediction MVs, which are MVs generated by combining the MV values ​​of the spatially adjacent prediction MVs and the temporally adjacent prediction MVs, and zero prediction MVs, which are MVs with a value of zero.

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

[0104] Furthermore, the variable length coding unit encodes the stream by describing merge_idx, which is a signal indicating which predicted MV has been selected.

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

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

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

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

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

[0110] Next, the template is used to search the surrounding areas of the candidate MVs in the first and second reference pictures, and the MV with the smallest cost is determined as the final MV. The cost value is calculated using the difference between each pixel value of the template and each pixel value of the search area, the MV value, etc.

[0111] The outline of the processing described here is basically the same for the encoding device and the decoding device.

[0112] Note that other processing may be used instead of the processing described here, as long as it is processing that can search the vicinity of the candidate MV and derive the final MV.

[0113] Here, a mode for generating a predicted image using LIC processing will be described.

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

[0115] First, an MV for obtaining a reference image corresponding to a block to be coded is derived from a reference picture that is a coded picture.

[0116] Next, for the block to be coded, the luminance pixel values ​​of the coded surrounding reference areas adjacent to the left and above and the luminance pixel values ​​at the equivalent positions in the reference picture specified by the MV are used to extract information indicating how the luminance values ​​have changed between the reference picture and the picture to be coded, and a luminance correction parameter is calculated.

[0117] A predicted image for the block to be coded is generated by performing luminance correction processing on a reference image in a reference picture specified by the MV using the luminance correction parameters.

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

[0119] Although the process of generating a predicted image from one reference picture has been described here, the process is similar when generating a predicted image from multiple reference pictures, and a luminance correction process is performed in a similar manner on the reference images obtained from each reference picture before generating a predicted image.

[0120] One method for determining whether to apply LIC processing is to use lic_flag, which is a signal indicating whether to apply LIC processing. As a specific example, an encoding device determines whether the encoding target block belongs to an area where a luminance change occurs, and if it belongs to an area where a luminance change occurs, sets the value of lic_flag to 1 and performs encoding by applying LIC processing, and if it does not belong to an area where a luminance change occurs, sets the value of lic_flag to 0 and performs encoding without applying LIC processing. On the other hand, a decoding device decodes lic_flag described in the stream, and switches whether to apply LIC processing depending on the value, and performs decoding.

[0121] As another method for determining whether to apply LIC processing, for example, there is also a method for determining whether LIC processing has been applied to surrounding blocks.As a specific example, when the block to be coded is in merge mode, it is determined whether the surrounding coded blocks selected when deriving MV in merge mode processing have been coded using LIC processing, and depending on the result, whether to apply LIC processing is switched and coded.In addition, in this example, the process in decoding is exactly the same.

[0122] [Overview of the decoding device] Next, an overview will be given of a decoding device capable of decoding the coded signal (coded bitstream) output from the above coding device 100. Fig. 10 is a block diagram showing the functional configuration of a decoding device 200 according to Embodiment 1. The decoding device 200 is a video / image decoding device that decodes video / images on a block-by-block basis.

[0123] As shown in FIG. 10, the decoding device 200 includes an entropy decoding unit 202, an inverse quantization unit 204, an inverse transform unit 206, an addition unit 208, a block memory 210, a loop filter unit 212, a frame memory 214, an intra prediction unit 216, an inter prediction unit 218, and a prediction control unit 220.

[0124] The decoding device 200 is realized by, for example, a general-purpose processor and memory. In this case, when a software program stored in the memory is executed by the processor, the processor functions as the entropy decoding unit 202, the inverse quantization unit 204, the inverse transform unit 206, the addition unit 208, the loop filter unit 212, the intra prediction unit 216, the inter prediction unit 218, and the prediction control unit 220. Alternatively, the decoding device 200 may be realized as one or more dedicated electronic circuits corresponding to the entropy decoding unit 202, the inverse quantization unit 204, the inverse transform unit 206, the addition unit 208, the loop filter unit 212, the intra prediction unit 216, the inter prediction unit 218, and the prediction control unit 220.

[0125] Each component included in the decoding device 200 will be described below.

[0126] [Entropy Decoding] The entropy decoding unit 202 entropy-decodes the coded bitstream. Specifically, the entropy decoding unit 202 arithmetically decodes the coded bitstream into a binary signal. The entropy decoding unit 202 then debinarizes the binary signal. As a result, the entropy decoding unit 202 outputs quantized coefficients to the inverse quantization unit 204 on a block-by-block basis.

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

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

[0129] For example, if the information interpreted from the encoded bitstream indicates that EMT or AMT is to be applied (e.g., the AMT flag is true), the inverse transform unit 206 inverse transforms the transform coefficients of the current block based on the interpreted information indicating the transform type.

[0130] Also, for example, if the information decoded from the coded bitstream indicates that NSST is to be applied, then inverse transform unit 206 applies an inverse re-transform to the transform coefficients.

[0131] [Addition section] The adder 208 reconstructs the current block by adding the prediction error input from the inverse transformer 206 and the prediction sample input from the prediction control unit 220. The adder 208 then outputs the reconstructed block to the block memory 210 and the loop filter unit 212.

[0132] [Block Memory] The block memory 210 is a storage unit for storing blocks that are referenced in intra prediction and are in a picture to be decoded (hereinafter referred to as a current picture). Specifically, the block memory 210 stores the reconstructed blocks output from the adder 208.

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

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

[0135] [Frame memory] The frame memory 214 is a storage unit for storing reference pictures used in inter prediction, and is sometimes called a frame buffer. Specifically, the frame memory 214 stores the reconstructed blocks filtered by the loop filter unit 212.

[0136] [Intra prediction section] The intra prediction unit 216 generates a prediction signal (intra prediction signal) by performing intra prediction based on the intra prediction mode interpreted from the encoded bitstream, by referring to blocks in the current picture stored in the block memory 210. Specifically, the intra prediction unit 216 generates the intra prediction signal by performing intra prediction by referring to samples (e.g., luminance values, chrominance values) of blocks adjacent to the current block, and outputs the intra prediction signal to the prediction control unit 220.

[0137] Note that when an intra prediction mode that references a luminance block in intra prediction of a chrominance block is selected, the intra prediction unit 216 may predict the chrominance component of the current block based on the luminance component of the current block.

[0138] Furthermore, when information interpreted from the coded bitstream indicates the application of PDPC, the intra prediction unit 216 corrects pixel values ​​after intra prediction based on the gradients of reference pixels in the horizontal and vertical directions.

[0139] [Inter prediction section] The inter prediction unit 218 predicts the current block by referring to a reference picture stored in the frame memory 214. The prediction is performed in units of the current block or sub-blocks (e.g., 4x4 blocks) within the current block. For example, the inter prediction unit 218 generates an inter prediction signal for the current block or sub-block by performing motion compensation using motion information (e.g., motion vectors) interpreted from the coded bitstream, and outputs the inter prediction signal to the prediction control unit 220.

[0140] In addition, if the information interpreted from the encoded bitstream indicates that the OBMC mode is to be applied, the inter prediction unit 218 generates an inter prediction signal using not only the motion information of the current block obtained by motion search, but also the motion information of adjacent blocks.

[0141] Furthermore, if the information interpreted from the coded bitstream indicates that the FRUC mode is to be applied, the inter prediction unit 218 derives motion information by performing motion search according to the pattern matching method (bilateral matching or template matching) interpreted from the coded bitstream. Then, the inter prediction unit 218 performs motion compensation using the derived motion information.

[0142] Furthermore, when the BIO mode is applied, the inter prediction unit 218 derives a motion vector based on a model assuming constant-velocity linear motion. Furthermore, when information interpreted from the coded bitstream indicates that the affine motion compensation prediction mode is to be applied, the inter prediction unit 218 derives a motion vector for each sub-block based on the motion vectors of multiple adjacent blocks.

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

[0144] (Embodiment 2) The encoding process and decoding process according to the second embodiment will be specifically described with reference to Figures 11 and 12, and the encoding device and decoding device according to the second embodiment will be specifically described with reference to Figures 15 and 16.

[0145] [Encoding process] FIG. 11 shows a video encoding process according to the second embodiment.

[0146] First, in step S1001, a first parameter identifying a partition mode from among a plurality of partition modes for dividing a first block into a plurality of sub-blocks is written into a bitstream. When a partition mode is used, the block is divided into a plurality of sub-blocks. When different partition modes are used, the block is divided into a plurality of sub-blocks with different shapes, heights, or widths.

[0147] FIG. 28 shows examples of partition modes for dividing a block of NxN pixels in the second embodiment. In FIG. 28, (a) to (h) indicate different partition modes. As shown in FIG. 28, when partition mode (a) is used, a block of NxN pixels (e.g., 16x16 pixels, where "N" can be any value that is an integer multiple of 4 between 8 and 128) is divided into two sub-blocks of N / 2xN pixels (e.g., 8x16 pixels). When partition mode (b) is used, the block of NxN pixels is divided into a sub-block of N / 4xN pixels (e.g., 4x16 pixels) and a sub-block of 3N / 4xN pixels (e.g., 12x16 pixels). When partition mode (c) is used, the block of NxN pixels is divided into a sub-block of 3N / 4xN pixels (e.g., 12x16 pixels) and a sub-block of N / 4xN pixels (e.g., 4x16 pixels). Using partition mode (d), an NxN pixel block is divided into a sub-block of (N / 4)xN pixels (e.g., 4x16 pixels), a sub-block of N / 2xN pixels (e.g., 8x16 pixels), and a sub-block of N / 4xN pixels (e.g., 4x16 pixels). Using partition mode (e), an NxN pixel block is divided into two sub-blocks of NxN / 2 pixels (e.g., 16x8 pixels). Using partition mode (f), an NxN pixel block is divided into a sub-block of NxN / 4 pixels (e.g., 16x4 pixels) and a sub-block of Nx3N / 4 pixels (e.g., 16x12 pixels). Using partition mode (g), an NxN pixel block is divided into a sub-block of Nx3N / 4 pixels (e.g., 16x12 pixels) and a sub-block of NxN / 4 pixels (e.g., 16x4 pixels). Using partition mode (h), a block of NxN pixels is divided into a sub-block of NxN / 4 pixels (e.g., 16x4 pixels), a sub-block of NxN / 2 pixels (e.g., 16x8 pixels), and a sub-block of NxN / 4 pixels (e.g., 16x4 pixels).

[0148] Next, in step S1002, it is determined whether the first parameter identifies the first partition mode.

[0149] Next, in step S1003, it is determined whether to select the second partition mode as a candidate for dividing the second block based at least on a determination of whether the first parameter identifies the first partition mode.

[0150] Two different partition mode sets may divide a block into sub-blocks of the same shape and size. For example, as shown in Figure 31A, the sub-blocks in (1b) and (2c) have the same shape and size. One partition mode set may include at least two partition modes. For example, as shown in (1a) and (1b) of Figure 31A, one partition mode set may include a ternary tree vertical division followed by a binary tree vertical division of the central sub-block and no division of the other sub-blocks. For example, as shown in (2a), (2b), and (2c) of Figure 31A, another partition mode set may include a binary tree vertical division followed by a binary tree vertical division of both sub-blocks. Both partition mode sets result in sub-blocks of the same shape and size.

[0151] When choosing between two partition mode sets that divide a block into sub-blocks of the same shape and size, and that have different numbers of bins or bits when encoded into a bitstream, the partition mode set with the fewer number of bins or bits is selected, where the number of bins and the number of bits correspond to the amount of code.

[0152] When choosing between two partition mode sets that divide a block into sub-blocks of the same shape and size and that have the same number of bins or bits when encoded into a bitstream, the partition mode set that appears first in a predetermined order of the multiple partition mode sets is selected, which may be, for example, based on the number of partition modes in each partition mode set.

[0153] 31A and 31B are diagrams showing an example of dividing a block into sub-blocks using a partition mode set with a smaller number of bins in partition mode encoding. In this example, when the left NxN pixel block is vertically divided into two sub-blocks, the second partition mode for the right NxN pixel block is not selected in step (2c). This is because, in the partition mode encoding method of FIG. 31B, the second partition mode set (2a, 2b, 2c) requires more bins for partition mode encoding compared to the first partition mode set (1a, 1b).

[0154] 32A to 32C are diagrams illustrating an example of dividing a block into sub-blocks using a partition mode set that appears first in a predetermined order of multiple partition mode sets. In this example, when a block of 2NxN / 2 pixels is vertically divided into three sub-blocks, the second partition mode for the lower 2NxN / 2 pixel block is not selected in step (2c). This is because, in the partition mode encoding method of FIG. 32B, the second partition mode set (2a, 2b, 2c) has the same number of bins as the first partition mode set (1a, 1b, 1c, 1d) and appears after the first partition mode set (1a, 1b, 1c, 1d) in the predetermined order of the partition mode sets shown in FIG. 32C. The predetermined order of multiple partition mode sets can be fixed or signaled in the bitstream.

[0155] 20 shows an example in which the second partition mode is not selected for dividing a block of 2NxN pixels, as shown in step (2c) in the second embodiment. As shown in FIG. 20, using the first division method (i), a block of 2Nx2N pixels (e.g., 16x16 pixels) can be equally divided into four sub-blocks of NxN pixels (e.g., 8x8 pixels), as shown in step (1a). Also, using the second division method (ii), a block of 2Nx2N pixels can be equally divided horizontally into two sub-blocks of 2NxN pixels (e.g., 16x8 pixels), as shown in step (2a). Here, in the second division method (ii), if the upper 2NxN pixel block (first block) is vertically divided into two NxN pixel sub-blocks by the first partition mode as in step (2b), the second partition mode that vertically divides the lower 2NxN pixel block (second block) into two NxN pixel sub-blocks in step (2c) is not selected as a possible candidate partition mode because it would generate the same sub-block size as the sub-block size obtained by the quartering in the first division method (i).

[0156] As described above, in FIG. 20, if the first partition mode is used to divide the first block equally into two sub-blocks vertically, and the second partition mode is used to divide the second block vertically adjacent to the first block equally into two sub-blocks vertically, the second partition mode is not selected as a candidate.

[0157] FIG. 21 shows an example in which the second partition mode is not selected for dividing an Nx2N pixel block, as shown in step (2c) in the second embodiment. As shown in FIG. 21, a 2Nx2N pixel block can be equally divided into four NxN pixel sub-blocks using the first partitioning method (i), as shown in step (1a). Alternatively, a 2Nx2N pixel block can be equally divided vertically into two 2NxN pixel (e.g., 8x16 pixel) sub-blocks using the second partitioning method (ii), as shown in step (2a). In the second partitioning method (ii), if the left Nx2N pixel block (first block) is horizontally divided into two NxN pixel sub-blocks using the first partitioning mode, as shown in step (2b), the second partition mode that divides the right Nx2N pixel block (second block) horizontally into two NxN pixel sub-blocks is not selected as a possible partition mode candidate in step (2c). This is because the sub-block size generated is the same as the sub-block size obtained by the first division method (i) of dividing into four.

[0158] As described above, in FIG. 21, if the first partition mode is used to divide the first block equally into two sub-blocks horizontally, and the second partition mode is used to divide the second block horizontally adjacent to the first block equally into two sub-blocks horizontally, the second partition mode is not selected as a candidate.

[0159] 22 shows an example in which the second partition mode is not selected for dividing an NxN pixel block, as shown in step (2c) in the second embodiment. As shown in FIG. 22, using the first division method (i), a block of 2NxN pixels (e.g., 16x8 pixels, where "N" can be any integer multiple of 4 from 8 to 128) can be divided vertically into N / 2xN pixel sub-blocks, NxN pixel sub-blocks, and N / 2xN pixel sub-blocks (e.g., 4x8 pixel sub-blocks, 8x8 pixel sub-blocks, and 4x8 pixel sub-blocks) as shown in step (1a). Also, using the second division method (ii), a block of 2NxN pixels can be divided into two NxN pixel sub-blocks as shown in step (2a). In the first division method (i), the central NxN pixel block can be vertically divided into two N / 2xN pixel (e.g., 4x8 pixel) sub-blocks in step (1b). In the second division method (ii), if the left NxN pixel block (first block) is vertically divided into two N / 2xN pixel sub-blocks as in step (2b), the partition mode that vertically divides the right NxN pixel block (second block) into two N / 2xN pixel sub-blocks in step (2c) is not selected as a possible partition mode candidate. This is because the sub-block size generated by the first division method (i), i.e., four N / 2xN pixel sub-blocks, is the same as the sub-block size obtained by the first division method (i).

[0160] As described above, in FIG. 22, if the first partition mode is used to divide the first block equally into two sub-blocks vertically, and the second partition mode is used to divide the second block horizontally adjacent to the first block equally into two sub-blocks vertically, the second partition mode is not selected as a candidate.

[0161] FIG. 23 shows an example in which the second partition mode is not selected for dividing an NxN pixel block, as shown in step (2c) in the second embodiment. As shown in FIG. 23, using the first division method (i), Nx2N pixels (e.g., 8x16 pixels, where "N" can be any value that is an integer multiple of 4 between 8 and 128) can be divided into NxN / 2 pixel sub-blocks, NxN pixel sub-blocks, and NxN / 2 pixel sub-blocks (e.g., 8x4 pixel sub-blocks, 8x8 pixel sub-blocks, and 8x4 pixel sub-blocks) as shown in step (1a). Also, using the second division method, division into two NxN pixel sub-blocks can be performed as shown in step (2a). In the first division method (i), the central NxN pixel block can be divided into two NxN / 2 pixel sub-blocks as shown in step (1b). In the second partitioning method (ii), when the upper NxN pixel block (first block) is horizontally divided into two NxN / 2 pixel sub-blocks as in step (2b), the partition mode of horizontally dividing the lower NxN pixel block (second block) into two NxN / 2 pixel sub-blocks in step (2c) is not selected as a candidate partition mode because the sub-block size would be the same as that obtained by the first partitioning method (i), i.e., four NxN / 2 pixel sub-blocks.

[0162] As described above, in FIG. 23, if the first partition mode is used to divide the first block equally into two sub-blocks horizontally, and the second partition mode is used to divide the second block vertically adjacent to the first block equally into two sub-blocks horizontally, the second partition mode is not selected as a candidate.

[0163] If it is determined that the second partition mode is selected as a candidate for dividing the second block (N in S1003), then in step S1004, a partition mode is selected from a plurality of partition modes including the second partition mode as a candidate. In step S1005, a second parameter indicating the selection result is written to the bitstream.

[0164] If it is determined that the second partition mode is not selected as a candidate for dividing the second block (Y in S1003), then in step S1006, a partition mode different from the second partition mode is selected for dividing the second block, where the selected partition mode divides the block into sub-blocks having different shapes or sizes compared to the sub-blocks generated by the second partition mode.

[0165] FIG. 24 shows an example of dividing a 2NxN pixel block using the selected partition mode when the second partition mode is not selected, as shown in step (3) in the second embodiment. As shown in FIG. 24, the selected partition mode can divide the 2NxN pixel current block (the bottom block in this example) into three sub-blocks, as shown in (c) and (f) of FIG. 24. The sizes of the three sub-blocks may be different. For example, in the three sub-blocks, the large sub-block may have twice the width / height of the small sub-block. Alternatively, for example, the selected partition mode can divide the current block into two sub-blocks of different sizes (asymmetric binary tree), as shown in (a), (b), (d), and (e) of FIG. 24. For example, when an asymmetric binary tree is used, the large sub-block may have three times the width / height of the small sub-block.

[0166] FIG. 25 shows an example of dividing an Nx2N pixel block using the selected partition mode when the second partition mode is not selected, as shown in step (3) in the second embodiment. As shown in FIG. 25, the selected partition mode can divide the Nx2N pixel current block (the right block in this example) into three sub-blocks, as shown in (c) and (f) of FIG. 25. The sizes of the three sub-blocks may be different. For example, in the three sub-blocks, the large sub-block may have twice the width / height of the small sub-block. Alternatively, the selected partition mode can divide the current block into two sub-blocks of different sizes (asymmetric binary tree), as shown in (a), (b), (d), and (e) of FIG. 25. For example, when an asymmetric binary tree is used, the large sub-block may have three times the width / height of the small sub-block.

[0167] FIG. 26 shows an example of dividing an NxN pixel block using a selected partition mode when the second partition mode is not selected, as shown in step (3) in the second embodiment. As shown in FIG. 26, in step (1), a 2NxN pixel block is vertically divided into two NxN pixel sub-blocks, and in step (2), the left NxN pixel block is vertically divided into two N / 2xN pixel sub-blocks. In step (3), the selected partition mode for the NxN pixel current block (the left block in this example) can be used to divide the current block into three sub-blocks, as shown in (c) and (f) of FIG. 26. The sizes of the three sub-blocks may be different. For example, in the three sub-blocks, the large sub-block may have twice the width / height of the small sub-block. Alternatively, for example, the selected partition mode can divide the current block into two sub-blocks of different sizes (asymmetric binary tree), as shown in (a), (b), (d), and (e) of FIG. 26. For example, if an asymmetric binary tree is used, the large sub-blocks may have three times the width / height of the small sub-blocks.

[0168] FIG. 27 shows an example of partitioning an NxN pixel block using a selected partition mode when the second partition mode is not selected, as shown in step (3) in the second embodiment. As shown in FIG. 27, in step (1), the Nx2N pixel block is horizontally divided into two NxN pixel sub-blocks, and in step (2), the upper NxN pixel block is horizontally divided into two NxN / 2 pixel sub-blocks. In step (3), the selected partition mode for the NxN pixel current block (the bottom block in this example) can be used to divide the current block into three sub-blocks, as shown in (c) and (f) of FIG. 27. The sizes of the three sub-blocks may be different. For example, in the three sub-blocks, the larger sub-block may have twice the width / height of the smaller sub-block. Alternatively, for example, the selected partition mode can divide the current block into two sub-blocks of different sizes (asymmetric binary tree), as shown in (a), (b), (d), and (e) of FIG. 27. For example, if an asymmetric binary tree is used, the large sub-blocks may have three times the width / height of the small sub-blocks.

[0169] Figure 17 illustrates possible locations of the first parameter within a compressed video stream. As shown in Figure 17, the first parameter may be located within a video parameter set, a sequence parameter set, a picture parameter set, a slice header, or a coding tree unit. The first parameter may indicate how to divide a block into multiple sub-blocks. For example, the first parameter may include a flag indicating whether to divide the block horizontally or vertically. The first parameter may also include a parameter indicating whether to divide the block into two or more sub-blocks.

[0170] Figure 18 illustrates possible locations of the second parameter within a compressed video stream. As shown in Figure 18, the second parameter may be located within a video parameter set, a sequence parameter set, a picture parameter set, a slice header, or a coding tree unit. The second parameter may indicate how to divide a block into multiple sub-blocks. For example, the second parameter may include a flag indicating whether to divide the block horizontally or vertically. The second parameter may also include a parameter indicating whether to divide the block into two or more sub-blocks. The second parameter is located following the first parameter in the bitstream, as shown in Figure 19.

[0171] The first block and the second block are different blocks. The first block and the second block may be included in the same frame. For example, the first block may be a block adjacent to the top of the second block. Also, for example, the first block may be a block adjacent to the left of the second block.

[0172] In step S1007, the second block is divided into sub-blocks using the selected partition mode, and in step S1008, the divided blocks are coded.

[0173] [Encoding device] FIG. 15 is a block diagram showing a structure of a video / image coding device according to the second or third embodiment.

[0174] The video encoding device 5000 is a device for encoding an input video / image for each block to generate an encoded output bitstream. As shown in Fig. 15, the video encoding device 5000 includes a transform unit 5001, a quantization unit 5002, an inverse quantization unit 5003, an inverse transform unit 5004, a block memory 5005, a frame memory 5006, an intra prediction unit 5007, an inter prediction unit 5008, an entropy encoding unit 5009, and a block division determination unit 5010.

[0175] An input video is input to the adder, and the sum is output to the transform unit 5001. The transform unit 5001 transforms the sum into a frequency coefficient based on the block partition mode derived by the block partition determination unit 5010, and outputs the frequency coefficient to the quantization unit 5002. The block partition mode may be associated with a block partition mode, a block partition type, or a block partition direction. The quantization unit 5002 quantizes the input quantization coefficient, and outputs the quantized value to the inverse quantization unit 5003 and the entropy coding unit 5009.

[0176] The inverse quantization unit 5003 inversely quantizes the quantized values ​​output from the quantization unit 5002, and outputs the frequency coefficients to the inverse transform unit 5004. The inverse transform unit 5004 performs an inverse frequency transform on the frequency coefficients based on the block partition mode derived by the block partition determination unit 5010, converts the frequency coefficients into sample values ​​of a bitstream, and outputs the sample values ​​to an adder.

[0177] The adder adds the sample values ​​of the bitstream output from the inverse transform unit 5004 to the predicted video / image values ​​output from the intra / inter predictors 5007 and 5008, and outputs the added value to the block memory 5005 or the frame memory 5006 for further prediction. The block partition determination unit 5010 collects block information from the block memory 5005 or the frame memory 5006 and derives a block partition mode and parameters related to the block partition mode. Using the derived block partition mode, the block is divided into multiple sub-blocks. The intra / inter predictors 5007 and 5008 search among the video / images stored in the block memory 5005 or the video / images in the frame memory 5006 reconstructed in the block partition mode derived by the block partition determination unit 5010, and estimate, for example, a video / image area that is most similar to the input video / image to be predicted.

[0178] The entropy coding unit 5009 codes the quantized value output from the quantization unit 5002, codes the parameters from the block division determination unit 5010, and outputs a bitstream.

[0179] [Decryption process] FIG. 12 shows a video decoding process according to the second embodiment.

[0180] First, in step S2001, a first parameter identifying a partition mode for dividing a first block into sub-blocks from a plurality of partition modes is read from the bitstream, where the partition mode divides the block into sub-blocks, and different partition modes divide the block into sub-blocks with different shapes, heights, or widths.

[0181] FIG. 28 shows examples of partition modes for dividing a block of NxN pixels in the second embodiment. In FIG. 28, (a) to (h) indicate different partition modes. As shown in FIG. 28, when partition mode (a) is used, a block of NxN pixels (e.g., 16x16 pixels, where "N" can be any value that is an integer multiple of 4 between 8 and 128) is divided into two sub-blocks of N / 2xN pixels (e.g., 8x16 pixels). When partition mode (b) is used, the block of NxN pixels is divided into a sub-block of N / 4xN pixels (e.g., 4x16 pixels) and a sub-block of 3N / 4xN pixels (e.g., 12x16 pixels). When partition mode (c) is used, the block of NxN pixels is divided into a sub-block of 3N / 4xN pixels (e.g., 12x16 pixels) and a sub-block of N / 4xN pixels (e.g., 4x16 pixels). Using partition mode (d), an NxN pixel block is divided into a sub-block of (N / 4)xN pixels (e.g., 4x16 pixels), a sub-block of N / 2xN pixels (e.g., 8x16 pixels), and a sub-block of N / 4xN pixels (e.g., 4x16 pixels). Using partition mode (e), an NxN pixel block is divided into two sub-blocks of NxN / 2 pixels (e.g., 16x8 pixels). Using partition mode (f), an NxN pixel block is divided into a sub-block of NxN / 4 pixels (e.g., 16x4 pixels) and a sub-block of Nx3N / 4 pixels (e.g., 16x12 pixels). Using partition mode (g), an NxN pixel block is divided into a sub-block of Nx3N / 4 pixels (e.g., 16x12 pixels) and a sub-block of NxN / 4 pixels (e.g., 16x4 pixels). Using partition mode (h), a block of NxN pixels is divided into a sub-block of NxN / 4 pixels (e.g., 16x4 pixels), a sub-block of NxN / 2 pixels (e.g., 16x8 pixels), and a sub-block of NxN / 4 pixels (e.g., 16x4 pixels).

[0182] Next, in step S2002, it is determined whether the first parameter identifies the first partition mode.

[0183] Next, in step S2003, it is determined whether to select the second partition mode as a candidate for dividing the second block based at least on a determination of whether the first parameter identifies the first partition mode.

[0184] Two different partition mode sets may divide a block into sub-blocks of the same shape and size. For example, as shown in Figure 31A, the sub-blocks in (1b) and (2c) have the same shape and size. One partition mode set may include at least two partition modes. For example, as shown in (1a) and (1b) of Figure 31A, one partition mode set may include a ternary tree vertical division followed by a binary tree vertical division of the central sub-block and no division of the other sub-blocks. For example, as shown in (2a), (2b), and (2c) of Figure 31A, another partition mode set may include a binary tree vertical division followed by a binary tree vertical division of both sub-blocks. Both partition mode sets result in sub-blocks of the same shape and size.

[0185] When choosing between two partition mode sets that divide a block into sub-blocks of the same shape and size, but that have different numbers of bins or bits when encoded into the bitstream, the partition mode set with the fewer number of bins or bits is selected.

[0186] When choosing between two partition mode sets that divide a block into sub-blocks of the same shape and size and that have the same number of bins or bits when encoded into a bitstream, the partition mode set that appears first in a predetermined order of the multiple partition mode sets is selected, which may be, for example, based on the number of partition modes in each partition mode set.

[0187] 31A and 31B are diagrams showing an example of dividing a block into sub-blocks using a partition mode set with a smaller number of bins in partition mode encoding. In this example, when the left NxN pixel block is vertically divided into two sub-blocks, the second partition mode for the right NxN pixel block is not selected in step (2c). This is because, in the partition mode encoding method of FIG. 31B, the second partition mode set (2a, 2b, 2c) requires more bins for partition mode encoding compared to the first partition mode set (1a, 1b).

[0188] FIG. 32A is a diagram showing an example of dividing a block into sub-blocks using a partition mode set that appears first in a predetermined order of multiple partition mode sets. In this example, when a block of 2NxN / 2 pixels is vertically divided into three sub-blocks, the second partition mode for the lower 2NxN / 2 pixel block is not selected in step (2c). This is because, in the partition mode encoding method of FIG. 32B, the second partition mode set (2a, 2b, 2c) has the same number of bins as the first partition mode set (1a, 1b, 1c, 1d) and appears after the first partition mode set (1a, 1b, 1c, 1d) in the predetermined order of the partition mode sets shown in FIG. 32C. The predetermined order of multiple partition mode sets can be fixed or signaled in the bitstream.

[0189] 20 shows an example in which the second partition mode is not selected for dividing a block of 2NxN pixels, as shown in step (2c) in the second embodiment. As shown in FIG. 20, using the first division method (i), a block of 2Nx2N pixels (e.g., 16x16 pixels) can be equally divided into four sub-blocks of NxN pixels (e.g., 8x8 pixels), as shown in step (1a). Also, using the second division method (ii), a block of 2Nx2N pixels can be equally divided horizontally into two sub-blocks of 2NxN pixels (e.g., 16x8 pixels), as shown in step (2a). In the second partitioning method (ii), if the first partition mode in step (2b) vertically divides the upper 2NxN pixel block (first block) into two NxN pixel sub-blocks, the second partition mode in step (2c) that vertically divides the lower 2NxN pixel block (second block) into two NxN pixel sub-blocks is not selected as a possible partition mode candidate because it would generate the same sub-block size as the sub-block size obtained by the quadrant in the first partitioning method (i).

[0190] As described above, in FIG. 20, if the first partition mode is used to divide the first block equally into two sub-blocks vertically, and the second partition mode is used to divide the second block vertically adjacent to the first block equally into two sub-blocks vertically, the second partition mode is not selected as a candidate.

[0191] FIG. 21 shows an example in which the second partition mode is not selected for dividing an Nx2N pixel block, as shown in step (2c) in the second embodiment. As shown in FIG. 21, a 2Nx2N pixel block can be equally divided into four NxN pixel sub-blocks using the first partitioning method (i), as shown in step (1a). Alternatively, a 2Nx2N pixel block can be equally divided vertically into two 2NxN pixel (e.g., 8x16 pixel) sub-blocks using the second partitioning method (ii), as shown in step (2a). In the second partitioning method (ii), if the left Nx2N pixel block (first block) is horizontally divided into two NxN pixel sub-blocks using the first partitioning mode, as shown in step (2b), the second partition mode that divides the right Nx2N pixel block (second block) horizontally into two NxN pixel sub-blocks is not selected as a possible partition mode candidate in step (2c). This is because the sub-block size generated is the same as the sub-block size obtained by the first division method (i) of dividing into four.

[0192] As described above, in FIG. 21, if the first partition mode is used to divide the first block equally into two sub-blocks horizontally, and the second partition mode is used to divide the second block horizontally adjacent to the first block equally into two sub-blocks horizontally, the second partition mode is not selected as a candidate.

[0193] 22 shows an example in which the second partition mode is not selected for dividing an NxN pixel block, as shown in step (2c) in the second embodiment. As shown in FIG. 22, using the first division method (i), a block of 2NxN pixels (e.g., 16x8 pixels, where "N" can be any integer multiple of 4 from 8 to 128) can be divided vertically into N / 2xN pixel sub-blocks, NxN pixel sub-blocks, and N / 2xN pixel sub-blocks (e.g., 4x8 pixel sub-blocks, 8x8 pixel sub-blocks, and 4x8 pixel sub-blocks) as shown in step (1a). Also, using the second division method (ii), a block of 2NxN pixels can be divided into two NxN pixel sub-blocks as shown in step (2a). In the first division method (i), the central NxN pixel block can be vertically divided into two N / 2xN pixel (e.g., 4x8 pixel) sub-blocks in step (1b). In the second division method (ii), if the left NxN pixel block (first block) is vertically divided into two N / 2xN pixel sub-blocks as in step (2b), the partition mode that vertically divides the right NxN pixel block (second block) into two N / 2xN pixel sub-blocks in step (2c) is not selected as a possible partition mode candidate. This is because the sub-block size generated by the first division method (i), i.e., four N / 2xN pixel sub-blocks, is the same as the sub-block size obtained by the first division method (i).

[0194] As described above, in FIG. 22, if the first partition mode is used to divide the first block equally into two sub-blocks vertically, and the second partition mode is used to divide the second block horizontally adjacent to the first block equally into two sub-blocks vertically, the second partition mode is not selected as a candidate.

[0195] FIG. 23 shows an example in which the second partition mode is not selected for dividing an NxN pixel block, as shown in step (2c) in the second embodiment. As shown in FIG. 23, using the first division method (i), Nx2N pixels (e.g., 8x16 pixels, where "N" can be any value that is an integer multiple of 4 between 8 and 128) can be divided into NxN / 2 pixel sub-blocks, NxN pixel sub-blocks, and NxN / 2 pixel sub-blocks (e.g., 8x4 pixel sub-blocks, 8x8 pixel sub-blocks, and 8x4 pixel sub-blocks) as shown in step (1a). Also, using the second division method, division into two NxN pixel sub-blocks can be performed as shown in step (2a). In the first division method (i), the central NxN pixel block can be divided into two NxN / 2 pixel sub-blocks as shown in step (1b). In the second partitioning method (ii), when the upper NxN pixel block (first block) is horizontally divided into two NxN / 2 pixel sub-blocks as in step (2b), the partition mode of horizontally dividing the lower NxN pixel block (second block) into two NxN / 2 pixel sub-blocks in step (2c) is not selected as a candidate partition mode because the sub-block size would be the same as that obtained by the first partitioning method (i), i.e., four NxN / 2 pixel sub-blocks.

[0196] As described above, in FIG. 23, if the first partition mode is used to divide the first block equally into two sub-blocks horizontally, and the second partition mode is used to divide the second block vertically adjacent to the first block equally into two sub-blocks horizontally, the second partition mode is not selected as a candidate.

[0197] If it is determined that the second partition mode is to be selected as a candidate for dividing the second block (N in S2003), in step S2004, the second parameter is decoded from the bitstream, and a partition mode is selected from a plurality of partition modes that include the second partition mode as a candidate.

[0198] If it is determined that the second partition mode is not selected as a candidate for dividing the second block (Y in S2003), then in step S2005, a partition mode different from the second partition mode is selected for dividing the second block, where the selected partition mode divides the block into sub-blocks having different shapes or sizes compared to the sub-blocks generated by the second partition mode.

[0199] FIG. 24 shows an example of dividing a 2NxN pixel block using the selected partition mode when the second partition mode is not selected, as shown in step (3) in the second embodiment. As shown in FIG. 24, the selected partition mode can divide the 2NxN pixel current block (the bottom block in this example) into three sub-blocks, as shown in (c) and (f) of FIG. 24. The sizes of the three sub-blocks may be different. For example, in the three sub-blocks, the large sub-block may have twice the width / height of the small sub-block. Alternatively, for example, the selected partition mode can divide the current block into two sub-blocks of different sizes (asymmetric binary tree), as shown in (a), (b), (d), and (e) of FIG. 24. For example, when an asymmetric binary tree is used, the large sub-block may have three times the width / height of the small sub-block.

[0200] FIG. 25 shows an example of dividing an Nx2N pixel block using the selected partition mode when the second partition mode is not selected, as shown in step (3) in the second embodiment. As shown in FIG. 25, the selected partition mode can divide the Nx2N pixel current block (the right block in this example) into three sub-blocks, as shown in (c) and (f) of FIG. 25. The sizes of the three sub-blocks may be different. For example, in the three sub-blocks, the large sub-block may have twice the width / height of the small sub-block. Alternatively, the selected partition mode can divide the current block into two sub-blocks of different sizes (asymmetric binary tree), as shown in (a), (b), (d), and (e) of FIG. 25. For example, when an asymmetric binary tree is used, the large sub-block may have three times the width / height of the small sub-block.

[0201] FIG. 26 shows an example of dividing an NxN pixel block using a selected partition mode when the second partition mode is not selected, as shown in step (3) in the second embodiment. As shown in FIG. 26, in step (1), a 2NxN pixel block is vertically divided into two NxN pixel sub-blocks, and in step (2), the left NxN pixel block is vertically divided into two N / 2xN pixel sub-blocks. In step (3), the selected partition mode for the NxN pixel current block (the left block in this example) can be used to divide the current block into three sub-blocks, as shown in (c) and (f) of FIG. 26. The sizes of the three sub-blocks may be different. For example, in the three sub-blocks, the large sub-block may have twice the width / height of the small sub-block. Alternatively, for example, the selected partition mode can divide the current block into two sub-blocks of different sizes (asymmetric binary tree), as shown in (a), (b), (d), and (e) of FIG. 26. For example, if an asymmetric binary tree is used, the large sub-blocks may have three times the width / height of the small sub-blocks.

[0202] FIG. 27 shows an example of partitioning an NxN pixel block using a selected partition mode when the second partition mode is not selected, as shown in step (3) in the second embodiment. As shown in FIG. 27, in step (1), the Nx2N pixel block is horizontally divided into two NxN pixel sub-blocks, and in step (2), the upper NxN pixel block is horizontally divided into two NxN / 2 pixel sub-blocks. In step (3), the selected partition mode for the NxN pixel current block (the bottom block in this example) can be used to divide the current block into three sub-blocks, as shown in (c) and (f) of FIG. 27. The sizes of the three sub-blocks may be different. For example, in the three sub-blocks, the larger sub-block may have twice the width / height of the smaller sub-block. Alternatively, for example, the selected partition mode can divide the current block into two sub-blocks of different sizes (asymmetric binary tree), as shown in (a), (b), (d), and (e) of FIG. 27. For example, if an asymmetric binary tree is used, the large sub-blocks may have three times the width / height of the small sub-blocks.

[0203] Figure 17 illustrates possible locations of the first parameter within a compressed video stream. As shown in Figure 17, the first parameter may be located within a video parameter set, a sequence parameter set, a picture parameter set, a slice header, or a coding tree unit. The first parameter may indicate how to divide a block into multiple sub-blocks. For example, the first parameter may include a flag indicating whether to divide the block horizontally or vertically. The first parameter may also include a parameter indicating whether to divide the block into two or more sub-blocks.

[0204] Figure 18 illustrates possible locations of the second parameter within a compressed video stream. As shown in Figure 18, the second parameter may be located within a video parameter set, a sequence parameter set, a picture parameter set, a slice header, or a coding tree unit. The second parameter may indicate how to divide a block into multiple sub-blocks. For example, the second parameter may include a flag indicating whether to divide the block horizontally or vertically. The second parameter may also include a parameter indicating whether to divide the block into two or more sub-blocks. The second parameter is located following the first parameter in the bitstream, as shown in Figure 19.

[0205] The first block and the second block are different blocks. The first block and the second block may be included in the same frame. For example, the first block may be a block adjacent to the top of the second block. Also, for example, the first block may be a block adjacent to the left of the second block.

[0206] In step S2006, the second block is divided into sub-blocks using the selected partition mode, and in step S2007, the divided blocks are decoded.

[0207] [Decryption device] FIG. 16 is a block diagram showing a structure of a video / image decoding device according to the second or third embodiment.

[0208] The video decoding device 6000 is a device for decoding an input coded bitstream for each block and outputting video / images. As shown in Fig. 16 , the video decoding device 6000 includes an entropy decoding unit 6001, an inverse quantization unit 6002, an inverse transform unit 6003, a block memory 6004, a frame memory 6005, an intra prediction unit 6006, an inter prediction unit 6007, and a block partition determination unit 6008.

[0209] An input coded bitstream is input to the entropy decoding unit 6001. After the input coded bitstream is input to the entropy decoding unit 6001, the entropy decoding unit 6001 decodes the input coded bitstream, outputs parameters to the block division determination unit 6008, and outputs decoded values ​​to the inverse quantization unit 6002.

[0210] The inverse quantization unit 6002 inverse quantizes the decoded values ​​and outputs the frequency coefficients to the inverse transform unit 6003. The inverse transform unit 6003 performs an inverse frequency transform on the frequency coefficients to convert them into sample values ​​based on the block partition mode derived by the block partition determination unit 6008, and outputs the sample values ​​to the adder. The block partition mode can be associated with the block partition mode, block partition type, or block partition direction. The adder adds the sample values ​​to the predicted video / image values ​​output from the intra / inter prediction units 6006 and 6007, outputs the added value to the display, and outputs the added value to the block memory 6004 or frame memory 6005 for further prediction. The block partition determination unit 6008 collects block information from the block memory 6004 or frame memory 6005 and derives a block partition mode using parameters decoded by the entropy decoding unit 6001. Using the derived block partition mode, the block is divided into multiple sub-blocks. Furthermore, the intra / inter prediction units 6006 and 6007 predict the video / image area of ​​the block to be decoded from the video / image stored in the block memory 6004 or the video / image in the frame memory 6005 reconstructed in the block partition mode derived by the block partition determination unit 6008.

[0211] [Effects, etc.] As described above, the video coding device 5000 according to this embodiment is an image coding device that codes blocks of an image, and includes a processor and a memory. The processor uses the memory to write a first parameter, which identifies a partition mode for dividing a first block into sub-blocks from among a plurality of partition modes, into a bitstream; determine whether the first parameter identifies the first partition mode; determine whether to select a second partition mode as a candidate for dividing a second block different from the first block, based on the determination of at least whether the first parameter identifies the first partition mode; if it is determined that the second partition mode is to be selected as a candidate for dividing the second block, select a partition mode from among a plurality of partition modes that include the second partition mode as a candidate; and write a second parameter indicating the selection result into the bitstream; if it is determined that the second partition mode is not to be selected as a candidate for dividing the second block, select a partition mode different from the second partition mode, which divides the block into sub-blocks that have a different shape or a different size than the sub-blocks generated by the second partition mode; divide the second block into sub-blocks using the selected partition mode; and encode the divided blocks.

[0212] According to this, when it is determined that the second partition mode should not be selected as a candidate for dividing the second block, a partition mode different from the second partition mode can be selected, thereby reducing the number of selectable partition modes and improving compression efficiency by reducing the amount of code for the partition modes.

[0213] Furthermore, in the video encoding device 5000 according to this embodiment, the selected partition mode different from the second partition mode may divide the block into more sub-blocks than the second partition mode, or may divide the block into the same number of sub-blocks as the second partition mode but of a different size.

[0214] According to this, when the second partition mode is not selected as a candidate, it is possible to divide into sub-blocks different from the sub-blocks obtained by the second partition mode.

[0215] Furthermore, in the video coding device 5000 according to this embodiment, when determining whether to not select the second partition mode, if the first parameter identifies a first partition mode, it is determined whether to not select the second partition mode as the candidate based on a first code amount of a first partition mode set including the first partition mode and the second partition mode, and a second code amount of a second partition mode set different from the first partition mode set, and the second partition mode set may include at least one partition mode for dividing a block into sub-blocks of the same shape and size as the shapes and sizes of sub-blocks obtained by dividing the first block and the second block using the first partition mode and the second partition mode.

[0216] This makes it possible to determine whether or not to select the second partition as a candidate based on the code amount of the partition mode set, thereby reducing the code amount of the partition mode and improving compression efficiency.

[0217] In addition, in the video encoding device 5000 according to this embodiment, when determining whether to select the second partition mode, it may be determined not to select the second partition mode if the first code amount is greater than the second code amount.

[0218] This makes it possible to prevent a partition mode set with a larger code amount from being selected, and to reduce the code amount of the partition mode and improve compression efficiency.

[0219] Furthermore, in the video coding device 5000 according to this embodiment, when determining whether to select the second partition mode, if the first code amount is equal to the second code amount, and the second partition mode set appears before the first partition mode set in a predetermined order of multiple partition mode sets including the first partition mode set and the second partition mode set, it may be determined that the second partition mode is not to be selected.

[0220] According to this, when two partition mode sets have the same code amount, the partition mode set can be selected based on a predetermined order.

[0221] As described above, the video decoding device 6000 according to this embodiment is an image decoding device that decodes blocks of an image, and includes a processor and a memory. The processor uses the memory to decode, from a bitstream, a first parameter that identifies a partition mode for dividing a first block into sub-blocks from among a plurality of partition modes, determine whether the first parameter identifies the first partition mode, and determine whether to select a second partition mode as a candidate for dividing a second block different from the first block, based on the determination of at least whether the first parameter identifies the first partition mode. If it is determined that the second partition mode is to be selected as a candidate for dividing the second block, the processor decodes, from the bitstream, a second parameter that is used to select a partition mode for dividing the second block from among a plurality of partition modes that include the second partition mode as a candidate. If it is determined that the second partition mode is not to be selected as a candidate for dividing the second block, the processor selects a partition mode that is different from the second partition mode and that divides the block into sub-blocks that have a different shape or a different size than the sub-blocks generated by the second partition mode, and divides the second block into sub-blocks using the selected partition mode, and decodes the divided blocks.

[0222] According to this, when it is determined that the second partition mode should not be selected as a candidate for dividing the second block, a partition mode different from the second partition mode can be selected, thereby reducing the number of selectable partition modes and improving compression efficiency by reducing the amount of code for the partition modes.

[0223] Furthermore, in the video decoding device 6000 according to this embodiment, the selected partition mode different from the second partition mode may divide the block into more sub-blocks than the second partition mode, or may divide the block into the same number of sub-blocks as the second partition mode but of a different size.

[0224] According to this, when the second partition mode is not selected as a candidate, it is possible to divide into sub-blocks different from the sub-blocks obtained by the second partition mode.

[0225] Furthermore, in the video decoding device 6000 according to this embodiment, when determining whether to not select the second partition mode, if the first parameter identifies a first partition mode, it is determined whether to not select the second partition mode as the candidate based on a first code amount of a first partition mode set including the first partition mode and the second partition mode, and a second code amount of a second partition mode set different from the first partition mode set, and the second partition mode set may include at least one partition mode for dividing a block into sub-blocks of the same shape and size as the shapes and sizes of sub-blocks obtained by dividing the first block and the second block using the first partition mode and the second partition mode.

[0226] This makes it possible to determine whether or not to select the second partition as a candidate based on the code amount of the partition mode set, thereby reducing the code amount of the partition mode and improving compression efficiency.

[0227] In addition, in the video decoding device 6000 according to this embodiment, when determining whether to select the second partition mode, it may be determined not to select the second partition mode if the first coding amount is greater than the second coding amount.

[0228] This prevents a partition mode set with a larger code amount from being selected, and reduces the code amount of the partition mode, thereby improving compression efficiency.

[0229] Furthermore, in the video decoding device 6000 according to this embodiment, when determining whether to select the second partition mode, if the first code amount is equal to the second code amount, and the second partition mode set appears before the first partition mode set in a predetermined order of multiple partition mode sets including the first partition mode set and the second partition mode set, it may be determined that the second partition mode is not to be selected.

[0230] According to this, when two partition mode sets have the same code amount, the partition mode set can be selected based on a predetermined order.

[0231] This aspect may be implemented in combination with at least a part of other aspects of the present disclosure. Also, some of the processes, some device configurations, and some syntaxes described in the flowcharts of this aspect may be implemented in combination with other aspects.

[0232] (Embodiment 3) The encoding process and the decoding process according to the third embodiment will be specifically described with reference to Fig. 13 and Fig. 14. The encoding device and the decoding device according to the third embodiment will be specifically described with reference to Fig. 15 and Fig. 16.

[0233] [Encoding process] FIG. 13 shows a video encoding process according to the third embodiment.

[0234] First, in step S3001, a first parameter that identifies a partition type for dividing a first block into sub-blocks from among a plurality of partition types is written into a bitstream.

[0235] In the next step S3002, a second parameter indicating a partition direction is written into the bitstream. The second parameter is placed in the bitstream following the first parameter. The partition type together with the partition direction may constitute a partition mode. The partition type indicates the number of sub-blocks and the partition ratio for dividing the block.

[0236] 29 shows an example of partition types and partition directions for dividing an NxN pixel block in the third embodiment. In FIG. 29, (1), (2), (3), and (4) are different partition types, (1a), (2a), (3a), and (4a) are partition modes with different partition types in the vertical partition direction, and (1b), (2b), (3b), and (4b) are partition modes with different partition types in the horizontal partition direction. As shown in FIG. 29, when the partition ratio is 1:1 and the block is divided into a symmetric binary tree (i.e., two sub-blocks) in the vertical direction, the block of NxN pixels is divided using partition mode (1a). When the partition ratio is 1:1 and the block is divided into a symmetric binary tree (i.e., two sub-blocks) in the horizontal direction, the block of NxN pixels is divided using partition mode (1b). A block of NxN pixels is partitioned using partition mode (2a) if the partition ratio is 1:3 and the block is divided vertically into an asymmetric binary tree (i.e., two sub-blocks). A block of NxN pixels is partitioned using partition mode (2b) if the partition ratio is 1:3 and the block is divided horizontally into an asymmetric binary tree (i.e., two sub-blocks). A block of NxN pixels is partitioned using partition mode (3a) if the partition ratio is 3:1 and the block is divided vertically into an asymmetric binary tree (i.e., two sub-blocks). A block of NxN pixels is partitioned using partition mode (3b) if the partition ratio is 3:1 and the block is divided horizontally into an asymmetric binary tree (i.e., two sub-blocks). A block of NxN pixels is partitioned using partition mode (4a) if the partition ratio is 1:2:1 and the block is divided vertically into a ternary tree (i.e., three sub-blocks). A block of NxN pixels is divided using partition mode (4b) where the partition ratio is 1:2:1 and the block is divided horizontally into ternary trees (ie, three sub-blocks).

[0237] Figure 17 illustrates possible locations of the first parameter within a compressed video stream. As shown in Figure 17, the first parameter may be located within a video parameter set, a sequence parameter set, a picture parameter set, a slice header, or a coding tree unit. The first parameter may indicate how to divide a block into multiple sub-blocks. For example, the first parameter may include a flag indicating whether to divide the block horizontally or vertically. The first parameter may also include a parameter indicating whether to divide the block into two or more sub-blocks.

[0238] Figure 18 illustrates possible locations of the second parameter within a compressed video stream. As shown in Figure 18, the second parameter may be located within a video parameter set, a sequence parameter set, a picture parameter set, a slice header, or a coding tree unit. The second parameter may indicate how to divide a block into multiple sub-blocks. For example, the second parameter may include a flag indicating whether to divide the block horizontally or vertically. The second parameter may also include a parameter indicating whether to divide the block into two or more sub-blocks. The second parameter is located following the first parameter in the bitstream, as shown in Figure 19.

[0239] FIG. 30 shows the advantage of encoding the partition type before the partition direction compared to encoding the partition direction before the partition type. In this example, if the horizontal partition direction is disabled due to an unsupported size (16x2 pixels), there is no need to encode the partition direction. In this example, the partition direction is determined as the vertical partition direction, and the horizontal partition direction is disabled. Coding the partition type before the partition direction reduces code bits due to encoding the partition direction compared to encoding the partition direction before the partition type.

[0240] In this way, it may be determined whether a block can be divided in each of the horizontal and vertical directions based on a predetermined condition for whether the block can be divided or not. Then, if it is determined that the block can be divided in only one of the horizontal and vertical directions, writing of the partition direction into the bitstream may be skipped. Furthermore, if it is determined that the block cannot be divided in both the horizontal and vertical directions, writing of the partition type into the bitstream in addition to the partition direction may be skipped.

[0241] The predetermined condition for whether a block can be divided or not is defined by, for example, the size (number of pixels) or the number of divisions. The condition for whether a block can be divided or not may be predefined in a standard. The condition for whether a block can be divided or not may also be included in a video parameter set, a sequence parameter set, a picture parameter set, a slice header, or a coding tree unit. The condition for whether a block can be divided or not may be fixed for all blocks, or may be dynamically switched depending on the characteristics of the block (e.g., luminance and chrominance blocks) or the characteristics of the picture (e.g., I, P, B picture).

[0242] In step S3003, the block is divided into sub-blocks using the identified partition type and the indicated partition direction. In step S3004, the divided blocks are coded.

[0243] [Encoding device] FIG. 15 is a block diagram showing a structure of a video / image coding device according to the second or third embodiment.

[0244] The video encoding device 5000 is a device for encoding an input video / image for each block to generate an encoded output bitstream. As shown in Fig. 15, the video encoding device 5000 includes a transform unit 5001, a quantization unit 5002, an inverse quantization unit 5003, an inverse transform unit 5004, a block memory 5005, a frame memory 5006, an intra prediction unit 5007, an inter prediction unit 5008, an entropy encoding unit 5009, and a block division determination unit 5010.

[0245] An input video is input to the adder, and the sum is output to the transform unit 5001. The transform unit 5001 transforms the sum into frequency coefficients based on the block partition type and direction derived by the block partition determination unit 5010, and outputs the frequency coefficients to the quantization unit 5002. The block partition type and direction may be associated with the block partition mode, block partition type, or block partition direction. The quantization unit 5002 quantizes the input quantized coefficients and outputs the quantized values ​​to the inverse quantization unit 5003 and the entropy coding unit 5009.

[0246] The inverse quantization unit 5003 inversely quantizes the quantized values ​​output from the quantization unit 5002, and outputs the frequency coefficients to the inverse transform unit 5004. The inverse transform unit 5004 performs an inverse frequency transform on the frequency coefficients based on the block partition type and direction derived by the block partition determination unit 5010, converts the frequency coefficients into sample values ​​of a bitstream, and outputs the sample values ​​to an adder.

[0247] The adder adds the sample values ​​of the bitstream output from the inverse transform unit 5004 to the predicted video / image values ​​output from the intra / inter predictors 5007 and 5008, and outputs the sum to the block memory 5005 or the frame memory 5006 for further prediction. The block partition determination unit 5010 collects block information from the block memory 5005 or the frame memory 5006 and derives block partition types and directions, as well as parameters related to the block partition types and directions. Using the derived block partition types and directions, the blocks are divided into multiple sub-blocks. The intra / inter predictors 5007 and 5008 search among the video / images stored in the block memory 5005 or the video / images in the frame memory 5006 reconstructed using the block partition types and directions derived by the block partition determination unit 5010, to estimate, for example, the video / image region that is most similar to the input video / image to be predicted.

[0248] The entropy coding unit 5009 codes the quantized value output from the quantization unit 5002, codes the parameters from the block division determination unit 5010, and outputs a bitstream.

[0249] [Decryption process] FIG. 14 shows a video decoding process according to the third embodiment.

[0250] First, in step S4001, a first parameter that identifies a partition type for dividing a first block into sub-blocks from among a plurality of partition types is read from the bitstream.

[0251] In the next step S4002, a second parameter indicating a partition direction is read from the bitstream. The second parameter follows the first parameter in the bitstream. The partition type together with the partition direction may constitute a partition mode. The partition type indicates the number of sub-blocks and the partition ratio for dividing the block.

[0252] 29 shows an example of partition types and partition directions for dividing an NxN pixel block in the third embodiment. In FIG. 29, (1), (2), (3), and (4) are different partition types, (1a), (2a), (3a), and (4a) are partition modes with different partition types in the vertical partition direction, and (1b), (2b), (3b), and (4b) are partition modes with different partition types in the horizontal partition direction. As shown in FIG. 29, when the partition ratio is 1:1 and the block is divided into a symmetric binary tree (i.e., two sub-blocks) in the vertical direction, the block of NxN pixels is divided using partition mode (1a). When the partition ratio is 1:1 and the block is divided into a symmetric binary tree (i.e., two sub-blocks) in the horizontal direction, the block of NxN pixels is divided using partition mode (1b). A block of NxN pixels is partitioned using partition mode (2a) if the partition ratio is 1:3 and the block is divided vertically into an asymmetric binary tree (i.e., two sub-blocks). A block of NxN pixels is partitioned using partition mode (2b) if the partition ratio is 1:3 and the block is divided horizontally into an asymmetric binary tree (i.e., two sub-blocks). A block of NxN pixels is partitioned using partition mode (3a) if the partition ratio is 3:1 and the block is divided vertically into an asymmetric binary tree (i.e., two sub-blocks). A block of NxN pixels is partitioned using partition mode (3b) if the partition ratio is 3:1 and the block is divided horizontally into an asymmetric binary tree (i.e., two sub-blocks). A block of NxN pixels is partitioned using partition mode (4a) if the partition ratio is 1:2:1 and the block is divided vertically into a ternary tree (i.e., three sub-blocks). A block of NxN pixels is divided using partition mode (4b) where the partition ratio is 1:2:1 and the block is divided horizontally into ternary trees (ie, three sub-blocks).

[0253] Figure 17 illustrates possible locations of the first parameter within a compressed video stream. As shown in Figure 17, the first parameter may be located within a video parameter set, a sequence parameter set, a picture parameter set, a slice header, or a coding tree unit. The first parameter may indicate how to divide a block into multiple sub-blocks. For example, the first parameter may include an identifier of a partition type as described above. For example, the first parameter may include a flag indicating whether to divide the block horizontally or vertically. The first parameter may also include a parameter indicating whether to divide the block into two or more sub-blocks.

[0254] Figure 18 illustrates possible locations of the second parameter in a compressed video stream. As shown in Figure 18, the second parameter may be located in a video parameter set, a sequence parameter set, a picture parameter set, a slice header, or a coding tree unit. The second parameter may indicate how to divide a block into multiple sub-blocks. For example, the second parameter may include a flag indicating whether to divide the block horizontally or vertically. That is, the second parameter may include a parameter indicating a partition direction. The second parameter may also include a parameter indicating whether to divide the block into two or more sub-blocks. The second parameter is located following the first parameter in the bitstream, as shown in Figure 19.

[0255] FIG. 30 shows the advantage of encoding the partition type before the partition direction compared to encoding the partition direction before the partition type. In this example, if the horizontal partition direction is disabled due to an unsupported size (16x2 pixels), there is no need to encode the partition direction. In this example, the partition direction is determined as the vertical partition direction, and the horizontal partition direction is disabled. Coding the partition type before the partition direction reduces code bits due to encoding the partition direction compared to encoding the partition direction before the partition type.

[0256] In this way, it may be determined whether a block can be divided in each of the horizontal and vertical directions based on a predetermined condition for whether the block can be divided or not. Then, if it is determined that the block can be divided in only one of the horizontal and vertical directions, deciphering from the bitstream in the partition direction may be skipped. Furthermore, if it is determined that the block cannot be divided in both the horizontal and vertical directions, deciphering from the bitstream of the partition type in addition to the partition direction may be skipped.

[0257] The predetermined condition for whether a block can be divided or not is defined by, for example, the size (number of pixels) or the number of divisions. The condition for whether a block can be divided or not may be predefined in a standard. The condition for whether a block can be divided or not may also be included in a video parameter set, a sequence parameter set, a picture parameter set, a slice header, or a coding tree unit. The condition for whether a block can be divided or not may be fixed for all blocks, or may be dynamically switched depending on the characteristics of the block (e.g., luminance and chrominance blocks) or the characteristics of the picture (e.g., I, P, B picture).

[0258] In step S4003, the block is divided into sub-blocks using the identified partition type and the indicated partition direction. In step S4004, the divided block is decoded.

[0259] [Decryption device] FIG. 16 is a block diagram showing a structure of a video / image decoding device according to the second or third embodiment.

[0260] The video decoding device 6000 is a device for decoding an input coded bitstream for each block and outputting video / images. As shown in Fig. 16 , the video decoding device 6000 includes an entropy decoding unit 6001, an inverse quantization unit 6002, an inverse transform unit 6003, a block memory 6004, a frame memory 6005, an intra prediction unit 6006, an inter prediction unit 6007, and a block partition determination unit 6008.

[0261] An input coded bitstream is input to the entropy decoding unit 6001. After the input coded bitstream is input to the entropy decoding unit 6001, the entropy decoding unit 6001 decodes the input coded bitstream, outputs parameters to the block division determination unit 6008, and outputs decoded values ​​to the inverse quantization unit 6002.

[0262] The inverse quantization unit 6002 inverse quantizes the decoded values ​​and outputs the frequency coefficients to the inverse transform unit 6003. The inverse transform unit 6003 performs an inverse frequency transform on the frequency coefficients based on the block partition type and direction derived by the block partition determination unit 6008 to convert the frequency coefficients into sample values ​​and output the sample values ​​to the adder. The block partition type and direction can be associated with the block partition mode, block partition type, or block partition direction. The adder adds the sample values ​​to the predicted video / image values ​​output from the intra / inter prediction units 6006 and 6007, outputs the added value to the display, and outputs the added value to the block memory 6004 or frame memory 6005 for further prediction. The block partition determination unit 6008 collects block information from the block memory 6004 or frame memory 6005 and derives the block partition type and direction using the parameters decoded by the entropy decoding unit 6001. Using the derived block partition type and direction, the block is divided into multiple sub-blocks. Furthermore, the intra / inter prediction units 6006 and 6007 predict the video / image area of ​​the block to be decoded from the video / image stored in the block memory 6004 or the video / image in the frame memory 6005 reconstructed using the block partition type and direction derived by the block partition determination unit 6008.

[0263] [Effects, etc.] As described above, the video coding device 5000 according to this embodiment is an image coding device that codes blocks of an image, and includes a processor and a memory. The processor uses the memory to write into a bitstream a first parameter that identifies a partition type for dividing a block into two or more sub-blocks from among a plurality of partition types, writes into the bitstream a second parameter that indicates a partition direction, the second parameter following the first parameter in the bitstream, divides the block into sub-blocks using the identified partition type and the indicated partition direction, and codes the divided blocks.

[0264] This allows a second parameter indicating the partition direction to be written after the first parameter that identifies the partition type. Therefore, when it is not necessary to indicate the partition direction, the second parameter can be omitted, reducing the amount of code for the partition mode and improving compression efficiency.

[0265] Furthermore, in the video encoding device 5000 according to this embodiment, when a partition type is used in conjunction with an identified partition direction, the block is divided into sub-blocks in the identified partition direction, and when a different partition type is used in conjunction with a partition direction, the block may be divided into sub-blocks of different shapes, different heights or different widths.

[0266] This allows the shape, height or width of the sub-block to be controlled by the partition type and partition direction.

[0267] Furthermore, in the video encoding device 5000 according to this embodiment, the processor may further use the partition type identified by the first parameter to determine whether the block can be divided horizontally and vertically, and if it is determined that the block can be divided in only one of the horizontal and vertical directions, skip writing the second parameter to the bitstream and divide the block into sub-blocks using the identified partition type and the other of the horizontal and vertical directions.

[0268] This allows skipping the writing of the second parameter indicating the partition direction when the block cannot be divided either horizontally or vertically, which means that the second parameter can be omitted in the bitstream, reducing the amount of code required for the block division method and improving compression efficiency.

[0269] As described above, the video decoding device 6000 according to this embodiment is an image decoding device that decodes blocks of an image, and includes a processor and a memory. The processor uses the memory to decode from the bitstream a first parameter that identifies a partition type for dividing a block into two or more sub-blocks from among a plurality of partition types, and to decode from the bitstream a second parameter that indicates a partition direction, the second parameter following the first parameter in the bitstream, and to divide the block into sub-blocks using the identified partition type and the indicated partition direction, and to decode the divided block.

[0270] This allows a second parameter indicating the partition direction to be written after the first parameter that identifies the partition type. Therefore, when it is not necessary to indicate the partition direction, the second parameter can be omitted, reducing the amount of code for the partition mode and improving compression efficiency.

[0271] Furthermore, in the video decoding device 6000 according to this embodiment, when a partition type is used together with an identified partition direction, the block is divided into sub-blocks in the identified partition direction, and when a different partition type is used together with a partition direction, the block may be divided into sub-blocks of different shapes, different heights or different widths.

[0272] This allows the shape, height or width of the sub-block to be controlled by the partition type and partition direction.

[0273] In addition, in the video decoding device 6000 according to this embodiment, the processor may further use the partition type identified by the first parameter to determine whether the block can be divided horizontally and vertically, and if it is determined that the block can be divided only in one of the horizontal and vertical directions, skip interpreting the second parameter from the bitstream, and divide the block into sub-blocks using the identified partition type and the other of the horizontal and vertical directions as the partition direction.

[0274] This allows skipping the interpretation of the second parameter indicating the partition direction when the block cannot be divided either horizontally or vertically. In other words, the second parameter can be omitted in the bitstream, reducing the amount of code related to the block division method and improving compression efficiency.

[0275] This aspect may be implemented in combination with at least a part of other aspects of the present disclosure. Also, some of the processes, some device configurations, and some syntaxes described in the flowcharts of this aspect may be implemented in combination with other aspects.

[0276] (Fourth embodiment) In each of the above embodiments, each of the functional blocks can typically be realized by an MPU, memory, etc. Furthermore, the processing by each of the functional blocks is typically realized by a program execution unit such as a processor reading and executing software (programs) recorded on a recording medium such as a ROM. The software may be distributed by downloading, etc., or may be recorded on a recording medium such as a semiconductor memory and distributed. Of course, each functional block can also be realized by hardware (dedicated circuits).

[0277] Furthermore, the processing described in each embodiment may be realized by centralized processing using a single device (system), or may be realized by distributed processing using multiple devices. The processor that executes the program may be a single processor or multiple processors. That is, centralized processing or distributed processing may be performed.

[0278] The aspects of the present disclosure are not limited to the above examples, and various modifications are possible, and these modifications are also included within the scope of the aspects of the present disclosure.

[0279] Furthermore, here, we will explain application examples of the video coding method (image coding method) or video decoding method (image decoding method) shown in each of the above embodiments and a system using the same. The system is characterized by having an image coding device using the image coding method, an image decoding device using the image decoding method, and an image coding / decoding device that includes both. Other components of the system can be appropriately changed depending on the situation.

[0280] [Usage example] 33 is a diagram showing the overall configuration of a content supply system ex100 that provides a content distribution service. The area where communication services are provided is divided into cells of a desired size, and base stations ex106, ex107, ex108, ex109, and ex110, which are fixed wireless stations, are installed in each cell.

[0281] In this content supply system ex100, devices such as a computer ex111, a game console ex112, a camera ex113, a home appliance ex114, and a smartphone ex115 are connected to the Internet ex101 via an Internet service provider ex102 or a communication network ex104 and base stations ex106 to ex110. The content supply system ex100 may be configured to connect a combination of any of the above elements. The devices may be connected to each other directly or indirectly via a telephone network or short-range wireless communication, without using the base stations ex106 to ex110, which are fixed wireless stations. Furthermore, a streaming server ex103 is connected to devices such as the computer ex111, the game console ex112, the camera ex113, the home appliance ex114, and the smartphone ex115 via the Internet ex101, etc. Furthermore, the streaming server ex103 is connected to a terminal in a hotspot on an airplane ex117, etc., via a satellite ex116.

[0282] Note that wireless access points, hotspots, etc. may be used instead of the base stations ex106 to ex110. Furthermore, the streaming server ex103 may be directly connected to the communication network ex104 without going through the Internet ex101 or the Internet service provider ex102, or may be directly connected to an airplane ex117 without going through a satellite ex116.

[0283] The camera ex113 is a device capable of taking still images and videos, such as a digital camera. The smartphone ex115 is a smartphone, mobile phone, or PHS (Personal Handyphone System) that is compatible with mobile communication systems generally known as 2G, 3G, 3.9G, 4G, and 5G.

[0284] The home appliance ex118 is a refrigerator or an appliance included in a home fuel cell cogeneration system.

[0285] In the content supply system ex100, a terminal having a photographing function is connected to a streaming server ex103 via a base station ex106 or the like, thereby enabling live streaming and the like. In live streaming, a terminal (such as a computer ex111, a game console ex112, a camera ex113, a home appliance ex114, a smartphone ex115, or a terminal on an airplane ex117) performs the encoding process described in each of the above embodiments on still images or video content captured by a user using the terminal, multiplexes the video data obtained by encoding with audio data obtained by encoding audio corresponding to the video, and transmits the obtained data to the streaming server ex103. That is, each terminal functions as an image encoding device according to one aspect of the present disclosure.

[0286] Meanwhile, the streaming server ex103 streams the transmitted content data to the requesting client. The client is a computer ex111, a game console ex112, a camera ex113, a home appliance ex114, a smartphone ex115, a terminal on an airplane ex117, or the like, which is capable of decoding the encoded data. Each device that receives the distributed data decodes and plays back the received data. That is, each device functions as an image decoding device according to one aspect of the present disclosure.

[0287] [Distributed processing] The streaming server ex103 may also be multiple servers or multiple computers that process, record, and distribute data in a distributed manner. For example, the streaming server ex103 may be implemented as a CDN (Content Delivery Network), where content distribution is achieved through a network connecting numerous edge servers distributed around the world. In a CDN, a physically nearby edge server is dynamically assigned depending on the client. Content is then cached and distributed to that edge server, thereby reducing delays. Furthermore, if an error occurs or communication conditions change due to increased traffic, processing can be distributed among multiple edge servers, the distribution entity can be switched to another edge server, or distribution can be continued by bypassing the affected network portion, thereby achieving high-speed and stable distribution.

[0288] In addition to the distributed processing of the distribution itself, the encoding of captured data can be performed on each device, on the server side, or shared among devices. For example, encoding generally involves two processing loops. The first loop detects the image complexity or code size for each frame or scene. The second loop maintains image quality while improving encoding efficiency. For example, a device can perform the first encoding process, and the server that receives the content can perform the second encoding process, thereby improving content quality and efficiency while reducing the processing load on each device. In this case, if there is a request for near-real-time reception and decoding, the data encoded by a device can be received and played back on another device, enabling more flexible real-time distribution.

[0289] As another example, the camera ex113 or the like extracts features from an image, compresses the data related to the features as metadata, and transmits the data to the server. The server performs compression according to the meaning of the image, for example, by determining the importance of an object from the features and switching the quantization precision accordingly. The feature data is particularly effective in improving the accuracy and efficiency of motion vector prediction when the server recompresses the image. Alternatively, the terminal may perform simple encoding such as VLC (variable length coding), and the server may perform encoding with a heavy processing load such as CABAC (context-adaptive binary arithmetic coding).

[0290] As another example, in a stadium, shopping mall, factory, etc., there may be multiple pieces of video data that have been shot by multiple terminals of almost the same scene. In this case, using the multiple terminals that shot the video and, as necessary, other terminals and servers that did not shoot the video, encoding processes are assigned to each of them, for example, in units of GOPs (Group of Pictures), pictures, or tiles obtained by dividing a picture, for distributed processing. This reduces delays and achieves better real-time performance.

[0291] Furthermore, since multiple pieces of video data are of nearly the same scene, the server may manage and / or instruct the video data shot by each terminal to be mutually referenced. Alternatively, the server may receive encoded data from each terminal and change the reference relationships between multiple pieces of data, or correct or replace the pictures themselves and re-encode them. This allows for the generation of streams with improved quality and efficiency for each piece of data.

[0292] The server may also perform transcoding to change the encoding format of the video data before distributing it. For example, the server may convert MPEG-based encoding to VP-based encoding, or convert H.264 to H.265.

[0293] In this way, the encoding process can be performed by a terminal or one or more servers. Therefore, although the following uses terms such as "server" or "terminal" to refer to the entity performing the process, some or all of the processing performed by the server may be performed by the terminal, and some or all of the processing performed by the terminal may be performed by the server. The same applies to the decoding process.

[0294] [3D, multi-angle] In recent years, there has been an increasing trend to integrate and use images or videos of different scenes or the same scene taken from different angles by multiple devices such as cameras ex113 and / or smartphones ex115 that are nearly synchronized with each other. The videos taken by each device are integrated based on the relative positional relationship between the devices obtained separately, or on areas where feature points included in the videos match.

[0295] The server may not only encode 2D video, but also encode still images automatically or at a time specified by the user based on scene analysis of the video and transmit them to the receiving terminal. Furthermore, if the server can acquire the relative positional relationship between the capturing terminals, it can generate a 3D shape of the scene based on not only the 2D video but also images of the same scene captured from different angles. The server may also separately encode 3D data generated by point clouds, or may select or reconstruct images to be transmitted to the receiving terminal from images captured by multiple terminals based on the results of recognizing or tracking people or objects using the 3D data.

[0296] In this way, users can enjoy scenes by selecting any video corresponding to each camera device, or can enjoy content in which video from any viewpoint is extracted from 3D data reconstructed using multiple images or videos. Furthermore, like the video, sound may also be collected from multiple different angles, and the server may multiplex and transmit sound from a specific angle or space in accordance with the video.

[0297] In recent years, content that associates the real world with a virtual world, such as Virtual Reality (VR) and Augmented Reality (AR), has also become popular. In the case of VR images, the server creates viewpoint images for the right eye and left eye, and may perform encoding that allows reference between the viewpoint images using Multi-View Coding (MVC) or the like, or may encode them as separate streams without mutual reference. When decoding the separate streams, it is preferable to play them in synchronization with each other so that a virtual three-dimensional space is reproduced according to the user's viewpoint.

[0298] In the case of AR images, the server superimposes virtual object information in virtual space onto camera information in real space based on the 3D position or the user's viewpoint movement. The decoding device may acquire or store virtual object information and 3D data, generate a 2D image according to the user's viewpoint movement, and smoothly connect the images to create superimposed data. Alternatively, the decoding device may send the user's viewpoint movement to the server in addition to a request for virtual object information, and the server may create superimposed data based on the viewpoint movement received from the 3D data stored on the server, encode the superimposed data, and distribute it to the decoding device. Note that the superimposed data may also have an α value indicating transparency in addition to RGB, and the server may set the α value of parts other than the object created from the 3D data to 0, etc., to encode the parts in a transparent state. Alternatively, the server may generate data by setting a predetermined RGB value as the background, like a chromakey, and using the background color for parts other than the object.

[0299] Similarly, the decoding of distributed data may be performed by each client terminal, by the server, or by multiple terminals. For example, one terminal may first send a reception request to the server, and then other terminals may receive and decode content according to the request, after which the decoded signal is transmitted to a device with a display. By distributing the processing and selecting appropriate content regardless of the capabilities of the communication terminals themselves, high-quality data can be reproduced. As another example, large-sized image data may be received on a TV or other device, and only a portion of the picture, such as a tile into which the picture is divided, may be decoded and displayed on the viewer's personal device. This allows the viewer to share the overall picture while checking their own area of ​​responsibility or an area of ​​interest in more detail.

[0300] In the future, it is expected that content will be seamlessly received by switching the appropriate data for the current connection using delivery system standards such as MPEG-DASH in situations where multiple short-, medium-, or long-distance wireless communications are available, both indoors and outdoors. This will allow users to freely select and switch between decoding and display devices, such as their own devices, indoors and outdoors, in real time. Decoding can also be performed by switching between decoding and display devices based on user location information. This will enable users to display map information on the wall or ground of a neighboring building with an embedded display device while traveling to their destination. It is also possible to switch the bit rate of received data based on the accessibility of the encoded data on the network, such as if the encoded data is cached on a server that can be quickly accessed from the receiving device or copied to an edge server in a content delivery service.

[0301] [Scalable Coding] Regarding content switching, we will explain it using a scalable stream, as shown in Figure 34, compressed and encoded using the video encoding method described in each of the above embodiments. The server may have multiple streams with the same content but different qualities, but may also switch content by taking advantage of the characteristics of a temporally / spatially scalable stream, which is achieved by encoding the content separately into layers, as shown in the figure. In other words, the decoding side determines which layer to decode based on internal factors such as performance and external factors such as communication bandwidth, allowing the decoding side to freely switch between low-resolution and high-resolution content. For example, if a user wants to continue watching a video they were watching on their smartphone ex115 while on the go on a device such as an Internet TV after returning home, the device can simply decode the same stream up to different layers, thereby reducing the burden on the server.

[0302] Furthermore, in addition to the above-described scalability configuration in which pictures are coded for each layer and an enhancement layer exists above a base layer, the enhancement layer may include meta-information based on image statistics, etc., and the decoding side may generate high-quality content by super-resolving pictures in the base layer based on the meta-information. Super-resolution may mean either improving the signal-to-noise ratio at the same resolution or increasing the resolution. The meta-information may include information for specifying linear or nonlinear filter coefficients used in the super-resolution process, or information for specifying parameter values ​​in the filter process, machine learning, or least-squares calculation used in the super-resolution process.

[0303] Alternatively, a picture may be divided into tiles or the like according to the meaning of objects in the image, and the decoding side may select tiles to decode and decode only a portion of the area. Furthermore, by storing the object's attributes (such as a person, a car, or a ball) and its position in the video (such as a coordinate position in the same image) as meta information, the decoding side can identify the position of a desired object based on the meta information and determine the tile containing the object. For example, as shown in FIG. 35, the meta information is stored using a data storage structure different from that of pixel data, such as an SEI message in HEVC. This meta information indicates, for example, the position, size, or color of the main object.

[0304] Furthermore, meta information may be stored in units consisting of multiple pictures, such as streams, sequences, or random access units, which allows the decoding side to obtain the time when a specific person appears in the video, and by combining this with information in units of pictures, it is possible to identify the picture in which the object exists and the position of the object within the picture.

[0305] [Webpage optimization] FIG. 36 is a diagram showing an example of a web page display screen on a computer ex111 or the like. FIG. 37 is a diagram showing an example of a web page display screen on a smartphone ex115 or the like. As shown in FIGS. 36 and 37, a web page may include multiple link images that are links to image content, and the appearance of the web page may differ depending on the device used to view the page. When multiple link images are visible on the screen, the display device (decoding device) may display a still image or I-picture contained in each content as a link image, display a video such as a GIF animation using multiple still images or I-pictures, or receive only the base layer and decode and display the video until the user explicitly selects a link image, or until the link image approaches the center of the screen or until the entire link image is within the screen.

[0306] When a link image is selected by a user, the display device decodes the base layer with the highest priority. If the HTML constituting the web page contains information indicating that the content is scalable, the display device may decode up to the enhancement layer. To ensure real-time performance, before a selection is made or when the communication bandwidth is very limited, the display device decodes and displays only forward-referenced pictures (I-pictures, P-pictures, and forward-reference-only B-pictures), thereby reducing the delay between the decoding time of the first picture and the display time (the delay from the start of content decoding to the start of display). Alternatively, the display device may intentionally ignore the picture reference relationships and roughly decode all B-pictures and P-pictures using forward reference, and then perform normal decoding as the number of received pictures increases over time.

[0307] [Autonomous driving] Furthermore, when transmitting and receiving still image or video data such as 2D or 3D map information for automatic driving or driving assistance of a vehicle, the receiving terminal may receive weather or construction information as meta information in addition to image data belonging to one or more layers, and may associate and decode these. Note that the meta information may belong to a layer, or may simply be multiplexed with the image data.

[0308] In this case, since a vehicle, drone, airplane, etc. including a receiving terminal moves, the receiving terminal can realize seamless reception and decoding while switching between base stations ex106 to ex110 by transmitting the location information of the receiving terminal at the time of a reception request. Also, the receiving terminal can dynamically switch how much meta information to receive or how much to update map information depending on the user's selection, user situation, or communication bandwidth status.

[0309] In this way, in the content supply system ex100, the client can receive, decode, and play back the encoded information sent by the user in real time.

[0310] [Distribution of personal content] Furthermore, the content supply system ex100 allows not only high-quality, long-duration content from video distribution companies, but also unicast or multicast distribution of low-quality, short-duration content from individuals. It is expected that such personal content will continue to increase in the future. To improve the quality of personal content, the server may perform editing before encoding. This can be achieved, for example, with the following configuration.

[0311] During shooting, either in real time or after accumulating the footage, the server performs recognition processing such as detecting shooting errors, scene search, semantic analysis, and object detection from the original image or encoded data. Based on the recognition results, the server manually or automatically corrects out-of-focus or camera shake, deletes less important scenes (e.g., scenes with lower brightness or out-of-focus compared to other pictures), emphasizes object edges, changes color, and performs other editing. The server then encodes the edited data based on the editing results. It is also known that viewing rates decrease if the shooting time is too long. Therefore, the server may automatically clip not only less important scenes as described above but also scenes with little movement, based on the image processing results, so that the content falls within a specific time range depending on the shooting time. Alternatively, the server may generate and encode a digest based on the results of the semantic analysis of the scene.

[0312] In some cases, personal content may contain content that infringes copyright, moral rights, or portrait rights, or may cause the scope of sharing to exceed the intended scope, resulting in inconvenience to individuals. Therefore, for example, the server may intentionally defocus images of people's faces on the periphery of the screen or the interior of a house before encoding. The server may also recognize whether the image to be encoded contains the face of a person other than a pre-registered person, and if so, perform processing such as blurring the face. Alternatively, as pre- or post-processing before encoding, the user may specify a person or background area they wish to modify in the image for copyright or other reasons, and the server may replace the specified area with another image or blur the focus. For a person, the server may track the person in the video and replace the image of the face.

[0313] Furthermore, because viewing personal content with small data volumes requires real-time performance, the decoding device first receives the base layer as a top priority, and then decodes and plays it back, depending on the bandwidth. The decoding device may also receive an enhancement layer during this time, and if the content is played back more than twice, such as when playback is looped, it may play back high-quality video, including the enhancement layer. A stream that has undergone scalable encoding in this way can provide an experience in which the video appears rough when not selected or when viewing begins, but gradually becomes smoother and the image quality improves. In addition to scalable encoding, a similar experience can also be provided by configuring a single stream consisting of a rough stream played the first time and a second stream that is encoded with reference to the first video.

[0314] [Other use cases] Furthermore, these encoding or decoding processes are generally performed by the LSIex500 possessed by each terminal. The LSIex500 may be a single chip or may be configured with multiple chips. It is also possible to incorporate video encoding or decoding software into some kind of recording medium (such as a CD-ROM, flexible disk, or hard disk) that can be read by the computer ex111, and perform the encoding or decoding process using that software. Furthermore, if the smartphone ex115 is equipped with a camera, video data captured by the camera may be transmitted. This video data is data that has been encoded by the LSIex500 possessed by the smartphone ex115.

[0315] The LSIex500 may be configured to download and activate application software. In this case, the terminal first determines whether it supports the content encoding method or has the capability to execute a specific service. If the terminal does not support the content encoding method or does not have the capability to execute a specific service, the terminal downloads the codec or application software and then acquires and plays the content.

[0316] Furthermore, at least one of the video encoding device (image encoding device) or video decoding device (image decoding device) of each of the above embodiments can be incorporated into a digital broadcasting system, not limited to the content supply system ex100 via the Internet ex101. Since multiplexed data in which video and audio are multiplexed is transmitted and received over broadcast radio waves using a satellite or the like, the content supply system ex100 is more suited to multicast than the content supply system ex100, which is more suited to unicast, but similar applications are possible with regard to encoding and decoding processes.

[0317] [Hardware configuration] FIG. 38 is a diagram illustrating a smartphone ex115. FIG. 39 is a diagram illustrating an example configuration of the smartphone ex115. The smartphone ex115 includes an antenna ex450 for transmitting and receiving radio waves to and from the base station ex110, a camera unit ex465 capable of capturing video and still images, and a display unit ex458 for displaying video captured by the camera unit ex465 and decoded data of the video and other data received by the antenna ex450. The smartphone ex115 further includes an operation unit ex466 such as a touch panel, an audio output unit ex457 such as a speaker for outputting voice or sound, an audio input unit ex456 such as a microphone for inputting voice, a memory unit ex467 capable of storing encoded data or decoded data such as captured video or still images, recorded voice, received video or still images, and email, and a slot unit ex464 that serves as an interface with a SIM ex468 for identifying users and authenticating access to various data, including networks. In addition, an external memory may be used instead of the memory unit ex467.

[0318] In addition, a main control unit ex460 that comprehensively controls the display unit ex458 and operation unit ex466, etc., is connected to a power supply circuit unit ex461, an operation input control unit ex462, a video signal processing unit ex455, a camera interface unit ex463, a display control unit ex459, a modulation / demodulation unit ex452, a multiplexing / separation unit ex453, an audio signal processing unit ex454, a slot unit ex464, and a memory unit ex467 via a bus ex470.

[0319] When the power key is turned on by a user, the power supply circuit unit ex461 supplies power from the battery pack to each unit, thereby starting up the smartphone ex115 into an operational state.

[0320] The smartphone ex115 processes calls, data communications, and other communications under the control of a main control unit ex460, which includes a CPU, ROM, RAM, and the like. During calls, the audio signal collected by the audio input unit ex456 is converted into a digital audio signal by the audio signal processing unit ex454, which then undergoes spectrum spread processing by the modulation / demodulation unit ex452, digital-to-analog conversion processing and frequency conversion processing by the transmission / reception unit ex451, and then transmitted via the antenna ex450. The received data is amplified, frequency-converted, and analog-to-digital converted, then subjected to spectrum despreading processing by the modulation / demodulation unit ex452, and converted into an analog audio signal by the audio signal processing unit ex454, which then outputs the amplified data from the audio output unit ex457. During data communications mode, text, still images, or video data is sent to the main control unit ex460 via the operation input control unit ex462 by operating the operation unit ex466, etc., of the main unit, and similar transmission and reception processing is performed. When transmitting video, still images, or video and audio in the data communication mode, the video signal processing unit ex455 compression-encodes the video signal stored in the memory unit ex467 or the video signal input from the camera unit ex465 using the video encoding method described in each of the above embodiments, and sends the encoded video data to the multiplexing / demultiplexing unit ex453. The audio signal processing unit ex454 also encodes the audio signal picked up by the audio input unit ex456 while the camera unit ex465 is capturing video, still images, etc., and sends the encoded audio data to the multiplexing / demultiplexing unit ex453. The multiplexing / demultiplexing unit ex453 multiplexes the encoded video data and encoded audio data using a predetermined method, and modulates and converts the data in the modulation / demodulation unit (modulation / demodulation circuit unit) ex452 and the transmission / reception unit ex451 before transmitting the data via the antenna ex450.

[0321] When receiving video attached to an email or chat, or video linked to a web page, etc., the multiplexed data received via the antenna ex450 is decoded by the multiplexing / separation unit ex453, which separates the multiplexed data into a video data bitstream and an audio data bitstream. The multiplexing / separation unit ex453 then supplies the encoded video data to the video signal processing unit ex455 via the synchronization bus ex470, and supplies the encoded audio data to the audio signal processing unit ex454. The video signal processing unit ex455 decodes the video signal using a video decoding method corresponding to the video encoding method described in each of the above embodiments, and displays the video or still image included in the linked video file on the display unit ex458 via the display control unit ex459. The audio signal processing unit ex454 decodes the audio signal, and the audio is output from the audio output unit ex457. Note that with the widespread use of real-time streaming, audio playback may be socially inappropriate depending on the user's circumstances. Therefore, a configuration that initially plays only the video data without playing the audio signal is desirable. The audio may be played in synchronization only when the user performs an operation such as clicking on the video data.

[0322] Although the smartphone ex115 has been used as an example, three types of implementation are possible for the terminal: a transmitting / receiving terminal having both an encoder and a decoder, a transmitting terminal having only an encoder, and a receiving terminal having only a decoder. Furthermore, in the digital broadcasting system, multiplexed data in which audio data and the like are multiplexed onto video data is received or transmitted, but the multiplexed data may also include text data related to the video in addition to audio data, or the video data itself may be received or transmitted instead of the multiplexed data.

[0323] While the main control unit ex460, which includes a CPU, controls the encoding and decoding processes, devices often also include a GPU. Therefore, a configuration is possible in which a memory shared by the CPU and GPU, or a memory with addresses managed for common use, is used to take advantage of the GPU's performance and process a large area at once. This shortens encoding time, ensures real-time performance, and achieves low latency. It is particularly efficient to perform motion estimation, deblocking filtering, SAO (Sample Adaptive Offset), and transformation and quantization processes at a picture level or other unit in the GPU rather than the CPU. [Industrial Applicability]

[0324] The present invention can be used for encoding / decoding multimedia data, particularly for image and video encoding / decoding devices that use block encoding / decoding. [Explanation of symbols]

[0325] 100 Encoding device 102 Division 104 Subtraction section 106, 5001 conversion unit 108, 5002 Quantization section 110, 5009 Entropy coding section 112, 5003, 6002 Inverse quantization section 114, 5004, 6003 Inverse conversion unit 116 Addition section 118, 5005, 6004 block memory 120 Loop filter section 122, 5006, 6005 frame memory 124, 5007, 6006 Intra prediction section 126, 5008, 6007 Inter prediction section 128 Predictive Control Unit 200 Decryption Device 202, 6001 Entropy Decoding Unit 204 Inverse quantization section 206 Inverse conversion unit 208 Addition section 210 Block Memory 212 Loop filter section 214 Frame Memory 216 Intra Prediction Unit 218 Inter Prediction Unit 220 Predictive control unit 5000 Video Encoding Device 5010, 6008 Block division decision unit 6000 Video Decoder

Claims

1. The circuit and a memory coupled to the circuit; The circuit, in operation, Obtaining a block from a coding tree unit (CTU); Dividing the block into a plurality of sub-blocks in a first direction using a first partition mode; encoding the plurality of sub-blocks; In the division of the block using the first partition mode, based on a parameter arranged in the coding tree unit regarding a partition mode to be written to a bitstream, if the size of the block is Nx2N pixels, the first direction is along 2N pixels, and N is an integer, select division of the block into a plurality of sub-blocks, including at least one sub-block of size N / 4x2N pixels, but not select division of the block into two sub-blocks of size N / 2x2N pixels; If the size of the block is 2NxN pixels, the first direction is along the 2N pixels, and N is an integer, select division of the block into a plurality of sub-blocks including at least one sub-block of 2NxN / 4 pixels in size, and do not select division of the block into two sub-blocks of 2NxN / 2 pixels in size; Image encoding device.

2. Obtaining a block from a coding tree unit (CTU); Dividing the block into a plurality of sub-blocks in a first direction using a first partition mode; encoding the plurality of sub-blocks; In the division of the block using the first partition mode, based on a parameter arranged in the coding tree unit regarding a partition mode to be written to a bitstream, if the size of the block is Nx2N pixels, the first direction is along 2N pixels, and N is an integer, select division of the block into a plurality of sub-blocks, including at least one sub-block of size N / 4x2N pixels, but not select division of the block into two sub-blocks of size N / 2x2N pixels; If the size of the block is 2NxN pixels, the first direction is along the 2N pixels, and N is an integer, select division of the block into a plurality of sub-blocks including at least one sub-block of 2NxN / 4 pixels in size, and do not select division of the block into two sub-blocks of 2NxN / 2 pixels in size; Encoding method.

3. The circuit and a memory coupled to the circuit; The circuit, in operation, Obtaining a block from a coding tree unit (CTU); Dividing the block into a plurality of sub-blocks in a first direction using a first partition mode; decoding the plurality of sub-blocks; In the division of the block using the first partition mode, based on a parameter arranged in the coding tree unit related to the partition mode interpreted from the bitstream, if the size of the block is Nx2N pixels, the first direction is along 2N pixels, and N is an integer, select division of the block into a plurality of sub-blocks, including at least one sub-block of size N / 4x2N pixels, but not select division of the block into two sub-blocks of size N / 2x2N pixels; If the size of the block is 2NxN pixels, the first direction is along the 2N pixels, and N is an integer, select division of the block into a plurality of sub-blocks including at least one sub-block of 2NxN / 4 pixels in size, and do not select division of the block into two sub-blocks of 2NxN / 2 pixels in size; Image decoding device.

4. Obtaining a block from a coding tree unit (CTU); Dividing the block into a plurality of sub-blocks in a first direction using a first partition mode; decoding the plurality of sub-blocks; In the division of the block using the first partition mode, based on a parameter arranged in the coding tree unit related to the partition mode interpreted from the bitstream, if the size of the block is Nx2N pixels, the first direction is along 2N pixels, and N is an integer, select division of the block into a plurality of sub-blocks, including at least one sub-block of size N / 4x2N pixels, but not select division of the block into two sub-blocks of size N / 2x2N pixels; If the size of the block is 2NxN pixels, the first direction is along the 2N pixels, and N is an integer, select division of the block into a plurality of sub-blocks including at least one sub-block of 2NxN / 4 pixels in size, and do not select division of the block into two sub-blocks of 2NxN / 2 pixels in size; Decryption method.

5. The circuit and a memory coupled to the circuit; The circuit, in operation, Obtaining a block from a coding tree unit (CTU); Dividing the block into a plurality of sub-blocks in a first direction using a first partition mode; encoding the plurality of sub-blocks; In the division of the block using the first partition mode, based on a parameter arranged in the coding tree unit regarding a partition mode to be written to a bitstream, if the size of the block is Nx2N pixels, the first direction is along 2N pixels, and N is an integer, select division of the block into a plurality of sub-blocks, including at least one sub-block of size N / 4x2N pixels, but not select division of the block into two sub-blocks of size N / 2x2N pixels; if the size of the block is 2NxN pixels, the first direction is along 2N pixels, and N is an integer, select division of the block into a plurality of sub-blocks, including at least one sub-block of 2NxN / 4 pixels in size, but not select division of the block into two sub-blocks of 2NxN / 2 pixels in size; transmitting a bitstream including parameters related to the partition mode; Bitstream transmitter.

6. Obtaining a block from a coding tree unit (CTU); Dividing the block into a plurality of sub-blocks in a first direction using a first partition mode; encoding the plurality of sub-blocks; In the division of the block using the first partition mode, based on a parameter arranged in the coding tree unit regarding a partition mode to be written to a bitstream, if the size of the block is Nx2N pixels, the first direction is along 2N pixels, and N is an integer, select division of the block into a plurality of sub-blocks, including at least one sub-block of size N / 4x2N pixels, but not select division of the block into two sub-blocks of size N / 2x2N pixels; if the size of the block is 2NxN pixels, the first direction is along 2N pixels, and N is an integer, select division of the block into a plurality of sub-blocks, including at least one sub-block of 2NxN / 4 pixels in size, but not select division of the block into two sub-blocks of 2NxN / 2 pixels in size; transmitting a bitstream including parameters related to the partition mode; Bitstream transmission method.

Images