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WO2018021373A1 - Dispositif de codage, dispositif de décodage, procédé de codage, et procédé de décodage - Google Patents

Dispositif de codage, dispositif de décodage, procédé de codage, et procédé de décodage Download PDF

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Publication number
WO2018021373A1
WO2018021373A1 PCT/JP2017/026959 JP2017026959W WO2018021373A1 WO 2018021373 A1 WO2018021373 A1 WO 2018021373A1 JP 2017026959 W JP2017026959 W JP 2017026959W WO 2018021373 A1 WO2018021373 A1 WO 2018021373A1
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block
unit
dct
decoding
encoding
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Japanese (ja)
Inventor
大川　真人
秀雄 齋藤
西　孝啓
遠間　正真
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Panasonic Intellectual Property Corp of America
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
    • H04N19/12—Selection from among a plurality of transforms or standards, e.g. selection between discrete cosine transform [DCT] and sub-band transform or selection between H.263 and H.264
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/134—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or criterion affecting or controlling the adaptive coding
    • H04N19/157—Assigned coding mode, i.e. the coding mode being predefined or preselected to be further used for selection of another element or parameter
    • H04N19/159—Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
    • H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
    • H04N19/17—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object
    • H04N19/176—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object the region being a block, e.g. a macroblock

Definitions

  • the present disclosure relates to an encoding device, a decoding device, an encoding method, and a decoding method.
  • HEVC High-Efficiency Video Coding
  • JCT-VC Joint Collaborative Team on Video Coding
  • Such encoding and decoding techniques are required to further improve the compression efficiency.
  • the present disclosure provides an encoding device, a decoding device, an encoding method, or a decoding method that can realize further improvement in compression efficiency.
  • An encoding apparatus is an encoding apparatus that encodes an encoding target block of an image, and includes a processor and a memory, and the processor uses the memory to encode the code. Determining whether intra prediction or inter prediction is used for the encoding target block, and selectively using a plurality of frequency transform bases including DCT-II and DCT-V, thereby predicting the prediction error of the encoding target block In the first frequency transform, when intra prediction is used for the encoding target block, a DCT-V base is used, and inter prediction is performed for the encoding target block. DCT-II base is used.
  • a decoding device is a decoding device that decodes a decoding target block of an image, and includes a processor and a memory, and the processor uses the memory to perform the decoding target block.
  • Intra prediction or inter prediction is used for the first and second bases of a plurality of inverse frequency transforms including inverse transforms of DCT-II and DCT-V are selectively used to determine the first prediction error of the decoding target block. 1 inverse frequency transform is performed, and in the first inverse frequency transform, when intra prediction is used for the block to be decoded, a base of DCT-V inverse transform is used, and an inter block for the block to be decoded is used. When prediction is used, the inverse transform base of DCT-II is used.
  • the present disclosure can provide an encoding device, a decoding device, an encoding method, or a decoding method that can further improve the compression efficiency.
  • FIG. 1 is a block diagram showing a functional configuration of the encoding apparatus according to Embodiment 1.
  • FIG. 2 is a diagram illustrating an example of block division in the first embodiment.
  • FIG. 3 is a table showing conversion basis functions corresponding to each conversion type.
  • FIG. 4A is a diagram illustrating an example of the shape of a filter used in ALF.
  • FIG. 4B is a diagram illustrating another example of the shape of a filter used in ALF.
  • FIG. 4C is a diagram illustrating another example of the shape of a filter used in ALF.
  • FIG. 5 is a diagram illustrating 67 intra prediction modes in intra prediction.
  • FIG. 6 is a diagram for explaining pattern matching (bilateral matching) between two blocks along the motion trajectory.
  • FIG. 1 is a block diagram showing a functional configuration of the encoding apparatus according to Embodiment 1.
  • FIG. 2 is a diagram illustrating an example of block division in the first embodiment.
  • FIG. 3 is a table showing conversion basis functions
  • FIG. 7 is a diagram for explaining pattern matching (template matching) between a template in the current picture and a block in the reference picture.
  • FIG. 8 is a diagram for explaining a model assuming constant velocity linear motion.
  • FIG. 9 is a diagram for explaining the derivation of motion vectors in units of sub-blocks based on the motion vectors of a plurality of adjacent blocks.
  • FIG. 10 is a block diagram showing a functional configuration of the decoding apparatus according to the first embodiment.
  • FIG. 11 is a block diagram showing an internal configuration of the conversion unit of the encoding apparatus according to Embodiment 1.
  • FIG. 12 is a flowchart showing processing of the conversion unit of the encoding device according to Embodiment 1.
  • FIG. 13 is a block diagram showing an internal configuration of the inverse transform unit of the decoding apparatus according to Embodiment 1.
  • FIG. 14 is a flowchart showing processing of the inverse transform unit of the decoding apparatus according to Embodiment 1.
  • FIG. 15A is a graph showing DCT-II conversion characteristics in a 32 ⁇ 32 size block.
  • FIG. 15B is a graph showing DCT-V conversion characteristics in a 32 ⁇ 32 size block.
  • FIG. 16A is a graph showing DCT-II conversion characteristics in a 4 ⁇ 4 size block.
  • FIG. 16B is a graph showing DCT-V conversion characteristics in a 4 ⁇ 4 size block.
  • FIG. 17 is a block diagram showing an internal configuration of a conversion unit of the encoding apparatus according to the first modification of the first embodiment.
  • FIG. 18 is a flowchart showing processing of the conversion unit of the encoding device according to Modification 1 of Embodiment 1.
  • FIG. 19 is a block diagram showing an internal configuration of the inverse transform unit of the decoding apparatus according to the first modification of the first embodiment.
  • FIG. 20 is a flowchart showing processing of the inverse transform unit of the decoding apparatus according to Modification 1 of Embodiment 1.
  • FIG. 21 is a block diagram showing an internal configuration of a conversion unit of the encoding apparatus according to the second modification of the first embodiment.
  • FIG. 22 is a diagram illustrating a plurality of examples of positions in the bitstream of threshold size or conversion mode information according to the second or third modification of the first embodiment.
  • FIG. 23 is a flowchart illustrating processing of the conversion unit of the encoding device according to the second modification of the first embodiment.
  • FIG. 24 is a block diagram showing an internal configuration of the inverse transform unit of the decoding apparatus according to the second modification of the first embodiment.
  • FIG. 25 is a flowchart showing processing of the inverse transform unit of the decoding device according to Modification 2 of Embodiment 1.
  • FIG. 26 is a block diagram showing an internal configuration of a conversion unit of the encoding apparatus according to the third modification of the first embodiment.
  • FIG. 27 is a flowchart showing processing of the conversion unit of the encoding device according to the third modification of the first embodiment.
  • FIG. 28 is a block diagram showing an internal configuration of the inverse transform unit of the decoding apparatus according to Modification 3 of Embodiment 1.
  • FIG. 29 is a flowchart showing processing of the inverse transform unit of the decoding device according to Modification 3 of Embodiment 1.
  • FIG. 30 is an overall configuration diagram of a content supply system that implements a content distribution service.
  • FIG. 31 is a diagram illustrating an example of a coding structure at the time of scalable coding.
  • FIG. 32 is a diagram illustrating an example of a coding structure at the time of scalable coding.
  • FIG. 33 shows an example of a web page display screen.
  • FIG. 34 shows an example of a web page display screen.
  • FIG. 35 is a diagram illustrating an example of a smartphone.
  • FIG. 36 is a block diagram illustrating a configuration example of a smartphone.
  • a DCT-II base is basically used as a frequency conversion base in an intra prediction block, but only a luminance block of 4 ⁇ 4 size is used.
  • the base of DST-VII is used.
  • an encoding device that encodes an encoding target block of an image, and includes a processor and a memory, and the processor uses the memory, It is determined whether intra prediction or inter prediction is used for the encoding target block, and a plurality of frequency transform bases including DCT-II and DCT-V are selectively used to determine the encoding target block.
  • a first frequency transform is performed on a prediction error, and in the first frequency transform, when intra prediction is used for the coding target block, a DCT-V base is used, and for the coding target block When inter prediction is used, the DCT-II basis is used.
  • the encoding target block when intra prediction is used for an encoding target block, the encoding target block can be converted using a DCT-V base.
  • DCT-V the amplitude decreases at a position close to the reference pixel in the direct current component, and therefore DCT-V is suitable for conversion of prediction error of intra prediction. Therefore, the encoding device can realize further improvement in compression efficiency.
  • the processor further determines whether or not the size of the encoding target block is a threshold size or less, and in the first frequency transform, When intra prediction is used for an encoding target block, (i) if the size of the encoding target block is equal to or smaller than the threshold size, a DCT-V base is used; and (ii) the encoding target If the block size is larger than the threshold size, a DCT-II basis may be used.
  • the encoding target block by switching the bases of DCT-II and DCT-V according to the size of the encoding target block for which intra prediction is used. If the block size is large, the prediction error tends to decrease as a whole in the block, and DCT-II is suitable for conversion of the prediction error of the encoding target block. On the other hand, if the block size is small, the prediction error tends to be smaller as the pixel is closer to the reference pixel, and DCT-V is suitable for conversion of the prediction error of the encoding target block. Therefore, if the size of the encoding target block is equal to or smaller than the threshold size, the encoding target block is converted using the DCT-V base. If the size of the encoding target block is larger than the threshold size, the base of the DCT-II is converted. By converting the block to be encoded using, it is possible to further improve the compression efficiency.
  • the processor may further write the threshold size information in a bitstream.
  • threshold size information can be written in the bitstream. Therefore, it is possible to use a threshold size that is adaptively determined according to the input image, and further improve the compression efficiency.
  • the processor further selects any one of a plurality of conversion modes including a first conversion mode and a second conversion mode as the encoding target block.
  • a first conversion mode When the first conversion mode is applied, the first frequency conversion is performed, and when the second conversion mode is applied, a second frequency different from the first frequency conversion is determined. Conversion may be performed.
  • frequency conversion can be switched using the conversion mode. Therefore, it is possible to realize further frequency conversion efficiency and further improve the compression efficiency.
  • the processor may further write information on a conversion mode applied to the encoding target block in the bitstream.
  • the conversion mode can be determined adaptively according to the input image, and further improvement in compression efficiency can be realized.
  • An encoding method is an encoding method for encoding an encoding target block of an image, and determines whether intra prediction or inter prediction is used for the encoding target block.
  • DCT-II and DCT-V are selectively used to perform a first frequency transform on the prediction error of the coding target block, and in the first frequency transform, the coding target A DCT-V basis is used when intra prediction is used for a block, and a DCT-II basis is used when inter prediction is used for the current block.
  • a decoding device is a decoding device that decodes a decoding target block of an image, and includes a processor and a memory, and the processor uses the memory to perform the decoding target block.
  • Intra prediction or inter prediction is used for the first and second bases of a plurality of inverse frequency transforms including inverse transforms of DCT-II and DCT-V are selectively used to determine the first prediction error of the decoding target block. 1 inverse frequency transform is performed, and in the first inverse frequency transform, when intra prediction is used for the block to be decoded, a base of DCT-V inverse transform is used, and an inter block for the block to be decoded is used. When prediction is used, the inverse transform base of DCT-II is used.
  • the decoding target block when intra prediction is used for a decoding target block, the decoding target block can be inversely transformed using a DCT-V inverse transformation base.
  • DCT-V the amplitude decreases at a position close to the reference pixel in the direct current component, and therefore DCT-V is suitable for conversion of prediction error of intra prediction. Therefore, the decoding device can realize further improvement in compression efficiency.
  • the processor further determines whether or not the size of the decoding target block is equal to or smaller than a threshold size, and the first inverse frequency transform includes the decoding When intra prediction is used for a target block, (i) if the size of the decoding target block is equal to or smaller than the threshold size, a base of inverse transform of DCT-V is used, and (ii) the decoding target block If the size is larger than the threshold size, a DCT-II inverse transform basis may be used.
  • the decoding target block can be inversely transformed by switching the bases of the inverse transformation of DCT-II and DCT-V according to the size of the decoding target block for which intra prediction is used. If the block size is large, the prediction error tends to be reduced in the whole block, and DCT-II is suitable for conversion of the prediction error of the decoding target block. On the other hand, if the block size is small, the prediction error tends to be smaller as the pixel is closer to the reference pixel, and DCT-V is suitable for conversion of the prediction error of the decoding target block.
  • the decoding target block is inversely transformed using the inverse transform base of DCT-V, and if the size of the decoding target block is larger than the threshold size, the DCT-II By further inversely transforming the decoding target block using the inverse transform base, further improvement in compression efficiency can be realized.
  • the processor may further read the threshold size information from the bitstream.
  • the threshold size information can be read from the bit stream. Therefore, it is possible to use a threshold size that is adaptively determined according to the input image, and further improve the compression efficiency.
  • the processor further applies which of the plurality of conversion modes including the first conversion mode and the second conversion mode to the decoding target block.
  • the first conversion mode When the first conversion mode is applied, the first reverse frequency conversion is performed, and when the second conversion mode is applied, the second reverse is different from the first reverse frequency conversion. Frequency conversion may be performed.
  • reverse frequency conversion can be switched using the conversion mode. Therefore, it is possible to realize further frequency conversion efficiency and further improve the compression efficiency.
  • the processor may further read information on a conversion mode applied to the block to be decoded from a bitstream.
  • the conversion mode applied to the decoding target block can be written in the bit stream. Therefore, the conversion mode can be determined adaptively according to the input image, and further improvement in compression efficiency can be realized.
  • a decoding method is a decoding method for decoding a decoding target block of an image, determines whether intra prediction or inter prediction is used for the decoding target block, and performs DCT-II and A first inverse frequency transform is performed on a prediction error of the decoding target block by selectively using a plurality of inverse frequency transform bases including an inverse transform of DCT-V.
  • the decoding target block is For this reason, the inverse transform base of DCT-V is used, and when the inter prediction is used for the decoding target block, the inverse transform base of DCT-II is used.
  • a recording medium such as a system, an integrated circuit, a computer program, or a computer-readable CD-ROM, and the system, the integrated circuit, the computer program, and the recording medium. You may implement
  • FIG. 1 is a block diagram showing a functional configuration of encoding apparatus 100 according to Embodiment 1.
  • the encoding device 100 is a moving image / image encoding device that encodes moving images / images in units of blocks.
  • an encoding apparatus 100 is an apparatus that encodes an image in units of blocks, and includes a dividing unit 102, a subtracting unit 104, a transforming unit 106, a quantizing unit 108, and entropy encoding.
  • Unit 110 inverse quantization unit 112, inverse transform unit 114, addition unit 116, block memory 118, loop filter unit 120, frame memory 122, intra prediction unit 124, inter prediction unit 126, A prediction control unit 128.
  • the encoding device 100 is realized by, for example, a general-purpose processor and a memory.
  • the processor when the software program stored in the memory is executed by the processor, the processor performs the division unit 102, the subtraction unit 104, the conversion unit 106, the quantization unit 108, the entropy encoding unit 110, and the inverse quantization unit 112.
  • the encoding apparatus 100 includes a dividing unit 102, a subtracting unit 104, a transforming unit 106, a quantizing unit 108, an entropy coding unit 110, an inverse quantizing unit 112, an inverse transforming unit 114, an adding unit 116, and a loop filter unit 120.
  • the intra prediction unit 124, the inter prediction unit 126, and the prediction control unit 128 may be implemented as one or more dedicated electronic circuits.
  • the dividing unit 102 divides each picture included in the input moving image into a plurality of blocks, and outputs each block to the subtracting unit 104.
  • the dividing unit 102 first divides a picture into blocks of a fixed size (for example, 128 ⁇ 128).
  • This fixed size block may be referred to as a coding tree unit (CTU).
  • the dividing unit 102 divides each of the fixed size blocks into blocks of a variable size (for example, 64 ⁇ 64 or less) based on recursive quadtree and / or binary tree block division.
  • This variable size block may be referred to as a coding unit (CU), a prediction unit (PU) or a transform unit (TU).
  • CU, PU, and TU do not need to be distinguished, and some or all blocks in a picture may be processing units of CU, PU, and TU.
  • FIG. 2 is a diagram showing an example of block division in the first embodiment.
  • a solid line represents a block boundary by quadtree block division
  • a broken line represents a block boundary by binary tree block division.
  • the block 10 is a 128 ⁇ 128 pixel square block (128 ⁇ 128 block).
  • the 128 ⁇ 128 block 10 is first divided into four square 64 ⁇ 64 blocks (quadtree block division).
  • the upper left 64 ⁇ 64 block is further divided vertically into two rectangular 32 ⁇ 64 blocks, and the left 32 ⁇ 64 block is further divided vertically into two rectangular 16 ⁇ 64 blocks (binary tree block division). As a result, the upper left 64 ⁇ 64 block is divided into two 16 ⁇ 64 blocks 11 and 12 and a 32 ⁇ 64 block 13.
  • the upper right 64 ⁇ 64 block is horizontally divided into two rectangular 64 ⁇ 32 blocks 14 and 15 (binary tree block division).
  • the lower left 64x64 block is divided into four square 32x32 blocks (quadrant block division). Of the four 32 ⁇ 32 blocks, the upper left block and the lower right block are further divided.
  • the upper left 32 ⁇ 32 block is vertically divided into two rectangular 16 ⁇ 32 blocks, and the right 16 ⁇ 32 block is further divided horizontally into two 16 ⁇ 16 blocks (binary tree block division).
  • the lower right 32 ⁇ 32 block is horizontally divided into two 32 ⁇ 16 blocks (binary tree block division).
  • the lower left 64 ⁇ 64 block is divided into a 16 ⁇ 32 block 16, two 16 ⁇ 16 blocks 17 and 18, two 32 ⁇ 32 blocks 19 and 20, and two 32 ⁇ 16 blocks 21 and 22.
  • the lower right 64x64 block 23 is not divided.
  • the block 10 is divided into 13 variable-size blocks 11 to 23 based on the recursive quadtree and binary tree block division.
  • Such division may be called QTBT (quad-tree plus binary tree) division.
  • one block is divided into four or two blocks (quadrature tree or binary tree block division), but the division is not limited to this.
  • one block may be divided into three blocks (triple tree block division).
  • Such a division including a tri-tree block division may be called an MBT (multi type tree) division.
  • the subtraction unit 104 subtracts the prediction signal (prediction sample) from the original signal (original sample) in units of blocks divided by the division unit 102. That is, the subtraction unit 104 calculates a prediction error (also referred to as a residual) of a coding target block (hereinafter referred to as a current block). Then, the subtraction unit 104 outputs the calculated prediction error to the conversion unit 106.
  • a prediction error also referred to as a residual of a coding target block (hereinafter referred to as a current block).
  • the original signal is an input signal of the encoding device 100, and is a signal (for example, a luminance (luma) signal and two color difference (chroma) signals) representing an image of each picture constituting the moving image.
  • a signal representing an image may be referred to as a sample.
  • the transform unit 106 transforms the prediction error in the spatial domain into a transform factor in the frequency domain, and outputs the transform coefficient 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 a prediction error in the spatial domain.
  • DCT discrete cosine transform
  • DST discrete sine transform
  • the conversion unit 106 adaptively selects a conversion type from a plurality of conversion types, and converts a prediction error into a conversion coefficient using a conversion basis function corresponding to the selected conversion type. May be. Such a conversion may be referred to as EMT (explicit multiple core transform) or AMT (adaptive multiple transform).
  • the plurality of conversion types include, for example, DCT-II, DCT-V, DCT-VIII, DST-I and DST-VII.
  • FIG. 3 is a table showing conversion basis functions corresponding to each conversion type. In FIG. 3, N indicates the number of input pixels. Selection of a conversion type from among these multiple conversion types may depend on, for example, the type of prediction (intra prediction and inter prediction), or may depend on an intra prediction mode.
  • Information indicating whether or not to apply such EMT or AMT (for example, called an AMT flag) and information indicating the selected conversion type are signaled at the CU level.
  • AMT flag information indicating whether or not to apply such EMT or AMT
  • the signalization of these pieces of information need not be limited to the CU level, but may be other levels (for example, a sequence level, a picture level, a slice level, a tile level, or a CTU level).
  • the conversion unit 106 may reconvert the conversion coefficient (conversion result). Such reconversion is sometimes referred to as AST (adaptive secondary transform) or NSST (non-separable secondary transform). For example, the conversion unit 106 performs re-conversion for each sub-block (for example, 4 ⁇ 4 sub-block) included in the block of the conversion coefficient corresponding to the intra prediction error. Information indicating whether or not NSST is applied and information related to the transformation matrix used for NSST are signaled at the CU level. Note that the signalization of these pieces of information need not be limited to the CU level, but may be other levels (for example, a sequence level, a picture level, a slice level, a tile level, or a CTU level).
  • the quantization unit 108 quantizes the transform coefficient 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 the quantization parameter (QP) corresponding to the scanned transform coefficients. Then, the quantization unit 108 outputs the quantized transform coefficient (hereinafter referred to as a quantization coefficient) of the current block to the entropy encoding unit 110 and the inverse quantization unit 112.
  • QP quantization parameter
  • the predetermined order is an order for quantization / inverse quantization of transform coefficients.
  • the predetermined scanning order is defined in ascending order of frequency (order from low frequency to high frequency) or descending order (order from high frequency to low frequency).
  • the quantization parameter is a parameter that defines a quantization step (quantization width). For example, if the value of the quantization parameter increases, the quantization step also increases. That is, if the value of the quantization parameter increases, the quantization error increases.
  • the entropy encoding unit 110 generates an encoded signal (encoded bit stream) by performing variable length encoding on the quantization coefficient that is input from the quantization unit 108. Specifically, the entropy encoding unit 110 binarizes the quantization coefficient, for example, and arithmetically encodes the binary signal.
  • the inverse quantization unit 112 inversely quantizes the quantization coefficient that is an input from the quantization unit 108. Specifically, the inverse quantization unit 112 inversely quantizes the quantization coefficient of the current block in a predetermined scanning order. Then, the inverse quantization unit 112 outputs the inverse-quantized transform coefficient of the current block to the inverse transform unit 114.
  • the inverse transform unit 114 restores the prediction error by inverse transforming the transform coefficient that is an 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 corresponding to the transform by the transform unit 106 on the transform coefficient. Then, the inverse transformation unit 114 outputs the restored prediction error to the addition unit 116.
  • the restored prediction error does not match the prediction error calculated by the subtraction unit 104 because information is lost due to quantization. That is, the restored prediction error includes a quantization error.
  • the adder 116 reconstructs the current block by adding the prediction error input from the inverse transform unit 114 and the prediction sample input from the prediction control unit 128. Then, the adding unit 116 outputs the reconfigured block to the block memory 118 and the loop filter unit 120.
  • the reconstructed block is sometimes referred to as a local decoding block.
  • the block memory 118 is a storage unit for storing blocks in an encoding target picture (hereinafter referred to as current picture) that are referred to in intra prediction. Specifically, the block memory 118 stores the reconstructed block output from the adding unit 116.
  • the loop filter unit 120 applies a loop filter to the block reconstructed by the adding 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), an adaptive loop filter (ALF), and the like.
  • a least square error filter is applied to remove coding distortion. For example, for each 2 ⁇ 2 sub-block in the current block, a plurality of multiples based on the direction of the local gradient and the activity are provided. One filter selected from the filters is applied.
  • sub-blocks for example, 2 ⁇ 2 sub-blocks
  • a plurality of classes for example, 15 or 25 classes.
  • the direction value D of the gradient is derived, for example, by comparing gradients in a plurality of directions (for example, horizontal, vertical, and two diagonal directions).
  • the gradient activation value A is derived, for example, by adding gradients in a plurality of directions and quantizing the addition result.
  • a filter for a sub-block is determined from among a plurality of filters.
  • FIG. 4A to 4C are diagrams showing a plurality of examples of filter shapes used in ALF.
  • 4A shows a 5 ⁇ 5 diamond shape filter
  • FIG. 4B shows a 7 ⁇ 7 diamond shape filter
  • FIG. 4C shows a 9 ⁇ 9 diamond shape filter.
  • Information indicating the shape of the filter is signalized at the picture level. It should be noted that the signalization of the information indicating the filter shape need not be limited to the picture level, but may be another level (for example, a sequence level, a slice level, a tile level, a CTU level, or a CU level).
  • ON / OFF of ALF is determined at the picture level or the CU level, for example. For example, for luminance, it is determined whether to apply ALF at the CU level, and for color difference, it is determined whether to apply ALF at the picture level.
  • Information indicating ALF on / off is signaled at the picture level or the CU level. Signaling of information indicating ALF on / off need not be limited to the picture level or the CU level, and may be performed at other levels (for example, a sequence level, a slice level, a tile level, or a CTU level). Good.
  • a coefficient set of a plurality of selectable filters (for example, up to 15 or 25 filters) is signalized at the picture level.
  • the signalization of the coefficient set need not be limited to the picture level, but may be another level (for example, sequence level, slice level, tile level, CTU level, CU level, or sub-block level).
  • the frame memory 122 is a storage unit for storing a reference picture used for inter prediction, and is sometimes called a frame buffer. Specifically, the frame memory 122 stores the reconstructed block filtered by the loop filter unit 120.
  • the intra prediction unit 124 generates a prediction signal (intra prediction signal) by referring to the block in the current picture stored in the block memory 118 and performing intra prediction (also referred to as intra-screen prediction) of the current block. Specifically, the intra prediction unit 124 generates an intra prediction signal by performing intra prediction with reference to a sample (for example, luminance value and color difference value) of a block adjacent to the current block, and performs prediction control on the intra prediction signal. To the unit 128.
  • the intra prediction unit 124 performs intra prediction using one of a plurality of predefined intra prediction modes.
  • the plurality of intra prediction modes include one or more non-directional prediction modes and a plurality of directional prediction modes.
  • One or more non-directional prediction modes are for example H.264. It includes Planar prediction mode and DC prediction mode defined by H.265 / HEVC (High-Efficiency Video Coding) standard (Non-patent Document 1).
  • the multiple directionality prediction modes are H. It includes 33-direction prediction modes defined in the H.265 / HEVC standard. In addition to the 33 directions, the plurality of directionality prediction modes may further include 32 direction prediction modes (a total of 65 directionality prediction modes).
  • FIG. 5 is a diagram illustrating 67 intra prediction modes (two non-directional prediction modes and 65 directional prediction modes) in intra prediction. The solid line arrows The 33 directions defined in the H.265 / HEVC standard are represented, and the dashed arrow represents the added 32 directions.
  • the luminance block may be referred to in the intra prediction of the color difference block. That is, the color difference component of the current block may be predicted based on the luminance component of the current block.
  • Such intra prediction is sometimes called CCLM (cross-component linear model) prediction.
  • the intra prediction mode (for example, called CCLM mode) of the color difference block which refers to such a luminance block may be added as one of the intra prediction modes of the color difference block.
  • the intra prediction unit 124 may correct the pixel value after intra prediction based on the gradient of the reference pixel in the horizontal / vertical direction. Intra prediction with such correction may be called PDPC (position dependent intra prediction combination). Information indicating whether or not PDPC is applied (for example, referred to as a PDPC flag) is signaled, for example, at the CU level.
  • the signalization of this information need not be limited to the CU level, but may be another level (for example, a sequence level, a picture level, a slice level, a tile level, or a CTU level).
  • the inter prediction unit 126 refers to a reference picture stored in the frame memory 122 and is different from the current picture, and performs inter prediction (also referred to as inter-screen prediction) of the current block, thereby generating a prediction signal (inter prediction signal). Prediction signal). Inter prediction is performed in units of a current block or a sub-block (for example, 4 ⁇ 4 block) in the current block. For example, the inter prediction unit 126 performs motion estimation in the reference picture for the current block or sub-block. Then, the inter prediction unit 126 generates an inter prediction signal of the current block or sub-block by performing motion compensation using motion information (for example, a motion vector) obtained by motion search. Then, the inter prediction unit 126 outputs the generated inter prediction signal to the prediction control unit 128.
  • inter prediction also referred to as inter-screen prediction
  • a motion vector predictor may be used for signalizing the motion vector. That is, the difference between the motion vector and the predicted motion vector may be signaled.
  • an 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 adjacent blocks. Specifically, the inter prediction signal is generated in units of sub-blocks in the current block by 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 adjacent blocks. May be.
  • Such inter prediction motion compensation
  • OBMC overlapped block motion compensation
  • OBMC block size information indicating the size of a sub-block for OBMC
  • OBMC flag information indicating whether or not to apply the OBMC mode
  • the level of signalization of these information does not need to be limited to the sequence level and the CU level, and may be other levels (for example, a picture level, a slice level, a tile level, a CTU level, or a sub-block level). Good.
  • the motion information may be derived on the decoding device side without being converted into a signal.
  • H.M. A merge mode defined in the H.265 / HEVC standard may be used.
  • the motion information may be derived by performing motion search on the decoding device side. In this case, motion search is performed without using the pixel value of the current block.
  • the mode in which the motion search is performed on the decoding device side is sometimes referred to as a PMMVD (patterned motion vector derivation) mode or an FRUC (frame rate up-conversion) mode.
  • PMMVD patterned motion vector derivation
  • FRUC frame rate up-conversion
  • a list of a plurality of candidates each having a predicted motion vector is generated Is done. Then, the evaluation value of each candidate included in the candidate list is calculated, and one candidate is selected based on the evaluation value.
  • a motion vector for the current block is derived based on the selected candidate motion vector.
  • the selected candidate motion vector is directly derived as a motion vector for the current block.
  • the motion vector for the current block may be derived by performing pattern matching in the peripheral region at the position in the reference picture corresponding to the selected candidate motion vector.
  • the evaluation value is calculated by pattern matching between an area in the reference picture corresponding to the motion vector and a predetermined area.
  • the first pattern matching and the second pattern matching may be referred to as bilateral matching and template matching, respectively.
  • pattern matching is performed between two blocks in two different reference pictures that follow the motion trajectory of the current block. Therefore, in the first pattern matching, a region in another reference picture along the motion trajectory of the current block is used as the predetermined region for calculating the candidate evaluation value described above.
  • FIG. 6 is a diagram for explaining pattern matching (bilateral matching) between two blocks along a motion trajectory.
  • pattern matching bilateral matching
  • two blocks along the motion trajectory of the current block (Cur block) and two blocks in two different reference pictures (Ref0, Ref1) are used.
  • Ref0, Ref1 two blocks in two different reference pictures
  • the motion vectors (MV0, MV1) pointing to the two reference blocks are temporal distances between the current picture (Cur Pic) and the two reference pictures (Ref0, Ref1). It is proportional to (TD0, TD1).
  • the first pattern matching uses a mirror-symmetric bi-directional motion vector Is derived.
  • pattern matching is performed between a template in the current picture (a block adjacent to the current block in the current picture (for example, 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 the predetermined region for calculating the candidate evaluation value described above.
  • FIG. 7 is a diagram for explaining pattern matching (template matching) between a template in the current picture and a block in the reference picture.
  • the current block is searched by searching 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).
  • Ref0 the reference picture
  • FRUC flag Information indicating whether or not to apply such FRUC mode
  • FRUC flag information indicating whether or not to apply such FRUC mode
  • 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 the FRUC mode flag) is signaled at the CU level. It becomes. Note that the signalization of these pieces of information need not be limited to the CU level, but may be other levels (for example, sequence level, picture level, slice level, tile level, CTU level, or sub-block level). .
  • motion information may be derived on the decoding device side by a method different from motion search.
  • the motion vector correction amount may be calculated using a peripheral pixel value for each pixel based on a model assuming constant velocity linear motion.
  • BIO bi-directional optical flow
  • FIG. 8 is a diagram for explaining a model assuming constant velocity linear motion.
  • (v x , v y ) indicates a velocity vector
  • ⁇ 0 and ⁇ 1 are the time between the current picture (Cur Pic) and two reference pictures (Ref 0 , Ref 1 ), respectively.
  • the distance. (MVx 0 , MVy 0 ) indicates a motion vector corresponding to the reference picture Ref 0
  • (MVx 1 , MVy 1 ) indicates a motion vector corresponding to the reference picture Ref 1 .
  • This optical flow equation consists of (i) the product of the time derivative of the luminance value, (ii) the horizontal component of the horizontal velocity and the spatial gradient of the reference image, and (iii) the vertical velocity and the spatial gradient of the reference image. Indicates that the sum of the products of the vertical components of is equal to zero. Based on a combination of this optical flow equation and Hermite interpolation, a block-based motion vector obtained from a merge list or the like is corrected in pixel units.
  • the motion vector may be derived on the decoding device side by a method different from the derivation of the motion vector based on the model assuming constant velocity linear motion.
  • a motion vector may be derived for each subblock based on the motion vectors of a plurality of adjacent blocks.
  • This mode may be referred to as an affine motion compensation prediction mode.
  • FIG. 9 is a diagram for explaining the derivation of motion vectors in units of sub-blocks based on the motion vectors of a plurality of adjacent blocks.
  • the current block includes 16 4 ⁇ 4 sub-blocks.
  • the motion vector v 0 of the upper left corner control point of the current block is derived based on the motion vector of the adjacent block
  • the motion vector v 1 of the upper right corner control point of the current block is derived based on the motion vector of the adjacent sub block. Is done.
  • the motion vector (v x , v y ) of each sub-block in the current block is derived by the following equation (2).
  • x and y indicate the horizontal position and vertical position of the sub-block, respectively, and w indicates a predetermined weight coefficient.
  • Such an affine motion compensation prediction mode may include several modes in which the motion vector derivation methods of the upper left and upper right corner control points are different.
  • Information indicating such an affine motion compensation prediction mode (for example, called an affine flag) is signaled at the CU level. Note that the information indicating the affine motion compensation prediction mode need not be limited to the CU level, but other levels (for example, sequence level, picture level, slice level, tile level, CTU level, or sub-block level). ).
  • 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.
  • FIG. 10 is a block diagram showing a functional configuration of decoding apparatus 200 according to Embodiment 1.
  • the decoding device 200 is a moving image / image decoding device that decodes moving images / images in units of blocks.
  • the decoding device 200 includes an entropy decoding unit 202, an inverse quantization unit 204, an inverse transformation unit 206, an addition unit 208, a block memory 210, a loop filter unit 212, and a frame memory 214. And an intra prediction unit 216, an inter prediction unit 218, and a prediction control unit 220.
  • the decoding device 200 is realized by, for example, a general-purpose processor and a memory.
  • the processor executes the entropy decoding unit 202, the inverse quantization unit 204, the inverse transformation unit 206, the addition unit 208, the loop filter unit 212, and the intra prediction unit. 216, the inter prediction unit 218, and the prediction control unit 220.
  • the decoding apparatus 200 is dedicated to the entropy decoding unit 202, the inverse quantization unit 204, the inverse transformation 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. It may be realized as one or more electronic circuits.
  • the entropy decoding unit 202 performs entropy decoding on the encoded bit stream. Specifically, the entropy decoding unit 202 performs arithmetic decoding from a coded bitstream to a binary signal, for example. Then, the entropy decoding unit 202 debinarizes the binary signal. As a result, the entropy decoding unit 202 outputs the quantized coefficient to the inverse quantization unit 204 in units of blocks.
  • the inverse quantization unit 204 inversely quantizes the quantization coefficient of a decoding target block (hereinafter referred to as a current block) that is an input from the entropy decoding unit 202. Specifically, the inverse quantization unit 204 inversely quantizes each quantization coefficient of the current block based on the quantization parameter corresponding to the quantization coefficient. Then, the inverse quantization unit 204 outputs the quantization coefficient (that is, the transform coefficient) obtained by inverse quantization of the current block to the inverse transform unit 206.
  • a decoding target block hereinafter referred to as a current block
  • the inverse quantization unit 204 inversely quantizes each quantization coefficient of the current block based on the quantization parameter corresponding to the quantization coefficient. Then, the inverse quantization unit 204 outputs the quantization coefficient (that is, the transform coefficient) obtained by inverse quantization of the current block to the inverse transform unit 206.
  • the inverse transform unit 206 restores the prediction error by inverse transforming the transform coefficient that is an input from the inverse quantization unit 204.
  • the inverse conversion unit 206 determines the current block based on the information indicating the read conversion type. Inversely transform the conversion coefficient of.
  • the inverse transform unit 206 applies inverse retransformation to the transform coefficient.
  • the adder 208 reconstructs the current block by adding the prediction error input from the inverse converter 206 and the prediction sample input from the prediction controller 220. Then, the adding unit 208 outputs the reconfigured block to the block memory 210 and the loop filter unit 212.
  • the block memory 210 is a storage unit for storing a block that is referred to in intra prediction and that is within a decoding target picture (hereinafter referred to as a current picture). Specifically, the block memory 210 stores the reconstructed block output from the adding unit 208.
  • the loop filter unit 212 applies a loop filter to the block reconstructed by the adding unit 208, and outputs the filtered reconstructed block to the frame memory 214, the display device, and the like.
  • one filter is selected from the plurality of filters based on the local gradient direction and activity, The selected filter is applied to the reconstruction block.
  • the frame memory 214 is a storage unit for storing a reference picture used for inter prediction, and is sometimes called a frame buffer. Specifically, the frame memory 214 stores the reconstructed block filtered by the loop filter unit 212.
  • the intra prediction unit 216 performs intra prediction with reference to the block in the current picture stored in the block memory 210 based on the intra prediction mode read from the encoded bitstream, so that a prediction signal (intra prediction Signal). Specifically, the intra prediction unit 216 generates an intra prediction signal by performing intra prediction with reference to a sample (for example, luminance value and color difference value) of a block adjacent to the current block, and performs prediction control on the intra prediction signal. Output to the unit 220.
  • a prediction signal for example, luminance value and color difference value
  • the intra prediction unit 216 may predict the color difference component of the current block based on the luminance component of the current block.
  • the intra prediction unit 216 corrects the pixel value after intra prediction based on the gradient of the reference pixel in the horizontal / vertical direction.
  • the inter prediction unit 218 refers to the reference picture stored in the frame memory 214 and predicts the current block. Prediction is performed in units of a current block or a sub-block (for example, 4 ⁇ 4 block) 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 (for example, a motion vector) read from the encoded bitstream, and generates the inter prediction signal. The result is output to the prediction control unit 220.
  • motion information for example, a motion vector
  • the inter prediction unit 218 When the information read from the encoded bitstream indicates that the OBMC mode is to be applied, the inter prediction unit 218 includes not only the motion information of the current block obtained by motion search but also the motion information of adjacent blocks. To generate an inter prediction signal.
  • the inter prediction unit 218 follows the pattern matching method (bilateral matching or template matching) read from the encoded stream. Motion information is derived by performing motion search. Then, the inter prediction unit 218 performs motion compensation using the derived motion information.
  • the inter prediction unit 218 derives a motion vector based on a model assuming constant velocity linear motion. Also, when the information read from the encoded bitstream indicates that the affine motion compensated prediction mode is applied, the inter prediction unit 218 determines the motion vector in units of subblocks based on the motion vectors of a plurality of adjacent blocks. Is derived.
  • the prediction control unit 220 selects either the intra prediction signal or the inter prediction signal, and outputs the selected signal to the adding unit 208 as a prediction signal.
  • FIG. 11 is a block diagram showing an internal configuration of conversion section 106 of encoding apparatus 100 according to Embodiment 1.
  • the conversion unit 106 includes an intra / inter determination unit 1061, a base selection unit 1062, and a frequency conversion unit 1063.
  • the intra / inter determination unit 1061 determines whether intra prediction or inter prediction is used for the current block. For example, the intra / inter determination unit 1061 determines whether to use intra prediction or inter prediction based on a comparison result between an input image signal and an image signal obtained by local decoding of a compressed image.
  • the base selection unit 1062 selects one base from a plurality of frequency conversion bases including DCT-II and DCT-V based on the determination result of the intra / inter determination unit 1061. Specifically, when intra prediction is used for the current block, the base selection unit 1062 selects a DCT-V base. On the other hand, when inter prediction is used for the current block, the base selection unit 1062 selects a DCT-II base.
  • the frequency conversion unit 1063 performs frequency conversion on the prediction error (residual) of the encoding target block using the base selected by the base selection unit 1062. That is, the frequency conversion unit 1063 performs frequency conversion on the prediction error of the encoding target block by selectively using a plurality of frequency conversion bases including DCT-II and DCT-V. Specifically, when intra prediction is used for an encoding target block, the frequency conversion unit 1063 performs frequency conversion using a DCT-V base. On the other hand, when inter prediction is used for an encoding target block, the frequency conversion unit 1063 performs frequency conversion using a DCT-II base.
  • the coefficient of the encoding target block output from the frequency conversion unit 1063 is quantized and dequantized by the quantization unit 108 and the inverse quantization unit 112.
  • the inverse transform unit 114 performs inverse frequency transform on the quantized and inverse quantized coefficients of the encoding target block.
  • the inverse transform unit 114 selects the basis of the inverse frequency transform based on the information of the selection result of the basis selection unit 1062. That is, the base of inverse transform of DCT-V is selected when intra prediction is used for the encoding target block, and the inverse transform of DCT-II is selected when inter prediction is used for the encoding target block. Bases are selected and an inverse frequency transform is performed using the selected bases.
  • FIG. 12 is a flowchart showing processing of the conversion unit 106 of the encoding device 100 according to Embodiment 1.
  • the intra / inter determination unit 1061 determines which of intra prediction and inter prediction is used for the current block (S101).
  • the base selection unit 1062 selects a DCT-V base (S102).
  • the base selection unit 1062 selects a DCT-II base (S103).
  • the frequency conversion unit 1063 performs frequency conversion on the prediction error of the encoding target block using the base selected in step S102 or step S103 (S104).
  • FIG. 13 is a block diagram showing an internal configuration of the inverse transform unit 206 of the decoding device 200 according to the first embodiment.
  • the inverse transform unit 206 includes an intra / inter determination unit 2061, a base selection unit 2062, and an inverse frequency transform unit 2063.
  • the intra / inter determination unit 2061 determines which of intra prediction and inter prediction is used for the decoding target block. For example, the intra / inter determination unit 2061 performs determination based on information obtained from the bitstream.
  • the basis selection unit 2062 selects one basis from a plurality of inverse frequency transform bases including DCT-II and DCT-V inverse transforms based on the determination result of the intra / inter determination unit 1061. Specifically, when intra prediction is used for a decoding target block, the base selection unit 2062 selects a base for inverse transform of DCT-V. On the other hand, when inter prediction is used for a decoding target block, the base selection unit 2062 selects a base for inverse transform of DCT-II.
  • the inverse frequency transform unit 2063 performs inverse frequency transform on the coefficient of the decoding target block using the basis selected by the basis selection unit 2062. That is, the inverse frequency transform unit 2063 performs inverse frequency transform on the coefficient of the decoding target block by selectively using a plurality of inverse frequency transform bases including DCT-II and DCT-V inverse transforms.
  • the inverse frequency transform unit 2063 performs inverse frequency transform using a DCT-V inverse transform base.
  • the inverse frequency transform unit 2063 performs inverse frequency transform using a DCT-II inverse transform base.
  • FIG. 14 is a flowchart showing processing of the inverse transform unit 206 of the decoding device 200 according to Embodiment 1.
  • the intra / inter determination unit 2061 determines which of intra prediction and inter prediction is used for a decoding target block (S201).
  • the base selection unit 2062 selects a base for inverse transformation of DCT-V (S202).
  • the base selection unit 2062 selects a base for inverse transform of DCT-II (S203).
  • the inverse frequency transform unit 2063 performs inverse frequency transform on the coefficient of the decoding target block using the basis selected in step S202 or step S203 (S204).
  • the base of DCT-V when intra prediction is used for the current block, the base of DCT-V Alternatively, the current block can be transformed or inverse transformed using a DCT-V inverse transformation basis.
  • DCT-V the amplitude decreases at a position close to the reference pixel in the DC component, and therefore DCT-V is suitable for conversion / inverse conversion of prediction error in intra prediction. Therefore, the encoding device 100 and the decoding device 200 can realize further improvement in compression efficiency.
  • FIG. 15A is a graph showing DCT-II conversion characteristics in a 32 ⁇ 32 size block.
  • FIG. 15B is a graph showing DCT-V conversion characteristics in a 32 ⁇ 32 size block.
  • FIG. 16A is a graph showing the conversion characteristics of DST-VII in a 4 ⁇ 4 size block.
  • FIG. 16B is a graph showing DCT-V conversion characteristics in a 4 ⁇ 4 size block. 15A to 16B, the horizontal axis represents the distance from the reference pixel, and the vertical axis represents the amplitude.
  • DCT-II is a type II discrete cosine transform.
  • the basis (basis function) shown in FIG. 3 is used.
  • the amplitude value is constant regardless of the distance. Therefore, DCT-II is effective for an inter prediction block in which the prediction error is relatively uniform within the block.
  • DCT-V is a type C discrete cosine transform.
  • the basis (basis function) shown in FIG. 3 is used.
  • DCT-V has a conversion characteristic close to that of DCT-II.
  • the DCT-V conversion characteristic has a small amplitude at a position close to the reference pixel in direct current, and is similar to the conversion characteristic of DST-VII.
  • the prediction error tends to be small at pixels close to the reference pixel (left and upper pixels).
  • a large block tends to be adopted when the prediction error is small, in a large block, the tendency that the prediction error is small at a pixel close to the reference pixel hardly appears.
  • DCT-V which has a transform characteristic similar to DCT-II in a large block and a transform characteristic similar to DST-VII in a small block
  • the intra-prediction block can be effectively frequency-converted / inverse-frequency-converted to a large size. Therefore, further improvement in compression efficiency can be realized by using the DCT-V base for intra prediction block conversion.
  • Modification 1 of Embodiment 1 differs from the first embodiment in that the base used for frequency conversion and inverse frequency conversion depends on the size of the current block.
  • the present modification will be specifically described with reference to FIGS. 17 to 20, focusing on differences from the first embodiment.
  • FIG. 17 is a block diagram showing an internal configuration of conversion section 106A of coding apparatus 100 according to Modification 1 of Embodiment 1.
  • the conversion unit 106A includes an intra / inter determination unit 1061, a base selection unit 1062A, a frequency conversion unit 1063, and a size determination unit 1064A.
  • the size determination unit 1064A determines whether or not the size of the encoding target block is equal to or smaller than a threshold size.
  • the base selection unit 1062A selects a DCT-V base if the size of the encoding target block is equal to or smaller than the threshold size when intra prediction is used for the encoding target block. On the other hand, even when intra prediction is used for the encoding target block, if the size of the encoding target block is larger than the threshold size, the base selection unit 1062A selects a DCT-II base. When inter prediction is used for the current block, the base selection unit 1062A selects a DCT-II base as in the first embodiment.
  • a fixed size for example, 16 ⁇ 16 pixels
  • the threshold size may be determined based on a signal included in the bit stream, or may be input from an external device or a user.
  • the threshold size may be determined based on an intra prediction mode, a quantization parameter, a prediction error, or the like.
  • FIG. 18 is a flowchart showing processing of conversion section 106A of coding apparatus 100 according to Modification 1 of Embodiment 1.
  • the intra / inter determination unit 1061 determines which of intra prediction and inter prediction is used for the current block (S101).
  • the size determination unit 1064A determines whether or not the size of the encoding target block is equal to or smaller than a threshold size (S111).
  • the base selection unit 1062A selects a DCT-V base (S102).
  • the base selection unit 1062A uses the base of DCT-II. Is selected (S103).
  • the frequency conversion unit 1063 performs frequency conversion on the prediction error of the encoding target block using the base selected in step S102 or step S103 (S104).
  • FIG. 19 is a block diagram showing an internal configuration of inverse transform section 206A of decoding apparatus 200 according to Modification 1 of Embodiment 1.
  • the inverse transform unit 206A includes an intra / inter determination unit 2061, a base selection unit 2062A, an inverse frequency transform unit 2063, and a size determination unit 2064A.
  • the size determination unit 2064A determines whether or not the size of the decoding target block is equal to or smaller than the threshold size.
  • the base selection unit 2062A selects a DCT-V base if the size of the decoding target block is equal to or smaller than the threshold size when intra prediction is used for the decoding target block. On the other hand, even when intra prediction is used for a decoding target block, if the size of the decoding target block is larger than the threshold size, the base selection unit 2062A selects a DCT-II base. When inter prediction is used for a decoding target block, the base selection unit 2062A selects a DCT-II base as in the first embodiment.
  • the threshold size the same threshold size as that used in the conversion unit 106A of the encoding apparatus 100 is used.
  • FIG. 20 is a flowchart showing processing of the inverse transform unit 206A of the decoding device 200 according to Modification 1 of Embodiment 1.
  • the intra / inter determination unit 2061 determines which of intra prediction and inter prediction is used for a decoding target block (S201).
  • the size determination unit 2064A determines whether or not the size of the decoding target block is equal to or smaller than a threshold size (S211).
  • the base selection unit 2062A selects a base for inverse transformation of DCT-V (S202).
  • the base selection unit 2062A When inter prediction is used for the decoding target block (Inter in S201), or when the size of the decoding target block is larger than the threshold size (No in S211), the base selection unit 2062A performs the inverse transform of DCT-II. A base is selected (S203). Finally, the inverse frequency transform unit 2063 performs inverse frequency transform on the coefficient of the decoding target block using the basis selected in step S202 or step S203 (S204).
  • DCT-II and DCT are used according to the size of the current block in which intra prediction is used.
  • the current block can be converted / inverted by switching the base of ⁇ V. If the block size is large, the prediction error tends to decrease as a whole in the block, and DCT-II is suitable for conversion of the prediction error of the block. On the other hand, if the block size is small, the prediction error tends to be smaller as the pixel is closer to the reference pixel, and DCT-V is suitable for conversion of the prediction error of the block.
  • the current block is converted / inverted by DCT-V. If the size of the encoding target block is larger than the threshold size, the current block is converted / inverted by DCT-II. By converting, further improvement in compression efficiency can be realized.
  • Modification 2 of Embodiment 1 a second modification of the first embodiment will be described. This modification differs from Modification 1 of Embodiment 1 above in that threshold size information is written in the bitstream.
  • the present modification will be specifically described with reference to FIGS. 21 to 25, focusing on differences from the first modification of the first embodiment.
  • FIG. 21 is a block diagram showing an internal configuration of conversion section 106B of coding apparatus 100 according to Modification 2 of Embodiment 1.
  • the conversion unit 106B includes an intra / inter determination unit 1061, a base selection unit 1062A, a frequency conversion unit 1063, a size determination unit 1064A, and a threshold size determination unit 1065B.
  • the threshold size determining unit 1065B adaptively determines the threshold size according to the input image signal or the like. The determined threshold size is used by the size determination unit 1064A.
  • the threshold size information is information indicating the threshold size, for example, a value indicating the threshold size itself or an index indicating the threshold size.
  • the threshold size information is written in at least one of a plurality of headers shown in (i) to (v) of FIG. 22, for example.
  • FIG. 22 is a diagram illustrating a plurality of examples of positions in the bitstream of threshold size or conversion mode information in the second or third modification of the first embodiment.
  • (I) of FIG. 22 shows that there is threshold size or conversion mode information in the video parameter set.
  • (Ii) of FIG. 22 shows that there is threshold size or conversion mode information in the sequence parameter set of the video stream.
  • (Iii) of FIG. 22 shows that there is threshold size or conversion mode information in the picture parameter set of a picture.
  • Iv) in FIG. 22 indicates that there is threshold size or conversion mode information in the slice header of the slice.
  • FIG. 22 shows that there is information on threshold size or conversion mode in a group of parameters for setting up or initializing a moving picture system or video decoder.
  • the threshold size or conversion mode information in a lower layer is the higher layer (eg, The threshold size or conversion mode information in the picture parameter set) is overwritten.
  • threshold size information may be written when it is changed. That is, when the same threshold size as that used immediately before is used, writing of threshold size information may be skipped.
  • FIG. 23 is a flowchart showing a process of converting section 106B of encoding apparatus 100 according to Modification 2 of Embodiment 1.
  • the intra / inter determination unit 1061 determines which of intra prediction and inter prediction is used for the current block (S101).
  • the threshold size determination unit 1065B adaptively determines the threshold size, and the information on the determined threshold size is an entropy encoding unit. 110 (S121). Thereafter, the processing after step S111 is executed.
  • FIG. 24 is a block diagram showing an internal configuration of inverse transform section 206B of decoding apparatus 200 according to Modification 2 of Embodiment 1.
  • the inverse conversion unit 206B includes an intra / inter determination unit 2061, a base selection unit 2062A, an inverse frequency conversion unit 2063, a size determination unit 2064A, and a threshold size acquisition unit 2065B.
  • the threshold size acquisition unit 2065B acquires a threshold size from the bitstream. For example, the threshold size acquisition unit 2065B acquires the threshold size based on the threshold size information read from the bitstream by the entropy decoding unit 202. The threshold size acquired here is used by the size determination unit 2064A.
  • FIG. 25 is a flowchart showing processing of the inverse transform unit 206B of the decoding device 200 according to the second modification of the first embodiment.
  • the intra / inter determination unit 2061 determines which of intra prediction and inter prediction is used for a decoding target block (S201).
  • the threshold size acquisition unit 2065B acquires a threshold size from the bitstream (S221). Thereafter, the processing after step S211 is executed.
  • Modification 3 of Embodiment 1 Next, a third modification of the first embodiment will be described.
  • the above-described implementation is that the first conversion mode using conversion and inverse conversion according to Modification 2 of Embodiment 1 can be switched between the second conversion mode using other conversion and inverse conversion. This is different from the second modification of the first embodiment.
  • the present modification will be specifically described with reference to FIGS. 26 to 29, focusing on differences from Modification 2 of the first embodiment.
  • FIG. 26 is a block diagram showing an internal configuration of conversion section 106C of coding apparatus 100 according to Modification 3 of Embodiment 1.
  • the conversion unit 106C includes an intra / inter determination unit 1061, a base selection unit 1062C, a frequency conversion unit 1063, a size determination unit 1064A, a threshold size determination unit 1065B, and a conversion mode determination unit 1066C.
  • the conversion mode determination unit 1066C determines which conversion mode among a plurality of conversion modes including the first conversion mode and the second conversion mode is to be applied to the encoding target block.
  • selectable bases may be different from each other, or selectable bases may be the same and selection methods may be different from each other.
  • the information on the conversion mode applied to the encoding target block is output to the entropy encoding unit 110 and written in the bitstream.
  • the conversion mode information is information for identifying the conversion mode, and is, for example, a flag or index indicating the conversion mode.
  • the conversion mode information is written, for example, in at least one of a plurality of headers shown in (i) to (v) of FIG. Note that the conversion mode information and the threshold size information need not be written in the same header, and may be written in different headers.
  • the base selection unit 1062C can select one base from a plurality of frequency conversion bases including DCT-II and DCT-V, as in the second modification of the first embodiment. Select.
  • the base selection unit 1062C selects one base from a plurality of frequency conversion bases different from the first conversion mode.
  • the frequency conversion unit 1063 performs frequency conversion on the prediction error of the encoding target block, using the base selected by the base selection unit 1062C. That is, the frequency conversion unit 1063 performs the first frequency conversion when the first conversion mode is applied, and performs the second frequency conversion when the second conversion mode is applied.
  • the first frequency conversion is the same as the frequency conversion according to the second modification of the first embodiment.
  • the second frequency conversion is different from the first frequency conversion.
  • a base different from the first frequency conversion is used in the second frequency conversion. Note that the base used in the first frequency transform and the base used in the second frequency transform do not have to be different under all conditions, and are the same under specific conditions (for example, when the block size is equal to or smaller than the threshold size). There may be.
  • FIG. 27 is a flowchart showing a process of conversion unit 106C of coding apparatus 100 according to Modification 3 of Embodiment 1.
  • the intra / inter determination unit 1061 determines which of intra prediction and inter prediction is used for the current block (S101).
  • the conversion mode determination unit 1066C determines a conversion mode to be applied to the encoding target block, and the entropy encoding unit 110. (S131).
  • the base selection unit 1062C selects a base for the second conversion mode (S133).
  • the frequency conversion unit 1063 performs frequency conversion of the encoding target block using the base selected in step S102, step S103, or step S133 (S104).
  • bases for the second conversion mode eight types of bases from type I to type VIII defined based on boundary conditions and symmetry in each of DCT and DST may be used.
  • a base for the encoding target block is selected from a total of 16 types of bases based on a prediction error or an evaluation value in consideration of a prediction error and a coding amount of information related to encoding of the prediction error. May be.
  • a base that minimizes the residual may be selected.
  • a base for the block to be encoded may be selected based on an intra prediction mode indicating the direction of intra prediction and the like.
  • a single base may be fixedly selected without selecting a base for an encoding target block from a plurality of frequency transform bases.
  • a base of DST-VII may be fixedly used in a size of 4 ⁇ 4, and a base may be adaptively selected in other sizes.
  • the base can be selected in a fixed manner, a signal indicating the selected base may not be written to the bit stream, and a signal indicating the selected base may be written to the bit stream only when the base is adaptively selected. .
  • the selectable bases may be different between the first conversion mode and the second conversion mode, or the selectable bases may be the same and the selection method may be different.
  • exclusion and duplication may be switched depending on the block size, and the same base can be selected with different block sizes, and different bases with the same block size. It is also possible to select such a configuration.
  • the base of DST-VII is fixedly selected, and when the block size exceeds 4 ⁇ 4, the base of DST-I or DST-VII is selected. Either may be selected adaptively.
  • the DCT-V base is fixedly selected when the block size is 16 ⁇ 16 or less, and the DCT-II base is fixedly selected when the block size exceeds 16 ⁇ 16. Good.
  • each base has one or more bases.
  • One base set may be selected from the plurality of base sets to be included, and one base may be selected from the selected base sets.
  • the plurality of base sets may include, for example, a first base set including a DST-I base and a DST-VII base, and a second base set including a DCT-VIII base and a DST-VII base. Note that the selection of the base set may be performed based on an intra prediction mode indicating the direction of intra prediction, for example.
  • the DCT-V base may be fixedly selected when the block size is 16 ⁇ 16 or smaller, and the DCT-II base may be fixedly selected when the block size exceeds 16 ⁇ 16. .
  • FIG. 28 is a block diagram showing an internal configuration of inverse transform section 206C of decoding apparatus 200 according to Modification 3 of Embodiment 1.
  • the inverse conversion unit 206C includes an intra / inter determination unit 2061, a base selection unit 2062C, an inverse frequency conversion unit 2063, a size determination unit 2064A, a threshold size acquisition unit 2065B, and a conversion mode determination unit 2066C.
  • the conversion mode determination unit 2066C determines which conversion mode among a plurality of conversion modes including the first conversion mode and the second conversion mode is to be applied to the decoding target block. For example, the conversion mode determination unit 2066C determines the conversion mode based on the conversion mode information read from the bitstream by the entropy decoding unit 202.
  • the base selection unit 2062C When the first conversion mode is applied, the base selection unit 2062C, among the plurality of inverse frequency conversion bases including the DCT-II and DCT-V inverse transforms, as in the second modification of the first embodiment. Select one basis from On the other hand, when the second conversion mode is applied, the base selection unit 2062C selects one base from a plurality of inverse frequency conversion bases different from the first conversion mode.
  • FIG. 29 is a flowchart showing processing of the inverse transform unit 206C of the decoding device 200 according to Modification 3 of Embodiment 1.
  • the intra / inter determination unit 2061 determines which of intra prediction and inter prediction is used for a decoding target block (S201).
  • the conversion mode determination unit 2066C determines which conversion mode of a plurality of conversion modes is applied to the decoding target block. (S232).
  • the first conversion mode is applied (the first conversion mode of S232)
  • the processes after step S221 are executed.
  • the base selection unit 2062C selects a base for the second conversion mode (S233).
  • the basis for the second transformation mode selected here is an inverse transformation basis corresponding to the basis for the second transformation mode selected by the encoding apparatus 100.
  • the inverse frequency transform unit 2063 performs inverse frequency transform of the decoding target block using the base selected in step S202, step S203, or step S233 (S204).
  • the conversion unit 106C of the encoding device 100 and the inverse conversion unit 206C of the decoding device 200 according to the present modification information on the conversion mode applied to the current block can be included in the bitstream. Therefore, the conversion mode can be determined adaptively according to the input image, and further improvement in compression efficiency can be realized.
  • the number of conversion modes is not limited to two.
  • the third conversion mode and / or the fourth conversion mode may be used.
  • a DST-VII base may be selected for a 4 ⁇ 4 size luminance block as in the prior art.
  • a DCT-V base is selected by frequency conversion for a block using intra prediction and other than a 4 ⁇ 4 size luminance block.
  • a DCT-II basis may be selected as in the prior art.
  • a DCT-V base is selected for the luminance block for which intra prediction is used.
  • the intra / inter determination unit 1061 performs intra prediction and inter prediction based on a comparison result between an input image signal and an image signal obtained by locally decoding a compressed image.
  • the determination may be made based on other signals.
  • DCT-II and DCT-V orthogonal transform bases are used.
  • similar transform characteristics are obtained.
  • a non-orthogonal transform basis may be used.
  • the base is selected based on the type of prediction (intra / inter) or the block size.
  • the present invention is not limited to this.
  • the intra prediction mode, the quantization parameter, or the residual of the encoding target block may be evaluated, and the base may be selected based on the evaluation result.
  • the base is selected regardless of the luminance and the color difference, but the present invention is not limited to this.
  • the DCT-II base may be fixedly used for the color difference block regardless of intra prediction / inter prediction.
  • DCT-II and DCT-V bases are used.
  • the present invention is not limited to this.
  • DST-VII bases may be used.
  • the DST-VII base when intra prediction is applied to the current block, (i) the DST-VII base is used when the current block size is equal to or smaller than the threshold size, and (ii) the current block size is larger than the threshold size.
  • the base of DCT-V may be used.
  • the conversion part or the inverse conversion part was provided with the base selection part, it is not necessary to provide a base selection part explicitly.
  • the function of the base selection unit may be integrated into the frequency conversion unit or the inverse frequency conversion unit.
  • each of the functional blocks can usually be realized by an MPU, a memory, and the like. Further, the processing by each functional block is usually realized by a program execution unit such as a processor reading and executing software (program) recorded on a recording medium such as a ROM. The software may be distributed by downloading or the like, or may be distributed by being recorded on a recording medium such as a semiconductor memory. Naturally, each functional block can be realized by hardware (dedicated circuit).
  • processing described in the embodiment and each modification may be realized by performing centralized processing using a single device (system), or realized by performing distributed processing using a plurality of devices. May be.
  • the number of processors that execute the program may be one or more. That is, centralized processing may be performed, or distributed processing may be performed.
  • the system includes an image encoding device using an image encoding method, an image decoding device using an image decoding method, and an image encoding / decoding device including both.
  • Other configurations in the system can be appropriately changed according to circumstances.
  • FIG. 30 is a diagram illustrating an overall configuration of a content supply system ex100 that implements a content distribution service.
  • the communication service providing area is divided into desired sizes, and base stations ex106, ex107, ex108, ex109, and ex110, which are fixed wireless stations, are installed in each cell.
  • devices such as a computer ex111, a game machine ex112, a camera ex113, a home appliance ex114, and a smartphone ex115 via the Internet ex101, the Internet service provider ex102 or the communication network ex104, and the base stations ex106 to ex110.
  • the content supply system ex100 may be connected by combining any of the above elements.
  • Each device may be directly or indirectly connected to each other via a telephone network or a short-range wireless communication without using the base stations ex106 to ex110 which are fixed wireless stations.
  • the streaming server ex103 is connected to each device such as a computer ex111, a game machine ex112, a camera ex113, a home appliance ex114, and a smartphone ex115 via the Internet ex101.
  • the streaming server ex103 is connected to a terminal in a hot spot in the airplane ex117 via the satellite ex116.
  • the streaming server ex103 may be directly connected to the communication network ex104 without going through the Internet ex101 or the Internet service provider ex102, or may be directly connected to the airplane ex117 without going through the satellite ex116.
  • the camera ex113 is a device that can shoot still images and moving images such as a digital camera.
  • the smartphone ex115 is a smartphone, a mobile phone, a PHS (Personal Handyphone System), or the like that corresponds to a mobile communication system generally called 2G, 3G, 3.9G, 4G, and 5G in the future.
  • PHS Personal Handyphone System
  • the home appliance ex118 is a device included in a refrigerator or a household fuel cell cogeneration system.
  • a terminal having a photographing function is connected to the streaming server ex103 through the base station ex106 or the like, thereby enabling live distribution or the like.
  • the terminal (computer ex111, game machine ex112, camera ex113, home appliance ex114, smartphone ex115, terminal in airplane ex117, etc.) is used for the still image or video content captured by the user using the terminal.
  • the encoding process described in the embodiment and each modification is performed, and the video data obtained by the encoding and the sound data obtained by encoding the sound corresponding to the video are multiplexed, and the obtained data is transmitted to the streaming server ex103.
  • each terminal functions as an image encoding device according to an aspect of the present invention.
  • the streaming server ex103 streams the content data transmitted to the requested client.
  • the client is a computer or the like in the computer ex111, the game machine ex112, the camera ex113, the home appliance ex114, the smart phone ex115, or the airplane ex117 that can decode the encoded data.
  • Each device that has received the distributed data decrypts and reproduces the received data. That is, each device functions as an image decoding device according to an aspect of the present invention.
  • the streaming server ex103 may be a plurality of servers or a plurality of computers, and may process, record, and distribute data in a distributed manner.
  • the streaming server ex103 may be realized by a CDN (Contents Delivery Network), and content distribution may be realized by a network connecting a large number of edge servers and edge servers distributed all over the world.
  • CDN Contents Delivery Network
  • edge servers that are physically close to each other are dynamically allocated according to clients. Then, the content can be cached and distributed to the edge server, thereby reducing the delay.
  • the processing is distributed among multiple edge servers, the distribution subject is switched to another edge server, or the part of the network where the failure has occurred Since detouring can be continued, high-speed and stable distribution can be realized.
  • the captured data may be encoded at each terminal, may be performed on the server side, or may be shared with each other.
  • a processing loop is performed twice.
  • the first loop the complexity of the image or the code amount in units of frames or scenes is detected.
  • the second loop processing for maintaining the image quality and improving the coding efficiency is performed.
  • the terminal performs the first encoding process
  • the server receiving the content performs the second encoding process, thereby improving the quality and efficiency of the content while reducing the processing load on each terminal. it can.
  • the encoded data of the first time performed by the terminal can be received and reproduced by another terminal, enabling more flexible real-time distribution.
  • the camera ex113 or the like extracts a feature amount from an image, compresses data relating to the feature amount as metadata, and transmits the metadata to the server.
  • the server performs compression according to the meaning of the image, for example, by determining the importance of the object from the feature amount and switching the quantization accuracy.
  • the feature data is particularly effective for improving the accuracy and efficiency of motion vector prediction at the time of re-compression on the server.
  • simple coding such as VLC (variable length coding) may be performed at the terminal, and coding with a large processing load such as CABAC (context adaptive binary arithmetic coding) may be performed at the server.
  • a plurality of video data in which almost the same scene is captured by a plurality of terminals.
  • a GOP Group of Picture
  • a picture unit or a tile obtained by dividing a picture using a plurality of terminals that have performed shooting and other terminals and servers that have not performed shooting as necessary.
  • Distributed processing is performed by assigning encoding processing in units or the like. Thereby, delay can be reduced and real-time property can be realized.
  • the server may manage and / or instruct the video data captured by each terminal to refer to each other.
  • the encoded data from each terminal may be received by the server and the reference relationship may be changed among a plurality of data, or the picture itself may be corrected or replaced to be encoded again. This makes it possible to generate a stream with improved quality and efficiency of each piece of data.
  • the server may distribute the video data after performing transcoding to change the encoding method of the video data.
  • the server may convert the MPEG encoding system to the VP encoding. H.264 in H.264. It may be converted into H.265.
  • the encoding process can be performed by a terminal or one or more servers. Therefore, in the following, description such as “server” or “terminal” is used as the subject performing processing, but part or all of processing performed by the server may be performed by the terminal, or processing performed by the terminal may be performed. Some or all may be performed at the server. The same applies to the decoding process.
  • the server not only encodes a two-dimensional moving image, but also encodes a still image automatically based on a scene analysis of the moving image or at a time specified by the user and transmits it to the receiving terminal. Also good.
  • the server can acquire the relative positional relationship between the photographing terminals, the server obtains the three-dimensional shape of the scene based on not only the two-dimensional moving image but also the video obtained by photographing the same scene from different angles. Can be generated.
  • the server may separately encode the three-dimensional data generated by the point cloud or the like, and the video to be transmitted to the receiving terminal based on the result of recognizing or tracking the person or the object using the three-dimensional data.
  • the images may be selected or reconstructed from videos captured by a plurality of terminals.
  • the user can arbitrarily select each video corresponding to each photographing terminal and enjoy a scene, or can display a video of an arbitrary viewpoint from three-dimensional data reconstructed using a plurality of images or videos. You can also enjoy the clipped content.
  • sound is collected from a plurality of different angles, and the server may multiplex and transmit sound from a specific angle or space according to the video.
  • the server may create viewpoint images for the right eye and the left eye, respectively, and perform encoding that allows reference between each viewpoint video by Multi-View Coding (MVC) or the like. You may encode as another stream, without referring. At the time of decoding another stream, it is preferable to reproduce in synchronization with each other so that a virtual three-dimensional space is reproduced according to the viewpoint of the user.
  • MVC Multi-View Coding
  • the server superimposes virtual object information in the virtual space on the camera information in the real space based on the three-dimensional position or the movement of the user's viewpoint.
  • the decoding device may acquire or hold virtual object information and three-dimensional data, generate a two-dimensional image according to the movement of the user's viewpoint, and create superimposition data by connecting them smoothly.
  • the decoding device transmits the movement of the user's viewpoint to the server in addition to the request for the virtual object information, and the server creates superimposition data according to the movement of the viewpoint received from the three-dimensional data held in the server,
  • the superimposed data may be encoded and distributed to the decoding device.
  • the superimposed data has an ⁇ value indicating transparency in addition to RGB
  • the server sets the ⁇ value of a portion other than the object created from the three-dimensional data to 0 or the like, and the portion is transparent. May be encoded.
  • the server may generate data in which a RGB value of a predetermined value is set as the background, such as a chroma key, and the portion other than the object is set to the background color.
  • the decryption processing of the distributed data may be performed at each terminal as a client, may be performed on the server side, or may be performed in a shared manner.
  • a terminal may once send a reception request to the server, receive content corresponding to the request at another terminal, perform a decoding process, and transmit a decoded signal to a device having a display.
  • a part of a region such as a tile in which a picture is divided may be decoded and displayed on a viewer's personal terminal while receiving large-size image data on a TV or the like. Accordingly, it is possible to confirm at hand the area in which the person is responsible or the area to be confirmed in more detail while sharing the whole image.
  • access to encoded data on the network such as when the encoded data is cached in a server that can be accessed from the receiving terminal in a short time, or copied to the edge server in the content delivery service. It is also possible to switch the bit rate of received data based on ease.
  • the server may have a plurality of streams of the same content and different quality as individual streams, but the temporal / spatial scalable implementation realized by dividing into layers as shown in the figure.
  • the configuration may be such that the content is switched by utilizing the characteristics of the stream.
  • the decoding side decides which layer to decode according to internal factors such as performance and external factors such as the state of communication bandwidth, so that the decoding side can combine low-resolution content and high-resolution content. You can switch freely and decrypt. For example, when the user wants to continue watching the video that was viewed on the smartphone ex115 while moving on a device such as an Internet TV after returning home, the device only has to decode the same stream to a different layer, so the load on the server side Can be reduced.
  • the enhancement layer includes meta information based on image statistical information, etc., in addition to the configuration in which the picture is encoded for each layer and the enhancement layer exists above the base layer.
  • the decoding side may generate content with high image quality by super-resolution of the base layer picture based on the meta information.
  • Super-resolution may be either improvement of the SN ratio at the same resolution or enlargement of the resolution.
  • the meta information includes information for specifying a linear or non-linear filter coefficient used for super-resolution processing, or information for specifying a parameter value in filter processing, machine learning, or least square calculation used for super-resolution processing. .
  • the picture may be divided into tiles or the like according to the meaning of the object in the image, and the decoding side may select only a part of the region by selecting the tile to be decoded.
  • the decoding side can determine the position of the desired object based on the meta information. Can be identified and the tile containing the object can be determined.
  • the meta information is stored using a data storage structure different from the pixel data such as the SEI message in HEVC. This meta information indicates, for example, the position, size, or color of the main object.
  • meta information may be stored in units composed of a plurality of pictures, such as streams, sequences, or random access units.
  • the decoding side can acquire the time when the specific person appears in the video, etc., and can match the picture in which the object exists and the position of the object in the picture by combining with the information in units of pictures.
  • FIG. 33 is a diagram showing an example of a web page display screen on the computer ex111 or the like.
  • FIG. 34 is a diagram illustrating a display screen example of a web page on the smartphone ex115 or the like.
  • the web page may include a plurality of link images that are links to the image content, and the appearance differs depending on the browsing device. When a plurality of link images are visible on the screen, the display device 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.
  • the (decoding device) displays a still image or an I picture included in each content as a link image, displays a video like a gif animation with a plurality of still images or I pictures, or receives only a base layer to receive a video. Are decoded and displayed.
  • the display device When the link image is selected by the user, 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 properties, the display device only decodes forward reference pictures (I picture, P picture, forward reference only B picture) before being selected or when the communication band is very strict. In addition, the delay between the decoding time of the first picture and the display time (delay from the start of content decoding to the start of display) can be reduced by displaying. Further, the display device may intentionally ignore the reference relationship of pictures and roughly decode all B pictures and P pictures with forward reference, and perform normal decoding as the number of received pictures increases over time.
  • forward reference pictures I picture, P picture, forward reference only B picture
  • the receiving terminal when transmitting and receiving still image or video data such as two-dimensional or three-dimensional map information for automatic driving or driving support of a car, the receiving terminal adds meta data to image data belonging to one or more layers. Weather or construction information may also be received and decoded in association with each other. The meta information may belong to a layer or may be simply multiplexed with image data.
  • the receiving terminal since the car, drone, airplane, or the like including the receiving terminal moves, the receiving terminal transmits the position information of the receiving terminal at the time of the reception request, thereby seamless reception and decoding while switching the base stations ex106 to ex110. Can be realized.
  • the receiving terminal can dynamically switch how much meta-information is received or how much map information is updated according to the user's selection, the user's situation, or the communication band state. become.
  • the encoded information transmitted by the user can be received, decoded and reproduced in real time by the client.
  • the content supply system ex100 can perform not only high-quality and long-time content by a video distributor but also unicast or multicast distribution of low-quality and short-time content by an individual. Moreover, such personal contents are expected to increase in the future.
  • the server may perform the encoding process after performing the editing process. This can be realized, for example, with the following configuration.
  • the server After shooting, the server performs recognition processing such as shooting error, scene search, semantic analysis, and object detection from the original image or encoded data. Then, the server manually or automatically corrects out-of-focus or camera shake based on the recognition result, or selects a less important scene such as a scene whose brightness is lower than that of other pictures or is out of focus. Edit such as deleting, emphasizing the edge of an object, and changing the hue.
  • the server encodes the edited data based on the editing result. It is also known that if the shooting time is too long, the audience rating will decrease, and the server will move not only in the less important scenes as described above, but also in motion according to the shooting time. A scene with few images may be automatically clipped based on the image processing result. Alternatively, the server may generate and encode a digest based on the result of the semantic analysis of the scene.
  • the server may change and encode the face of the person in the periphery of the screen or the inside of the house into an unfocused image.
  • the server recognizes whether or not a face of a person different from the person registered in advance is shown in the encoding target image, and if so, performs processing such as applying a mosaic to the face part. May be.
  • the user designates a person or background area that the user wants to process an image from the viewpoint of copyright, etc., and the server replaces the designated area with another video or blurs the focus. It is also possible to perform such processing. If it is a person, the face image can be replaced while tracking the person in the moving image.
  • the decoding device first receives the base layer with the highest priority and performs decoding and reproduction, depending on the bandwidth.
  • the decoding device may receive the enhancement layer during this time, and may play back high-quality video including the enhancement layer when played back twice or more, such as when playback is looped.
  • a stream that is scalable in this way can provide an experience in which the stream becomes smarter and the image is improved gradually, although it is a rough moving picture when it is not selected or at the beginning of viewing.
  • the same experience can be provided even if the coarse stream played back the first time and the second stream coded with reference to the first video are configured as one stream. .
  • these encoding or decoding processes are generally processed in the LSI ex500 included in each terminal.
  • the LSI ex500 may be configured as a single chip or a plurality of chips.
  • moving image encoding or decoding software is incorporated into some recording medium (CD-ROM, flexible disk, hard disk, etc.) that can be read by the computer ex111 and the like, and encoding or decoding processing is performed using the software. Also good.
  • moving image data acquired by the camera may be transmitted. The moving image data at this time is data encoded by the LSI ex500 included in the smartphone ex115.
  • the LSI ex500 may be configured to download and activate application software.
  • the terminal first determines whether the terminal is compatible with the content encoding method or has a specific service execution capability. If the terminal does not support the content encoding method or does not have the capability to execute a specific service, the terminal downloads a codec or application software, and then acquires and reproduces the content.
  • the digital broadcast system is not limited to at least the moving image encoding device (image encoding device) or the moving image decoding device (image decoding device) of the above embodiment and each modification.
  • One of the decoding devices) can be incorporated.
  • the unicasting of the content supply system ex100 is suitable for multicasting because it uses a satellite or the like to transmit and receive multiplexed data in which video and sound are multiplexed on broadcasting radio waves.
  • the same application is possible for the encoding process and the decoding process.
  • FIG. 35 is a diagram illustrating the smartphone ex115.
  • FIG. 36 is a diagram illustrating a configuration example of the smartphone ex115.
  • the smartphone ex115 receives the antenna ex450 for transmitting / receiving radio waves to / from the base station ex110, the camera unit ex465 capable of taking video and still images, the video captured by the camera unit ex465, and the antenna ex450.
  • a display unit ex458 for displaying data obtained by decoding the video or the like.
  • the smartphone ex115 further includes an operation unit ex466 that is a touch panel or the like, a voice output unit ex457 that is a speaker or the like for outputting voice or sound, a voice input unit ex456 that is a microphone or the like for inputting voice, and photographing.
  • Memory unit ex467 that can store encoded video or still image, recorded audio, received video or still image, encoded data such as mail, or decoded data, and a user, and network
  • An external memory may be used instead of the memory unit ex467.
  • a main control unit ex460 that comprehensively controls the display unit ex458, the operation unit ex466, and the like, a power supply circuit unit ex461, an operation input control unit ex462, a video signal processing unit ex455, a camera interface unit ex463, a display control unit ex459, a modulation / Demodulation unit ex452, multiplexing / demultiplexing unit ex453, audio signal processing unit ex454, slot unit ex464, and memory unit ex467 are connected via bus ex470.
  • the power supply circuit unit ex461 starts up the smartphone ex115 in an operable state by supplying power from the battery pack to each unit.
  • the smartphone ex115 performs processing such as calling and data communication based on the control of the main control unit ex460 having a CPU, a ROM, a RAM, and the like.
  • the voice signal picked up by the voice input unit ex456 is converted into a digital voice signal by the voice signal processing unit ex454, spread spectrum processed by the modulation / demodulation unit ex452, and digital / analog converted by the transmission / reception unit ex451.
  • the data is transmitted via the antenna ex450.
  • the received data is amplified and subjected to frequency conversion processing and analog-digital conversion processing, spectrum despreading processing is performed by the modulation / demodulation unit ex452, and converted to analog audio signal by the audio signal processing unit ex454, and then this is output to the audio output unit ex457.
  • text, still image, or video data is sent to the main control unit ex460 via the operation input control unit ex462 by the operation of the operation unit ex466 of the main body unit, and transmission / reception processing is performed similarly.
  • the video signal processing unit ex455 uses the video signal stored in the memory unit ex467 or the video signal input from the camera unit ex465 as described in the above embodiment.
  • the video data is compressed and encoded by the moving image encoding method shown in each modification, and the encoded video data is sent to the multiplexing / demultiplexing unit ex453.
  • the audio signal processing unit ex454 encodes the audio signal picked up by the audio input unit ex456 while the camera unit ex465 captures a video or a still image, and sends the encoded audio data to the multiplexing / separating unit ex453. To do.
  • the multiplexing / demultiplexing unit ex453 multiplexes the encoded video data and the encoded audio data by a predetermined method, and the modulation / demodulation unit (modulation / demodulation circuit unit) ex452 and the modulation / demodulation unit ex451 perform modulation processing and conversion.
  • the data is processed and transmitted via the antenna ex450.
  • the multiplexing / demultiplexing unit ex453 performs multiplexing By separating the data, the multiplexed data is divided into a bit stream of video data and a bit stream of audio data, and the encoded video data is supplied to the video signal processing unit ex455 via the synchronization bus ex470. The converted audio data is supplied 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 the above embodiment and each modification, and from the display unit ex458 via the display control unit ex459, A video or still image included in the linked moving image file is displayed.
  • the audio signal processing unit ex454 decodes the audio signal, and the audio is output from the audio output unit ex457. Since real-time streaming is widespread, depending on the user's situation, there may be occasions where audio playback is not socially appropriate. Therefore, it is desirable that the initial value is a configuration in which only the video data is reproduced without reproducing the audio signal. Audio may be synchronized and played back only when the user performs an operation such as clicking on video data.
  • the smartphone ex115 has been described here as an example, in addition to a transmission / reception terminal having both an encoder and a decoder as a terminal, a transmission terminal having only an encoder and a reception having only a decoder There are three possible mounting formats: terminals.
  • terminals In the digital broadcasting system, it has been described as receiving or transmitting multiplexed data in which audio data or the like is multiplexed with video data.
  • multiplexed data includes character data related to video in addition to audio data. Multiplexing may be performed, and video data itself may be received or transmitted instead of multiplexed data.
  • the terminal often includes a GPU. Therefore, a configuration may be adopted in which a wide area is processed in a lump by utilizing the performance of the GPU by using a memory shared by the CPU and the GPU or a memory whose addresses are managed so as to be used in common. As a result, the encoding time can be shortened, real-time performance can be ensured, and low delay can be realized. In particular, it is efficient to perform motion search, deblocking filter, SAO (Sample Adaptive Offset), and transformation / quantization processing in batches in units of pictures or the like instead of the CPU.
  • SAO Sample Adaptive Offset
  • the present disclosure can be used for, for example, a television receiver, a digital video recorder, a car navigation, a mobile phone, a digital camera, or a digital video camera.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • Discrete Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Compression Or Coding Systems Of Tv Signals (AREA)

Abstract

Selon l'invention, un dispositif de codage (100) destiné à coder des blocs devant être codés dans une image comprend : une unité de détermination intra/inter (1061) qui détermine si une intraprédiction ou une interprédiction doit être utilisée pour un bloc devant être codé ; et une unité de transformation de fréquence (1063) qui utilise sélectivement une pluralité de bases de transformation de fréquence, DCT-II et DCT-V notamment, pour exécuter une première transformation de fréquence sur l'erreur de prédiction du bloc à coder. Dans la première transformation de fréquence, la base de DCT-V est utilisée en cas d'intraprédiction pour le bloc devant être codé et la base de DCT-II est utilisée en cas d'interprédiction pour le bloc devant être codé.
PCT/JP2017/026959 2016-07-29 2017-07-26 Dispositif de codage, dispositif de décodage, procédé de codage, et procédé de décodage Ceased WO2018021373A1 (fr)

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US11575933B2 (en) 2018-04-06 2023-02-07 Vid Scale, Inc. Bi-directional optical flow method with simplified gradient derivation
RU2830998C2 (ru) * 2018-04-06 2024-11-28 Вид Скейл, Инк. Метод двунаправленного оптического потока с упрощенным выведением градиента
CN114630115A (zh) * 2018-05-22 2022-06-14 松下电器（美国）知识产权公司 编码装置及解码装置
CN112513938A (zh) * 2018-08-06 2021-03-16 松下电器（美国）知识产权公司 三维数据保存方法、三维数据获得方法、三维数据保存装置以及三维数据获得装置
CN112673627A (zh) * 2018-08-09 2021-04-16 Lg电子株式会社 在图像编码系统中使用仿射合并候选列表的基于仿射运动预测的图像解码方法和装置
CN112673627B (zh) * 2018-08-09 2023-08-04 Lg电子株式会社 在图像编码系统中使用仿射合并候选列表的基于仿射运动预测的图像解码方法和装置
CN113196776A (zh) * 2018-12-20 2021-07-30 夏普株式会社 预测图像生成装置、运动图像解码装置、运动图像编码装置以及预测图像生成方法
CN113196776B (zh) * 2018-12-20 2023-12-19 夏普株式会社 预测图像生成装置、运动图像解码装置、运动图像编码装置以及预测图像生成方法

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