Encoding device and decoding device

Abstract

To reduce the data amount that is held in memory.SOLUTION: An encoding device 100 determines a filter to be used for deblocking filtering from among a plurality of filters including a first filter, a second filter, and a third filter (S102). The first filter uses M pixels located at an upper side of the block boundary and M pixels located at a lower side of the block boundary, the second filter uses N pixels (N=integer larger than M) located at the upper side of the block boundary and N pixels located at the lower side of the block boundary, and the third filter uses a first pixel at the upper side of the block boundary and a second pixel at the lower side of the block boundary. The number of the first pixels is any one of a plurality of first candidate values, and the number of the second pixels is any one of a plurality of second candidate values. The plurality of first pixel candidate values and the plurality of second pixel candidate values respectively are greater than or equal to N.SELECTED DRAWING: Figure 16

Description

[Technical field]

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

[0002] Conventionally, H.265 exists as a standard for encoding moving images. H.265 is also called High Efficiency Video Coding (HEVC). [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] In such coding methods, it is desirable to propose new methods in order to improve coding efficiency, improve image quality, reduce circuit scale, and so on.

[0005] Each of the configurations or methods disclosed in the embodiments or parts thereof in the present disclosure may contribute to at least one of, for example, improved encoding efficiency, reduced encoding / decoding processing volume, reduced circuit size, improved encoding / decoding speed, and appropriate selection of components / operations such as filters, blocks, sizes, motion vectors, reference pictures, and reference blocks in encoding and decoding.

[0006] Note that the present disclosure also includes disclosure of configurations or methods that can provide benefits other than those described above, such as configurations or methods that improve coding efficiency while suppressing an increase in the amount of processing. [Means for solving the problem]

[0007] An encoding device according to an embodiment of the present disclosure includes a circuit and a memory, the circuit using the memory to determine a filter to be used for deblocking filtering from a plurality of filters including a first filter, a second filter, and a third filter, and performs the deblocking filtering on a block boundary using the determined filter, the first filter being a filter that uses M (M is an integer equal to or greater than 2) pixels above the block boundary and M pixels below the block boundary, and the second filter being a filter that uses N (N is an integer greater than M) pixels above the block boundary. the third filter is a filter that uses a first pixel above the block boundary and a second pixel below the block boundary, the number of first pixels is any one of a first plurality of candidate values, the number of second pixels is any one of a second plurality of candidate values, each of the first plurality of candidate values ​​and each of the second plurality of candidate values ​​is N or a value greater than N, and N is used for the first number of pixels when the block boundary is the top of a coding tree unit (CTU).

[0008] A decoding device according to an embodiment of the present disclosure includes a circuit and a memory, the circuit using the memory to determine a filter to be used for deblocking filtering from a plurality of filters including a first filter, a second filter, and a third filter, and performs the deblocking filtering on a block boundary using the determined filter, the first filter being a filter using M (M is an integer equal to or greater than 2) pixels above the block boundary and M pixels below the block boundary, and the second filter being a filter using N (N is an integer greater than M) pixels above the block boundary. the third filter is a filter that uses a first pixel above the block boundary and a second pixel below the block boundary, the number of first pixels is any one of a first plurality of candidate values, the number of second pixels is any one of a second plurality of candidate values, each of the first plurality of candidate values ​​and each of the second plurality of candidate values ​​is N or a value greater than N, and when the block boundary is at the top of a coding tree unit (CTU), N is used for the first number of pixels.

[0009] In addition, these comprehensive or specific aspects may be realized by a system, an apparatus, a method, an integrated circuit, a computer program, or a non-transitory recording medium such as a computer-readable CD-ROM, or may be realized by any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium. Effect of the Invention

[0010] The present disclosure can provide an encoding device, a decoding device, an encoding method, or a decoding method that can contribute to at least one of the following: improved encoding efficiency, reduced encoding / decoding processing volume, reduced circuit size, improved encoding / decoding speed, and appropriate selection of components / operations such as filters, blocks, sizes, motion vectors, reference pictures, and reference blocks in encoding and decoding.

[0011] Note that the present disclosure also includes disclosure of configurations or methods that can provide benefits other than those described above. For example, a configuration or method that improves encoding efficiency while suppressing an increase in throughput.

Brief Description of Drawings

[0012] [Figure 1] FIG. 1 is a block diagram showing the functional configuration of an encoding apparatus according to Embodiment 1. [Diagram 2] FIG. 2 is a diagram showing an example of block division in Embodiment 1. [Diagram 3] FIG. 3 is a table showing conversion basis functions corresponding to each conversion 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 a filter used in ALF. [Figure 4C] FIG. 4C is a diagram showing another example of the shape of a 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 the outline of prediction image correction processing by OBMC processing. [Figure 5C] FIG. 5C is a conceptual diagram for explaining the outline of prediction image correction processing by OBMC processing. [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 overview of the motion vector derivation process in the merge mode. [Figure 9C] FIG. 9C is a conceptual diagram for explaining an overview of the DMVR process. [Figure 9D] FIG. 9D is a diagram for explaining an outline of a predicted image generating 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. As shown in FIG. [Figure 11] FIG. 11 is a flowchart of the deblocking filter process according to the first embodiment. [Figure 12] FIG. 12 is a diagram showing examples of filter candidates according to the first embodiment. [Figure 13] FIG. 13 is a flowchart of a process of determining filter candidates according to the first aspect of the first embodiment. [Figure 14] FIG. 14 is a diagram showing examples of filter candidates including an asymmetric filter according to the first aspect of the first embodiment. [Figure 15] FIG. 15 is a flowchart of a process of determining filter candidates according to the second aspect of the first embodiment. [Figure 16] FIG. 16 is a diagram showing examples of filter candidates including a filter including extrapolation processing according to the second aspect of the first embodiment. [Figure 17] FIG. 17 is a block diagram showing an implementation example of the encoding device. [Figure 18] FIG. 18 is a block diagram showing an implementation example of a decoding device. [Figure 19] FIG. 19 is a diagram showing the overall configuration of a content supply system that realizes a content distribution service. [Figure 20] FIG. 20 is a diagram showing an example of a coding structure in scalable coding. [Figure 21]FIG. 21 is a diagram showing an example of a coding structure in scalable coding. [Figure 22] FIG. 22 is a diagram showing an example of a display screen of a web page. [Figure 23] FIG. 23 is a diagram showing an example of a display screen of a web page. [Figure 24] FIG. 24 is a diagram illustrating an example of a smartphone. [Diagram 25] FIG. 25 is a block diagram showing an example of the configuration of a smartphone. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] An encoding device according to an embodiment of the present disclosure includes a circuit and a memory, wherein the circuit uses the memory to determine a filter to be used for deblocking filtering from a plurality of filters including a first filter and a second filter, and performs the deblocking filtering on a block boundary using the determined filter, wherein the first filter is a filter that uses M (M is an integer equal to or greater than 2) pixels above the block boundary and M pixels below the block boundary, and the second filter is a filter that uses a first pixel above the block boundary and a second pixel below the block boundary, wherein the number of the first pixels is any one of a first plurality of candidate values, the number of the second pixels is any one of a second plurality of candidate values, and each of the first plurality of candidate values ​​and each of the second plurality of candidate values ​​is a value greater than M or M.

[0014] This allows the encoding device to reduce the number of pixels on the upper or left side of the block boundary used in the deblocking filter process, which may reduce the amount of data stored in the memory. Note that the left pixel may be used instead of the upper pixel, and the right pixel may be used instead of the lower pixel.

[0015] For example, the second filter may have the same number of first pixels and the same number of second pixels, or may have a different number of first pixels and the same number of second pixels.

[0016] For example, each of the first plurality of candidate values ​​and each of the second plurality of candidate values ​​may be a value equal to or greater than four.

[0017] For example, among the plurality of filters, filters other than the second filter may use the same number of pixels above and below the block boundary.

[0018] For example, the maximum value that the number of the first pixels can take may be limited depending on whether the position of the block boundary is a predetermined position or not.

[0019] For example, the predetermined position may be the top of a coding tree unit (CTU).

[0020] When the second filter is applied to the vertical and horizontal boundaries, the number of pixels used in the second filter may be limited only to the vertical boundaries, or may be limited to both the vertical and horizontal boundaries. In other words, the predetermined position may be only the top end of the CTU, or may be the top or bottom end of the CTU.

[0021] For example, the predetermined position may be the top end of a coding unit (CU).

[0022] In addition, when the second filter is applied to the vertical and horizontal boundaries, the number of pixels used in the second filter may be limited only to the vertical boundaries, or may be limited to the vertical and horizontal boundaries. In other words, the predetermined position may be only the upper end of the CU, or may be the upper end or the lower end of the CU.

[0023] For example, the maximum value that the number of the first pixels can take may be equal to or less than the number of pixels above the block boundary used by a filter among the plurality of filters that uses the next largest number of pixels after the second filter.

[0024] For example, the maximum value that the number of the first pixels can take may be less than or equal to the number of pixels above the block boundary of a process that uses the largest number of pixels above the block boundary among processes included in the loop filter process including the deblocking filter process, excluding the second filter.

[0025] For example, when the number of the first pixels is different from the number of the second pixels, the second filter may have different filter tap lengths on either side of the block boundary.

[0026] For example, when the number of the first pixels and the number of the second pixels are different, the second filter is a filter that uses the first pixels to generate a third pixel that is adjacent to the upper side of the first pixels, and uses the first pixels, the second pixels, and the third pixels, and the sum of the number of the first pixels and the number of the third pixels may be equal to the number of the second pixels.

[0027] A decoding device according to an embodiment of the present disclosure includes a circuit and a memory, wherein the circuit uses the memory to determine a filter to be used for deblocking filtering from a plurality of filters including a first filter and a second filter, and performs the deblocking filtering on a block boundary using the determined filter, wherein the first filter is a filter that uses M (M is an integer greater than or equal to 2) pixels above the block boundary and M pixels below the block boundary, and the second filter is a filter that uses a first pixel above the block boundary and a second pixel below the block boundary, wherein the number of the first pixels is any one of a first plurality of candidate values, the number of the second pixels is any one of a second plurality of candidate values, and each of the first plurality of candidate values ​​and each of the second plurality of candidate values ​​is a value greater than M or M.

[0028] This enables the decoding device to reduce the number of pixels above or to the left of the block boundary to be used in the deblocking filter process, potentially reducing the amount of data to be held in memory.

[0029] For example, the second filter may have the same number of first pixels and the same number of second pixels, or may have a different number of first pixels and the same number of second pixels.

[0030] For example, each of the first plurality of candidate values ​​and each of the second plurality of candidate values ​​may be a value equal to or greater than four.

[0031] For example, among the plurality of filters, filters other than the second filter may use the same number of pixels above and below the block boundary.

[0032] For example, the maximum value that the number of the first pixels can take may be limited depending on whether the position of the block boundary is a predetermined position or not.

[0033] For example, the predetermined position may be the top of a coding tree unit (CTU).

[0034] When the second filter is applied to the vertical and horizontal boundaries, the number of pixels used in the second filter may be limited only to the vertical boundaries, or may be limited to both the vertical and horizontal boundaries. In other words, the predetermined position may be only the top end of the CTU, or may be the top or bottom end of the CTU.

[0035] For example, the predetermined position may be the top end of a coding unit (CU).

[0036] In addition, when the second filter is applied to the vertical and horizontal boundaries, the number of pixels used in the second filter may be limited only to the vertical boundaries, or may be limited to the vertical and horizontal boundaries. In other words, the predetermined position may be only the upper end of the CU, or may be the upper end or the lower end of the CU.

[0037] For example, the maximum value that the number of the first pixels can take may be equal to or less than the number of pixels above the block boundary used by a filter among the plurality of filters that uses the next largest number of pixels after the second filter.

[0038] For example, the maximum value that the number of the first pixels can take may be less than or equal to the number of pixels above the block boundary of a process that uses the largest number of pixels above the block boundary among processes included in the loop filter process including the deblocking filter process, excluding the second filter.

[0039] For example, when the number of the first pixels is different from the number of the second pixels, the second filter may have different filter tap lengths on either side of the block boundary.

[0040] For example, when the number of the first pixels and the number of the second pixels are different, the second filter is a filter that uses the first pixels to generate a third pixel that is adjacent to the upper side of the first pixels, and uses the first pixels, the second pixels, and the third pixels, and the sum of the number of the first pixels and the number of the third pixels may be equal to the number of the second pixels.

[0041] An encoding method according to one embodiment of the present disclosure determines a filter to be used for deblocking filtering from a plurality of filters including a first filter and a second filter, and performs the deblocking filtering on a block boundary using the determined filter, wherein the first filter is a filter that uses M (M is an integer equal to or greater than 2) pixels above the block boundary and M pixels below the block boundary, the second filter is a filter that uses a first pixel above the block boundary and a second pixel below the block boundary, the number of the first pixels is any one of a first plurality of candidate values, the number of the second pixels is any one of a second plurality of candidate values, and each of the first plurality of candidate values ​​and each of the second plurality of candidate values ​​is a value greater than M or M.

[0042] According to this, the encoding method can reduce the number of pixels on the upper or left side of the block boundary to be used in the deblocking filter process, which may reduce the amount of data held in memory.

[0043] A decoding method according to one embodiment of the present disclosure includes determining a filter to be used for deblocking filtering from a plurality of filters including a first filter and a second filter, and performing the deblocking filtering on a block boundary using the determined filter, wherein the first filter is a filter that uses M (M is an integer equal to or greater than 2) pixels above the block boundary and M pixels below the block boundary, the second filter is a filter that uses a first pixel above the block boundary and a second pixel below the block boundary, the number of the first pixels is any one of a first plurality of candidate values, the number of the second pixels is any one of a second plurality of candidate values, and each of the first plurality of candidate values ​​and each of the second plurality of candidate values ​​is a value greater than M or M.

[0044] According to this, the decoding method can reduce the number of pixels on the upper or left side of the block boundary to be used in the deblocking filter process, which may reduce the amount of data held in memory.

[0045] Furthermore, these comprehensive or specific aspects may be realized in a system, an apparatus, a method, an integrated circuit, a computer program, or a non-transitory recording medium such as a computer-readable CD-ROM, or may be realized in any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium.

[0046] Hereinafter, the embodiment will be described in detail with reference to the drawings.

[0047] The embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, component arrangement and connection forms, steps, and order of steps 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 an independent claim showing a top concept are described as optional components.

[0048] (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.

[0049] 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.

[0050] (1) For the encoding device or the decoding device of the first embodiment, among the multiple components constituting the encoding device or the 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) In the encoding device or decoding device of the first embodiment, any modification such as addition, replacement, or deletion of functions or processes performed by some of the components constituting the encoding device or decoding device is made, and then the 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. (3) Adding a process to the method implemented by the encoding device or decoding device of the first embodiment, and / or replacing or deleting some of the processes included in the method, and then replacing the process corresponding to 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) Implementing a component having some of the functions of some of the multiple components constituting the encoding device or decoding device of embodiment 1, or a component that performs some of the processing performed by some of the multiple components constituting the encoding device or decoding device of embodiment 1, in combination with a component described in each aspect of the present disclosure, a component having some of the functions of the component described in each aspect of the present disclosure, or a component that performs some of the processing performed by the component described in each aspect of the present disclosure. (6) In the method implemented by the encoding device or the decoding device of the first embodiment, among a plurality of processes included in the method, a process corresponding to a process described in each aspect of the present disclosure is replaced with a process described in each aspect of the present disclosure. (7) Some of the processes included in the method implemented by the encoding device or the decoding device of the first embodiment may be implemented in combination with the processes described in each aspect of the present disclosure. 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, the processes and / or configurations may be implemented in a device used for a purpose other than the video / image encoding device or video / image decoding device disclosed in the first embodiment, 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.

[0051] [Outline of the encoding device] First, a description will be given of an overview of a coding device according to embodiment 1. 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.

[0052] 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.

[0053] The encoding device 100 is realized by, for example, a general-purpose processor and a memory. In this case, when the 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. The encoding device 100 may also 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.

[0054] Each component included in the encoding device 100 will be described below.

[0055] [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 may be 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 may be called coding units (CUs), prediction units (PUs), or transform units (TUs). Note that in this embodiment, it is not necessary to distinguish between CUs, PUs, and TUs, and some or all of the blocks in a picture may be the processing units of CUs, PUs, and TUs.

[0056] 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.

[0057] 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).

[0058] 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.

[0059] The top right 64x64 block is divided horizontally into two rectangular 64x32 blocks 14, 15 (binary tree block division).

[0060] The bottom left 64x64 block is divided into four square 32x32 blocks (quadtree block division). Of the four 32x32 blocks, the top left and bottom right blocks are further divided. The top 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 division). The bottom right 32x32 block is divided horizontally into two 32x16 blocks (binary tree block division). As a result, the bottom left 64x64 block is divided into a 16x32 block 16, two 16x16 blocks 17, 18, two 32x32 blocks 19, 20, and two 32x16 blocks 21, 22.

[0061] The bottom right 64x64 block 23 is not split.

[0062] 2, the block 10 is divided into 13 variable-sized blocks 11 to 23 based on recursive quad-tree and binary tree block division. Such division is sometimes called QTBT (quad-tree plus binary tree) division.

[0063] 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.

[0064] [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 called a residual error) 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.

[0065] 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 the image may also be referred to as a sample.

[0066] [Conversion section] The transform unit 106 transforms the prediction error in the spatial domain into transform coefficients in the frequency domain, 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 prediction error in the spatial domain.

[0067] 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 may be called an explicit multiple core transform (EMT) or an adaptive multiple transform (AMT).

[0068] The multiple transform types include, for example, DCT-II, DCT-V, DCT-VIII, DST-I, and DST-VII. Figure 3 is a table showing the transform basis functions corresponding to each transform type. In Figure 3, N indicates the number of input pixels. The selection of the transform type from among the multiple transform types may depend on, for example, the type of prediction (intra prediction and inter prediction) or the intra prediction mode.

[0069] Such information indicating whether EMT or AMT is applied (e.g., called an AMT flag) and information indicating the selected transformation type are signaled at the CU level. Note that the signaling of such 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).

[0070] Furthermore, the transform unit 106 may retransform the transform coefficients (transformation results). Such retransformation may be called AST (adaptive secondary transform) or NSST (non-separable secondary transform). For example, the transform unit 106 performs retransformation for each subblock (e.g., 4x4 subblock) included in a block of transform coefficients corresponding to intra-prediction errors. Information indicating whether or not to apply NSST and information regarding a transform matrix used in NSST are signaled at a CU level. Note that signaling of these pieces of 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).

[0071] 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 together.

[0072] 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 a 16x16 transformation matrix is ​​used to transform the array.

[0073] Another example of a non-separable transformation is the Hypercube Givens Transform, which treats a 4x4 input block as a single array with 16 elements and then performs Givens rotations on that array multiple times.

[0074] [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 a quantization parameter (QP) corresponding to the scanned transform coefficients. Then, the quantization unit 108 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.

[0075] The predetermined order is an order for quantization / dequantization of the transform coefficients. For example, the predetermined scanning order is defined as ascending (low to high) or descending (high to low) frequency order.

[0076] The quantization parameter is a parameter that defines the quantization step (quantization width). For example, if the value of the quantization parameter increases, the quantization step also increases. In other words, if the value of the quantization parameter increases, the quantization error increases.

[0077] [Entropy coding part] 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.

[0078] [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. Then, the inverse quantization unit 112 outputs the inverse quantized transform coefficients of the current block to the inverse transform unit 114.

[0079] [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.

[0080] 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. That is, the restored prediction error includes a quantization error.

[0081] [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.

[0082] [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.

[0083] [Loop filter section] The loop filter unit 120 applies a loop filter to the block reconstructed by the adder unit 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).

[0084] In ALF, a least squared error filter is applied to remove coding artifacts. For example, for each 2x2 sub-block in the current block, one filter is selected from among multiple filters based on local gradient direction and activity.

[0085] Specifically, first, sub-blocks (e.g., 2x2 sub-blocks) are classified into a plurality of classes (e.g., 15 or 25 classes). The classification of the sub-blocks is performed 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).

[0086] The gradient direction value D is derived, for example, by comparing gradients in multiple directions (e.g., horizontal, vertical, and two diagonal directions), and the gradient activity value A is derived, for example, by adding gradients in multiple directions and quantizing the sum.

[0087] Based on the result of such classification, a filter for the sub-block is determined from among a plurality of filters.

[0088] The shape of the filter used in the ALF is, for example, a circularly symmetric shape. FIGS. 4A to 4C are diagrams showing a number of examples of the shape of the filter used in the ALF. FIG. 4A shows a 5×5 diamond-shaped filter, FIG. 4B shows a 7×7 diamond-shaped filter, and FIG. 4C shows a 9×9 diamond-shaped filter. Information indicating the shape of the filter is signaled at the picture level. Note that the signaling of the information indicating the shape of the filter does not need to be limited to the picture level, and may be at other levels (for example, the sequence level, slice level, tile level, CTU level, or CU level).

[0089] The on / off of ALF is determined, for example, at the picture level or the CU level. For example, whether or not to apply ALF is determined for luminance at the CU level, and whether or not to apply ALF is determined for chrominance at the picture level. Information indicating whether or not to apply ALF is signaled at the picture level or the CU level. Note that the signaling of information indicating whether or not to apply ALF is not 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).

[0090] 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 be at other levels (e.g., sequence level, slice level, tile level, CTU level, CU level, or sub-block level).

[0091] [Frame memory] The frame memory 122 is a storage unit for storing reference pictures used in inter prediction, and may be called a frame buffer. Specifically, the frame memory 122 stores the reconstructed block filtered by the loop filter unit 120.

[0092] [Intra prediction section] The intra prediction unit 124 generates a prediction signal (intra prediction signal) by performing intra prediction (also called intra-screen prediction) of the current block with reference to a block in the current picture stored in the block memory 118. Specifically, the intra prediction unit 124 generates an intra prediction signal by performing intra prediction with reference to 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.

[0093] 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.

[0094] 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).

[0095] The multiple directional prediction modes include, for example, 33 prediction modes defined in the H.265 / HEVC standard. The multiple directional prediction modes may include 32 prediction modes in addition to the 33 directions (a total of 65 directional prediction modes). FIG. 5A is a diagram showing 67 intra prediction modes (2 non-directional prediction modes and 65 directional prediction modes) in intra prediction. The solid arrows represent the 33 directions defined in the H.265 / HEVC standard, and the dashed arrows represent the additional 32 directions.

[0096] In addition, in the intra prediction of the chrominance block, the luminance block may be referenced. That is, the chrominance component of the current block may be predicted based on the luminance component of the current block. Such intra prediction may be called CCLM (cross-component linear model) prediction. An intra prediction mode of the chrominance block that refers to such a luminance block (for example, called a CCLM mode) may be added as one of the intra prediction modes of the chrominance block.

[0097] The intra prediction unit 124 may correct pixel values ​​after intra prediction based on the gradient of reference pixels in the horizontal / vertical directions. Intra prediction with such correction may be called position dependent intra prediction combination (PDPC). Information indicating whether or not PDPC is applied (e.g., called a PDPC flag) is signaled, for example, at a CU level. Note that the 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).

[0098] [Inter prediction section] The inter prediction unit 126 generates a prediction signal (inter prediction signal) by performing inter prediction (also called inter prediction) of the current block with reference to a reference picture stored in the frame memory 122 and different from the current picture. The inter prediction is performed in units of the current block or a sub-block (e.g., 4x4 block) in the current block. For example, the inter prediction unit 126 performs motion estimation in the reference picture for the current block or the sub-block. Then, the inter prediction unit 126 generates an inter prediction signal of the current block or the sub-block by performing motion compensation using motion information (e.g., a motion vector) obtained by the motion estimation. Then, the inter prediction unit 126 outputs the generated inter prediction signal to the prediction control unit 128.

[0099] The motion information used for the 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.

[0100] In addition, the inter prediction signal may be generated using not only the motion information of the current block obtained by motion search, but also the motion information of the adjacent block. Specifically, the inter prediction signal may be generated for each sub-block in the current block by performing weighted addition of the prediction signal based on the motion information obtained by motion search and the prediction signal based on the motion information of the adjacent block. Such inter prediction (motion compensation) may be called OBMC (overlapped block motion compensation).

[0101] In such an OBMC mode, information indicating the size of a sub-block for OBMC (e.g., called OBMC block size) is signaled at the sequence level. Also, information indicating whether or not to apply the OBMC mode (e.g., called OBMC flag) is signaled at the CU level. Note that the signaling level of these pieces of information does not need to be limited to the sequence level and CU level, and may be other levels (e.g., picture level, slice level, tile level, CTU level, or sub-block level).

[0102] The OBMC mode will now be described in more detail. Figures 5B and 5C are a flowchart and a conceptual diagram for explaining an overview of the predicted image correction process in the OBMC process.

[0103] First, a predicted image (Pred) is obtained by normal motion compensation using a motion vector (MV) assigned to a block to be coded.

[0104] Next, the motion vector (MV_L) of the already-encoded left adjacent block is applied to the block to be encoded to obtain a predicted image (Pred_L), and the predicted image is weighted and superimposed with Pred_L to perform a first correction of the predicted image.

[0105] Similarly, the motion vector (MV_U) of the already-encoded adjacent block above is applied to the block to be encoded 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.

[0106] 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 more than two stages of correction are performed using the right adjacent block or the lower adjacent block.

[0107] The area in which overlapping is performed does not have to be the entire pixel area of ​​the block, but may be only a part of the area near the block boundary.

[0108] Note that although the above describes the process of correcting a predicted image from one reference picture, 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 then overlaid to obtain the final predicted image.

[0109] The block to be processed may be a prediction block unit, or a sub-block unit obtained by further dividing the prediction block.

[0110] As a method of determining whether or not to apply OBMC processing, for example, there is a method of using obmc_flag, which is a signal indicating whether or not to apply OBMC processing. As a specific example, in an encoding device, it is determined whether or not the encoding target block belongs to an area with complex motion, and if it belongs to an area with complex motion, a value of 1 is set as obmc_flag and encoding is performed by applying OBMC processing, and if it does not belong to an area with complex motion, a value of 0 is set as obmc_flag and encoding is performed without applying OBMC processing. On the other hand, in a decoding device, by decoding obmc_flag described in a stream, decoding is performed by switching whether or not to apply OBMC processing according to the value.

[0111] In addition, 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. Also, for example, 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.

[0112] 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.

[0113] An example of the FRUC process is shown in FIG. 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 encoded blocks spatially or temporally adjacent to the current block. Next, a best candidate MV is selected from 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.

[0114] Then, based on the motion vector of the selected candidate, a motion vector for the current block is derived. Specifically, for example, the motion vector of the selected candidate (best candidate MV) is derived as it is as the motion vector for the current block. Also, for example, the motion vector for the current block may be derived by performing pattern matching in the surrounding area of ​​the position in the reference picture corresponding to the motion vector of the selected candidate. That is, a search is performed in the surrounding area of ​​the best candidate MV in the same manner, and if there is an MV with a better evaluation value, the best candidate MV may be updated to the MV, and the MV may be set as the final MV of the current block. It is also possible to configure the system without performing this process.

[0115] The same processing may be performed when processing is performed in sub-block units.

[0116] The evaluation value is calculated by finding a difference value of the reconstructed image by pattern matching between an area in a reference picture corresponding to the motion vector and a predetermined area. The evaluation value may be calculated using information other than the difference value.

[0117] As the pattern matching, a first pattern matching or a second pattern matching is used. The first pattern matching and the second pattern matching are sometimes called bilateral matching and template matching, respectively.

[0118] 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 along the motion trajectory of the current block is used as a predetermined area for calculating the evaluation value of the above-mentioned candidate.

[0119] FIG. 6 is a diagram for explaining an example of pattern matching (bilateral matching) between two blocks along a motion trajectory. As shown in FIG. 6, in the first pattern matching, two motion vectors (MV0, MV1) are derived by searching for a pair of two blocks that are along the motion trajectory of a current block (Cur block) and are in two different reference pictures (Ref0, Ref1) that best match each other. Specifically, for the current block, a difference is derived between a reconstructed image at a designated position in a first coded reference picture (Ref0) designated by a candidate MV and a reconstructed image at a designated position in a second coded reference picture (Ref1) designated by a symmetric MV obtained by scaling the candidate MV by a display time interval, and an evaluation value is calculated using the obtained difference value. It is preferable to select the candidate MV with the best evaluation value among a plurality of candidate MVs as the final MV.

[0120] Under the assumption of continuous motion trajectories, the motion vectors (MV0, MV1) pointing to two reference blocks are proportional to the temporal distances (TD0, TD1) between the current picture (Cur Pic) and the two reference pictures (Ref0, Ref1). For example, if the current picture is located between two reference pictures in time 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.

[0121] 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, a block adjacent to the current block in the current picture is used as a predetermined area for calculating the evaluation value of the above-mentioned candidate.

[0122] FIG. 7 is a diagram for explaining an example of pattern matching (template matching) between a template in a current picture and a block in a reference picture. As shown in FIG. 7, in the second pattern matching, the motion vector of the current block is derived by searching in the reference picture (Ref0) for the block that most closely matches the block adjacent to the current block (Cur block) in the current picture (Cur Pic). Specifically, for the current block, the difference between the reconstructed image of the encoded region of both or either of the left and upper adjacent blocks and the reconstructed image at the equivalent position in the encoded reference picture (Ref0) specified by the candidate MV is derived, an evaluation value is calculated using the obtained difference value, and the candidate MV with the best evaluation value among the plurality of candidate MVs is selected as the best candidate MV.

[0123] Information indicating whether or not to apply such a FRUC mode (for example, called a FRUC flag) is signaled at the CU level. Also, when the FRUC mode is applied (for example, when the FRUC flag is true), information indicating the pattern matching method (first pattern matching or second pattern matching) (for example, called a FRUC mode flag) is signaled at the CU level. Note that the signaling of this information does not necessarily have to be limited to the CU level and may be at other levels (for example, sequence level, picture level, slice level, tile level, CTU level, or sub-block level).

[0124] Here, a mode for deriving a motion vector based on a model assuming uniform linear motion will be described. This mode is sometimes called the BIO (bi-directional optical flow) mode.

[0125] FIG. 8 is a diagram for explaining a model assuming uniform linear motion. In FIG. 8, (v x , v y ) indicates the velocity vector, and τ 0 , τ 1respectively represent the current picture (Cur Pic) and two reference pictures (Ref 0 ,Ref 1 ) indicates the time distance between (MVx 0 ,MVy 0 ) is the reference picture Ref 0 Let us denote the motion vector corresponding to (MVx 1 , M.V.y. 1 ) is the reference picture Ref 1 The motion vector corresponding to

[0126] At this time, the velocity vector (v x ,v y Under the assumption of uniform linear motion of (MVx 0 ,MVy 0 ) and (MVx 1 ,MVy 1 ) are respectively, (v x τ 0 ,v y τ 0 ) and (-v x τ 1 ,-v y τ 1 ) and the following optical flow equation (1) holds:

[0127]

number

[0128] 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.

[0129] Note that the motion vector may be derived on the decoding device side by a method other than the method based on a model assuming uniform linear motion. For example, the motion vector may be derived on a sub-block basis based on the motion vectors of multiple adjacent blocks.

[0130] Here, a mode in which a motion vector is derived for each sub-block based on the motion vectors of a plurality of adjacent blocks will be described. This mode is sometimes called an affine motion compensation prediction mode.

[0131] 9A is a diagram for explaining derivation of a motion vector for each sub-block based on the motion vectors of multiple adjacent blocks. In FIG. 9A, the current block includes 16 4x4 sub-blocks. Here, the motion vector v of the upper left corner control point of the current block is derived based on the motion vectors of the adjacent blocks. 0 is derived, and the motion vector v of the upper right corner control point of the current block is calculated based on the motion vectors of the neighboring sub-blocks. 1 Then, two motion vectors v 0 and v 1 Using the above, the motion vector (v x ,v y ) is derived.

[0132]

number

[0133] Here, x and y respectively indicate the horizontal and vertical positions of the sub-block, and w indicates a predetermined weighting factor.

[0134] Such affine motion compensation prediction mode may include several modes with different methods of deriving the motion vectors of the upper left and upper right corner control points. Information indicating such affine motion compensation prediction mode (e.g., called 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., sequence level, picture level, slice level, tile level, CTU level, or subblock level).

[0135] [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.

[0136] Here, an example of deriving a motion vector for a picture to be coded in the merge mode will be described. Fig. 9B is a diagram for explaining an overview of a motion vector derivation process in the merge mode.

[0137] 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 located spatially around the block to be coded, temporally adjacent prediction MVs, which are MVs held by nearby blocks projected onto the position of the block to be coded in the coded reference picture, joint prediction MVs, which are MVs generated by combining the MV values ​​of spatially adjacent prediction MVs and temporally adjacent prediction MVs, and zero prediction MVs, which are MVs with a value of zero.

[0138] Next, one prediction MV is selected from the multiple prediction MVs registered in the prediction MV list, and is determined as the MV for the block to be coded.

[0139] Furthermore, the variable length coding unit writes merge_idx, which is a signal indicating which predicted MV has been selected, into the stream and codes it.

[0140] 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 additional predicted MVs other than the types of predicted MVs shown in the figure.

[0141] Note that the final MV may be determined by performing DMVR processing, which will be described later, using the MV of the block to be coded derived in the merge mode.

[0142] Here, an example of determining the MV using the DMVR process will be described.

[0143] FIG. 9C is a conceptual diagram for explaining an overview of the DMVR process.

[0144] 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 taking the average of each reference pixel.

[0145] Next, the template is used to search the surrounding areas of the candidate MVs of 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 value between each pixel value of the template and each pixel value of the search area, the MV value, etc.

[0146] The outline of the processing described here is basically the same for the encoding device and the decoding device.

[0147] 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.

[0148] Here, a mode in which a predicted image is generated using LIC processing will be described.

[0149] FIG. 9D is a diagram for explaining an outline of a predicted image generating method using luminance correction processing by LIC processing.

[0150] First, a MV for obtaining a reference image corresponding to a block to be coded from a reference picture that is a coded picture is derived.

[0151] 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.

[0152] A luminance correction process is performed on a reference image in a reference picture specified by the MV using the luminance correction parameter, thereby generating a predicted image for the block to be coded.

[0153] It should be noted that the shape of the peripheral reference region in FIG. 9D is just an example, and other shapes may be used.

[0154] 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.

[0155] As a method of determining whether or not to apply LIC processing, for example, there is a method of using lic_flag, which is a signal indicating whether or not to apply LIC processing. As a specific example, in an encoding device, it is determined whether or not 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, a value of 1 is set as lic_flag and encoding is performed by applying LIC processing, and if it does not belong to an area where a luminance change occurs, a value of 0 is set as lic_flag and encoding is performed without applying LIC processing. On the other hand, a decoding device decodes lic_flag described in a stream, and switches whether or not to apply LIC processing depending on the value, and performs decoding.

[0156] Another method of determining whether to apply LIC processing is, for example, a method of determining according to whether LIC processing is applied to surrounding blocks.As a specific example, when the block to be coded is in merge mode, determine whether the surrounding coded blocks selected when deriving MV in merge mode processing have been coded by applying LIC processing, and switch whether to apply LIC processing according to the result and perform coding.In addition, in this example, the process in decoding is exactly the same.

[0157] [Overview of the Decryption Device] Next, a description will be given of an overview of a decoding device capable of decoding the coded signal (coded bit stream) output from the above coding device 100. Fig. 10 is a block diagram showing a functional configuration of a decoding device 200 according to the first embodiment. The decoding device 200 is a video / image decoding device that decodes a video / image on a block-by-block basis.

[0158] 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.

[0159] The decoding device 200 is realized by, for example, a general-purpose processor and a memory. In this case, when the 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. The decoding device 200 may also 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.

[0160] Each component included in the decoding device 200 will be described below.

[0161] [Entropy Decoding Part] The entropy decoding unit 202 entropy decodes the coded bit stream. Specifically, the entropy decoding unit 202 arithmetically decodes the coded bit stream into a binary signal, for example. 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.

[0162] [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. Then, the inverse quantization unit 204 outputs the inverse quantized quantized coefficients (i.e., transform coefficients) of the current block to the inverse transform unit 206.

[0163] [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 .

[0164] 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.

[0165] Also for example, if the information interpreted from the coded bitstream indicates to apply NSST, then inverse transform unit 206 applies an inverse re-transform to the transform coefficients.

[0166] [Addition section] The adder 208 reconstructs the current block by adding the prediction error, which is an input from the inverse transformer 206, and the prediction sample, which is an 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.

[0167] [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 block output from the adder 208.

[0168] [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.

[0169] If the information indicating ALF on / off read from the encoded bitstream indicates ALF on, one filter is selected from among multiple filters based on the local gradient direction and activity, and the selected filter is applied to the reconstructed block.

[0170] [Frame memory] The frame memory 214 is a storage unit for storing reference pictures used in inter prediction, and may be called a frame buffer. Specifically, the frame memory 214 stores the reconstructed blocks filtered by the loop filter unit 212.

[0171] [Intra prediction section] The intra prediction unit 216 generates a prediction signal (intra prediction signal) by performing intra prediction with reference to a block in the current picture stored in the block memory 210 based on an intra prediction mode interpreted from the encoded bit stream. Specifically, the intra prediction unit 216 generates an 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 220.

[0172] 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.

[0173] Furthermore, when information interpreted from the encoded 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 / vertical directions.

[0174] [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) in the current block. For example, the inter prediction unit 218 generates an inter prediction signal of the current block or sub-block by performing motion compensation using motion information (e.g., motion vectors) interpreted from the encoded bitstream, and outputs the inter prediction signal to the prediction control unit 220.

[0175] In addition, when 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.

[0176] Also, if the information interpreted from the encoded bitstream indicates that the FRUC mode is 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 encoded bitstream. Then, the inter prediction unit 218 performs motion compensation using the derived motion information.

[0177] In addition, when the BIO mode is applied, the inter prediction unit 218 derives a motion vector based on a model assuming uniform linear motion. In addition, when information interpreted from the encoded bitstream indicates that an affine motion compensation prediction mode is applied, the inter prediction unit 218 derives a motion vector on a sub-block basis based on the motion vectors of multiple adjacent blocks.

[0178] [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.

[0179] [Deblocking filter processing] Next, the deblocking filter processing performed in the encoding device 100 and the decoding device 200 configured as above will be specifically described with reference to the drawings. Note that, although the operation of the loop filter unit 120 provided in the encoding device 100 will be mainly described below, the operation of the loop filter unit 212 provided in the decoding device 200 is also similar.

[0180] As described above, when encoding an image, the encoding device 100 calculates a prediction error by subtracting a prediction signal generated by the intra prediction unit 124 or the inter prediction unit 126 from an original signal. The encoding device 100 generates a quantized coefficient by performing an orthogonal transform process and a quantization process on the prediction error. Furthermore, the encoding device 100 restores the prediction error by inverse quantizing and inverse orthogonal transforming the obtained quantized coefficient. Here, since the quantization process is a lossy process, the restored prediction error has an error (quantization error) with respect to the prediction error before transformation.

[0181] The deblocking filter process performed by the loop filter unit 120 is a type of filter process that is performed for the purpose of reducing this quantization error, etc. The deblocking filter process is applied to block boundaries in order to remove block noise.

[0182] 11 is a flowchart showing an outline of the deblocking filter process according to the present embodiment. First, the loop filter unit 120 determines whether or not to perform deblocking filter process on a target boundary, which is a block boundary to be processed, using, for example, pixel values ​​of pixels in the block or quantization parameters (S101). If it is determined that deblocking filter process is to be performed (Yes in S101), the loop filter unit 120 determines filter characteristics (S102) and performs deblocking filter process on the target boundary using the determined filter characteristics (S103).

[0183] For example, in determining the filter characteristics, the loop filter unit 120 selects a filter to be used from several types of filter candidates that differ in the number of pixels used in the filter. For example, there may be a weak filter that uses a small number of pixels, a strong filter that uses a larger number of pixels than the weak filter, and a super-strong filter that uses an even larger number of pixels than the strong filter as filter candidates.

[0184] Fig. 12 is a diagram showing examples of these filter candidates. For example, as shown in Fig. 12, the number of pixels used for each filter may be such that a weak filter uses three pixels on either side of the boundary, a strong filter uses four pixels on either side of the boundary, and a very strong filter uses eight pixels on either side of the boundary, or a different number of pixels may be used. Note that, although an example of upper and lower block boundaries is shown here, the same applies to left and right block boundaries.

[0185] Furthermore, the multiple filter candidates may include multiple filters that use the same number of pixels but have different filter characteristics due to different filter coefficients.

[0186] Note that the number of pixels used in the filter does not have to be the same as the number of pixels to be filtered. For example, in a strong filter, the loop filter unit 120 calculates the displacement using four pixels on each side of the boundary, but may perform filtering on three pixels on each side of the boundary. In other words, the number of pixels used in the filter may be greater than the number of pixels to be filtered.

[0187] [First aspect of filter candidate determination process] In the above-mentioned filter characteristic determination (S102), the loop filter unit 120 determines a plurality of filter candidates, and selects a filter to be used in the deblocking filtering process from the determined plurality of filter candidates. A first aspect of the filter candidate determination process will be described below. Fig. 13 is a flowchart showing a first aspect of the filter candidate determination process included in the deblocking filtering process by the encoding device 100 of this embodiment.

[0188] First, the loop filter unit 120 acquires the position of a target boundary, which is a block boundary to be filtered (S111). In the following, of two blocks adjacent to the target boundary, the lower or right block is called the target block, and the upper or left block is called the adjacent block.

[0189] Next, the loop filter unit 120 determines whether the position of the target boundary is a predetermined position (S112). Here, the predetermined position may be, for example, the upper end of the CTU to which the target block belongs, the upper end or left end of the CTU to which the target block belongs, the upper end of the CU to which the target block belongs, or the upper end or left end of the CU to which the target block belongs. In other words, the predetermined position is a unit block (CTU or CU) including multiple blocks, and may be the upper end, upper end or left end of the unit block to which the target block belongs.

[0190] If the position of the target boundary is a predetermined position (Yes in S112), the loop filter unit 120 adds an asymmetric filter to the filter candidates (S113). Specifically, the loop filter unit 120 adds an asymmetric filter to the filter candidates instead of a filter candidate having the largest number of pixels used in the filter among the initial multiple filter candidates. Here, the asymmetric filter is a filter in which the number of pixels used in the filter is asymmetric across the boundary. In other words, the asymmetric filter is a filter in which the number of pixels used in the filter in the target block is different from the number of pixels in the adjacent block. Specifically, the asymmetric filter is a filter in which the filter tap lengths are different across the target boundary.

[0191] 12, when a weak filter using three pixels on each side of the boundary, a strong filter using four pixels on each side of the boundary, and a very strong filter using eight pixels on each side of the boundary exist as initial filter candidates, loop filter unit 120 replaces the very strong filter with an asymmetric filter. That is, loop filter unit 120 may determine which filter to use from among the multiple candidates, and when the filter to be used is a very strong filter, determine whether to replace the very strong filter with an asymmetric filter.

[0192] Fig. 14 is a diagram showing an example of a filter candidate after replacement. For example, as shown in Fig. 14, a very strong filter is replaced with a filter that uses 4 pixels and 12 pixels asymmetrically on either side of a boundary. For example, in an asymmetric filter, the number of pixels used on the adjacent block side is smaller than the number of pixels used on the target block side.

[0193] Moreover, the number of pixels on the adjacent block side used in the very strong filter shown in Fig. 14 is smaller than the number of pixels on the adjacent block side used in the very strong filter shown in Fig. 12. Moreover, the number of pixels on the target block side used in the very strong filter shown in Fig. 14 is larger than the number of pixels on the target block side used in the very strong filter shown in Fig. 12. Moreover, the sum of the number of pixels on the adjacent block side and the number of pixels on the target block side used in the very strong filter shown in Fig. 14 is equal to the sum of the number of pixels on the adjacent block side and the number of pixels on the target block side used in the very strong filter shown in Fig. 12.

[0194] The number of pixels on the target block side of the asymmetric filter may be the same as the number of pixels on the target block side of the filter before replacement, and the total number of pixels used in the asymmetric filter may be different from the total number of pixels used in the filter before replacement.

[0195] On the other hand, if the position of the target boundary is not the predetermined position (No in S112), the loop filter unit 120 does not add the asymmetric filter to the filter candidates, and selects a filter to be used from, for example, the initial filter candidates. For example, the loop filter unit 120 selects a filter to be used from a plurality of filter candidates that do not include the asymmetric filter shown in FIG.

[0196] [Effect of the first aspect] As described above, according to the configuration of the first aspect, it is possible to reduce the amount of data stored in the line memory. Specifically, by using an asymmetric filter, the number of pixels used in the filter can be changed, and the number of pixels stored in the memory can be changed. Therefore, it is possible to reduce the capacity of the memory for storing pixel values ​​of a block.

[0197] [Second aspect of filter candidate determination process] Hereinafter, a second aspect of the process of determining filter candidates will be described. In the first aspect, an example was described in which a filter having different tap lengths on the target block side and the adjacent block side is used as an asymmetric filter. In this aspect, a filter including extrapolation processing is used as an asymmetric filter.

[0198] FIG. 15 is a flowchart showing a second mode of the process of determining filter candidates to be included in the deblocking filtering process by the encoding device 100 according to this embodiment.

[0199] First, the loop filter unit 120 acquires the position of a target boundary, which is a block boundary to be filtered (S121). Next, the loop filter unit 120 determines whether the position of the target boundary is a predetermined position (S122). Here, the predetermined position may be, for example, the upper end of the CTU to which the target block belongs, the upper end or left end of the CTU to which the target block belongs, the upper end of the CU to which the target block belongs, or the upper end or left end of the CU to which the target block belongs. In other words, the predetermined position is a unit block (CTU or CU) including multiple blocks, and may be the upper end, upper end or left end of the unit block to which the target block belongs.

[0200] If the position of the target boundary is a predetermined position (Yes in S122), the loop filter unit 120 generates a pixel value of a predetermined pixel by extrapolation processing, and performs filter processing using the generated pixel value, and adds a filter including extrapolation processing to the filter candidates (S123). Specifically, the loop filter unit 120 adds a filter including extrapolation processing to the filter candidates instead of a filter candidate that uses the largest number of pixels among multiple filter candidates. Moreover, the predetermined pixel is a pixel included in an adjacent block and located near the target boundary.

[0201] For example, in the case where a weak filter using every three pixels on either side of a boundary, a strong filter using every four pixels on either side of a boundary, and a very strong filter using every eight pixels on either side of a boundary are present as initial filter candidates as shown in FIG. 12, loop filter unit 120 replaces the very strong filter with a filter including extrapolation processing.

[0202] Fig. 16 is a diagram showing an example of a filter candidate after replacement. For example, as shown in Fig. 16, in a filter including extrapolation, the loop filter unit 120 uses the pixel values ​​of the four pixels above the target boundary to generate pixel values ​​of the four pixels above the four pixels by extrapolation. Next, the loop filter unit 120 performs a filter process using the pixel values ​​of the four pixels above the target boundary, the four pixels generated by the extrapolation, and the pixel values ​​of the eight pixels below the target boundary.

[0203] Here, the extrapolation process is, for example, a padding process or a mirroring process. In the padding process, the pixel value of the pixel to be extrapolated is generated by, for example, copying the pixel value of the pixel adjacent to the pixel. For example, in the example shown in FIG. 16, the fourth pixel value on the upper side of the target boundary is copied. In the mirroring process, the multiple pixel values ​​to be extrapolated are generated by inverting and arranging the multiple pixel values ​​to be used in the extrapolation process at the boundary between the multiple pixel values ​​to be used in the extrapolation process and the multiple pixel values ​​to be extrapolated. For example, in the example shown in FIG. 16, the four pixel values ​​on the upper side of the target boundary are inverted up and down to generate the four pixel values ​​to be extrapolated. Here, the process of filling in the missing pixels to make the number of pixels used in the filter symmetrical across the boundary is called the extrapolation process, but it may also be called an extrapolation process, an interpolation process, a pixel generation process, or the like.

[0204] Moreover, the number of pixels on the adjacent block side used in the very strong filter shown in Fig. 16 is smaller than the number of pixels on the adjacent block side used in the very strong filter shown in Fig. 12. Moreover, the number of pixels on the target block side used in the very strong filter shown in Fig. 16 is equal to the number of pixels on the target block side used in the very strong filter shown in Fig. 12. Moreover, the pixels to be extrapolated are one or more pixels adjacent to the pixels on the adjacent block side used on the opposite side (upper or left side) of the target boundary.

[0205] In addition, the filter using the pixel values ​​generated by the extrapolation process may be the same as the filter before replacement. In other words, the filter using the pixel values ​​generated by the extrapolation process may be a filter using pixel values ​​of the same number of pixels on either side of the block boundary. For example, in this example, a very strong filter using eight pixels on either side of the boundary as shown in FIG. 12 may be used.

[0206] On the other hand, if the position of the target boundary is not a predetermined position (No in S122), the loop filter unit 120 does not add a filter including extrapolation to the filter candidates, and selects a filter to be used from, for example, the initial filter candidates. For example, the loop filter unit 120 selects a filter to be used from a plurality of filter candidates that do not include the asymmetric filter shown in FIG.

[0207] [Effect of the second aspect] As described above, according to the configuration of the second aspect, it is possible to reduce the amount of data stored in the line memory. Specifically, the number of pixels used in the filter can be changed by using a filter including extrapolation processing. Therefore, it is possible to reduce the capacity of the memory for storing pixel values ​​of a block.

[0208] Furthermore, compared to the first aspect, there is no need to change the filter itself, so the processing may be simplified.

[0209] [Variations] In the asymmetric filters described in the first and second aspects, the number of pixels used on the adjacent block side (upper side or left side) of the block boundary may be made smaller than the number of pixels used on the target block side (right side or lower side) of the block boundary.

[0210] For example, the number of pixels required by the asymmetric filter on the adjacent block side of the block boundary may be equal to or less than the number of pixels on the adjacent block side of the block boundary used by a filter candidate (e.g., the strong filters shown in FIGS. 12, 14, and 16) that uses fewer pixels than the filter candidate to be replaced (e.g., the very strong filter shown in FIG. 12) included in the initial filter candidates. For example, in the examples shown in FIGS. 12, 14, and 16, since the strong filter uses four pixels on each side across the boundary, the number of pixels used by the asymmetric filter on the left side or upper side of the filter boundary is four pixels, which is equal to the number of pixels used by the strong filter.

[0211] Also, for example, the number of pixels required by the asymmetric filter on the adjacent block side of the block boundary may be equal to or less than the number of pixels on the adjacent block side used in the process that uses the most pixels on the adjacent block side among all the processes included in the loop filter processing, excluding the filter candidate before replacement (e.g., the very strong filter shown in FIG. 12). For example, in the case where six pixels are required from the filter target pixel to a position in the ALF process, the number of pixels used by the asymmetric filter on the adjacent block side of the block boundary may be six pixels or less.

[0212] The above processing may be controlled to be On / Off for luminance (Luma) and color difference (Chroma). For example, the above processing may be applied to one of luminance and color difference and not applied to the other. Also, the behavior may be switched between luminance and color difference.

[0213] Also, information indicating whether or not to perform the above processing may be written in the syntax. That is, the encoding device may generate a bitstream including information indicating whether or not to perform the above processing. The decoding device may decode the information indicating whether or not to perform the above processing from the bitstream, and switch whether or not to perform the above processing according to the decoded information.

[0214] In the above description, whether or not to use an asymmetric filter is determined when the position of the target boundary is a predetermined position, but whether or not to use an asymmetric filter may be determined by other methods. For example, the loop filter unit 120 may calculate an evaluation value based on a predetermined criterion for each of an image obtained using an asymmetric filter and an image obtained without using an asymmetric filter, and select a method with a high evaluation value. For example, RD (rate distortion) optimization or the like may be used for this evaluation.

[0215] In addition, in this embodiment, the "number of pixels to be used in the filter" may refer to all pixels used in the filter process, or may refer to pixels located on either side of the boundary to be filtered among the pixels used in the filter process.

[0216] Furthermore, when a pixel used in the filtering process satisfies a predetermined condition, the loop filter unit 120 may replace at least one of the predefined filter candidates with a different filter candidate, or may add a different filter candidate to the predefined filter candidates. That is, in this embodiment, the loop filter unit 120 may set a predetermined filter as a candidate instead of a very strong filter, or may add a predetermined filter to the filter candidates in addition to the very strong filter.

[0217] Furthermore, the pixels used in the filtering process may be, for example, pixels used in determining whether or not to apply a filter, pixels used in determining filter characteristics, or pixels to which filtering process is applied.

[0218] Although the above mainly describes the operation of loop filter unit 120 included in encoding device 100, loop filter unit 212 included in decoding device 200 also performs a similar operation.

[0219] Furthermore, all of the processes described in this embodiment are not necessarily always necessary, and only a part of the processes in this embodiment may be performed.

[0220] [summary] As described above, the encoding device 100 according to this embodiment determines a filter to be used for deblocking filtering from a plurality of filters including a first filter and a second filter (S102), and performs deblocking filtering on a block boundary using the determined filter (S103). The first filter is a filter that uses M (M is an integer of 2 or more) pixels above the block boundary and M pixels below the block boundary, the second filter is a filter that uses a first pixel above the block boundary and a second pixel below the block boundary, the number of the first pixels is any one of a first plurality of candidate values, the number of the second pixels is any one of a second plurality of candidate values, and each of the first plurality of candidate values ​​and each of the second plurality of candidate values ​​is a value greater than M or M.

[0221] This enables the encoding device 100 to reduce the number of pixels on the upper or left side of the block boundary to be used in the deblocking filter process, potentially reducing the amount of data held in memory.

[0222] For example, the second filter may have the same number of first pixels and the same number of second pixels, or may have a different number of first pixels and the same number of second pixels.

[0223] For example, each of the first plurality of candidate values ​​and each of the second plurality of candidate values ​​is a value equal to or greater than four.

[0224] For example, among the multiple filters, filters other than the second filter use the same number of pixels above and below the block boundary.

[0225] For example, the encoding device 100 limits the maximum value that the number of first pixels can take, depending on whether the position of the block boundary is at a predetermined position.

[0226] For example, the predetermined position is a top end of a coding tree unit (CTU). For example, the predetermined position is a top end and a left end of a coding tree unit (CTU). For example, the predetermined position is a top end of a coding unit (CU). For example, the predetermined position is a top end and a left end of a coding unit (CU).

[0227] For example, the maximum value that the number of first pixels can take is equal to or less than the number of pixels above the block boundary used by a filter (e.g., the strong filter shown in Figure 12) that uses the next largest number of pixels among the multiple filters after the second filter (e.g., the very strong filter shown in Figure 12).

[0228] For example, the maximum value that the number of first pixels can take is equal to or less than the number of pixels above the block boundary of the process that uses the largest number of pixels above the block boundary among the processes included in the loop filter process including the deblocking filter process, excluding the second filter (e.g., the very strong filter shown in Figure 12).

[0229] For example, as described in the first embodiment, when the number of first pixels and the number of second pixels differ, the second filter has different filter tap lengths on either side of the block boundary.

[0230] For example, as described in the second aspect, when the number of first pixels is different from the number of second pixels, the second filter is a filter that uses the first pixels to generate a third pixel adjacent to the upper side of the first pixels, and uses the first pixels, second pixels, and third pixels, and the sum of the number of first pixels and the number of third pixels is equal to the number of second pixels.

[0231] Moreover, the decoding device 200 according to this embodiment determines a filter to be used for deblocking filtering from a plurality of filters including a first filter and a second filter (S102), and performs deblocking filtering on a block boundary using the determined filter (S103). The first filter is a filter that uses M (M is an integer of 2 or more) pixels above the block boundary and M pixels below the block boundary, the second filter is a filter that uses a first pixel above the block boundary and a second pixel below the block boundary, the number of the first pixels is any one of a first plurality of candidate values, the number of the second pixels is any one of a second plurality of candidate values, and each of the first plurality of candidate values ​​and each of the second plurality of candidate values ​​is M or a value larger than M.

[0232] This allows the decoding device 200 to reduce the number of pixels on the upper or left side of the block boundary to be used in the deblocking filter process, which may reduce the amount of data held in memory.

[0233] For example, the second filter may have the same number of first pixels and the same number of second pixels, or may have a different number of first pixels and the same number of second pixels.

[0234] For example, each of the first plurality of candidate values ​​and each of the second plurality of candidate values ​​is a value equal to or greater than four.

[0235] For example, among the multiple filters, filters other than the second filter use the same number of pixels above and below the block boundary.

[0236] For example, the decoding device 200 limits the maximum value that the number of first pixels can take, depending on whether the position of the block boundary is at a predetermined position.

[0237] For example, the predetermined position is a top end of a coding tree unit (CTU). For example, the predetermined position is a top end and a left end of a coding tree unit (CTU). For example, the predetermined position is a top end of a coding unit (CU). For example, the predetermined position is a top end and a left end of a coding unit (CU).

[0238] For example, the maximum value that the number of first pixels can take is equal to or less than the number of pixels above the block boundary used by a filter (e.g., the strong filter shown in Figure 12) that uses the next largest number of pixels among the multiple filters after the second filter (e.g., the very strong filter shown in Figure 12).

[0239] For example, the maximum value that the number of first pixels can take is equal to or less than the number of pixels above the block boundary of the process that uses the largest number of pixels above the block boundary among the processes included in the loop filter process including the deblocking filter process, excluding the second filter (e.g., the very strong filter shown in Figure 12).

[0240] For example, as described in the first embodiment, when the number of first pixels and the number of second pixels differ, the second filter has different filter tap lengths on either side of the block boundary.

[0241] For example, as described in the second aspect, when the number of first pixels is different from the number of second pixels, the second filter is a filter that uses the first pixels to generate a third pixel adjacent to the upper side of the first pixels, and uses the first pixels, second pixels, and third pixels, and the sum of the number of first pixels and the number of third pixels is equal to the number of second pixels.

[0242] The coding device 100 according to the present embodiment includes a division unit 102 that divides an image into a plurality of blocks, an intra prediction unit 124 that predicts a block included in the image using a reference picture included in the image, an inter prediction unit 126 that predicts a block included in the image using a reference block included in another image different from the image, a loop filter unit 120 that applies a filter to the block included in the image, a conversion unit 106 that converts a prediction error between a prediction signal generated by the intra prediction unit 124 or the inter prediction unit 126 and an original signal to generate a conversion coefficient, a quantization unit 108 that quantizes the conversion coefficient to generate a quantization coefficient, and an entropy coding unit 110 that generates an encoded bit stream by variable-length coding the quantization coefficient. The loop filter unit 120 determines a filter to be used for deblocking filter processing from a plurality of filters including a first filter and a second filter (S102), and performs deblocking filter processing on block boundaries using the determined filter (S103). The first filter is a filter that uses M (M is an integer greater than or equal to 2) pixels above the block boundary and M pixels below the block boundary, and the second filter is a filter that uses a first pixel above the block boundary and a second pixel below the block boundary, where the number of the first pixels is one of a first plurality of candidate values ​​and the number of the second pixels is one of a second plurality of candidate values, and each of the first plurality of candidate values ​​and each of the second plurality of candidate values ​​is M or a value greater than M.

[0243] Moreover, the decoding device 200 according to this embodiment includes a decoding unit (entropy decoding unit 202) that decodes an encoded bit stream and outputs a quantized coefficient, an inverse quantization unit 204 that inversely quantizes the quantized coefficient and outputs a transform coefficient, an inverse transform unit 206 that inversely transforms the transform coefficient and outputs a prediction error, an intra prediction unit 216 that predicts a block included in an image using a reference picture included in the image, an inter prediction unit 218 that predicts a block included in the image using a reference block included in another image different from the image, and a loop filter unit 212 that applies a filter to a block included in the image. The loop filter unit 212 determines a filter to be used for deblocking filter processing from a plurality of filters including a first filter and a second filter (S102), and performs deblocking filter processing on a block boundary using the determined filter (S103). The first filter is a filter that uses M (M is an integer greater than or equal to 2) pixels above the block boundary and M pixels below the block boundary, and the second filter is a filter that uses a first pixel above the block boundary and a second pixel below the block boundary, where the number of the first pixels is one of a first plurality of candidate values ​​and the number of the second pixels is one of a second plurality of candidate values, and each of the first plurality of candidate values ​​and each of the second plurality of candidate values ​​is M or a value greater than M.

[0244] [Example of an encoding device implementation] Fig. 17 is a block diagram showing an implementation example of the encoding device 100 according to embodiment 1. The encoding device 100 includes a circuit 160 and a memory 162. For example, a number of components of the encoding device 100 shown in Fig. 1 are implemented by the circuit 160 and the memory 162 shown in Fig. 17.

[0245] The circuit 160 is a circuit that performs information processing and is a circuit that can access the memory 162. For example, the circuit 160 is a dedicated or general-purpose electronic circuit that encodes moving images. The circuit 160 may be a processor such as a CPU. The circuit 160 may also be a collection of multiple electronic circuits. For example, the circuit 160 may play the roles of multiple components of the encoding device 100 shown in FIG. 1 and the like, excluding components for storing information.

[0246] The memory 162 is a dedicated or general-purpose memory in which information for the circuit 160 to encode a moving image is stored. The memory 162 may be an electronic circuit and may be connected to the circuit 160. The memory 162 may be included in the circuit 160. The memory 162 may be a collection of multiple electronic circuits. The memory 162 may be a magnetic disk, an optical disk, or the like, and may be expressed as a storage or a recording medium, or the like. The memory 162 may be a non-volatile memory or a volatile memory.

[0247] For example, the memory 162 may store a video to be encoded, or a bit string corresponding to the encoded video, or may store a program for the circuit 160 to encode the video.

[0248] Also, for example, the memory 162 may play the role of a component for storing information among the multiple components of the encoding device 100 shown in Fig. 1 etc. Specifically, the memory 162 may play the role of the block memory 118 and the frame memory 122 shown in Fig. 1. More specifically, the memory 162 may store reconstructed blocks, reconstructed pictures, etc.

[0249] It should be noted that not all of the components shown in Fig. 1 and the like may be implemented, and not all of the processes described above may be performed, in the encoding device 100. Some of the components shown in Fig. 1 and the like may be included in another device, and some of the processes described above may be executed by another device.

[0250] [Example of implementation of a decryption device] Fig. 18 is a block diagram showing an implementation example of the decoding device 200 according to embodiment 1. The decoding device 200 includes a circuit 260 and a memory 262. For example, a plurality of components of the decoding device 200 shown in Fig. 10 are implemented by the circuit 260 and the memory 262 shown in Fig. 18.

[0251] The circuit 260 is a circuit that performs information processing and is a circuit that can access the memory 262. For example, the circuit 260 is a dedicated or general-purpose electronic circuit that decodes moving images. The circuit 260 may be a processor such as a CPU. The circuit 260 may also be a collection of multiple electronic circuits. For example, the circuit 260 may play the role of multiple components of the decoding device 200 shown in FIG. 10 and the like, excluding components for storing information.

[0252] The memory 262 is a dedicated or general-purpose memory in which information for the circuit 260 to decode a moving image is stored. The memory 262 may be an electronic circuit and may be connected to the circuit 260. The memory 262 may be included in the circuit 260. The memory 262 may be a collection of multiple electronic circuits. The memory 262 may be a magnetic disk, an optical disk, or the like, and may be expressed as a storage or a recording medium, or the like. The memory 262 may be a non-volatile memory or a volatile memory.

[0253] For example, the memory 262 may store a bit string corresponding to an encoded video, or a video corresponding to a decoded bit string, or may store a program for the circuit 260 to decode the video.

[0254] Also, for example, the memory 262 may play the role of a component for storing information among the multiple components of the decoding device 200 shown in Fig. 10 etc. Specifically, the memory 262 may play the role of the block memory 210 and the frame memory 214 shown in Fig. 10. More specifically, the memory 262 may store reconstructed blocks, reconstructed pictures, etc.

[0255] Note that not all of the components shown in Fig. 10 and the like may be implemented, and not all of the above-described processes may be performed, in the decoding device 200. Some of the components shown in Fig. 10 and the like may be included in another device, and some of the above-described processes may be executed by another device.

[0256] [supplement] Furthermore, the encoding device 100 and the decoding device 200 in this embodiment may be used as an image encoding device and an image decoding device, respectively, or as a video encoding device and a video decoding device.

[0257] In the present embodiment, each component may be implemented by dedicated hardware or by executing a software program suitable for each component. Each component may be implemented by a program execution unit such as a CPU or processor reading and executing a software program recorded on a recording medium such as a hard disk or semiconductor memory.

[0258] Specifically, each of the encoding device 100 and the decoding device 200 may include a processing circuitry and a storage device electrically connected to and accessible from the processing circuitry. For example, the processing circuitry corresponds to the circuit 160 or 260, and the storage device corresponds to the memory 162 or 262.

[0259] The processing circuit includes at least one of dedicated hardware and a program execution unit, and executes processing using a storage device. Further, when the processing circuit includes a program execution unit, the storage device stores a software program executed by the program execution unit.

[0260] Here, the software that realizes the encoding device 100 or the decoding device 200 in the present embodiment is the following program.

[0261] Also, as described above, each component may be a circuit. These circuits may form one circuit as a whole, or may be separate circuits respectively. Further, each component may be realized by a general-purpose processor or a dedicated processor.

[0262] Also, the processing executed by a specific component may be executed by another component. Also, the order in which the processing is executed may be changed, or a plurality of processes may be executed in parallel. Also, the encoding / decoding device may include the encoding device 100 and the decoding device 200.

[0263] As described above, the aspects of the encoding device 100 and the decoding device 200 have been described based on the embodiment, but the aspects of the encoding device 100 and the decoding device 200 are not limited to this embodiment. Without departing from the spirit of the present disclosure, various modifications conceived by those skilled in the art applied to this embodiment or forms constructed by combining components in different embodiments may also be included within the scope of the aspects of the encoding device 100 and the decoding device 200.

[0264] This aspect may be implemented in combination with at least a part of other aspects in the present disclosure. Also, a part of the processing described in the flowchart of this aspect, a part of the configuration of the device, a part of the syntax, etc. may be implemented in combination with other aspects.

[0265] (Embodiment 2) In each of the above embodiments, each of the functional blocks can usually be realized by an MPU, a memory, etc. Furthermore, the processing by each of the functional blocks is usually 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 circuitry).

[0266] Furthermore, the processes 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 above program may be either single or multiple. That is, centralized processing or distributed processing may be performed.

[0267] The aspects of the present disclosure are not limited to the above examples, and various modifications are possible, which are also included within the scope of the aspects of the present disclosure.

[0268] Further, here, 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 will be described. 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 equipped with both. Other configurations in the system can be appropriately changed depending on the case.

[0269] [Usage example] 19 is a diagram showing the overall configuration of a content supply system ex100 that realizes 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.

[0270] In this content supply system ex100, devices such as computer ex111, game console ex112, camera ex113, home appliance ex114, and smartphone ex115 are connected to the Internet ex101 via Internet service provider ex102 or communication network ex104 and base stations ex106 - ex110. The content supply system ex100 may be configured to connect by combining any of the above elements. The devices may be directly or indirectly connected to each other via a telephone network or short - range wireless, etc., without passing through base stations ex106 - ex110 which are fixed wireless stations. Also, streaming server ex103 is connected to devices such as computer ex111, game console ex112, camera ex113, home appliance ex114, and smartphone ex115 via Internet ex101, etc. Further, streaming server ex103 is connected to terminals within a hotspot in an airplane ex117 via satellite ex116.

[0271] Note that a wireless access point or hotspot, etc. may be used instead of base stations ex106 - ex110. Also, streaming server ex103 may be directly connected to communication network ex104 without passing through Internet ex101 or Internet service provider ex102, or may be directly connected to airplane ex117 without passing through satellite ex116.

[0272] Camera ex113 is a device capable of taking still images and videos such as a digital camera. Also, smartphone ex115 is a smartphone device, mobile phone, or PHS (Personal Handyphone System), etc. that generally supports the mobile communication system standards known as 2G, 3G, 3.9G, 4G, and in the future 5G.

[0273] Home appliance ex118 is a device such as a refrigerator or a device included in a household fuel cell cogeneration system.

[0274] 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 distribution and the like. In live distribution, a terminal (such as a computer ex111, a game machine ex112, a camera ex113, a home appliance ex114, a smartphone ex115, and a terminal in an airplane ex117) performs the encoding process described in each of the above embodiments on still image or video content photographed by a user using the terminal, multiplexes the video data obtained by the 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.

[0275] Meanwhile, the streaming server ex103 streams the transmitted content data to the requesting client. The client is a computer ex111, a game machine ex112, a camera ex113, a home appliance ex114, a smartphone ex115, a terminal in an airplane ex117, or the like, 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.

[0276] [Distributed processing] The streaming server ex103 may be a plurality of servers or computers that process, record, and distribute data in a distributed manner. For example, the streaming server ex103 may be realized by a CDN (Contents Delivery Network), and content distribution may be realized by a network that connects a large number of edge servers distributed around the world. In a CDN, an edge server that is physically close to the client is dynamically assigned according to the client. The content is cached and distributed to the edge server, thereby reducing delays. In addition, when an error occurs or the communication state changes due to an increase in traffic, the 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 part of the network where a failure has occurred, thereby realizing high-speed and stable distribution.

[0277] In addition to the distributed processing of the distribution itself, the encoding processing of the captured data may be performed by each terminal, may be performed by the server side, or may be shared among the terminals. As an example, in the encoding processing, a processing loop is generally performed twice. In the first loop, the complexity of the image or the amount of code is detected for each frame or scene. In the second loop, processing is performed to maintain the image quality and improve the encoding efficiency. For example, the terminal performs the first encoding processing, and the server side that receives the content performs the second encoding processing, thereby improving the quality and efficiency of the content while reducing the processing load on each terminal. In this case, if there is a request to receive and decode almost in real time, the data encoded once by the terminal can be received and played back by other terminals, making it possible to perform more flexible real-time distribution.

[0278] As another example, the camera ex113 etc. extracts features from an image, compresses data related to the features as metadata, and transmits the compressed 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. The feature data is particularly effective in improving the precision and efficiency of motion vector prediction when the server performs recompression. Alternatively, the terminal may perform simple encoding such as VLC (variable length coding), and the server may perform encoding with a large processing load such as CABAC (context-adaptive binary arithmetic coding).

[0279] As another example, in a stadium, a shopping mall, a factory, etc., there may be a plurality of video data in which almost the same scene has been shot by a plurality of terminals. In this case, using the plurality of terminals that shot the video and, as necessary, other terminals and servers that did not shoot the video, coding processing is assigned to each of them, for example, in units of GOPs (Group of Pictures), in units of pictures, or in units of tiles obtained by dividing a picture, for distributed processing. This reduces delays and realizes better real-time performance.

[0280] In addition, since the multiple video data are of almost 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 the encoded data from each terminal and change the reference relationship between the multiple data, or correct or replace the pictures themselves and re-encode them. This makes it possible to generate a stream with improved quality and efficiency for each piece of data.

[0281] The server may also perform transcoding to change the encoding format of the video data before distributing it. For example, the server may convert an MPEG-based encoding format into a VP-based encoding format, or convert H.264 into H.265.

[0282] In this way, the encoding process can be performed by a terminal or one or more servers. Therefore, in the following, descriptions such as "server" or "terminal" are used to indicate the entity performing the processing, but 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.

[0283] [3D, multi-angle] In recent years, it has become common 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 almost synchronized with each other. The videos taken by the devices are integrated based on the relative positional relationship between the devices that is obtained separately, or on areas where feature points included in the videos match.

[0284] 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. If the server can obtain the relative positional relationship between the shooting terminals, the server may generate a 3D shape of the scene based on not only 2D video but also images of the same scene captured from different angles. The server may separately encode 3D data generated by point clouds, etc., or may generate images to be transmitted to the receiving terminal by selecting or reconstructing images from images captured by multiple terminals based on the results of recognizing or tracking people or objects using the 3D data.

[0285] In this way, the user can enjoy a scene by selecting any video corresponding to each shooting terminal, or can enjoy content in which a video from any viewpoint is cut out from 3D data reconstructed using multiple images or videos. Furthermore, sound may be collected from multiple different angles, just like the video, and the server may multiplex the sound from a specific angle or space with the video and transmit it in accordance with the video.

[0286] 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 the left eye, respectively, and may perform encoding that allows reference between each viewpoint video 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.

[0287] In the case of an AR image, the server superimposes virtual object information in the virtual space on camera information in the real space based on the three-dimensional position or the movement of the user's viewpoint. The decoding device may obtain or hold virtual object information and three-dimensional data, generate a two-dimensional image according to the movement of the user's viewpoint, and smoothly connect them to create superimposed data. Alternatively, the decoding device may transmit the movement of the user's viewpoint to the server in addition to a request for virtual object information, and the server may create superimposed data according to the movement of the viewpoint received from the three-dimensional data held by the server, encode the superimposed data, and deliver it to the decoding device. Note that the superimposed data has an α value indicating the transparency in addition to RGB, and the server may set the α value of the part other than the object created from the three-dimensional data to 0, etc., and encode the data in a state in which the part is transparent. Alternatively, the server may generate data in which a predetermined value of RGB value is set to the background like a chromakey, and the part other than the object is the background color.

[0288] Similarly, the decoding process of the distributed data may be performed by each client terminal, or may be performed by the server side, or may be shared among them. As an example, a certain terminal may once send a reception request to the server, and the content corresponding to the request may be received by other terminals, decoded, and the decoded signal may be transmitted to a device having a display. By distributing the processing and selecting appropriate content regardless of the performance of the communication-enabled terminals themselves, data with good image quality can be reproduced. In another example, while large-sized image data is received by a TV or the like, a part of the area, such as tiles into which the picture is divided, may be decoded and displayed on the viewer's personal terminal. This allows the viewer to share the overall picture while checking his / her own area of ​​responsibility or the area he / she wants to check in more detail at hand.

[0289] In the future, it is expected that content will be seamlessly received by switching appropriate data for the currently connected communication using delivery system standards such as MPEG-DASH under circumstances where multiple short-distance, medium-distance, or long-distance wireless communication is available, regardless of whether indoors or outdoors. This allows users to freely select and switch in real time not only their own terminals but also decoding devices or display devices such as displays installed indoors and outdoors. In addition, decoding can be performed while switching the decoding device and the display device based on the user's location information, etc. This makes it possible to move while displaying map information on the wall or part of the ground of a neighboring building where a displayable device is embedded while moving to a destination. It is also possible to switch the bit rate of the received data based on the accessibility of the encoded data on the network, such as when the encoded data is cached on a server that can be accessed from the receiving terminal in a short time, or when it is copied to an edge server in a content delivery service.

[0290] [Scalable Coding] The switching of contents will be described using a scalable stream compressed and coded by applying the video coding method shown in each of the above embodiments, as shown in FIG. 20. The server may have multiple streams with the same content but different qualities as individual streams, but may be configured to switch contents by taking advantage of the characteristics of a temporal / spatial scalable stream realized by coding in layers as shown in the figure. In other words, the decoding side can freely switch between low-resolution content and high-resolution content by determining which layer to decode according to an internal factor such as performance and an external factor such as the state of the communication band. For example, if you want to continue watching a video you were watching on your smartphone ex115 while on the move on a device such as an Internet TV after you get home, the device can decode the same stream up to a different layer, reducing the burden on the server side.

[0291] Furthermore, as described above, in addition to the configuration that realizes scalability 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 of the base layer based on the meta-information. Super-resolution may be either an improvement in the signal-to-noise ratio at the same resolution or an increase in resolution. The meta-information includes information for specifying linear or 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.

[0292] Alternatively, a picture may be divided into tiles or the like according to the meaning of an object in an image, and the decoding side may select a tile to decode to decode only a part of the area. Also, by storing the attribute of an object (person, car, ball, etc.) and its position in a video (coordinate position in the same image, etc.) 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. 21, the meta information is stored using a data storage structure different from pixel data such as an SEI message in HEVC. This meta information indicates, for example, the position, size, or color of a main object.

[0293] Meta information may also be stored in units consisting of multiple pictures, such as streams, sequences, or random access units, etc. This allows the decoding side to obtain the time when a specific person appears in the video, and by combining this with picture-by-picture information, it is possible to identify the picture in which an object exists and the position of the object within the picture.

[0294] [Web page optimization] FIG. 22 is a diagram showing an example of a display screen of a web page in a computer ex111 or the like. FIG. 23 is a diagram showing an example of a display screen of a web page in a smartphone ex115 or the like. As shown in FIG. 22 and FIG. 23, a web page may include multiple link images that are links to image content, and the appearance of the web page differs depending on the device used to view the page. When multiple link images are visible on the screen, the display device (decoding device) displays a still image or I-picture that each content has as a link image, displays an image such as a gif animation using multiple still images or I-pictures, or receives only the base layer to decode and display the image until the user explicitly selects the link image, or until the link image approaches the center of the screen or the entire link image enters the screen.

[0295] When a user selects a linked image, the display device decodes the base layer with the highest priority. If there is information indicating that the HTML constituting the web page is scalable content, the display device may decode up to the enhancement layer. Also, in order to ensure real-time performance, before the selection or when the communication bandwidth is very strict, the display device can reduce the delay (the delay from the start of content decoding to the start of display) between the decoding time and the display time of the leading picture by decoding and displaying only the forward reference pictures (I pictures, P pictures, B pictures with only forward reference). Further, the display device may deliberately ignore the reference relationship of the pictures, perform rough decoding with all B pictures and P pictures as forward references, and perform normal decoding as the received pictures increase over time.

[0296] [Autonomous driving] Also, when transmitting and receiving still image or video data such as two-dimensional or three-dimensional map information for the autonomous driving or driving support of a vehicle, the receiving terminal may receive, in addition to the image data belonging to one or more layers, weather or construction information, etc. as meta information, and decode them in association with each other. Note that the meta information may belong to a layer or may simply be multiplexed with the image data.

[0297] In this case, since a vehicle, drone, airplane, etc. including the receiving terminal moves, the receiving terminal can realize seamless reception and decoding by transmitting the position information of the receiving terminal at the time of a reception request while switching between base stations ex106 to ex110. Also, the receiving terminal can dynamically switch how much meta information to receive or how much to update the map information according to the user's selection, the user's situation, or the state of the communication bandwidth.

[0298] As described above, in the content supply system ex100, the client can receive, decode, and play back the encoded information transmitted by the user in real time.

[0299] [Delivery of personal content] Furthermore, the content supply system ex100 allows not only high-quality, long-duration content from video distributors, but also low-quality, short-duration content from individuals via unicast or multicast distribution. 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 processing before encoding processing. This can be achieved, for example, by the following configuration.

[0300] During shooting, in real time or after accumulating, the server performs recognition processing such as shooting errors, scene search, semantic analysis, and object detection from the original image or encoded data. Then, based on the recognition result, the server manually or automatically corrects out-of-focus or camera shake, deletes less important scenes such as scenes that are less bright than other pictures or are out of focus, emphasizes object edges, changes color, and performs other editing. The server encodes the edited data based on the editing result. It is also known that if the shooting time is too long, the viewer rating will decrease, and the server may automatically clip not only scenes of less importance as described above but also scenes with little movement based on the image processing result so that the content will be within a specific time range depending on the shooting time. Alternatively, the server may generate a digest based on the result of the semantic analysis of the scene and encode it.

[0301] Note that personal content may sometimes contain elements that, as they are, would infringe copyrights, moral rights of the author, or portrait rights, etc., and may be inconvenient for individuals, such as when the scope of sharing exceeds the intended scope. Therefore, for example, the server may deliberately change the image to one that is out of focus, such as the face of a person in the peripheral part of the screen or the inside of a house, and then encode it. Also, the server may recognize whether a face of a person different from the pre-registered person appears in the image to be encoded, and if it does, perform processing such as applying a mosaic to the face part. Alternatively, as pre-processing or post-processing of encoding, from the perspective of copyright, etc., the user designates a person or background area that the user wants to process the image, and the server can perform processing such as replacing the designated area with another video or blurring the focus. In the case of a person, the video of the face part can be replaced while tracking the person in the moving image.

[0302] Also, since the viewing of personal content with a small data volume has a strong requirement for real-time performance, depending on the bandwidth, the decoding device first receives the base layer with the highest priority and decodes and plays it back. During this period, the decoding device may receive the enhancement layer and, when the playback is looped or played back two or more times, play back a high-quality video including the enhancement layer. For a stream encoded in a scalable manner like this, it is a rough video when not selected or at the beginning of viewing, but it can provide an experience where the stream gradually becomes smarter and the image quality improves. In addition to scalable encoding, a similar experience can be provided even if a rough stream played back for the first time and a second stream encoded with reference to the first video are configured as one stream.

[0303] [Other Usage Examples] Moreover, these encoding or decoding processes are generally processed in an LSIex500 possessed by each terminal. The LSIex500 may be a single chip or may be configured with multiple chips. Note that software for encoding or decoding moving images may be incorporated into some kind of recording medium (such as a CD-ROM, a flexible disk, or a hard disk) that can be read by the computer ex111 or the like, and the encoding or decoding process may be performed using the software. Furthermore, if the smartphone ex115 has a camera, video data captured by the camera may be transmitted. The video data in this case is data that has been encoded by the LSIex500 possessed by the smartphone ex115.

[0304] The LSIex500 may be configured to download and activate application software. In this case, the terminal first determines whether the terminal supports the encoding method of the content or has the ability to execute a specific service. If the terminal does not support the encoding method of the content or does not have the ability to execute a specific service, the terminal downloads a codec or application software, and then acquires and plays the content.

[0305] 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 carried and transmitted over broadcasting radio waves using a satellite or the like, there is a difference in that it is more suitable for multicast compared to the content supply system ex100, which has a configuration that is easy to use for unicast, but similar applications are possible with regard to the encoding process and decoding process.

[0306] [Hardware configuration] FIG. 24 is a diagram showing a smartphone ex115. FIG. 25 is a diagram showing a configuration example of the smartphone ex115. The smartphone ex115 includes an antenna ex450 for transmitting and receiving radio waves to and from the base station ex110, a camera unit ex465 capable of taking videos and still images, and a display unit ex458 for displaying data obtained by decrypting the video captured by the camera unit ex465 and the video 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 audio or sound, an audio input unit ex456 such as a microphone for inputting audio, a memory unit ex467 capable of storing encoded data such as captured video or still images, recorded audio, received video or still images, and e-mail, or decoded data, and a slot unit ex464 which is an interface unit with a SIMex468 for identifying a user and authenticating access to various data including a network. In addition, an external memory may be used instead of the memory unit ex467.

[0307] In addition, a main control unit ex460, which comprehensively controls the display unit ex458 and the 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.

[0308] When the power key is turned on by a user's operation, the power supply circuit unit ex461 starts up the smartphone ex115 into an operational state by supplying power to each unit from the battery pack.

[0309] The smartphone ex115 performs processes such as telephone calls and data communications under the control of a main control unit ex460 having a CPU, a ROM, and a RAM. During a telephone call, a voice signal collected by a voice input unit ex456 is converted into a digital voice signal by a voice signal processing unit ex454, which is then subjected to spectrum spreading processing by a modulation / demodulation unit ex452, and the digital-to-analog conversion processing and frequency conversion processing by a transmission / reception unit ex451 is then transmitted via an antenna ex450. In addition, the received data is amplified, and subjected to frequency conversion processing and analog-to-digital conversion processing, and the spectrum inverse spreading processing by a modulation / demodulation unit ex452 is then performed, and the analog voice signal is converted into an analog voice signal by a voice signal processing unit ex454, which is then output from a voice output unit ex457. During a data communication mode, text, still images, or video data is sent to the main control unit ex460 via an operation input control unit ex462 by operating an operation unit ex466 or the like of the main unit, and transmission and reception processing is performed in the same manner. When transmitting video, still images, or video and audio in the data communication mode, the video signal processing unit ex455 compresses and encodes the video signal stored in the memory unit ex467 or the video signal input from the camera unit ex465 by the moving image encoding method shown in each of the above embodiments, and sends the encoded video data to the multiplexing / separation unit ex453. The audio signal processing unit ex454 also encodes the audio signal collected by the audio input unit ex456 while the camera unit ex465 is capturing the video or still images, and sends the encoded audio data to the multiplexing / separation unit ex453. The multiplexing / separation unit ex453 multiplexes the encoded video data and the encoded audio data by a predetermined method, and performs modulation and conversion processing in the modulation / demodulation unit (modulation / demodulation circuit unit) ex452 and the transmission / reception unit ex451, and transmits the data via the antenna ex450.

[0310] When receiving a video attached to an e-mail or chat, or a video linked to a web page, etc., in order to decode the multiplexed data received via the antenna ex450, the multiplexing / separation unit ex453 separates the multiplexed data into a bit stream of video data and a bit stream of audio data by separating the multiplexed data, and supplies the encoded video data to the video signal processing unit ex455 via the synchronization bus ex470, and supplies the encoded audio data to the audio signal processing unit ex454. The video signal processing unit ex455 decodes the video signal by a video decoding method corresponding to the video encoding method shown in each of the above embodiments, and displays the video or still image contained in the linked video file on the display unit ex458 via the display control unit ex459. The audio signal processing unit ex454 also decodes the audio signal, and audio is output from the audio output unit ex457. Note that since real-time streaming is widespread, there may be cases where audio playback is socially inappropriate depending on the user's situation. Therefore, as an initial value, a configuration in which only video data is played without playing audio signals is preferable. The audio may be played in sync only when the user performs an operation such as clicking on the video data.

[0311] In addition, although the smartphone ex115 has been described as an example here, three types of implementation formats 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 with video data is received or transmitted, but the multiplexed data may 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.

[0312] Although the main control unit ex460 including the CPU controls the encoding or decoding process, terminals often have a GPU. Therefore, a configuration may be used in which a wide area is processed collectively by utilizing the performance of the GPU using a memory shared by the CPU and GPU, or a memory whose addresses are managed so that they can be used in common. This can shorten the encoding time, ensure real-time performance, and achieve low latency. In particular, it is efficient to perform the processing of motion search, deblocking filter, SAO (Sample Adaptive Offset), and transformation and quantization collectively in units such as pictures by the GPU, rather than by the CPU.

[0313] This aspect may be implemented in combination with at least a part of other aspects of the present disclosure. Also, some of the processes, some of the configurations of the device, and some of the syntax described in the flowcharts of this aspect may be implemented in combination with other aspects. [Industrial Applicability]

[0314] The present disclosure is applicable to, for example, television receivers, digital video recorders, car navigation systems, mobile phones, digital cameras, digital video cameras, video conference systems, electronic mirrors, and the like. [Explanation of symbols]

[0315] 100 Encoding device 102 Division 104 Subtraction section 106 Conversion unit 108 Quantization section 110 Entropy coding unit 112, 204 Inverse quantization section 114, 206 Inverse conversion unit 116, 208 Addition section 118, 210 Block Memory 120, 212 Loop filter section 122, 214 frame memory 124, 216 Intra prediction section 126, 218 Inter prediction section 128, 220 Predictive control unit 160, 260 circuits 162, 262 memory 200 Decryption device 202 Entropy Decoding Unit

Claims

1. The circuit, A memory, The circuit uses the memory to: determining a filter to be used for deblocking filtering from a plurality of filters including a first filter, a second filter, and a third filter; performing the deblocking filter process on block boundaries using the determined filter; the first filter is a filter that uses M (M is an integer equal to or greater than 2) pixels on an upper side of the block boundary and M pixels on a lower side of the block boundary, the second filter is a filter that uses N pixels (N is an integer greater than M) above the block boundary and N pixels below the block boundary, the third filter is a filter that uses a first pixel on an upper side of the block boundary and a second pixel on a lower side of the block boundary; the first number of pixels being one of a first plurality of candidate values; the second number of pixels being one of a second plurality of candidate values; each of the first plurality of candidate values ​​and each of the second plurality of candidate values ​​is N or a value greater than N; If the block boundary is the top of a coding tree unit (CTU), then N is used as the first number of pixels. Encoding device.

2. The circuit, A memory, The circuit uses the memory to: determining a filter to be used for deblocking filtering from a plurality of filters including a first filter, a second filter, and a third filter; performing the deblocking filter process on block boundaries using the determined filter; the first filter is a filter that uses M (M is an integer equal to or greater than 2) pixels on an upper side of the block boundary and M pixels on a lower side of the block boundary, the second filter is a filter that uses N pixels (N is an integer greater than M) above the block boundary and N pixels below the block boundary, the third filter is a filter that uses a first pixel on an upper side of the block boundary and a second pixel on a lower side of the block boundary; the first number of pixels being one of a first plurality of candidate values; the second number of pixels being one of a second plurality of candidate values; each of the first plurality of candidate values ​​and each of the second plurality of candidate values ​​is N or a value greater than N; If the block boundary is the top of a coding tree unit (CTU), then N is used as the first number of pixels. Decryption device.

Images