WO2022210101A1 - 復号方法、符号化方法、復号装置及び符号化装置 - Google Patents
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Definitions
- the present disclosure relates to decoding methods, encoding methods, decoding devices, and encoding devices.
- the video coding technology is H. 261 and MPEG-1 to H.261 and MPEG-1.
- 264/AVC Advanced Video Coding
- MPEG-LA High Efficiency Video Coding
- H.264. 265/HEVC High Efficiency Video Coding
- H.265/HEVC. 266/VVC Very Video Codec
- Non-Patent Document 1 relates to an example of conventional standards related to the above-described video coding technology.
- H. 265 (ISO/IEC 23008-2 HEVC)/HEVC (High Efficiency Video Coding)
- the present disclosure may contribute to one or more of, for example, improved coding efficiency, improved image quality, reduced processing amount, reduced circuit size, improved processing speed, and appropriate selection of elements or operations.
- the present disclosure may include configurations or methods that may contribute to benefits other than those described above.
- a decoding method is (i) a sub-picture among a plurality of independently decodable sub-pictures forming a picture, and (ii) the top and left ends of the sub-picture.
- Each embodiment in the present disclosure, or a configuration or method of a part thereof is, for example, improving coding efficiency, improving image quality, reducing the amount of coding/decoding processing, reducing circuit size, or reducing code at least one of improving the processing speed of encoding/decoding.
- each of the embodiments in the present disclosure, or the configurations or methods of portions thereof each uses appropriate components/operations such as filters, blocks, sizes, motion vectors, reference pictures, reference blocks, etc. in encoding and decoding. allows you to make choices, etc.
- the present disclosure also includes disclosure of configurations or methods that may provide benefits other than those described above. For example, it is a configuration or method that improves coding efficiency while suppressing an increase in the amount of processing.
- the configuration or method according to one aspect of the present disclosure is, for example, improving coding efficiency, improving image quality, reducing processing amount, reducing circuit scale, improving processing speed, and appropriate selection of elements or operations. can contribute to one or more of them. Note that the configuration or method according to one aspect of the present disclosure may contribute to benefits other than those described above.
- FIG. 1 is a schematic diagram showing an example of the configuration of a transmission system according to an embodiment.
- FIG. 2 is a diagram showing an example of the hierarchical structure of data in a stream.
- FIG. 3 is a diagram showing an example of a slice configuration.
- FIG. 4 is a diagram showing an example of a tile configuration.
- FIG. 5 is a diagram showing an example of a coding structure for scalable coding.
- FIG. 6 is a diagram showing an example of a coding structure for scalable coding.
- FIG. 7 is a block diagram showing an example of the configuration of the encoding device according to the embodiment.
- FIG. 8 is a block diagram showing an implementation example of the encoding device.
- FIG. 9 is a flowchart showing an example of overall encoding processing by the encoding device.
- FIG. 10 is a diagram showing an example of block division.
- FIG. 11 is a diagram illustrating an example of a configuration of a dividing unit;
- FIG. 12 is a diagram showing examples of division patterns.
- FIG. 13A is a diagram showing an example of a syntax tree of division patterns.
- FIG. 13B is a diagram showing another example of a syntax tree of division patterns.
- FIG. 14 is a table showing transformation basis functions corresponding to each transformation type.
- FIG. 15 is a diagram showing an example of SVT.
- FIG. 16 is a flowchart illustrating an example of processing by a conversion unit;
- FIG. 17 is a flowchart illustrating another example of processing by the conversion unit;
- FIG. 18 is a block diagram showing an example of the configuration of a quantization section;
- FIG. 16 is a flowchart illustrating an example of processing by a conversion unit
- FIG. 17 is a flowchart illustrating another example of processing by the conversion unit
- FIG. 18 is a block diagram
- FIG. 19 is a flowchart illustrating an example of quantization by a quantization unit
- FIG. 20 is a block diagram showing an example of the configuration of an entropy coding unit.
- FIG. 21 is a diagram showing the flow of CABAC in the entropy coding unit.
- FIG. 22 is a block diagram showing an example of the configuration of the loop filter section.
- FIG. 23A is a diagram showing an example of the shape of a filter used in an ALF (adaptive loop filter).
- FIG. 23B is a diagram showing another example of the shape of a filter used in ALF.
- FIG. 23C is a diagram showing another example of the shape of a filter used in ALF.
- FIG. 23A is a diagram showing an example of the shape of a filter used in an ALF (adaptive loop filter).
- FIG. 23B is a diagram showing another example of the shape of a filter used in ALF.
- FIG. 23C is a diagram showing another example of the shape of a filter used in
- FIG. 23D shows an example where a Y sample (first component) is used for Cb CCALF and Cr CCALF (multiple components different from the first component).
- FIG. 23E shows a diamond-shaped filter.
- FIG. 23F is a diagram showing an example of JC-CCALF.
- FIG. 23G is a diagram showing an example of JC-CCALF weight_index candidates.
- FIG. 24 is a block diagram showing an example of a detailed configuration of a loop filter section that functions as a DBF.
- FIG. 25 is a diagram showing an example of a deblocking filter with symmetrical filter characteristics with respect to block boundaries.
- FIG. 26 is a diagram for explaining an example of block boundaries on which deblocking and filtering are performed.
- FIG. 27 is a diagram showing an example of Bs values.
- FIG. 28 is a flowchart illustrating an example of processing performed by a prediction unit of the encoding device
- FIG. 29 is a flowchart illustrating another example of processing performed by the prediction unit of the encoding device.
- FIG. 30 is a flow chart showing another example of processing performed by the prediction unit of the encoding device.
- FIG. 31 is a diagram showing an example of 67 intra prediction modes in intra prediction.
- 32 is a flowchart illustrating an example of processing by an intra prediction unit;
- FIG. 33 is a diagram showing an example of each reference picture.
- FIG. 34 is a conceptual diagram showing an example of a reference picture list.
- FIG. 35 is a flow chart showing a basic processing flow of inter prediction.
- FIG. 36 is a flowchart showing an example of MV derivation.
- FIG. 37 is a flow chart showing another example of MV derivation.
- FIG. 38A is a diagram showing an example of classification of each mode of MV derivation.
- FIG. 38B is a diagram showing an example of classification of each mode of MV derivation.
- FIG. 39 is a flowchart showing an example of inter prediction in normal inter mode.
- FIG. 40 is a flowchart illustrating an example of inter prediction in normal merge mode.
- FIG. 41 is a diagram for explaining an example of MV derivation processing in normal merge mode.
- FIG. 42 is a diagram for explaining an example of MV derivation processing in HMVP (History-based Motion Vector Prediction/Predictor) mode.
- FIG. 43 is a flowchart showing an example of FRUC (frame rate up conversion).
- FIG. 38A is a diagram showing an example of classification of each mode of MV derivation.
- FIG. 38B is a diagram showing an example of classification of each mode of MV derivation.
- FIG. 44 is a diagram for explaining an example of pattern matching (bilateral matching) between two blocks along the motion trajectory.
- FIG. 45 is a diagram for explaining an example of pattern matching (template matching) between a template in the current picture and blocks in the reference picture.
- FIG. 46A is a diagram for explaining an example of derivation of MV for each subblock in affine mode using two control points.
- FIG. 46B is a diagram for explaining an example of derivation of MV for each subblock in affine mode using three control points.
- FIG. 47A is a conceptual diagram for explaining an example of MV derivation of control points in an affine mode.
- FIG. 47B is a conceptual diagram for explaining an example of MV derivation of control points in affine mode.
- FIG. 47A is a conceptual diagram for explaining an example of MV derivation of control points in an affine mode.
- FIG. 47B is a conceptual diagram for explaining an example of MV derivation of control points in affine
- FIG. 47C is a conceptual diagram for explaining an example of MV derivation of control points in affine mode.
- FIG. 48A is a diagram for explaining an affine mode with two control points.
- FIG. 48B is a diagram for explaining an affine mode with three control points.
- FIG. 49A is a conceptual diagram for explaining an example of a control point MV derivation method when an encoded block and a current block have different numbers of control points.
- FIG. 49B is a conceptual diagram for explaining another example of the control point MV derivation method when the encoded block and the current block have different numbers of control points.
- FIG. 50 is a flowchart showing an example of processing in the affine merge mode.
- FIG. 51 is a flowchart showing an example of processing in affine inter mode.
- FIG. 52A is a diagram for explaining generation of predicted images of two triangles.
- FIG. 52B is a conceptual diagram showing an example of the first portion of the first partition and the first and second sample sets.
- FIG. 52C is a conceptual diagram showing the first part of the first partition.
- FIG. 53 is a flow chart showing an example of the triangle mode.
- FIG. 54 is a diagram showing an example of ATMVP (Advanced Temporal Motion Vector Prediction/Predictor) mode in which MV is derived for each subblock.
- FIG. 55 is a diagram showing the relationship between merge modes and DMVR (dynamic motion vector refreshing).
- FIG. 56 is a conceptual diagram for explaining an example of DMVR.
- FIG. 57 is a conceptual diagram for explaining another example of DMVR for determining MV.
- FIG. 58A is a diagram showing an example of motion estimation in DMVR.
- FIG. 58B is a flowchart illustrating an example of motion estimation in DMVR.
- FIG. 59 is a flow chart showing an example of generating a predicted image.
- FIG. 60 is a flowchart showing another example of predicted image generation.
- FIG. 61 is a flowchart for explaining an example of predictive image correction processing by OBMC (overlapped block motion compensation).
- FIG. 62 is a conceptual diagram for explaining an example of predictive image correction processing by OBMC.
- FIG. 63 is a diagram for explaining a model that assumes uniform linear motion.
- FIG. 64 is a flowchart illustrating an example of inter prediction according to BIO.
- FIG. 65 is a diagram illustrating an example of the configuration of an inter prediction unit that performs inter prediction according to BIO.
- FIG. 66A is a diagram for explaining an example of a predicted image generation method using luminance correction processing by LIC (local illumination compensation).
- FIG. 66B is a flowchart showing an example of a predicted image generation method using luminance correction processing by LIC.
- 67 is a block diagram showing the configuration of the decoding device according to the embodiment.
- FIG. FIG. 68 is a block diagram showing an implementation example of a decoding device.
- FIG. 69 is a flowchart showing an example of overall decoding processing by the decoding device.
- FIG. 70 is a diagram showing the relationship between the division determining unit and other components.
- FIG. 71 is a block diagram showing an example of the configuration of an entropy decoding unit.
- FIG. 72 is a diagram showing the flow of CABAC in the entropy decoding unit.
- FIG. 75 is a flowchart illustrating an example of processing by an inverse transform unit;
- FIG. FIG. 76 is a flow chart showing another example of processing by the inverse transform unit.
- FIG. 77 is a block diagram showing an example of the configuration of the loop filter section.
- FIG. 78 is a flow chart showing an example of processing performed by a prediction unit of the decoding device.
- FIG. 73 is a diagram showing the flow of CABAC in the entropy decoding unit.
- FIG. 73 is a block diagram showing an example of the configuration of an inverse quantization section;
- FIG. 80A is a flowchart showing part of another example of processing performed by the prediction unit of the decoding device.
- FIG. 80B is a flowchart showing the remainder of another example of processing performed by the prediction unit of the decoding device.
- 81 is a diagram illustrating an example of processing by an intra prediction unit of a decoding device;
- FIG. 82 is a flowchart showing an example of MV derivation in the decoding device.
- FIG. 83 is a flowchart showing another example of MV derivation in the decoding device.
- FIG. 84 is a flowchart showing an example of inter prediction in normal inter mode in the decoding device.
- FIG. 85 is a flowchart showing an example of inter prediction in normal merge mode in a decoding device.
- FIG. 86 is a flowchart showing an example of inter prediction in FRUC mode in a decoding device.
- 87 is a flowchart illustrating an example of inter prediction in affine merge mode in a decoding device;
- FIG. 88 is a flowchart showing an example of inter prediction in affine inter mode in a decoding device.
- FIG. 89 is a flowchart illustrating an example of inter prediction in triangle mode in a decoding device.
- FIG. 90 is a flow chart showing an example of motion search by DMVR in a decoding device.
- FIG. 91 is a flowchart showing a detailed example of motion search by DMVR in the decoding device.
- FIG. 92 is a flowchart showing an example of prediction image generation in the decoding device.
- FIG. 93 is a flowchart showing another example of predicted image generation in the decoding device.
- FIG. 94 is a flowchart showing an example of prediction image correction by OBMC in the decoding device.
- FIG. 95 is a flowchart showing an example of predicted image correction by BIO in the decoding device.
- FIG. 96 is a flowchart showing an example of prediction image correction by LIC in the decoding device.
- FIG. 97 is a schematic diagram showing the values of the sub-picture index and sub-picture identifier when extracting sub-pictures from one bitstream to another bitstream.
- FIG. 98 is a schematic diagram showing an exemplary implementation in which a mosaic of sub-pictures guides the user to select a sub-picture.
- FIG. 99 is a schematic diagram showing a mosaic picture of four sub-pictures with at least one dimension whose size is not an integer multiple of a coding tree unit.
- FIG. 100 is a schematic diagram showing a mosaic picture with lines padded to achieve that the upper subpicture has a vertical size that is an integer multiple of a coding tree unit.
- FIG. 101 is a table illustrating some parameter settings of cropping window and sub-pictures specific for the mosaic picture implementation.
- FIG. 102 is a flowchart illustrating an exemplary method for generating a bitstream containing mosaic pictures.
- FIG. 103 is a flowchart illustrating an exemplary method for decoding a bitstream containing mosaic pictures.
- FIG. 104 is a flowchart illustrating an exemplary implementation of a method for generating a bitstream containing mosaic pictures.
- FIG. 105 is a flowchart illustrating an exemplary implementation of a method for decoding at least one sub-picture from a mosaic picture.
- 106 is a flowchart illustrating operations performed by the encoding apparatus according to the embodiment;
- FIG. 107 is a flowchart showing operations performed by the decoding device according to the embodiment.
- FIG. FIG. 108 is an overall configuration diagram of a content supply system that realizes a content distribution service.
- FIG. 109 is a diagram showing an example of a web page display screen.
- FIG. 110 is a diagram showing an example of a web page display screen.
- FIG. 111 is a diagram illustrating an example of a smart phone;
- FIG. 112 is a block diagram illustrating a
- each sub-picture within a picture is defined as a rectangular region.
- Each coding unit in the picture belongs to only one of the sub-pictures in the picture.
- multiple sub-pictures within a picture may each correspond to multiple videos. Specifically, first, a picture including a plurality of sub-pictures corresponding to a plurality of videos is decoded and displayed, and then only one video selected from the plurality of videos is decoded and displayed as a picture.
- each coding unit in a picture belongs to only one of the multiple sub-pictures in the picture, so the size of each sub-picture corresponds to the size of one or more coding units.
- the size of each video does not necessarily correspond to the size of one or more coding units. Therefore, the size of the subpictures may not correspond to the size of the video.
- a sub-picture among a plurality of independently decodable sub-pictures forming a picture (ii) the top of the sub-picture and (iii) one of the plurality of sub-pictures is opposite the at least one edge of the sub-picture; at least one sub-picture is contiguous, and (iv) the size of the sub-picture in at least one direction by padding at the at least one edge of the picture reaches an integer multiple of a preset coding unit size; decoding from a bitstream cropping information indicating a cropping amount corresponding to a padding amount of a first subpicture, which is a subpicture padded at the at least one edge of the subpicture; and converting the first subpicture to the bitstream.
- At least one of the number of upper sample rows and the number of left sample columns removed from the first sub-picture is indicated as the cropping amount.
- subpicture boundaries in the center of the screen and coding unit boundaries can match. Also, after decoding a sub-picture padded to reach an integer multiple of a preset coding unit size, it may be possible to crop the sub-picture according to a cropping amount corresponding to the padding amount. Therefore, after decoding a sub-picture, it may be possible to match the size of the sub-picture to the size of the video corresponding to the sub-picture.
- the picture corresponds to 4K resolution
- each of the plurality of sub-pictures corresponds to HD (High Definition) resolution.
- This may make it possible to decode one of a plurality of sub-pictures included in a picture corresponding to 4K resolution and corresponding to HD resolution.
- it may be possible to decode a video with HD resolution from a bitstream in which multiple videos with HD resolution are encoded as videos with 4K resolution.
- the picture corresponds to 8K resolution
- each of the plurality of sub-pictures corresponds to 4K resolution
- This may make it possible to decode one of a plurality of sub-pictures included in a picture corresponding to 8K resolution and corresponding to 4K resolution.
- it may be possible to decode a video with 4K resolution from a bitstream in which multiple videos with 4K resolution are encoded as videos with 8K resolution.
- the cropping information includes at least one of sps_conformance_window_flag, sps_conf_win_top_offset, and sps_conf_win_left_offset, each of which is a syntax element relating to a VVC (Versatile Video Coding) conformance cropping window.
- VVC Very Video Coding
- the decoding method further comprises obtaining input from a user for selecting the first sub-picture of the plurality of sub-pictures; decoding the first sub-picture without decoding one or more sub-pictures other than the first sub-picture.
- the bitstream includes settings for the plurality of sub-pictures in parameter sets applicable to the pictures
- the decoding method further comprising: decoding the settings from the bitstream; Deriving sub-picture identification information for the first sub-picture according to the configuration and the input; decoding from the bitstream the first sub-picture identified by the sub-picture identification information.
- sub-picture identification information such as sub-picture indices or sub-picture identifiers
- sub-picture identification information such as sub-picture indices or sub-picture identifiers
- the bitstream conforms to VVC (Versatile Video Coding)
- the parameter set is SPS (Sequence Parameter Set) or PPS (Picture Parameter Set)
- the settings are whether the plurality of sub-pictures have the same size; one or more sizes applied to the plurality of sub-pictures with respect to one or more directions; and applying to the picture with respect to the one or more directions.
- the total number of the plurality of sub-pictures is given by the VVC syntax element sps_num_subpics_minus1, and whether or not the plurality of sub-pictures have the same size.
- VVC syntax element sps_subpic_same_size_flag is given by the VVC syntax element sps_subpic_same_size_flag
- the one or more sizes applied to the plurality of subpictures are at least one of the VVC syntax elements sps_subpic_width_minus1 and sps_subpic_height_minus1, respectively.
- the one or more sizes applied to the picture are given by at least one of sps_pic_width_max_in_luma_samples and sps_pic_height_max_in_luma_samples, which are syntax elements of VVC, respectively.
- the first sub-picture and the second sub-picture corresponding to the at least one sub-picture are arranged spatially continuously, and For one direction, the total size of the first sub-picture and the second sub-picture corresponds to the size of the picture, and for the one direction, the first sub-picture is cropped and the second sub-picture is cropped. is not cropped.
- the first sub-picture and the second sub-picture corresponding to the at least one sub-picture are arranged spatially continuously, and For one direction, the total size of said first sub-picture and said second sub-picture corresponds to the size of said picture, and for said one direction, both said first sub-picture and said second sub-picture. is cropped.
- the cropping information includes at least one of sps_conf_win_bottom_offset and sps_conf_win_right_offset, which are syntax elements relating to conformance cropping windows of VVC, as information indicating the amount of cropping of the second sub-picture.
- the picture includes a plurality of slices that spatially equally correspond to the plurality of sub-pictures on a one-to-one basis, and a plurality of tiles that spatially correspond to the plurality of sub-pictures on an equal and one-to-one basis. including at least one of
- the encoding method is (i) a sub-picture among a plurality of sub-pictures forming a picture, and (ii) at least one of the top end and the left end of the sub-picture. (iii) at least one sub-picture of said plurality of sub-pictures is opposite said at least one edge of said sub-picture; A first sub-picture that is an adjacent sub-picture is padded at the at least one edge of the picture such that the size of the first sub-picture in at least one direction reaches an integer multiple of a preset coding unit size.
- At the at least one edge of the first sub-picture encoding cropping information indicating a cropping amount corresponding to the padding amount of the first sub-picture into a bitstream; independently encoding the plurality of sub-pictures, including one sub-picture, into the bitstream, wherein the cropping information is added to the first sub-picture by padding the first sub-picture. At least one of the number of upper sample rows and the number of left sample columns is indicated as the cropping amount corresponding to the padding amount.
- This may allow sub-picture padding so that the size of the sub-picture corresponds to an integer multiple of the preset coding unit size. Then, it may be possible to encode cropping information for cropping sub-pictures according to the amount of padding. Therefore, it may be possible to encode information to match the size of the sub-pictures to the size of the video corresponding to the sub-pictures.
- the picture corresponds to 4K resolution
- each of the plurality of sub-pictures corresponds to HD (High Definition) resolution.
- the picture corresponds to 8K resolution
- each of the plurality of sub-pictures corresponds to 4K resolution
- the cropping information includes at least one of sps_conformance_window_flag, sps_conf_win_top_offset, and sps_conf_win_left_offset, each of which is a syntax element relating to a VVC (Versatile Video Coding) conformance cropping window.
- VVC Very Video Coding
- the encoding method further comprises encoding settings of the plurality of sub-pictures into the bitstream, wherein the bitstream comprises the settings within a parameter set applicable to the picture. .
- the bitstream conforms to VVC (Versatile Video Coding)
- the parameter set is SPS (Sequence Parameter Set) or PPS (Picture Parameter Set)
- the settings are whether the plurality of sub-pictures have the same size; one or more sizes applied to the plurality of sub-pictures with respect to one or more directions; and applying to the picture with respect to the one or more directions.
- the total number of the plurality of sub-pictures is given by the VVC syntax element sps_num_subpics_minus1, and whether or not the plurality of sub-pictures have the same size.
- VVC syntax element sps_subpic_same_size_flag is given by the VVC syntax element sps_subpic_same_size_flag
- the one or more sizes applied to the plurality of subpictures are at least one of the VVC syntax elements sps_subpic_width_minus1 and sps_subpic_height_minus1, respectively.
- the one or more sizes applied to the picture are given by at least one of sps_pic_width_max_in_luma_samples and sps_pic_height_max_in_luma_samples, which are syntax elements of VVC, respectively.
- the first sub-picture and the second sub-picture corresponding to the at least one sub-picture are arranged spatially continuously, and For one direction, the total size of the first sub-picture and the second sub-picture corresponds to the size of the picture, and for the one direction, the first sub-picture is padded and the second sub-picture is padded. Pictures are not padded.
- the first sub-picture and the second sub-picture corresponding to the at least one sub-picture are arranged spatially continuously, and For one direction, the total size of said first sub-picture and said second sub-picture corresponds to the size of said picture, and for said one direction, both said first sub-picture and said second sub-picture. is padded.
- This may make it possible to pad both the first sub-picture and the second sub-picture that are spatially consecutively arranged. Therefore, it may be possible to apply similar processing to both the first sub-picture and the second sub-picture. Therefore, it may be possible to reduce the complexity of processing.
- the cropping information includes at least one of sps_conf_win_bottom_offset and sps_conf_win_right_offset, which are syntax elements relating to conformance cropping windows of VVC, as information indicating the amount of cropping of the second sub-picture.
- This may allow encoding the cropping information for cropping the second sub-picture according to the syntax element for the cropping window.
- the picture includes a plurality of slices that spatially equally correspond to the plurality of sub-pictures on a one-to-one basis, and a plurality of tiles that spatially correspond to the plurality of sub-pictures on an equal and one-to-one basis. including at least one of
- a decoding device includes a circuit and a memory connected to the circuit, and in operation, the circuit is configured to (i) independently decode pictures constituting pictures a sub-picture of a plurality of sub-pictures, (ii) at least one of a top edge and a left edge of the sub-picture being included in at least one of a top edge and a left edge of the picture; (iii) (iv) adjacent to at least one sub-picture of said plurality of sub-pictures opposite said at least one edge of said sub-picture; a cropping amount corresponding to a padding amount of a first sub-picture, which is a sub-picture padded at the at least one end of the sub-picture so that the size of the sub-picture reaches an integer multiple of a preset coding unit size; decoding the indicated cropping information from the bitstream; decoding the first sub-picture from the bitstream; cropping the first sub-picture at the at least
- the decoding apparatus can crop the sub-picture according to the cropping amount corresponding to the padding amount after decoding the sub-picture padded so that the size reaches an integral multiple of the preset coding unit size. There is Therefore, after decoding the sub-picture, the decoding device may be able to match the size of the sub-picture to the size of the video corresponding to the sub-picture.
- an encoding apparatus includes a circuit and a memory connected to the circuit, and the circuit, in operation, performs (i) among a plurality of subpictures forming a picture: (ii) at least one of the top and left edges of the sub-picture is included in at least one of the top and left edges of the picture; (iii) the at least one of the top and left edges of the sub-picture a first sub-picture, which is a sub-picture adjacent to at least one sub-picture of said plurality of sub-pictures on opposite sides of one edge, in said at least one direction by padding at said at least one edge of said picture; padding at the at least one edge of the first sub-picture so that the size of the first sub-picture reaches an integer multiple of a preset coding unit size, and a cropping amount corresponding to the padding amount of the first sub-picture; and encoding the plurality of sub-pictures including the padded first sub-picture into
- the encoding device may be able to pad sub-pictures so that the sub-picture size corresponds to an integral multiple of the preset coding unit size.
- the encoding device may then encode cropping information for cropping the sub-picture according to the padding amount.
- the encoder may be able to encode information to match the size of the sub-pictures to the size of the video corresponding to the sub-pictures.
- a decoding device includes an input unit, an entropy decoding unit, an inverse quantization unit, an inverse transform unit, an intra prediction unit, an inter prediction unit, a loop filter unit, and an output unit.
- An encoded bitstream is input to the input unit.
- the entropy decoding unit applies variable length decoding to the encoded bitstream to derive quantization coefficients.
- the inverse quantization unit inversely quantizes the quantized coefficients to derive transform coefficients.
- the inverse transform unit inverse transforms the transform coefficients to derive a prediction error.
- the intra prediction unit uses a reference image included in the current picture to generate a prediction signal for the current block included in the current picture.
- the inter prediction unit generates a prediction signal of a current block included in the current picture using a reference picture included in a reference picture different from the current picture.
- the loop filter unit applies a filter to the reconstructed block of the current block included in the current picture. Then, the current picture is output from the output unit.
- the entropy decoding unit (i) is a sub-picture among a plurality of independently decodable sub-pictures forming a picture, and (iii) at least one of said plurality of sub-pictures on the opposite side of said at least one edge of said sub-picture; (iv) said sub-pictures are adjacent to each other, and (iv) said sub-pictures are such that padding at said at least one edge of said pictures causes said sub-pictures to reach an integer multiple of a preset coding unit size in at least one direction; decoding from the bitstream cropping information indicating a cropping amount corresponding to a padding amount of a first subpicture that is a subpicture padded at the at least one end of the bitstream, decoding the first subpicture from the bitstream; cropping the first sub-picture at the at least one edge of the first sub-picture according to the cropping amount, wherein the cropping information is top samples removed from the first sub-picture by
- an encoding device includes an input unit, a division unit, an intra prediction unit, an inter prediction unit, a loop filter unit, a transform unit, a quantization unit, and an entropy code and an output unit.
- a current picture is input to the input unit.
- the dividing unit divides the current picture into a plurality of blocks.
- the intra prediction unit uses a reference image included in the current picture to generate a prediction signal for the current block included in the current picture.
- the inter prediction unit generates a prediction signal of a current block included in the current picture using a reference picture included in a reference picture different from the current picture.
- the loop filter unit applies a filter to reconstructed blocks of a current block included in the current picture.
- the transform unit transforms the prediction error between the original signal of the current block included in the current picture and the prediction signal generated by the intra prediction unit or the inter prediction unit to generate transform coefficients.
- the quantization unit quantizes the transform coefficients to generate quantized coefficients.
- the entropy encoder applies variable length coding to the quantized coefficients to generate an encoded bitstream. Then, the output unit outputs the coded bitstream including the quantized coefficients to which variable length coding is applied and control information.
- the entropy encoding unit in operation, is (i) a sub-picture among a plurality of sub-pictures forming a picture, and (ii) at least one end of the top end and the left end of the sub-picture. is included at at least one of the top and left edges of said picture, and (iii) at least one sub-picture of said plurality of sub-pictures is adjacent to said sub-picture opposite said at least one edge of said sub-picture.
- said first sub-picture being a sub-picture such that padding at said at least one edge of said picture results in a size of said first sub-picture in at least one direction reaching an integer multiple of a preset coding unit size; padding at the at least one edge of a first sub-picture and encoding cropping information indicating a cropping amount corresponding to the padding amount of the first sub-picture into a bitstream; are independently encoded into the bitstream, and the cropping information is the number of upper sample rows and left sample columns added to the first sub-picture by padding the first sub-picture. is shown as the cropping amount corresponding to the padding amount.
- Exemplary embodiments relate to using conformance cropping windows to enable the creation of mosaic video from multiple VVC sub-pictures having sizes that do not correspond to multiples of the CTU size used for encoding.
- Image A data unit composed of a set of pixels, which consists of a picture or blocks smaller than a picture, and includes still pictures as well as moving pictures.
- Block A processing unit of a set containing a specific number of pixels is not limited, and includes, for example, a rectangle made up of M ⁇ N pixels, a square made up of M ⁇ M pixels, as well as a triangle, a circle, and other shapes.
- Pixel/sample A minimum unit point that constitutes an image, including not only pixels at integer positions but also pixels at decimal positions generated based on pixels at integer positions.
- Pixel value/Sample value A value unique to a pixel, including not only luminance values, color difference values, and RGB gradations, but also depth values or binary values of 0 and 1.
- Flag In addition to 1-bit flags, multi-bit flags are also included. For example, parameters and indexes of 2 or more bits may be used. Moreover, not only binary numbers using binary numbers, but also multi-value numbers using other base numbers may be used.
- Signal Symbolized and coded for the purpose of transmitting information, including discrete digital signals as well as analog signals that take continuous values.
- a stream/bitstream refers to a data string of digital data or a flow of digital data.
- a stream/bitstream may be composed of a single stream or a plurality of streams divided into a plurality of layers.
- the case of transmitting by packet communication over a plurality of transmission lines is also included.
- Chroma An adjective, denoted by the symbols Cb and Cr, that designates that a sample array or single sample represents one of two color difference signals related to the primary colors. Instead of the term chroma, the term chrominance can also be used.
- Luminance A symbol or adjective subscripted Y or L designating that a sample array or single sample represents a monochrome signal associated with a primary color. Instead of the term luma, the term luminance can also be used.
- Embodiments of an encoding device and a decoding device will be described below.
- An embodiment is an example of an encoding device and a decoding device to which processing and/or configurations described in each aspect of the present disclosure can be applied.
- Processes and/or configurations can also be implemented in encoding and decoding devices different from the embodiments. For example, any of the following may be implemented with respect to the processing and/or configuration applied to the embodiments.
- Some of the components that constitute the encoding device or the decoding device of the embodiments may be combined with the components described in any of the aspects of the present disclosure. , may be combined with a component that includes part of the functions described in any of the aspects of the present disclosure, or a component that performs part of the processing performed by the components described in each aspect of the present disclosure may be combined with
- a component that includes part of the functions of the encoding device or decoding device of the embodiment, or a component that implements part of the processing of the encoding device or decoding device of the embodiment A component described in any of the aspects of the present disclosure, a component including a part of the function described in any of the aspects of the present disclosure, or a part of the processing described in any of the aspects of the present disclosure Implementing components may be combined or substituted.
- any of the plurality of processes included in the method is the process described in any of the aspects of the present disclosure, or similar Either treatment may be substituted or combined.
- the method of implementing the processing and/or configuration described in each aspect of the present disclosure is not limited to the encoding device or decoding device of the embodiment.
- the processing and/or configuration may be implemented in a device that is used for purposes other than the video encoding or video decoding disclosed in the embodiments.
- FIG. 1 is a schematic diagram showing an example of the configuration of a transmission system according to this embodiment.
- the transmission system Trs is a system that transmits streams generated by encoding images and decodes the transmitted streams.
- Such a transmission system Trs includes an encoding device 100, a network Nw, and a decoding device 200, as shown in FIG. 1, for example.
- An image is input to the encoding device 100 .
- the encoding device 100 encodes the input image to generate a stream, and outputs the stream to the network Nw.
- the stream includes, for example, encoded images and control information for decoding the encoded images. This encoding compresses the image.
- the original image before being encoded which is input to the encoding device 100, is also called an original image, an original signal, or an original sample.
- the image may be a moving image or a still image.
- images are generic concepts such as sequences, pictures, and blocks, and are not subject to spatial and temporal domain restrictions unless otherwise specified.
- An image also consists of an array of pixels or pixel values, and the signals representing the image, or pixel values, are also called samples.
- a stream may also be called a bitstream, an encoded bitstream, a compressed bitstream, or an encoded signal.
- the encoding device may be called an image encoding device or a video encoding device
- the encoding method by the encoding device 100 may be an encoding method, an image encoding method, or a video encoding method.
- the network Nw transmits the stream generated by the encoding device 100 to the decoding device 200.
- the network Nw may be the Internet, a wide area network (WAN), a small network (LAN: local area network), or a combination thereof.
- the network Nw is not necessarily a two-way communication network, and may be a one-way communication network that transmits broadcast waves such as terrestrial digital broadcasting or satellite broadcasting.
- the network Nw may be replaced by a storage medium recording a stream, such as a DVD (Digital Versatile Disc) or a BD (Blu-Ray Disc (registered trademark)).
- the decoding device 200 generates a decoded image that is, for example, an uncompressed image by decoding the stream transmitted by the network Nw. For example, the decoding device decodes the stream according to the decoding method corresponding to the encoding method by the encoding device 100 .
- the decoding device may be called an image decoding device or a video decoding device, and the decoding method by the decoding device 200 may be called a decoding method, an image decoding method, or a video decoding method.
- FIG. 2 is a diagram showing an example of the hierarchical structure of data in a stream.
- a stream includes, for example, a video sequence.
- this video sequence includes a VPS (Video Parameter Set), an SPS (Sequence Parameter Set), a PPS (Picture Parameter Set), an SEI (Supplemental Enhancement Information), and a plurality of including pictures of
- VPS Video Parameter Set
- SPS Sequence Parameter Set
- PPS Position Parameter Set
- SEI Supplemental Enhancement Information
- a VPS includes coding parameters common to a plurality of layers in a video composed of multiple layers, and coding parameters related to multiple layers included in the video or individual layers.
- the SPS contains the parameters used for the sequence, that is, the coding parameters that the decoding device 200 refers to in order to decode the sequence.
- the coding parameter may indicate the width or height of the picture.
- a plurality of SPSs may exist.
- the PPS contains parameters used for pictures, that is, coding parameters that the decoding device 200 refers to in order to decode each picture in the sequence.
- the coding parameters may include a reference value for the quantization width used to decode the picture and a flag indicating application of weighted prediction.
- a plurality of PPSs may exist. Also, SPS and PPS are sometimes simply referred to as parameter sets.
- a picture may include a picture header and one or more slices, as shown in FIG. 2(b).
- a picture header contains coding parameters that decoding apparatus 200 refers to to decode one or more slices of the picture header.
- a slice includes a slice header and one or more bricks, as shown in (c) of FIG.
- a slice header contains coding parameters that decoding device 200 refers to in order to decode the one or more bricks.
- a brick includes one or more CTUs (Coding Tree Units), as shown in (d) of FIG.
- a picture may contain tile groups instead of slices without slices.
- a tile group contains one or more tiles.
- Bricks may also contain slices.
- a CTU is also called a superblock or basic division unit.
- Such a CTU includes a CTU header and one or more CUs (Coding Units), as shown in FIG. 2(e).
- the CTU header includes encoding parameters that decoding device 200 refers to in order to decode one or more CUs.
- a CU may be split into multiple smaller CUs.
- a CU includes a CU header, prediction information, and residual coefficient information, as shown in (f) of FIG.
- the prediction information is information for predicting the CU
- the residual coefficient information is information indicating a prediction residual, which will be described later.
- a CU is basically the same as a PU (Prediction Unit) and a TU (Transform Unit), but for example, in an SBT described later, a plurality of TUs smaller than the CU may be included.
- a CU may be processed for each VPDU (Virtual Pipeline Decoding Unit) that constitutes the CU.
- a VPDU is, for example, a fixed unit that can be processed in one stage when pipeline processing is performed in hardware.
- a picture that is currently being processed by a device such as the encoding device 100 or the decoding device 200 is called a current picture. If the process is encoding, the current picture is synonymous with the picture to be encoded, and if the process is decoding, the current picture is synonymous with the picture to be decoded.
- a block such as a CU or a CU that is currently being processed by a device such as the encoding device 100 or the decoding device 200 is called a current block. If the process is encoding, the current block is synonymous with the encoding target block, and if the process is decoding, the current block is synonymous with the decoding target block.
- pictures may be organized in units of slices or tiles.
- a slice is a basic unit of coding that makes up a picture.
- a picture consists of one or more slices, for example. Also, a slice consists of one or more consecutive CTUs.
- FIG. 3 is a diagram showing an example of a slice configuration.
- a picture contains 11 ⁇ 8 CTUs and is divided into 4 slices (slices 1-4).
- Slice 1 consists of, for example, 16 CTUs
- slice 2 consists of, for example, 21 CTUs
- slice 3 consists of, for example, 29 CTUs
- slice 4 consists of, for example, 22 CTUs.
- each CTU in a picture belongs to any slice.
- the shape of a slice is the shape of a picture divided horizontally.
- the slice boundary does not have to be the edge of the screen, and can be anywhere on the boundary of the CTU within the screen.
- the processing order (encoding order or decoding order) of CTUs in a slice is, for example, raster scan order.
- a slice also includes a slice header and encoded data.
- the slice header may describe the characteristics of the slice, such as the CTU address at the beginning of the slice and the slice type.
- a tile is a unit of rectangular area that makes up a picture.
- a number called TileId may be assigned to each tile in raster scan order.
- FIG. 4 is a diagram showing an example of a tile configuration.
- a picture contains 11 ⁇ 8 CTUs and is divided into four rectangular tiles (tiles 1-4).
- the processing order of CTUs is changed compared to when tiles are not used. If tiles are not used, multiple CTUs in a picture are processed, for example, in raster-scan order. If tiles are used, in each of the plurality of tiles, at least one CTU is processed, eg, in raster scan order.
- the processing order of the plurality of CTUs included in tile 1 is from the left end of the first column of tile 1 to the right end of the first column of tile 1, then the left end of the second column of tile 1. to the right end of the second column of tile 1.
- one tile may include one or more slices, and one slice may include one or more tiles.
- a picture may be configured in units of tilesets.
- a tileset may include one or more tile groups and may include one or more tiles.
- a picture may consist of only one of a tile set, a tile group, and a tile. For example, the order in which the tiles of each tileset are scanned in raster order is the base encoding order of the tiles.
- a tile group is defined as a collection of one or more tiles whose basic encoding order is continuous in each tile set.
- Such pictures may be constructed by the division unit 102 (see FIG. 7), which will be described later.
- [Scalable encoding] 5 and 6 are diagrams showing an example of the structure of a scalable stream.
- the encoding device 100 may generate a temporally/spatially scalable stream by encoding each of a plurality of pictures in one of a plurality of layers, as shown in FIG.
- the encoding apparatus 100 implements scalability in which an enhancement layer exists above a base layer by encoding a picture for each layer.
- Such encoding of each picture is called scalable encoding.
- the decoding device 200 can switch the image quality of the displayed image by decoding the stream. That is, decoding apparatus 200 determines up to which layer to decode according to an internal factor such as its own performance and an external factor such as the state of the communication band.
- the decoding device 200 can freely switch between low-resolution content and high-resolution content to decode the same content.
- a user of the stream uses a smartphone to watch the moving image of the stream partway while moving, and after returning home, uses a device such as an Internet TV to watch the rest of the moving image.
- a device such as an Internet TV to watch the rest of the moving image.
- each of the smartphone and the device described above incorporates a decoding device 200 having the same or different performance. In this case, if the device decodes up to the upper layers of the stream, the user can view high-quality moving images after returning home. As a result, the encoding apparatus 100 does not need to generate multiple streams with the same content but different image qualities, and can reduce the processing load.
- the enhancement layer may contain meta information based on image statistical information.
- the decoding device 200 may generate a moving image with high image quality by super-resolving the base layer picture based on the meta information.
- Super-resolution may be either improvement in SN (Signal-to-Noise) ratio at the same resolution or expansion of resolution.
- Meta information includes information for specifying linear or nonlinear filter coefficients used for super-resolution processing, information for specifying parameter values in filter processing used for super-resolution processing, machine learning, or least squares calculation. You can stay.
- the picture may be divided into tiles or the like according to the meaning of each object in the picture.
- the decoding device 200 may decode only a partial area of the picture by selecting a tile to be decoded.
- Object attributes person, car, ball, etc.
- positions in pictures coordinate positions in the same picture, etc.
- the decoding device 200 can identify the position of the desired object based on the meta information and determine the tile containing the object. For example, as shown in FIG. 6, meta information is stored using a data storage structure different from image data, such as SEI in HEVC. This meta information indicates, for example, the position, size or color of the main object.
- Meta information may also be stored in units composed of multiple pictures, such as streams, sequences, or random access units.
- the decoding device 200 can acquire the time at which the specific person appears in the moving image, and the like, and by using the time and the information in units of pictures, the picture in which the object exists and the object in the picture can be obtained. position can be specified.
- FIG. 7 is a block diagram showing an example of the configuration of encoding apparatus 100 according to the embodiment.
- the encoding device 100 encodes an image in units of blocks.
- the encoding device 100 is a device 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 an entropy encoding unit.
- a unit 110, an inverse quantization unit 112, an inverse transform unit 114, an addition unit 116, a block memory 118, a loop filter unit 120, a frame memory 122, an intra prediction unit 124, an inter prediction unit 126, A prediction control unit 128 and a prediction parameter generation unit 130 are provided. Note that each of the intra prediction unit 124 and the inter prediction unit 126 is configured as part of the prediction processing unit.
- FIG. 8 is a block diagram showing an implementation example of the encoding device 100.
- the encoding device 100 comprises a processor a1 and a memory a2.
- the components of encoding device 100 shown in FIG. 7 are implemented by processor a1 and memory a2 shown in FIG.
- the processor a1 is a circuit that performs information processing and is a circuit that can access the memory a2.
- processor a1 is a dedicated or general purpose electronic circuit for encoding images.
- Processor a1 may be a processor such as a CPU.
- the processor a1 may be an assembly of a plurality of electronic circuits.
- the processor a1 may serve as a plurality of components of the encoding device 100 shown in FIG. 7, excluding a component for storing information.
- the memory a2 is a dedicated or general-purpose memory that stores information for encoding an image by the processor a1.
- the memory a2 may be an electronic circuit and may be connected to the processor a1. Also, the memory a2 may be included in the processor a1. Also, the memory a2 may be an aggregate of a plurality of electronic circuits. Also, the memory a2 may be a magnetic disk, an optical disk, or the like, or may be expressed as a storage, recording medium, or the like. Also, the memory a2 may be a non-volatile memory or a volatile memory.
- the memory a2 may store an image to be encoded, or may store a stream corresponding to the encoded image. Further, the memory a2 may store a program for encoding an image by the processor a1.
- the memory a2 may serve as a component for storing information among the plurality of components of the encoding device 100 shown in FIG. Specifically, memory a2 may serve as block memory 118 and frame memory 122 shown in FIG. More specifically, the memory a2 may store reconstructed images (specifically, reconstructed blocks, reconstructed pictures, etc.).
- the encoding device 100 may not implement all of the plurality of components shown in FIG. 7, and may not perform all of the plurality of processes described above. Some of the components shown in FIG. 7 may be included in other devices, and some of the processes described above may be performed by other devices.
- FIG. 9 is a flowchart showing an example of overall encoding processing by the encoding device 100.
- FIG. 9 is a flowchart showing an example of overall encoding processing by the encoding device 100.
- the dividing unit 102 of the encoding device 100 divides a picture included in the original image into a plurality of fixed-size blocks (128 ⁇ 128 pixels) (step Sa_1). Then, the division unit 102 selects a division pattern for the fixed-size block (step Sa_2). In other words, the dividing unit 102 further divides the fixed-size block into a plurality of blocks forming the selected division pattern. Encoding apparatus 100 then performs the processing of steps Sa_3 to Sa_9 for each of the plurality of blocks.
- a prediction processing unit consisting of the intra prediction unit 124 and the inter prediction unit 126, and the prediction control unit 128 generate a prediction image of the current block (step Sa_3).
- a predicted image is also called a predicted signal, a predicted block, or a predicted sample.
- the subtraction unit 104 generates the difference between the current block and the predicted image as a prediction residual (step Sa_4).
- a prediction residual is also called a prediction error.
- the transformation unit 106 and the quantization unit 108 generate a plurality of quantized coefficients by transforming and quantizing the predicted image (step Sa_5).
- the entropy coding unit 110 generates a stream by performing coding (specifically, entropy coding) on the plurality of quantized coefficients and prediction parameters related to generation of predicted images ( Step Sa_6).
- the inverse quantization unit 112 and the inverse transform unit 114 restore the prediction residual by performing inverse quantization and inverse transform on the plurality of quantized coefficients (step Sa_7).
- the adding unit 116 reconstructs the current block by adding the predicted image to the restored prediction residual (step Sa_8).
- a reconstructed image is thereby generated.
- a reconstructed image is also called a reconstructed block, and in particular, a reconstructed image generated by the encoding device 100 is also called a local decoded block or a local decoded image.
- the loop filter unit 120 performs filtering on the reconstructed image as necessary (step Sa_9).
- step Sa_10 determines whether or not the encoding of the entire picture has been completed (step Sa_10), and if it is determined that the encoding has not been completed (No in step Sa_10), the processing from step Sa_2 is repeatedly executed. do.
- encoding apparatus 100 selects one division pattern for a fixed-size block and encodes each block according to the division pattern. Encoding of each block may be performed. In this case, the encoding device 100 evaluates the cost for each of the plurality of division patterns, and selects, for example, the stream obtained by encoding according to the division pattern with the lowest cost as the stream to be finally output. You may
- steps Sa_1 to Sa_10 may be sequentially performed by the encoding device 100, some of the processing may be performed in parallel, and the order may be changed.
- Such encoding processing by the encoding device 100 is hybrid encoding using predictive encoding and transform encoding.
- Predictive coding includes a subtracting unit 104, a transforming unit 106, a quantizing unit 108, an inverse quantizing unit 112, an inverse transforming unit 114, an adding unit 116, a loop filter unit 120, a block memory 118, a frame memory 122, and intra prediction.
- This is done by an encoding loop consisting of unit 124 , inter prediction unit 126 and prediction control unit 128 . That is, the prediction processing unit including the intra prediction unit 124 and the inter prediction unit 126 constitutes a part of the encoding loop.
- the dividing unit 102 divides each picture included in the original 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 fixed size (for example, 128 ⁇ 128 pixels). This fixed size block is sometimes called a coding tree unit (CTU).
- Divider 102 then divides each of the fixed-size blocks into blocks of variable size (e.g., 64x64 pixels or less), e.g., based on recursive quadtree and/or binary tree block partitioning. To divide. That is, division section 102 selects a division pattern.
- This variable-sized block is sometimes called a coding unit (CU), a prediction unit (PU), or a transform unit (TU). Note that in various implementation examples, CUs, PUs, and TUs need not be distinguished, and some or all blocks in a picture may serve as processing units for CUs, PUs, or TUs.
- FIG. 10 is a diagram showing an example of block division in the embodiment.
- solid lines represent block boundaries due to quadtree block division
- dashed lines represent block boundaries according to binary tree block division.
- block 10 is a square block of 128x128 pixels. This block 10 is first divided into four square blocks of 64 ⁇ 64 pixels (quadtree block division).
- the top left square block of 64x64 pixels is further divided vertically into two rectangular blocks of 32x64 pixels each, and the left rectangular block of 32x64 pixels is further vertically divided into two rectangular blocks of 16x64 pixels each. (binary tree block division).
- the upper left square block of 64 ⁇ 64 pixels is divided into two rectangular blocks 11 and 12 of 16 ⁇ 64 pixels and a rectangular block 13 of 32 ⁇ 64 pixels.
- the upper right square block of 64x64 pixels is horizontally divided into two rectangular blocks 14 and 15 of 64x32 pixels each (binary tree block division).
- the lower left square block of 64x64 pixels is divided into four square blocks of 32x32 pixels each (quadtree block division).
- the upper left and lower right blocks of the four square blocks of 32 ⁇ 32 pixels each are further divided.
- the upper left square block of 32x32 pixels is split vertically into two rectangular blocks of 16x32 pixels each, and the right 16x32 pixel square block is further split horizontally into two square blocks of 16x16 pixels each. (binary tree block division).
- the lower right square block of 32x32 pixels is horizontally split into two rectangular blocks of 32x16 pixels each (binary tree block split).
- the lower left square block of 64x64 pixels consists of a rectangular block 16 of 16x32 pixels, two square blocks 17 and 18 of 16x16 pixels each, two square blocks 19 and 20 of 32x32 pixels each, and two square blocks of 32x32 pixels each. It is divided into two rectangular blocks 21 and 22 .
- the lower right block 23 consisting of 64x64 pixels is not divided.
- block 10 is divided into 13 variable-sized blocks 11-23 based on recursive quadtree and binary tree block division.
- Such partitioning is sometimes called QTBT (quad-tree plus binary tree) partitioning.
- one block is divided into four or two blocks in FIG. 10 (quadtree or binary tree block division), the division is not limited to these.
- one block may be divided into three blocks (ternary tree block division).
- a partition including such a ternary tree block partition is sometimes called an MBT (multi-type tree) partition.
- FIG. 11 is a diagram showing an example of the configuration of the division unit 102.
- the dividing section 102 may include a block division determining section 102a.
- the block division determination unit 102a may perform the following processing.
- the block division determination unit 102a collects block information from the block memory 118 or the frame memory 122, and determines the above division pattern based on the block information.
- the division unit 102 divides the original image according to the division pattern, and outputs one or more blocks obtained by the division to the subtraction unit 104 .
- the block division determination unit 102a outputs parameters indicating the above-described division pattern to the transformation unit 106, the inverse transformation unit 114, the intra prediction unit 124, the inter prediction unit 126, and the entropy coding unit 110, for example.
- the transformation unit 106 may transform the prediction residual based on the parameters, and the intra prediction unit 124 and the inter prediction unit 126 may generate predicted images based on the parameters.
- entropy coding section 110 may perform entropy coding on the parameter.
- the parameters related to the division pattern may be written to the stream as follows.
- FIG. 12 is a diagram showing examples of division patterns.
- the division patterns include, for example, a quadrant (QT) that divides a block into two in the horizontal and vertical directions, and a three-division (QT) that divides a block in the same direction at a ratio of 1:2:1.
- QT quadrant
- QT three-division
- HT or VT bipartition
- HB or VB bipartition
- NS no division
- the division pattern does not have the block division direction, and in the case of 2-division and 3-division, the division pattern has division direction information.
- FIG. 13A and 13B are diagrams showing examples of syntax trees of division patterns.
- S Split flag
- QT QT flag
- TT TT flag or BT: BT flag
- Ver Vertical flag or Hor: Horizontal flag
- the results of the decisions made may be encoded into a stream according to the encoding order disclosed in the syntax tree shown in FIG. 13A.
- the information is arranged in the order of S, QT, TT, Ver, but even if the information is arranged in the order of S, QT, Ver, BT good. That is, in the example of FIG. 13B, first, there is information (S: Split flag) indicating whether or not to perform splitting, and then there is information (QT: QT flag) indicating whether or not to perform 4 splitting. do. Next, there is information indicating the division direction (Ver: Vertical flag or Hor: Horizontal flag), and finally there is information indicating whether to divide into two or three (BT: BT flag or TT: TT flag). is doing.
- division pattern described here is just an example, and a division pattern other than the described division pattern may be used, or only a part of the described division pattern may be used.
- the subtraction unit 104 subtracts the prediction image (prediction image input from the prediction control unit 128) from the original image in units of blocks input from the division unit 102 and divided by the division unit 102 . That is, the subtraction unit 104 calculates the prediction residual of the current block. Subtraction section 104 then outputs the calculated prediction residual to conversion section 106 .
- An original image is an input signal to the encoding device 100, and is, for example, a signal (eg, a luma signal and two chroma signals) representing an image of each picture forming a moving image.
- a signal eg, a luma signal and two chroma signals
- Transformation section 106 transforms the prediction residual in the spatial domain into transform coefficients in the frequency domain, and outputs the transform coefficients to quantization section 108 .
- the transform unit 106 performs a predetermined discrete cosine transform (DCT) or discrete sine transform (DST) on the prediction residual in the spatial domain, for example.
- DCT discrete cosine transform
- DST discrete sine transform
- the transform unit 106 adaptively selects a transform type from among a plurality of transform types, and uses a transform basis function corresponding to the selected transform type to transform the prediction residual into a transform coefficient. may be converted.
- Such transforms are sometimes called EMT (explicit multiple core transform) or AMT (adaptive multiple transform). Transformation basis functions are also sometimes simply referred to as basis functions.
- transform types include, for example, DCT-II, DCT-V, DCT-VIII, DST-I and DST-VII. Note that these transform types may be denoted as DCT2, DCT5, DCT8, DST1 and DST7, respectively.
- FIG. 14 is a table showing transformation basis functions corresponding to each transformation type. In FIG. 14, N indicates the number of input pixels. Selection of a transform type from among these multiple transform types may depend, for example, on the type of prediction (intra prediction, inter prediction, etc.) or may depend on the intra prediction mode.
- EMT flag or AMT flag Information indicating whether to apply such EMT or AMT
- information indicating the selected conversion type are typically signaled at the CU level. Note that the signaling of these information need not be limited to the CU level, but may be at other levels (eg sequence level, picture level, slice level, brick level or CTU level).
- the transformation unit 106 may retransform the transformation coefficients (that is, transformation results). Such retransformation is sometimes called AST (adaptive secondary transform) or NSST (non-separable secondary transform). For example, the transform unit 106 re-transforms each sub-block (for example, a sub-block of 4 ⁇ 4 pixels) included in the block of transform coefficients corresponding to the intra-prediction residual.
- Information indicating whether to apply NSST and information about the transformation matrix used for NSST are typically signaled at the CU level. Note that the signaling of these information need not be limited to the CU level, but may be at other levels (eg sequence level, picture level, slice level, brick level or CTU level).
- the conversion unit 106 may apply separable conversion and non-separable conversion.
- a separable transformation is a method that separates each direction by the number of input dimensions and transforms multiple times. This is a method of collectively treating them as one-dimensional and converting them collectively.
- non-separable transformation if the input is a block of 4 ⁇ 4 pixels, it is regarded as one array with 16 elements, and 16 ⁇ 16 transformation is performed on that array. Examples include those that perform conversion processing with matrices.
- a transformation Hypercube Given Transform
- the transformation unit 106 it is also possible to switch the transformation type of the transformation basis function to be transformed into the frequency domain according to the region within the CU.
- One example is SVT (Spatially Varying Transform).
- FIG. 15 is a diagram showing an example of SVT.
- the CU is divided into two equal parts in the horizontal direction or the vertical direction, and only one of the areas is transformed into the frequency domain.
- a transform type may be set for each region, and for example, DST7 and DCT8 are used.
- DST7 and DCT8 may be used for the region at position 0 of the two regions obtained by vertically bisecting the CU.
- DST7 is used for the area at position 1 of the two areas.
- DST7 and DCT8 are used for the region at position 0 of the two regions obtained by horizontally bisecting the CU.
- DST7 is used for the area at position 1 of the two areas.
- the dividing method may be divided into four equal parts instead of the two equal parts. Further, it is also possible to make it more flexible, such as by encoding information indicating the partitioning method and signaling it in the same way as CU partitioning. Note that SVT is also called SBT (Sub-block Transform).
- the aforementioned AMT and EMT may be called MTS (Multiple Transform Selection).
- MTS Multiple Transform Selection
- a transform type such as DST7 or DCT8 can be selected, and information indicating the selected transform type may be encoded as index information for each CU.
- IMTS Implicit MTS
- IMTS is a process of selecting a transform type to be used for orthogonal transform without encoding index information based on the shape of the CU.
- IMTS may be usable only in intra-predicted blocks, or may be usable in both intra-predicted blocks and inter-predicted blocks.
- selection processes for selectively switching the transform type used for the orthogonal transform Only the selection process of is valid. Whether or not each selection process is valid can be identified by flag information in a header such as SPS. For example, if all three selection processes are valid, one of the three selection processes is selected and orthogonally transformed for each CU. Note that the selection process for selectively switching the conversion type may use a selection process different from the above three selection processes as long as at least one of the following four functions [1] to [4] can be realized. Each of the above three selection processes may be replaced with another process.
- Function [1] is a function of orthogonally transforming the entire range within the CU and encoding information indicating the transform type used for the transform.
- Function [2] is a function of orthogonally transforming the entire range of the CU and determining the transform type based on a predetermined rule without encoding information indicating the transform type.
- Function [3] is a function of orthogonally transforming a partial region of the CU and encoding information indicating the transform type used for the transform.
- Function [4] is a function of orthogonally transforming a partial region of the CU and determining the transform type based on a predetermined rule without encoding information indicating the transform type used for the transform.
- MTS Mobility Management Entity
- IMTS IMTS
- SBT SBT whether or not to apply each of MTS, IMTS, and SBT may be determined for each processing unit. For example, the presence or absence of application may be determined in sequence units, picture units, brick units, slice units, CTU units, or CU units.
- the tool for selectively switching the transformation type in the present disclosure may be rephrased as a method of adaptively selecting a basis used for transformation processing, a selection process, or a process of selecting a basis.
- a tool that selectively switches the conversion type may be rephrased as a mode that adaptively selects the conversion type.
- FIG. 16 is a flowchart showing an example of processing by the conversion unit 106.
- FIG. 16 is a flowchart showing an example of processing by the conversion unit 106.
- the transformation unit 106 determines whether or not to perform orthogonal transformation (step St_1).
- the transformation unit 106 selects a transformation type to be used for orthogonal transformation from a plurality of transformation types (step St_2).
- the transform unit 106 performs orthogonal transform by applying the selected transform type to the prediction residual of the current block (step St_3).
- transforming section 106 outputs information indicating the selected transform type to entropy coding section 110 to encode the information (step St_4).
- the transform unit 106 determines not to perform the orthogonal transform (No in step St_1), the transform unit 106 outputs information indicating that the orthogonal transform is not performed to the entropy coding unit 110, thereby encoding the information ( Step St_5).
- the determination of whether or not to perform the orthogonal transform in step St_1 may be made based on, for example, the size of the transform block, the prediction mode applied to the CU, and the like. Further, information indicating the transform type used for orthogonal transform may not be encoded, and orthogonal transform may be performed using a predefined transform type.
- FIG. 17 is a flowchart showing another example of processing by the conversion unit 106.
- FIG. 17 is an example of orthogonal transform in the case of applying a method of selectively switching the transform type used for orthogonal transform, like the example shown in FIG.
- the first transform type group may include DCT2, DST7 and DCT8.
- the second set of transform types may include DCT2.
- the conversion types included in the first conversion type group and the second conversion type group may partially overlap, or may be completely different conversion types.
- the conversion unit 106 determines whether or not the conversion size is equal to or less than a predetermined value (step Su_1). Here, if it is determined that the value is equal to or less than the predetermined value (Yes in step Su_1), the transform unit 106 orthogonally transforms the prediction residual of the current block using a transform type included in the first transform type group (step Su_2 ). Next, transformation section 106 outputs information indicating which transformation type to use among one or more transformation types included in the first transformation type group to entropy encoding section 110, thereby converting the information into is encoded (step Su_3). On the other hand, when the transform unit 106 determines that the transform size is not equal to or smaller than the predetermined value (No in step Su_1), it orthogonally transforms the prediction residual of the current block using the second transform type group (step Su_4).
- the information indicating the transform type used for the orthogonal transform may be information indicating a combination of the transform type applied in the vertical direction and the transform type applied in the horizontal direction of the current block.
- the first transform type group may contain only one transform type, and information indicating the transform type used for the orthogonal transform may not be encoded.
- the second transform type group may include a plurality of transform types, and information indicating the transform type used for the orthogonal transform among the one or more transform types included in the second transform type group is encoded.
- the transform type may be determined based only on the transform size. Note that the process of determining the transform type to be used for the orthogonal transform based on the transform size is not limited to determining whether the transform size is equal to or less than a predetermined value.
- Quantization section 108 quantizes the transform coefficients output from transform section 106 . Specifically, the quantization unit 108 scans a plurality of transform coefficients of the current block in a predetermined scanning order, and quantizes the transform coefficients based on a quantization parameter (QP) corresponding to the scanned transform coefficients. do. Quantization section 108 then outputs a plurality of quantized transform coefficients of the current block (hereinafter referred to as quantized coefficients) to entropy encoding section 110 and inverse quantization section 112 .
- QP quantization parameter
- the predetermined scanning order is the order for quantization/inverse quantization of transform coefficients.
- the predetermined scan order may be defined in ascending frequency order (from low frequency to high frequency) or descending frequency order (high frequency to low frequency).
- a quantization parameter is a parameter that defines a quantization step (quantization width). For example, the quantization step increases as the value of the quantization parameter increases. That is, as the value of the quantization parameter increases, the quantization coefficient error (quantization error) increases.
- a quantization matrix may be used for quantization.
- quantization matrices may be used corresponding to frequency transform sizes such as 4x4 and 8x8, prediction modes such as intra-prediction and inter-prediction, and pixel components such as luminance and chrominance.
- quantization refers to digitizing values sampled at predetermined intervals in association with predetermined levels, and in this technical field, expressions such as rounding, rounding, or scaling are used. In some cases.
- a method of using a quantization matrix there are a method of using a quantization matrix directly set on the encoding device 100 side and a method of using a default quantization matrix (default matrix).
- default matrix default matrix
- the quantization matrix may be coded, for example, at the sequence level, picture level, slice level, brick level or CTU level.
- the quantization unit 108 scales the quantization width and the like obtained from the quantization parameter and the like for each transform coefficient using the values of the quantization matrix.
- the quantization processing performed without using a quantization matrix may be processing for quantizing transform coefficients based on a quantization width obtained from a quantization parameter or the like.
- the quantization width may be multiplied by a predetermined value common to all transform coefficients in the block.
- FIG. 18 is a block diagram showing an example of the configuration of the quantization section 108. As shown in FIG.
- the quantization unit 108 includes, for example, a differential quantization parameter generation unit 108a, a predicted quantization parameter generation unit 108b, a quantization parameter generation unit 108c, a quantization parameter storage unit 108d, and a quantization processing unit 108e. .
- FIG. 19 is a flowchart showing an example of quantization by the quantization unit 108.
- FIG. 19 is a flowchart showing an example of quantization by the quantization unit 108.
- the quantization unit 108 may perform quantization for each CU based on the flowchart shown in FIG. Specifically, the quantization parameter generation unit 108c determines whether or not to perform quantization (step Sv_1). Here, if it is determined that quantization is to be performed (Yes in step Sv_1), the quantization parameter generation unit 108c generates a quantization parameter for the current block (step Sv_2), and stores the quantization parameter in the quantization parameter storage unit 108d. (step Sv_3).
- the quantization processing unit 108e quantizes the transform coefficients of the current block using the quantization parameter generated in step Sv_2 (step Sv_4).
- the predicted quantization parameter generation unit 108b acquires a quantization parameter for a processing unit different from that of the current block from the quantization parameter storage unit 108d (step Sv_5).
- the predicted quantization parameter generation unit 108b generates the predicted quantization parameter of the current block based on the acquired quantization parameter (step Sv_6).
- the difference quantization parameter generation unit 108a generates the difference between the quantization parameter of the current block generated by the quantization parameter generation unit 108c and the predicted quantization parameter of the current block generated by the prediction quantization parameter generation unit 108b. is calculated (step Sv_7).
- a difference quantization parameter is generated by calculating this difference.
- the differential quantization parameter generating unit 108a encodes the differential quantization parameter by outputting the differential quantization parameter to the entropy encoding unit 110 (step Sv_8).
- differential quantization parameter may be encoded at the sequence level, picture level, slice level, brick level, or CTU level.
- initial values of the quantization parameters may be coded at the sequence level, picture level, slice level, brick level or CTU level.
- the quantization parameter may be generated using the initial value of the quantization parameter and the differential quantization parameter.
- the quantization unit 108 may include a plurality of quantizers, and may apply dependent quantization that quantizes transform coefficients using a quantization method selected from a plurality of quantization methods.
- FIG. 20 is a block diagram showing an example of the configuration of entropy coding section 110. As shown in FIG.
- the entropy coding unit 110 generates a stream by performing entropy coding on the quantization coefficients input from the quantization unit 108 and the prediction parameters input from the prediction parameter generation unit 130 .
- CABAC Context-based Adaptive Binary Arithmetic Coding
- the entropy coding unit 110 includes, for example, a binarization unit 110a, a context control unit 110b, and a binary arithmetic coding unit 110c.
- the binarization unit 110a performs binarization to convert multilevel signals such as quantized coefficients and prediction parameters into binary signals.
- Binarization methods include, for example, Truncated Rice Binarization, Exponential Golomb codes, Fixed Length Binarization, and the like.
- the context control unit 110b derives a context value according to the characteristics of the syntax element or the surrounding situation, that is, the probability of occurrence of the binary signal. Methods of deriving this context value include, for example, bypass, syntax element reference, upper/left adjacent block reference, hierarchical information reference, and others.
- Binary arithmetic coding section 110c performs arithmetic coding on the binarized signal using the derived context value.
- FIG. 21 is a diagram showing the flow of CABAC in entropy coding section 110.
- FIG. 21 is a diagram showing the flow of CABAC in entropy coding section 110.
- CABAC in the entropy coding unit 110 is initialized.
- initialization in the binary arithmetic coding unit 110c and setting of initial context values are performed.
- the binarization unit 110a and the binary arithmetic coding unit 110c sequentially perform binarization and arithmetic coding on each of the plurality of quantized coefficients of the CTU, for example.
- the context control unit 110b updates the context value each time arithmetic coding is performed.
- the context control unit 110b saves the context value as post-processing. This saved context value is used, for example, for the initial context value for the next CTU.
- the inverse quantization section 112 inversely quantizes the quantized coefficients input from the quantization section 108 . Specifically, the inverse quantization unit 112 inversely quantizes the quantized coefficients of the current block in a predetermined scanning order. The inverse quantization unit 112 then outputs the inversely quantized transform coefficients of the current block to the inverse transform unit 114 .
- the inverse transform unit 114 restores the prediction residual by inverse transforming the transform coefficients input from the inverse quantization unit 112 . Specifically, the inverse transform unit 114 restores the prediction residual of the current block by performing an inverse transform corresponding to the transform by the transform unit 106 on the transform coefficients. Then, inverse transform section 114 outputs the restored prediction residual to addition section 116 .
- the reconstructed prediction residual usually contains quantization error.
- the addition unit 116 adds the prediction residual input from the inverse transform unit 114 and the prediction image input from the prediction control unit 128 to reconstruct the current block. As a result, a reconstructed image is generated. The addition section 116 then outputs the reconstructed image to the block memory 118 and the loop filter section 120 .
- the block memory 118 is, for example, a storage unit for storing blocks in the current picture that are referenced in intra prediction. Specifically, the block memory 118 stores the reconstructed image output from the adder 116 .
- the frame memory 122 is, for example, a storage unit for storing reference pictures used for inter prediction, and is sometimes called a frame buffer. Specifically, the frame memory 122 stores the reconstructed image filtered by the loop filter section 120 .
- the loop filter unit 120 applies loop filter processing to the reconstructed image output from the addition unit 116 and outputs the filtered reconstructed image to the frame memory 122 .
- a loop filter is a filter (in-loop filter) used in an encoding loop, and includes, for example, an adaptive loop filter (ALF), a deblocking filter (DF or DBF), and a sample adaptive offset (SAO). .
- ALF adaptive loop filter
- DF or DBF deblocking filter
- SAO sample adaptive offset
- FIG. 22 is a block diagram showing an example of the configuration of the loop filter section 120. As shown in FIG. 22
- the loop filter unit 120 includes a deblocking filter processing unit 120a, an SAO processing unit 120b, and an ALF processing unit 120c.
- the deblocking/filtering unit 120a performs the deblocking/filtering described above on the reconstructed image.
- the SAO processing unit 120b performs the above-described SAO processing on the reconstructed image after deblocking and filtering.
- the ALF processing unit 120c applies the above-described ALF processing to the reconstructed image after the SAO processing. Details of the ALF and deblocking filters are provided below.
- the SAO process is a process for improving image quality by reducing ringing (a phenomenon in which pixel values undulate around edges) and correcting deviations in pixel values.
- This SAO processing includes, for example, edge offset processing and band offset processing.
- the loop filter unit 120 may not include all the processing units disclosed in FIG. 22, and may include only some of the processing units. Also, the loop filter unit 120 may be configured to perform each of the above processes in an order different from the process order disclosed in FIG. 22 .
- loop filter section > Adaptive loop filter In ALF, a least squares error filter is applied to remove the coding distortion, e.g. A filter selected from among multiple filters is applied.
- sub-blocks eg, 2 ⁇ 2 pixel sub-blocks
- the classification of sub-blocks is based, for example, on gradient direction and activity.
- the gradient direction value D eg, 0-2 or 0-4
- the gradient activity value A eg, 0-4
- the sub-blocks are classified into a plurality of classes.
- the directional value D of the gradient is derived, for example, by comparing the gradients in multiple directions (eg horizontal, vertical and two diagonal directions). Also, 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 the sub-block is determined from among the plurality of filters based on the result of such classification.
- FIGS. 23A-23C are diagrams showing several examples of filter shapes used in ALF.
- Figure 23A shows a 5x5 diamond shaped filter
- Figure 23B shows a 7x7 diamond shaped filter
- Figure 23C shows a 9x9 diamond shaped filter.
- Information indicating the shape of the filter is typically signaled at the picture level. It should be noted that the signalization of the information indicating the shape of the filter need not be limited to the picture level, and may be at other levels (eg sequence level, slice level, brick level, CTU level or CU level).
- ALF on/off may be determined at the picture level or the CU level, for example. For example, for luminance, it may be determined whether to apply ALF at the CU level, and for chrominance, it may be determined at the picture level whether to apply ALF.
- Information indicating ALF on/off is typically signaled at the picture level or CU level. It should be noted that the signaling of information indicating on/off of ALF need not be limited to the picture level or CU level, and may be at other levels (eg, sequence level, slice level, brick level or CTU level). good.
- one filter is selected from a plurality of filters and ALF processing is performed on the sub-blocks.
- the coefficient set of coefficients used in that filter is typically signaled at the picture level. Note that the signaling of coefficient sets need not be limited to the picture level, but may be at other levels (eg sequence level, slice level, brick level, CTU level, CU level or sub-block level).
- FIG. 23D shows an example where a Y sample (first component) is used for Cb CCALF and Cr CCALF (multiple components different from the first component).
- FIG. 23E shows a diamond-shaped filter.
- CC-ALF operates by applying a linear diamond filter (FIGS. 23D, 23E) to the luminance channel of each chrominance component. For example, filter coefficients are sent in APS, scaled by a factor of 2 ⁇ 10, and rounded for fixed point representation. Filter application is controlled by a variable block size and signaled by a context-encoded flag received for each block of samples. The block size and CC-ALF enable flag are received at the slice level for each chroma component.
- CC-ALF syntax and semantics are provided in the Appendix. Contributors support block sizes of 16x16, 32x32, 64x64, 128x128 (in chrominance samples).
- FIG. 23F is a diagram showing an example of JC-CCALF.
- FIG. 23G is a diagram showing an example of JC-CCALF weight_index candidates.
- JC-CCALF uses only one CCALF filter to produce one CCALF filter output as a color difference adjusted signal for only one color component, and an appropriately weighted version of the same color difference adjusted signal. Apply to other color components. In this way, the complexity of existing CCALFs is roughly halved.
- a weight value is encoded into a sign flag and a weight index.
- the weight index (denoted weight_index) is encoded in 3 bits and specifies the magnitude of the JC-CCALF weight JcCcWeight. cannot be the same as 0.
- the magnitude of JcCcWeight is determined as follows.
- JcCcWeight is equal to 4/(weight_index-4).
- the block-level on/off control of ALF filtering for Cb and Cr is separate. This is the same as CCALF, where two separate sets of block-level on/off control flags are encoded.
- CCALF unlike CCALF, only one block size variable is encoded since the on/off control block sizes for Cb, Cr are the same.
- loop filter unit 120 reduces distortion occurring at the block boundaries of the reconstructed image by performing filtering on the block boundaries.
- FIG. 24 is a block diagram showing an example of the detailed configuration of the deblocking/filtering unit 120a.
- the deblocking filter processing unit 120a includes, for example, a boundary determination unit 1201, a filter determination unit 1203, a filter processing unit 1205, a processing determination unit 1208, a filter characteristic determination unit 1207, and switches 1202, 1204 and 1206. Prepare.
- a boundary determination unit 1201 determines whether or not a pixel to be deblocked and filtered (that is, a target pixel) exists near a block boundary. Then, boundary determination section 1201 outputs the determination result to switch 1202 and processing determination section 1208 .
- the switch 1202 outputs the image before filtering to the switch 1204 when the boundary determination unit 1201 determines that the target pixel exists near the block boundary. Conversely, when the boundary determination unit 1201 determines that the target pixel does not exist near the block boundary, the switch 1202 outputs the image before filtering to the switch 1206 .
- the image before filtering is an image including the target pixel and at least one peripheral pixel around the target pixel.
- the filter determination unit 1203 determines whether or not to perform deblocking filter processing on the target pixel based on the pixel value of at least one peripheral pixel around the target pixel. Then, filter determination section 1203 outputs the determination result to switch 1204 and processing determination section 1208 .
- the switch 1204 When the filter determination unit 1203 determines that the target pixel is to be deblocked and filtered, the switch 1204 outputs the pre-filtering image acquired via the switch 1202 to the filter processing unit 1205 . Conversely, when the filter determination unit 1203 determines not to perform deblocking filter processing on the target pixel, the switch 1204 outputs the pre-filtering image acquired via the switch 1202 to the switch 1206 .
- filtering unit 1205 When an image before filtering is acquired via switches 1202 and 1204, filtering unit 1205 performs deblocking filtering with the filter characteristics determined by filter characteristics determining unit 1207 on the target pixel. Run. Then, the filter processing unit 1205 outputs the filtered pixel to the switch 1206 .
- a switch 1206 selectively outputs pixels that have not undergone deblocking/filtering and pixels that have undergone deblocking/filtering by the filtering unit 1205 under the control of the processing determination unit 1208 .
- the processing determination unit 1208 controls the switch 1206 based on the determination results of the boundary determination unit 1201 and the filter determination unit 1203 . That is, when the boundary determination unit 1201 determines that the target pixel exists near the block boundary, and the filter determination unit 1203 determines that the target pixel is subjected to deblocking filter processing, the processing determination unit 1208 causes the deblocking filtered pixels to be output from switch 1206 . Also, in cases other than the above, the processing determination unit 1208 causes the switch 1206 to output pixels that have not undergone deblocking/filter processing. By repeating such output of pixels, an image after filter processing is output from the switch 1206 . Note that the configuration shown in FIG. 24 is an example of the configuration of the deblocking/filtering unit 120a, and the deblocking/filtering unit 120a may have other configurations.
- FIG. 25 is a diagram showing an example of a deblocking filter having filter characteristics symmetrical with respect to block boundaries.
- deblocking filtering for example, one of two deblocking filters with different characteristics, ie, a strong filter and a weak filter, is selected using pixel values and quantization parameters.
- the strong filter as shown in FIG. 25, when there are pixels p0 to p2 and pixels q0 to q2 across the block boundary, the pixel values of the pixels q0 to q2 are calculated by the following equations. By doing so, the pixel values are changed to q'0 to q'2.
- p0-p2 and q0-q2 are pixel values of pixels p0-p2 and pixels q0-q2, respectively.
- q3 is the pixel value of the pixel q3 adjacent to the pixel q2 on the opposite side of the block boundary.
- the coefficient by which the pixel value of each pixel used for deblocking filtering is multiplied is the filter coefficient.
- clip processing may be performed so that post-computation pixel values do not change beyond a threshold.
- the pixel value after calculation by the above formula is clipped to "pre-calculation pixel value ⁇ 2 ⁇ threshold" using a threshold determined from the quantization parameter. This can prevent excessive smoothing.
- FIG. 26 is a diagram for explaining an example of block boundaries on which deblocking and filtering are performed.
- FIG. 27 is a diagram showing an example of BS values.
- a block boundary on which deblocking filtering is performed is, for example, a boundary of a CU, PU or TU of an 8 ⁇ 8 pixel block as shown in FIG.
- Deblocking filtering is performed, for example, in units of 4 rows or 4 columns.
- Bs Band Strength
- the Bs value in FIG. 27 it may be determined whether or not to perform deblocking filter processing with different strengths even for block boundaries belonging to the same image.
- Deblocking filtering for color difference signals is performed when the Bs value is two.
- Deblocking filter processing for the luminance signal is performed when the Bs value is 1 or more and a predetermined condition is satisfied.
- the conditions for determining the Bs value are not limited to those shown in FIG. 27, and may be determined based on other parameters.
- FIG. 28 is a flowchart showing an example of processing performed by the prediction unit of the encoding device 100.
- the prediction unit includes all or part of the intra prediction unit 124 , inter prediction unit 126 , and prediction control unit 128 .
- the prediction processing unit includes an intra prediction unit 124 and an inter prediction unit 126, for example.
- the prediction unit generates a predicted image of the current block (step Sb_1).
- Predicted images include, for example, intra-predicted images (intra-predicted signals) and inter-predicted images (inter-predicted signals).
- the predictor is already obtained by generating prediction images for other blocks, generating prediction residuals, generating quantization coefficients, restoring prediction residuals, and adding prediction images.
- a predicted image of the current block is generated using the reconstructed image.
- the reconstructed image may be, for example, an image of a reference picture, or an image of an encoded block (i.e., the other block mentioned above) in the current picture, which is the picture containing the current block.
- a coded block in the current picture is, for example, a neighboring block of the current block.
- FIG. 29 is a flowchart showing another example of processing performed by the prediction unit of the encoding device 100.
- FIG. 29 is a flowchart showing another example of processing performed by the prediction unit of the encoding device 100.
- the prediction unit generates a predicted image by the first method (step Sc_1a), generates a predicted image by the second method (step Sc_1b), and generates a predicted image by the third method (step Sc_1c).
- the first method, the second method, and the third method are different methods for generating a predicted image, for example, an inter prediction method, an intra prediction method, and other prediction methods, respectively. There may be. These prediction schemes may use the reconstructed images described above.
- the prediction unit evaluates the predicted images generated in steps Sc_1a, Sc_1b, and Sc_1c (step Sc_2). For example, the prediction unit calculates a cost C for each of the predicted images generated in steps Sc_1a, Sc_1b, and Sc_1c, and compares the costs C of these predicted images to evaluate those predicted images. .
- D is the encoding distortion of the predicted image, which is represented, for example, by the sum of the absolute differences between the pixel values of the current block and the pixel values of the predicted image.
- R is the bit rate of the stream.
- ⁇ is, for example, a Lagrangian undetermined multiplier.
- the prediction unit selects one of the predicted images generated in steps Sc_1a, Sc_1b, and Sc_1c (step Sc_3). That is, the predictor selects a scheme or mode for obtaining the final predicted image. For example, the prediction unit selects the prediction image with the lowest cost C based on the costs C calculated for those prediction images.
- the evaluation in step Sc_2 and the selection of the predicted image in step Sc_3 may be performed based on parameters used in the encoding process.
- Encoding apparatus 100 may signal information to identify the selected prediction image, scheme or mode into the stream. The information may be, for example, a flag. Based on this information, the decoding device 200 can thereby generate a predicted image according to the method or mode selected by the encoding device 100 .
- the prediction unit selects one of the predicted images after generating the predicted images by each method.
- the prediction unit may select a method or mode based on the parameters used in the above-described encoding process before generating the predicted images, and generate the predicted images according to the selected method or mode. good.
- the first method and the second method are intra prediction and inter prediction, respectively, and the prediction unit selects the final predicted image for the current block from the predicted images generated according to these prediction methods. You may
- FIG. 30 is a flowchart showing another example of processing performed by the prediction unit of the encoding device 100.
- FIG. 30 is a flowchart showing another example of processing performed by the prediction unit of the encoding device 100.
- the prediction unit generates a predicted image by intra prediction (step Sd_1a) and generates a predicted image by inter prediction (step Sd_1b).
- a predicted image generated by intra prediction is also called an intra predicted image
- a predicted image generated by inter prediction is also called an inter predicted image.
- the prediction unit evaluates each of the intra-predicted image and the inter-predicted image (step Sd_2).
- the above-described cost C may be used for this evaluation.
- the prediction unit may select the prediction image for which the lowest cost C is calculated from the intra prediction images and the inter prediction images as the final prediction image of the current block (step Sd_3). That is, a prediction scheme or mode is selected for generating a predicted image of the current block.
- the intra prediction unit 124 refers to blocks in the current picture stored in the block memory 118 and performs intra prediction (also referred to as intra-screen prediction) of the current block to generate a prediction image of the current block (that is, an intra prediction image). to generate Specifically, the intra prediction unit 124 generates an intra prediction image by performing intra prediction with reference to pixel values (for example, luminance values and color difference values) of blocks adjacent to the current block, and predicts the intra prediction image. Output to the control unit 128 .
- intra prediction also referred to as intra-screen prediction
- the intra prediction unit 124 performs intra prediction using one of a plurality of predefined intra prediction modes.
- Multiple intra-prediction modes typically include one or more non-directional prediction modes and multiple directional prediction modes.
- One or more non-directional prediction modes are, for example, H.264. including Planar prediction mode and DC prediction mode specified in H.265/HEVC standard.
- a plurality of directional prediction modes can be used, for example, in H.264. It includes 33 prediction modes defined in the H.265/HEVC standard. Note that the multiple directional prediction modes may include 32 directional prediction modes in addition to the 33 directional prediction modes (65 directional prediction modes in total).
- FIG. 31 is a diagram showing all 67 intra prediction modes (2 non-directional prediction modes and 65 directional prediction modes) in intra prediction. Solid arrows indicate H. 33 directions defined in the H.265/HEVC standard, and the dashed arrows represent the additional 32 directions (two non-directional prediction modes are not shown in FIG. 31).
- the luminance block may be referenced in the intra prediction of the chrominance block. That is, the chrominance 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.
- An intra-prediction mode of a chroma block that refers to such a luma block (eg, called CCLM mode) may be added as one of the intra-prediction modes of a chroma block.
- the intra prediction unit 124 may correct pixel values after intra prediction based on gradients of reference pixels in the horizontal/vertical directions. Intra prediction with such correction is sometimes called PDPC (position dependent intra prediction combination). Information indicating whether or not PDPC is applied (for example called a PDPC flag) is typically signaled at the CU level. Note that the signaling of this information need not be limited to the CU level, but may be at other levels (eg sequence level, picture level, slice level, brick level or CTU level).
- FIG. 32 is a flowchart showing an example of processing by the intra prediction unit 124.
- FIG. 32 is a flowchart showing an example of processing by the intra prediction unit 124.
- the intra prediction unit 124 selects one intra prediction mode from a plurality of intra prediction modes (step Sw_1). Then, the intra prediction unit 124 generates a predicted image according to the selected intra prediction mode (step Sw_2). Next, the intra prediction unit 124 determines MPM (Most Probable Modes) (step Sw_3).
- MPM consists of six intra prediction modes, for example. Two of the six intra-prediction modes may be Planar prediction mode and DC prediction mode, and the remaining four modes may be directional prediction modes. Then, the intra prediction unit 124 determines whether or not the intra prediction mode selected in step Sw_1 is included in the MPM (step Sw_4).
- the intra prediction unit 124 sets the MPM flag to 1 (step Sw_5), (step Sw_6).
- the MPM flag set to 1 and the information indicating its intra prediction mode are each encoded by the entropy encoding unit 110 as prediction parameters.
- the intra prediction unit 124 when determining that the selected intra prediction mode is not included in the MPM (No in step Sw_4), the intra prediction unit 124 sets the MPM flag to 0 (step Sw_7). Alternatively, the intra prediction unit 124 does not set the MPM flag. Then, the intra prediction unit 124 generates information indicating the intra prediction mode selected from one or more intra prediction modes not included in the MPM (step Sw_8). Note that the MPM flag set to 0 and the information indicating its intra prediction mode are each encoded by the entropy encoding unit 110 as prediction parameters. The information indicating the intra-prediction mode indicates any value from 0 to 60, for example.
- the inter prediction unit 126 refers to a reference picture stored in the frame memory 122 and different from the current picture to perform inter prediction (also called inter prediction) of the current block, thereby generating a predicted image (inter generate a predicted image). Inter prediction is performed in units of the current block or the current subblock within the current block.
- a sub-block is contained in a block and is a smaller unit than the block.
- the sub-block size may be 4x4 pixels, 8x8 pixels, or any other size.
- the sub-block size may be switched in units of slices, bricks, pictures, or the like.
- the inter prediction unit 126 performs motion estimation within a reference picture for the current block or current sub-block to find the reference block or sub-block that best matches the current block or current sub-block.
- the inter prediction unit 126 then obtains motion information (eg, motion vector) that compensates for motion or change from the reference block or sub-block to the current block or sub-block.
- the inter prediction unit 126 performs motion compensation (or motion prediction) based on the motion information to generate an inter prediction image of the current block or sub-block.
- the inter prediction section 126 outputs the generated inter prediction image to the prediction control section 128 .
- the motion information used for motion compensation may be signaled as inter-predicted images in various forms.
- motion vectors may be signaled.
- the difference between a motion vector and a motion vector predictor may be signaled.
- FIG. 33 is a diagram showing an example of each reference picture
- FIG. 34 is a conceptual diagram showing an example of a reference picture list.
- a reference picture list is a list that indicates one or more reference pictures stored in frame memory 122 .
- rectangles indicate pictures
- arrows indicate picture reference relationships
- the horizontal axis indicates time
- I, P, and B in the rectangles are intra-prediction pictures, uni-prediction pictures, and bi-prediction pictures, respectively.
- the numbers in the rectangles indicate the order of decoding.
- the decoding order of each picture is I0, P1, B2, B3 and B4, and the display order of each picture is I0, B3, B2, B4 and P1.
- FIG. 33 the decoding order of each picture is I0, P1, B2, B3 and B4 and the display order of each picture is I0, B3, B2, B4 and P1.
- the reference picture list is a list representing reference picture candidates, and for example, one picture (or slice) may have one or more reference picture lists.
- one reference picture list is used if the current picture is a uni-predictive picture
- two reference picture lists are used if the current picture is a bi-predictive picture.
- picture B3 which is the current picture currPic
- picture B3 has two reference picture lists, the L0 list and the L1 list. If the current picture currPic is picture B3, the candidate reference pictures for the current picture currPic are I0, P1 and B2, and each reference picture list (ie L0 list and L1 list) points to these pictures.
- the inter prediction unit 126 or the prediction control unit 128 designates which picture in each reference picture list is to be actually referred to by the reference picture index refIdxLx.
- reference pictures P1 and B2 are designated by reference picture indexes refIdxL0 and refIdxL1.
- Such a reference picture list may be generated per sequence, per picture, per slice, per brick, per CTU, or per CU. Also, among the reference pictures shown in the reference picture list, a reference picture index indicating a reference picture referred to in inter prediction is encoded at the sequence level, picture level, slice level, brick level, CTU level, or CU level. good too. Also, a common reference picture list may be used in a plurality of inter prediction modes.
- FIG. 35 is a flowchart showing the basic flow of inter prediction.
- the inter prediction unit 126 first generates a predicted image (steps Se_1 to Se_3). Next, the subtraction unit 104 generates a difference between the current block and the predicted image as a prediction residual (step Se_4).
- the inter prediction unit 126 determines the motion vector (MV) of the current block (steps Se_1 and Se_2) and performs motion compensation (step Se_3) to generate the predicted image. to generate Also, in determining the MV, the inter prediction unit 126 determines the MV by, for example, selecting a candidate motion vector (candidate MV) (step Se_1) and deriving the MV (step Se_2). Selection of candidate MVs is performed, for example, by the inter prediction unit 126 generating a candidate MV list and selecting at least one candidate MV from the candidate MV list. MVs derived in the past may be added to the candidate MV list as candidate MVs.
- the inter prediction unit 126 further selects at least one candidate MV from the at least one candidate MV, thereby determining the selected at least one candidate MV as the MV of the current block. may Alternatively, the inter prediction unit 126 may determine the MV of the current block for each of the at least one selected candidate MV by searching the region of the reference picture indicated by the candidate MV. Note that searching for this reference picture region may also be referred to as motion estimation.
- steps Se_1 to Se_3 are performed by the inter prediction unit 126, but the processing of step Se_1 or step Se_2, for example, may be performed by other components included in the encoding device 100. .
- a candidate MV list may be created for each process in each inter-prediction mode, or a common candidate MV list may be used in a plurality of inter-prediction modes.
- the processing of steps Se_3 and Se_4 corresponds to the processing of steps Sa_3 and Sa_4 shown in FIG. 9, respectively. Further, the processing of step Se_3 corresponds to the processing of step Sd_1b in FIG.
- FIG. 36 is a flowchart showing an example of MV derivation.
- the inter prediction unit 126 may derive the MV of the current block in a motion information (eg, MV) encoding mode.
- motion information may be coded as prediction parameters and signalized. That is, encoded motion information is included in the stream.
- the inter prediction unit 126 may derive MVs in a mode that does not encode motion information. In this case no motion information is included in the stream.
- MV derivation modes include normal inter mode, normal merge mode, FRUC mode, and affine mode, which will be described later.
- modes for encoding motion information include normal inter mode, normal merge mode, and affine mode (specifically, affine inter mode and affine merge mode).
- the motion information may include not only the MV but also predicted MV selection information, which will be described later.
- Modes in which motion information is not encoded include FRUC mode and the like.
- the inter prediction unit 126 selects a mode for deriving the MV of the current block from these multiple modes, and uses the selected mode to derive the MV of the current block.
- FIG. 37 is a flowchart showing another example of MV derivation.
- the inter prediction unit 126 may derive the MV of the current block in the differential MV encoding mode.
- the difference MV is coded as a prediction parameter and signalized. That is, the encoded differential MV is included in the stream.
- This difference MV is the difference between the MV of the current block and its predicted MV.
- the predicted MV is a predicted motion vector.
- the inter prediction unit 126 may derive the MV in a mode that does not encode the difference MV. In this case, the coded differential MV is not included in the stream.
- MV derivation modes include normal inter, normal merge mode, FRUC mode, and affine mode, which will be described later.
- modes for encoding differential MVs include normal inter mode and affine mode (more specifically, affine inter mode).
- Modes in which differential MVs are not encoded include FRUC mode, normal merge mode, and affine mode (specifically, affine merge mode).
- the inter prediction unit 126 selects a mode for deriving the MV of the current block from these multiple modes, and uses the selected mode to derive the MV of the current block.
- [MV derivation mode] 38A and 38B are diagrams showing an example of classification of each mode of MV derivation.
- MV derivation modes are roughly classified into three modes depending on whether motion information is encoded and whether differential MV is encoded.
- the three modes are inter mode, merge mode, and FRUC (frame rate up-conversion) mode.
- the inter mode is a mode for performing motion search, and is a mode for encoding motion information and difference MV.
- inter modes include affine inter modes and normal inter modes.
- the merge mode is a mode in which no motion search is performed, in which MVs are selected from neighboring coded blocks and the MVs of the current block are derived using the selected MVs.
- This merge mode is basically a mode that encodes motion information and does not encode differential MVs.
- the merge modes include normal merge mode (also called normal merge mode or regular merge mode), MMVD (Merge with Motion Vector Difference) mode, CIIP (Combined inter merge/intra prediction) mode. , triangle mode, ATMVP mode, and affine merge mode.
- MMVD Merge with Motion Vector Difference
- CIIP Combined inter merge/intra prediction
- the above-described affine merge mode and affine inter mode are modes included in affine modes.
- the affine mode is a mode in which the MV of each of a plurality of sub-blocks forming the current block is derived as the MV of the current block, assuming affine transformation.
- the FRUC mode is a mode in which the MV of the current block is derived by searching between coded regions, and neither motion information nor differential MV is coded. The details of each of these modes will be described later.
- each mode shown in FIGS. 38A and 38B is an example, and is not limited to this. For example, if a differential MV is encoded in CIIP mode, the CIIP mode is classified as an inter mode.
- Normal inter mode is an inter prediction mode that derives the MV of the current block by finding blocks similar to the image of the current block from the regions of the reference picture indicated by the candidate MVs. Also, in this normal inter mode, the difference MV is encoded.
- FIG. 39 is a flowchart showing an example of inter prediction in normal inter mode.
- the inter prediction unit 126 first obtains a plurality of candidate MVs for the current block based on information such as MVs of a plurality of encoded blocks temporally or spatially surrounding the current block (step Sg_1). That is, the inter prediction unit 126 creates a candidate MV list.
- the inter prediction unit 126 selects each of N (N is an integer equal to or greater than 2) candidate MVs from among the plurality of candidate MVs acquired in step Sg_1 as predicted MV candidates, and assigns a predetermined priority to each of them. (step Sg_2).
- the order of priority is predetermined for each of the N candidate MVs.
- the inter prediction unit 126 selects one prediction MV candidate from among the N prediction MV candidates as the prediction MV of the current block (step Sg_3). At this time, the inter prediction unit 126 encodes prediction MV selection information for identifying the selected prediction MV into a stream. That is, the inter prediction unit 126 outputs the prediction MV selection information to the entropy encoding unit 110 as prediction parameters via the prediction parameter generation unit 130 .
- the inter prediction unit 126 derives the MV of the current block by referring to the encoded reference picture (step Sg_4). At this time, the inter prediction unit 126 further encodes a difference value between the derived MV and the predicted MV as a difference MV into a stream. That is, inter prediction section 126 outputs difference MV to entropy encoding section 110 via prediction parameter generation section 130 as a prediction parameter.
- the encoded reference picture is a picture composed of a plurality of blocks reconstructed after encoding.
- the inter prediction unit 126 generates a predicted image of the current block by performing motion compensation on the current block using the derived MV and the encoded reference picture (step Sg_5).
- the processing of steps Sg_1 to Sg_5 is performed for each block. For example, when the processing of steps Sg_1 to Sg_5 is executed for each of all blocks included in a slice, inter prediction using normal inter mode for that slice ends. Also, when the processing of steps Sg_1 to Sg_5 is executed for each of all the blocks included in the picture, the inter prediction using the normal inter mode for that picture ends. Note that the processing of steps Sg_1 to Sg_5 is not performed on all blocks included in the slice, and when performed on some blocks, inter prediction using the normal inter mode for that slice ends. may Similarly, when the processing of steps Sg_1 to Sg_5 is performed on some blocks included in a picture, inter prediction using the normal inter mode for that picture may end.
- the predicted image is the inter-predicted signal described above.
- Information indicating the inter prediction mode (normal inter mode in the above example) used to generate the predicted image, which is included in the encoded signal, is encoded as, for example, a prediction parameter.
- the candidate MV list may be used in common with lists used in other modes.
- the process for candidate MV lists may be applied to the process for lists used in other modes. Processing related to this candidate MV list includes, for example, extraction or selection of candidate MVs from the candidate MV list, rearrangement of candidate MVs, deletion of candidate MVs, and the like.
- Normal merge mode is an inter-prediction mode that derives a candidate MV from a candidate MV list by selecting it as the MV of the current block.
- the normal merge mode is a narrowly defined merge mode and is sometimes simply called a merge mode. In this embodiment, a distinction is made between normal merge mode and merge mode, and merge mode is used in a broad sense.
- FIG. 40 is a flowchart showing an example of inter prediction in normal merge mode.
- the inter prediction unit 126 first obtains a plurality of candidate MVs for the current block based on information such as MVs of a plurality of encoded blocks temporally or spatially surrounding the current block (step Sh_1). That is, the inter prediction unit 126 creates a candidate MV list.
- the inter prediction unit 126 derives the MV of the current block by selecting one candidate MV from the plurality of candidate MVs acquired in step Sh_1 (step Sh_2). At this time, the inter prediction unit 126 encodes MV selection information for identifying the selected candidate MV into a stream. That is, inter prediction section 126 outputs MV selection information to entropy encoding section 110 as a prediction parameter via prediction parameter generation section 130 .
- the inter prediction unit 126 generates a predicted image of the current block by performing motion compensation on the current block using the derived MV and the encoded reference picture (step Sh_3).
- the processing of steps Sh_1 to Sh_3 is executed for each block, for example. For example, when the processing of steps Sh_1 to Sh_3 is executed for each of all blocks included in a slice, inter prediction using normal merge mode for that slice ends. Also, when the processing of steps Sh_1 to Sh_3 is executed for each of all the blocks included in the picture, inter prediction using the normal merge mode for that picture ends. Note that the processing of steps Sh_1 to Sh_3 is not performed on all blocks included in the slice, and if it is performed on some blocks, inter prediction using the normal merge mode for that slice ends. may Similarly, when the processing of steps Sh_1 to Sh_3 is performed on some blocks included in a picture, inter prediction using the normal merge mode for that picture may end.
- information indicating the inter prediction mode (normal merge mode in the above example) used to generate the predicted image, which is included in the stream is encoded as, for example, a prediction parameter.
- FIG. 41 is a diagram for explaining an example of MV derivation processing for the current picture in normal merge mode.
- the inter prediction unit 126 generates a candidate MV list in which candidate MVs are registered.
- Candidate MVs include spatially adjacent candidate MVs that are MVs of a plurality of encoded blocks spatially positioned around the current block, and MVs of neighboring blocks that are projected onto the position of the current block in the encoded reference picture. , a combined candidate MV that is an MV generated by combining the MV values of the spatially adjacent candidate MV and the temporally adjacent candidate MV, and a zero candidate MV that is an MV with a value of zero.
- the inter prediction unit 126 selects one candidate MV from among multiple candidate MVs registered in the candidate MV list, thereby determining that one candidate MV as the MV of the current block.
- the entropy encoding unit 110 describes and encodes merge_idx, which is a signal indicating which candidate MV has been selected, in the stream.
- the candidate MVs registered in the candidate MV list described in FIG. 41 are only examples, and the number may differ from the number in the figure, or the configuration may exclude some types of candidate MVs in the figure, It may be a configuration in which candidate MVs other than the types of candidate MVs in the figure are added.
- the final MV may be determined by performing DMVR (dynamic motion vector refreshing), which will be described later, using the MV of the current block derived by the normal merge mode.
- DMVR dynamic motion vector refreshing
- the difference MV is not encoded in the normal merge mode, but is encoded in the MMVD mode.
- the MMVD mode selects one candidate MV from the candidate MV list as in the normal merge mode, but encodes the difference MV.
- Such MMVDs may be categorized into merge mode along with normal merge mode, as shown in FIG. 38B. Note that the difference MV in the MMVD mode may not be the same as the difference MV used in the inter mode. It may be a small process.
- a combined inter merge/intra prediction (CIIP) mode may be performed in which a predicted image generated by inter prediction and a predicted image generated by intra prediction are superimposed to generate a predicted image of the current block.
- CIIP inter merge/intra prediction
- candidate MV list may also be referred to as a candidate list.
- merge_idx is MV selection information.
- FIG. 42 is a diagram for explaining an example of the current picture MV derivation process in the HMVP mode.
- the MV of the current block eg, CU
- the candidate MV list generated with reference to the encoded block eg, CU
- other candidate MVs may be registered in the candidate MV list.
- the mode in which such other candidate MVs are registered is called HMVP mode.
- candidate MVs are managed using a FIFO (First-In First-Out) buffer for HMVP separately from the candidate MV list in normal merge mode.
- FIFO First-In First-Out
- the FIFO buffer stores motion information such as MVs of previously processed blocks in order from newest to newest.
- motion information such as MVs of previously processed blocks in order from newest to newest.
- the MV of the newest block i.e. the most recently processed CU
- the MV of the oldest CU in the FIFO buffer i.e. The MVs of the earliest processed CU
- HMVP1 is the newest block MV
- HMVP5 is the oldest block MV.
- the inter prediction unit 126 for each MV managed in the FIFO buffer, sequentially from HMVP1, the MV is different from all candidate MVs already registered in the normal merge mode candidate MV list. Check if there is Then, when the inter prediction unit 126 determines that the MV is different from all candidate MVs, the MV managed in the FIFO buffer may be added as a candidate MV to the normal merge mode candidate MV list. At this time, one or more candidate MVs may be registered from the FIFO buffer.
- HMVP mode By using the HMVP mode in this way, not only the MVs of blocks spatially or temporally adjacent to the current block, but also the MVs of previously processed blocks can be added to the candidates. As a result, the variation of candidate MVs for the normal merge mode is increased, which increases the possibility that the encoding efficiency can be improved.
- the above MV may be motion information.
- the information stored in the candidate MV list and the FIFO buffer may include not only MV values, but also information about pictures to be referred to, direction to refer to, number of pictures to be referred to, and other information.
- the above-mentioned block is, for example, a CU.
- the candidate MV list and FIFO buffer in FIG. 42 are examples, and the candidate MV list and FIFO buffer may be lists or buffers of different sizes from those in FIG. 42, or register candidate MVs in an order different from that in FIG. It may be a configuration. Also, the processing described here is common to both the encoding device 100 and the decoding device 200 .
- the HMVP mode can also be applied to modes other than the normal merge mode.
- motion information such as MVs of blocks processed in the affine mode in the past may be stored in a FIFO buffer in order from newest to used as candidate MVs.
- a mode obtained by applying the HMVP mode to the affine mode may be called a history affine mode.
- the motion information may be derived at the decoding device 200 side without being signaled from the encoding device 100 side.
- motion information may be derived by performing a motion search on the decoding device 200 side.
- motion search is performed without using the pixel values of the current block.
- Modes in which the decoding apparatus 200 performs motion estimation include a FRUC (frame rate up-conversion) mode, a PMMVD (pattern matched motion vector derivation) mode, and the like.
- FRUC processing An example of FRUC processing is shown in FIG.
- First refer to the MVs of each encoded block spatially or temporally adjacent to the current block, and list these MVs as candidate MVs (i.e., the candidate MV list, which is the candidate MV list for normal merge mode). list) is generated (step Si_1).
- the best candidate MV is selected from a plurality of candidate MVs registered in the candidate MV list (step Si_2). For example, the evaluation value of each candidate MV included in the candidate MV list is calculated, and one candidate MV is selected as the best candidate MV based on the evaluation value.
- the MV for the current block is then derived based on the selected best candidate MV (step Si_4).
- the selected best candidate MV is directly derived as the MV for the current block.
- the MV for the current block may be derived by performing pattern matching in the region around the location in the reference picture corresponding to the selected best candidate MV. That is, the area around the best candidate MV is searched using pattern matching and evaluation value in the reference picture, and if there is an MV with a good evaluation value, the best candidate MV is set to that MV. It may be updated to make it the final MV of the current block. Updates to MVs with better evaluation values may not be performed.
- the inter prediction unit 126 performs motion compensation on the current block using the derived MV and the encoded reference picture to generate a predicted image of the current block (step Si_5).
- the processing of steps Si_1 to Si_5 is performed for each block, for example. For example, when the processing of steps Si_1 to Si_5 is performed for each of all blocks included in a slice, inter prediction using the FRUC mode for that slice ends. Further, when the processing of steps Si_1 to Si_5 is executed for each of all the blocks included in the picture, inter prediction using the FRUC mode for that picture ends. Note that the processing of steps Si_1 to Si_5 is not performed on all blocks included in a slice, and when performed on some blocks, inter prediction using the FRUC mode for that slice ends. good too. Similarly, when the processing of steps Si_1 to Si_5 is performed on some blocks included in a picture, inter prediction using the FRUC mode for that picture may end.
- Sub-block units may be processed in the same manner as the block units described above.
- the evaluation value may be calculated by various methods. For example, a reconstructed image of a region in the reference picture corresponding to the MV and a predetermined region (the region is, for example, the region of another reference picture or the region of the adjacent block of the current picture, as shown below) may be used) to compare with the reconstructed image. Then, the difference between the pixel values of the two reconstructed images may be calculated and used as the MV evaluation value. Note that the evaluation value may be calculated using information other than the difference value.
- one candidate MV included in the candidate MV list (also called merge list) is selected as a starting point for searching by pattern matching.
- first pattern matching or second pattern matching may be used.
- First pattern matching and second pattern matching are sometimes referred to as bilateral matching and template matching, respectively.
- FIG. 44 is a diagram for explaining an example of first pattern matching (bilateral matching) between two blocks in two reference pictures along the motion trajectory.
- first pattern matching in two pairs of blocks in two different reference pictures (Ref0, Ref1) that are along the motion trajectory of the current block (Cur block), Two MVs (MV0, MV1) are derived by searching for the best matching pair.
- the reconstructed image at the specified position in the first encoded reference picture (Ref0) specified by the candidate MV and the symmetric MV obtained by scaling the candidate MV by the display time interval A difference from the reconstructed image at the designated position in the second encoded reference picture (Ref1) designated by is derived, and the obtained difference value is used to calculate the evaluation value.
- the candidate MV with the best evaluation value among the plurality of candidate MVs is preferably selected as the best candidate MV.
- the MVs (MV0, MV1) pointing to the two reference blocks are the temporal distances ( proportional to TD0, TD1). For example, if the current picture is temporally located between two reference pictures, and the temporal distances from the current picture to the two reference pictures are equal, in the first pattern matching, the mirror-symmetric bidirectional MV derived.
- MV derivation > FRUC > template matching In the second pattern matching (template matching), pattern matching is performed between a template in the current picture (blocks adjacent to the current block in the current picture (e.g. upper and/or left neighbors)) and blocks in the reference picture. done. Therefore, in the second pattern matching, a block adjacent to the current block in the current picture is used as the predetermined area for calculating the candidate MV evaluation value described above.
- FIG. 45 is a diagram for explaining an example of pattern matching (template matching) between a template in the current picture and blocks in the reference picture.
- the block adjacent to the current block (Cur block) in the current picture (Cur Pic) is searched in the reference picture (Ref0) for the block that best matches the current block.
- MV is derived.
- the reconstructed image of the left and/or above coded region and the equivalent in the coded reference picture (Ref0) specified by the candidate MV A difference from the reconstructed image at the position is derived, and the obtained difference value is used to calculate the evaluation value.
- the candidate MV with the best evaluation value among the plurality of candidate MVs is preferably selected as the best candidate MV.
- Information indicating whether to apply such a FRUC mode may be signaled at the CU level. Also, when the FRUC mode is applied (e.g. when the FRUC flag is true), information indicating the applicable pattern matching method (first pattern matching or second pattern matching) may be signaled at the CU level. . Note that the signaling of these information need not be limited to the CU level, but may be at other levels (eg sequence level, picture level, slice level, brick level, CTU level or sub-block level). .
- the affine mode is a mode in which MVs are generated using affine transform.
- MVs may be derived in units of subblocks based on MVs of a plurality of adjacent blocks. This mode is sometimes called an affine motion compensation prediction mode.
- FIG. 46A is a diagram for explaining an example of derivation of MVs in units of subblocks based on MVs of a plurality of adjacent blocks.
- the current block includes, for example, sub-blocks of 16 4 ⁇ 4 pixels.
- the motion vector v0 of the upper left corner control point of the current block is derived based on the MV of the adjacent block
- the motion vector v1 of the upper right corner control point of the current block is derived based on the MV of the adjacent sub-block. derived.
- the two motion vectors v 0 and v 1 are projected to derive the motion vector (v x , v y ) of each sub-block in the current block according to Equation (1A) below.
- x and y indicate the horizontal and vertical positions of the sub-block, respectively, and w indicates a predetermined weighting factor.
- Information indicating such an affine mode may be signaled at the CU level. It should be noted that the signaling of information indicating this affine mode need not be limited to the CU level, but could be at other levels (eg sequence level, picture level, slice level, brick level, CTU level or sub-block level). may
- affine modes may include several modes in which the method of deriving the MVs of the upper left and upper right corner control points is different.
- affine modes include two modes, an affine inter (also referred to as affine normal inter) mode and an affine merge mode.
- FIG. 46B is a diagram for explaining an example of derivation of MV for each subblock in affine mode using three control points.
- the current block includes, for example, sub-blocks of 16 4 ⁇ 4 pixels.
- the motion vector v 0 of the upper left corner control point of the current block is derived based on the MV of the neighboring block.
- the motion vector v1 of the upper right corner control point of the current block is derived based on the MV of the adjacent block
- the motion vector v2 of the lower left corner control point of the current block is derived based on the MV of the adjacent block.
- the three motion vectors v 0 , v 1 and v 2 are projected to derive the motion vector (v x , v y ) of each sub-block in the current block according to Equation (1B) below.
- x and y indicate the horizontal and vertical positions of the sub-block center, respectively, and w and h indicate predetermined weighting factors.
- w may indicate the width of the current block, and h may indicate the height of the current block.
- Affine modes that use different numbers of control points may be switched and signaled at the CU level. It should be noted that information indicating the number of affine mode control points used at the CU level may be signaled at other levels (for example, sequence level, picture level, slice level, brick level, CTU level or sub-block level). good.
- an affine mode with three control points may include several modes with different methods of deriving the MVs of the upper left, upper right, and lower left corner control points.
- an affine mode with three control points has two modes, an affine inter mode and an affine merge mode, like the affine mode with two control points described above.
- each sub-block included in the current block is not limited to 4x4 pixels, and may be other sizes.
- the size of each sub-block may be 8x8 pixels.
- [MV derivation > affine mode > control point] 47A, 47B, and 47C are conceptual diagrams for explaining an example of MV derivation of control points in affine mode.
- affine mode As shown in FIG. 47A, for example, encoded block A (left), block B (top), block C (top right), block D (bottom left) and block E (top left) adjacent to the current block.
- a prediction MV for each of the control points of the current block is calculated based on the plurality of MVs corresponding to the block encoded in the affine mode. Specifically, encoded block A (left), block B (top), block C (top right), block D (bottom left) and block E (top left) are examined in order, and in affine mode The first valid block encoded is identified. Based on the plurality of MVs corresponding to this specified block, the MV of the control point of the current block is calculated.
- step Sj_1 shown in FIG. may be used to derive the predicted MV for each control point of the current block in .
- 48A and 48B are conceptual diagrams for explaining another example of deriving the control point MV in the affine mode.
- FIG. 48A is a diagram for explaining an affine mode with two control points.
- the MVs selected from the MVs of the encoded blocks A, B and C adjacent to the current block are the motion vector v of the upper left corner control point of the current block. Used as 0 .
- the MV selected from the MVs of each of the encoded blocks D and E adjacent to the current block is used as the motion vector v1 of the upper right corner control point of the current block.
- FIG. 48B is a diagram for explaining an affine mode with three control points.
- the MVs selected from the MVs of the encoded blocks A, B and C adjacent to the current block are the motion vector v of the upper left corner control point of the current block. Used as 0 .
- the MV selected from the MVs of each of the encoded blocks D and E adjacent to the current block is used as the motion vector v1 of the upper right corner control point of the current block.
- the MV selected from the MVs of each of the encoded blocks F and G adjacent to the current block is used as the motion vector v2 of the lower left corner control point of the current block.
- the MV derivation method shown in FIGS. 48A and 48B may be used for deriving the MV of each control point of the current block in step Sk_1 shown in FIG. It may be used to derive the predicted MV for each control point of the current block.
- the number of control points may differ between the encoded block and the current block.
- FIGS. 49A and 49B are conceptual diagrams for explaining an example of a control point MV derivation method when the encoded block and the current block have different numbers of control points.
- the current block has three control points, the upper left corner, the upper right corner and the lower left corner, and the block A adjacent to the left of the current block is coded in affine mode with two control points. It is In this case, motion vectors v3 and v4 projected to the upper left and upper right corner positions of the encoded block containing block A are derived. Then, from the derived motion vectors v3 and v4 , the motion vector v0 of the upper left corner control point and the motion vector v1 of the upper right corner control point of the current block are calculated. Furthermore, the motion vector v2 of the lower left corner control point is calculated from the derived motion vectors v0 and v1 .
- the current block has two control points in the upper left and upper right corners, and the block A adjacent to the left of the current block is encoded in an affine mode with three control points. .
- motion vectors v 3 , v 4 and v 5 projected to the upper left, upper right and lower left corner positions of the encoded block containing block A are derived.
- the motion vector v 0 of the upper left corner control point and the motion vector v 1 of the upper right corner control point of the current block are calculated.
- the MV derivation method shown in FIGS. 49A and 49B may be used for deriving the MV of each control point of the current block in step Sk_1 shown in FIG. It may be used to derive the predicted MV for each control point of the current block.
- FIG. 50 is a flow chart showing an example of the affine merge mode.
- the inter prediction unit 126 first derives the MV of each control point of the current block (step Sk_1).
- the control points are the upper left and upper right corner points of the current block, as shown in FIG. 46A, or the upper left, upper right, and lower left corner points of the current block, as shown in FIG. 46B.
- the inter prediction unit 126 may encode MV selection information for identifying two or three derived MVs into the stream.
- the inter prediction unit 126 when using the MV derivation method shown in FIGS. 47A to 47C, the inter prediction unit 126, as shown in FIG. , block D (bottom left) and block E (top left), and identify the first valid block encoded in affine mode.
- Inter predictor 126 derives the MV of the control points using the first valid block encoded in the identified affine mode. For example, if block A is identified and block A has two control points, then inter predictor 126 determines motion vectors v 3 and v4 , the motion vector v0 of the upper left corner control point of the current block and the motion vector v1 of the upper right corner control point are calculated. For example, inter prediction unit 126 projects the motion vectors v 3 and v 4 of the upper left corner and upper right corner of the encoded block onto the current block to obtain the motion vector v 0 of the upper left corner control point of the current block, Calculate the motion vector v1 of the upper right corner control point.
- inter prediction unit 126 may generate the upper left corner, upper right corner, and lower left corner of the encoded block including block A, as shown in FIG. 47C. From the motion vectors v3 , v4 , and v5 , calculate the motion vector v0 of the upper left corner control point, the motion vector v1 of the upper right corner control point, and the motion vector v2 of the lower left corner control point of the current block. .
- the inter prediction unit 126 projects the motion vectors v 3 , v 4 , and v 5 of the upper left corner, upper right corner, and lower left corner of the encoded block onto the current block, so that the motion vectors of the upper left corner control point of the current block are Calculate the motion vector v0 , the motion vector v1 of the upper right corner control point, and the motion vector v2 of the lower left corner control point.
- the MVs of the three control points may be calculated, , block A is identified, and if block A has three control points, then the MVs of the two control points may be calculated.
- the inter prediction unit 126 performs motion compensation on each of the multiple sub-blocks included in the current block. That is, inter prediction unit 126 uses two motion vectors v 0 and v 1 and Equation (1A) above for each of the plurality of sub-blocks, or three motion vectors v 0 , v 1 and v 2 and equation (1B) above, the MV of the sub-block is calculated as an affine MV (step Sk_2). Then, the inter prediction unit 126 performs motion compensation on the sub-block using those affine MVs and encoded reference pictures (step Sk_3).
- the prediction image generation process using the affine merge mode for the current block ends. That is, motion compensation is performed on the current block to generate a predicted image of the current block.
- the candidate MV list described above may be generated.
- the candidate MV list may be, for example, a list containing candidate MVs derived using multiple MV derivation methods for each control point. Multiple MV derivation methods, MV derivation method shown in FIGS. 47A to 47C, MV derivation method shown in FIGS. 48A and 48B, MV derivation method shown in FIGS. 49A and 49B, and other MV derivation Any combination of methods may be used.
- the candidate MV list may include candidate MVs for modes other than the affine mode that perform prediction in units of subblocks.
- a candidate MV list including affine merge mode candidate MVs having two control points and affine merge mode candidate MVs having three control points may be generated.
- a candidate MV list including affine merge mode candidate MVs with two control points and a candidate MV list including affine merge mode candidate MVs with three control points may be generated respectively.
- a candidate MV list including candidate MVs in one of the affine merge mode with two control points and the affine merge mode with three control points may be generated.
- the candidate MVs may be, for example, the MVs of encoded block A (left), block B (top), block C (top right), block D (bottom left) and block E (top left), and the MVs of those blocks. It may be the MV of one of the valid blocks.
- an index indicating which candidate MV in the candidate MV list may be sent.
- FIG. 51 is a flow chart showing an example of the affine inter mode.
- the inter predictor 126 first derives predictions MV (v 0 , v 1 ) or (v 0 , v 1 , v 2 ) of the two or three control points of the current block, respectively ( step Sj_1).
- the control point is the point at the upper left corner, upper right corner, or lower left corner of the current block, as shown in FIG. 46A or 46B.
- the inter prediction unit 126 calculates the By choosing the MV, we derive the prediction MV (v 0 ,v 1 ) or (v 0 ,v 1 ,v 2 ) of the current block's control points. At this time, the inter prediction unit 126 encodes prediction MV selection information for identifying the selected two or three prediction MVs into a stream.
- the inter prediction unit 126 uses cost evaluation or the like to determine which block MV to select from the encoded blocks adjacent to the current block as the prediction MV of the control point, and which prediction MV is selected.
- a flag indicating is may be described in the bitstream. That is, inter prediction section 126 outputs prediction MV selection information such as a flag to entropy encoding section 110 via prediction parameter generation section 130 as a prediction parameter.
- the inter prediction unit 126 performs motion search (steps Sj_3 and Sj_4) while updating the prediction MVs selected or derived in step Sj_1 (step Sj_2). That is, the inter prediction unit 126 calculates the MV of each sub-block corresponding to the updated prediction MV as an affine MV using the above formula (1A) or formula (1B) (step Sj_3). Then, the inter prediction unit 126 performs motion compensation on each subblock using those affine MVs and encoded reference pictures (step Sj_4). The processing of steps Sj_3 and Sj_4 is performed for all blocks within the current block each time the prediction MV is updated in step Sj_2.
- the inter prediction unit 126 determines, for example, the prediction MV that yields the lowest cost as the control point MV (step Sj_5). At this time, the inter prediction unit 126 further encodes the difference value between the determined MV and the predicted MV as a difference MV into a stream. That is, inter prediction section 126 outputs difference MV to entropy encoding section 110 via prediction parameter generation section 130 as a prediction parameter.
- the inter prediction unit 126 generates a predicted image of the current block by performing motion compensation on the current block using the determined MV and the encoded reference picture (step Sj_6).
- the candidate MV list described above may be generated.
- the candidate MV list may be, for example, a list containing candidate MVs derived using multiple MV derivation methods for each control point. Multiple MV derivation methods, MV derivation method shown in FIGS. 47A to 47C, MV derivation method shown in FIGS. 48A and 48B, MV derivation method shown in FIGS. 49A and 49B, and other MV derivation Any combination of methods may be used.
- the candidate MV list may include candidate MVs for modes other than the affine mode that perform prediction in units of subblocks.
- a candidate MV list including affine inter mode candidate MVs having two control points and affine inter mode candidate MVs having three control points may be generated.
- a candidate MV list including affine inter mode candidate MVs with two control points and a candidate MV list including affine inter mode candidate MVs with three control points may be generated respectively.
- a candidate MV list may be generated that includes candidate MVs for one of an affine inter mode with two control points and an affine inter mode with three control points.
- the candidate MVs may be, for example, the MVs of encoded block A (left), block B (top), block C (top right), block D (bottom left) and block E (top left), and the MVs of those blocks. It may be the MV of one of the valid blocks.
- an index indicating which candidate MV in the candidate MV list may be sent.
- the inter prediction unit 126 generates one rectangular predicted image for the rectangular current block. However, the inter prediction unit 126 generates a plurality of predicted images having shapes different from the rectangle for the rectangular current block, and combines the plurality of predicted images to generate a final rectangular predicted image. You may A shape different from a rectangle may be, for example, a triangle.
- FIG. 52A is a diagram for explaining the generation of predicted images of two triangles.
- the inter prediction unit 126 generates a triangular predicted image by performing motion compensation on the triangular first partition in the current block using the first MV of the first partition. Similarly, the inter prediction unit 126 generates a triangular predicted image by performing motion compensation on the triangular second partition in the current block using the second MV of the second partition. The inter prediction unit 126 then combines these predicted images to generate a rectangular predicted image that is the same as the current block.
- the first MV may be used to generate a rectangular first predicted image corresponding to the current block.
- a second rectangular predicted image corresponding to the current block may be generated using the second MV.
- a predicted image of the current block may be generated by weighted addition of the first predicted image and the second predicted image. Note that the weighted addition may be performed only on a part of the area sandwiching the boundary between the first partition and the second partition.
- FIG. 52B is a conceptual diagram showing an example of a first portion of a first partition that overlaps a second partition, and a first sample set and a second sample set that may be weighted as part of the correction process.
- the first portion may be, for example, a quarter of the width or height of the first partition.
- the first portion may have a width corresponding to N samples adjacent to the edge of the first partition. where N is an integer greater than zero, for example N may be the integer two.
- FIG. 52B shows a rectangular partition with a rectangular portion that is one quarter the width of the first partition.
- the first sample set includes samples outside the first portion and samples inside the first portion
- the second sample set includes samples within the first portion.
- FIG. 52B shows a rectangular partition with a rectangular portion that is one-fourth the height of the first partition.
- the first sample set includes samples outside the first portion and samples inside the first portion
- the second sample set includes samples within the first portion.
- the right example in FIG. 52B shows a triangular partition with a polygonal portion of height corresponding to two samples.
- the first sample set includes samples outside the first portion and samples inside the first portion
- the second sample set includes samples within the first portion.
- the first part may be the part of the first partition that overlaps with the adjacent partition.
- FIG. 52C is a conceptual diagram showing a first portion of a first partition that is a portion of the first partition that overlaps a portion of an adjacent partition.
- rectangular partitions are shown having overlapping portions with spatially adjacent rectangular partitions.
- Partitions having other shapes, such as triangular partitions, may be used, and overlapping portions may overlap adjacent partitions in space or time.
- a predicted image may be generated for at least one partition using intra prediction.
- FIG. 53 is a flow chart showing an example of the triangle mode.
- the inter prediction unit 126 divides the current block into a first partition and a second partition (step Sx_1). At this time, the inter prediction unit 126 may encode partition information, which is information about division into partitions, into the stream as a prediction parameter. That is, the inter prediction unit 126 may output the partition information as a prediction parameter to the entropy encoding unit 110 via the prediction parameter generation unit 130 .
- the inter prediction unit 126 first acquires a plurality of candidate MVs for the current block based on information such as MVs of a plurality of encoded blocks temporally or spatially surrounding the current block. (step Sx_2). That is, the inter prediction unit 126 creates a candidate MV list.
- the inter prediction unit 126 selects the candidate MV for the first partition and the candidate MV for the second partition as the first MV and the second MV, respectively, from among the plurality of candidate MVs acquired in step Sx_2 (step Sx_3).
- the inter prediction unit 126 may encode MV selection information for identifying the selected candidate MV into the stream as a prediction parameter. That is, the inter prediction unit 126 may output the MV selection information to the entropy encoding unit 110 via the prediction parameter generation unit 130 as prediction parameters.
- the inter prediction unit 126 performs motion compensation using the selected first MV and encoded reference picture to generate a first predicted image (step Sx_4). Similarly, the inter prediction unit 126 performs motion compensation using the selected second MV and encoded reference pictures to generate a second predicted image (step Sx_5).
- the inter prediction unit 126 generates a predicted image of the current block by weighted addition of the first predicted image and the second predicted image (step Sx_6).
- first partition and the second partition are triangular in the example shown in FIG. 52A, they may be trapezoidal or may have different shapes. Furthermore, although the current block is composed of two partitions in the example shown in FIG. 52A, it may be composed of three or more partitions.
- first partition and the second partition may overlap. That is, the first partition and the second partition may contain the same pixel area.
- the predicted image of the current block may be generated using the predicted image of the first partition and the predicted image of the second partition.
- a predicted image is generated by inter prediction for both partitions is shown, but a predicted image may be generated by intra prediction for at least one partition.
- the candidate MV list for selecting the first MV and the candidate MV list for selecting the second MV may be different, or may be the same candidate MV list.
- the partition information may include at least an index indicating the direction of partitioning the current block into a plurality of partitions.
- the MV selection information may include an index indicating the selected first MV and an index indicating the selected second MV.
- One index may indicate multiple pieces of information. For example, one index collectively indicating part or all of the partition information and part or all of the MV selection information may be encoded.
- FIG. 54 is a diagram showing an example of ATMVP mode in which MV is derived for each subblock.
- ATMVP mode is a mode classified as merge mode. For example, in the ATMVP mode, candidate MVs in units of subblocks are registered in the candidate MV list used in the normal merge mode.
- the A temporal MV reference block is identified in the encoded reference picture specified by the MV (MV0) of the block adjacent to the lower left of the current block. Then, for each sub-block within the current block, identify the MV that was used when coding the region corresponding to that sub-block within the temporal MV reference block. The MVs identified in this way are included in the candidate MV list as candidate MVs for sub-blocks of the current block. If a candidate MV for each such sub-block is selected from the candidate MV list, motion compensation is performed for that sub-block using the candidate MV as the MV for the sub-block. Thereby, a predicted image of each sub-block is generated.
- the block adjacent to the lower left of the current block is used as the peripheral MV reference block, but other blocks may be used.
- the size of the sub-block may be 4 ⁇ 4 pixels, 8 ⁇ 8 pixels, or any other size.
- the sub-block size may be switched in units of slices, bricks, pictures, or the like.
- FIG. 55 is a diagram showing the relationship between merge modes and DMVR.
- the inter prediction unit 126 derives the MV of the current block in merge mode (step Sl_1).
- the inter prediction unit 126 determines whether or not to perform MV search, ie, motion search (step Sl_2).
- the inter prediction unit 126 determines not to perform motion search (No in step Sl_2), it determines the MV derived in step Sl_1 as the final MV for the current block (step Sl_4). That is, in this case, the MV of the current block is determined in merge mode.
- step Sl_3 the inter prediction unit 126 searches for the peripheral region of the reference picture indicated by the MV derived in step Sl_1, for the current block. to derive the final MV (step Sl_3). That is, in this case, DMVR determines the MV of the current block.
- FIG. 56 is a conceptual diagram for explaining an example of DMVR for determining MV.
- select candidate MVs (L0 and L1) for the current block for example in merge mode.
- the reference pixels are identified from the first reference picture (L0), which is the encoded picture in the L0 list.
- the candidate MV (L1) identify the reference pixels from the second reference picture (L1), which is the encoded picture in the L1 list.
- a template is generated by averaging these reference pixels.
- the peripheral regions of the candidate MVs of the first reference picture (L0) and the second reference picture (L1) are searched, respectively, and the MV with the lowest cost is selected as the final MV of the current block.
- the cost may be calculated using, for example, the difference value between each pixel value of the template and each pixel value of the search area, the candidate MV value, and the like.
- Any process other than the process described here may be used as long as it can search the vicinity of the candidate MV and derive the final MV.
- FIG. 57 is a conceptual diagram for explaining another example of DMVR for determining MV.
- the cost is calculated without generating a template.
- the inter prediction unit 126 searches around reference blocks included in reference pictures in the L0 list and L1 list based on initial MVs that are candidate MVs acquired from the candidate MV list. For example, as shown in FIG. 57, the initial MV corresponding to the reference block of the L0 list is InitMV_L0, and the initial MV corresponding to the reference block of the L1 list is InitMV_L1.
- the inter prediction unit 126 first sets search positions for reference pictures in the L0 list.
- a difference vector indicating the set search position specifically, a difference vector from the position indicated by the initial MV (that is, InitMV_L0) to the search position is MVd_L0.
- the inter prediction unit 126 determines search positions in the reference pictures of the L1 list. This search position is indicated by the difference vector from the position indicated by the initial MV (ie, InitMV_L1) to the search position. Specifically, the inter prediction unit 126 determines the difference vector as MVd_L1 by mirroring MVd_L0. That is, the inter prediction unit 126 sets the search position to a position symmetrical to the position indicated by the initial MV in each of the reference pictures of the L0 list and the L1 list. For each search position, the inter prediction unit 126 calculates the sum of absolute differences (SAD) of pixel values in the block at that search position as a cost, and finds the search position with the lowest cost.
- SAD sum of absolute differences
- FIG. 58A is a diagram showing an example of motion search in DMVR
- FIG. 58B is a flowchart showing an example of the motion search.
- Step 1 the inter prediction unit 126 calculates the costs at the search position indicated by the initial MV (also referred to as the start point) and the eight search positions surrounding it. Then, the inter prediction unit 126 determines whether or not the search positions other than the starting point have the lowest cost. Here, if the inter prediction unit 126 determines that the search position other than the starting point has the lowest cost, it moves to the search position with the lowest cost, and performs the processing of Step 2 . On the other hand, if the cost of the starting point is the lowest, the inter prediction unit 126 skips the process of Step 2 and performs the process of Step 3 .
- Step 2 the inter prediction unit 126 performs the same search as in Step 1 using the search position moved according to the processing result of Step 1 as a new starting point. Then, the inter prediction unit 126 determines whether or not the cost of search positions other than the starting point is the lowest. Here, the inter prediction unit 126 performs the process of Step 4 if the cost of the search positions other than the starting point is the minimum. On the other hand, the inter prediction unit 126 performs the processing of Step 3 if the cost of the starting point is the minimum.
- Step 4 the inter prediction unit 126 treats the search position of the starting point as the final search position, and determines the difference between the position indicated by the initial MV and the final search position as a difference vector.
- the inter prediction unit 126 determines the decimal-precision pixel position with the lowest cost based on the costs at the four points above, below, and to the left and right of the starting point in Step 1 or Step 2, and sets that pixel position as the final search position. .
- the decimal-precision pixel position is expressed by the four-point vectors ((0, 1), (0, -1), (-1, 0), (1, 0)) at the top, bottom, left, and right, respectively. is determined by weighted addition using the cost at the search position of .
- the inter prediction unit 126 determines the difference between the position indicated by the initial MV and its final search position as a difference vector.
- Motion compensation has a mode of generating a predicted image and correcting the predicted image.
- the modes are, for example, BIO, OBMC, and LIC, which will be described later.
- FIG. 59 is a flowchart showing an example of predicted image generation.
- the inter prediction unit 126 generates a predicted image (step Sm_1), and corrects the predicted image using one of the above modes (step Sm_2).
- FIG. 60 is a flowchart showing another example of predicted image generation.
- the inter prediction unit 126 derives the MV of the current block (step Sn_1). Next, the inter prediction unit 126 generates a predicted image using the MV (step Sn_2), and determines whether or not to perform correction processing (step Sn_3). If the inter prediction unit 126 determines to perform correction processing (Yes in step Sn_3), the inter prediction unit 126 corrects the predicted image to generate a final predicted image (step Sn_4). Note that in the LIC described later, luminance and color difference may be corrected in step Sn_4. On the other hand, when the inter prediction unit 126 determines not to perform correction processing (No in step Sn_3), it outputs the predicted image as a final predicted image without correcting it (step Sn_5).
- An inter-predicted image 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, a prediction image based on motion information obtained by motion search (in the reference picture) and a prediction image based on the motion information of the adjacent block (in the current picture) are weighted and added to obtain the current An inter-predicted image may be generated for each sub-block within a block.
- Such inter prediction (motion compensation) is sometimes called OBMC (overlapped block motion compensation) or OBMC mode.
- OBMC mode information indicating the size of sub-blocks for OBMC (eg called OBMC block size) may be signaled at the sequence level. Furthermore, information indicating whether to apply the OBMC mode (eg called OBMC flag) may be signaled at the CU level. It should be noted that the level of signaling of these information need not be limited to the sequence level and CU level, but may be other levels (e.g. picture level, slice level, brick level, CTU level or sub-block level). good.
- 61 and 62 are flowcharts and conceptual diagrams for explaining an outline of predictive image correction processing by OBMC.
- the MV assigned to the current block is used to obtain a predicted image (Pred) by normal motion compensation.
- the arrow "MV" points to a reference picture and indicates what the current block of the current picture refers to to obtain the prediction image.
- the MV (MV_L) already derived for the encoded left adjacent block is applied (reused) to the current block to obtain a predicted image (Pred_L).
- the MV (MV_L) is indicated by an arrow "MV_L" pointing from the current block to the reference picture.
- the first correction of the predicted image is performed by overlapping the two predicted images Pred and Pred_L. This has the effect of blending the boundaries between adjacent blocks.
- the MV (MV_U) already derived for the coded upper adjacent block is applied (reused) to the current block to obtain a predicted image (Pred_U).
- the MV (MV_U) is indicated by an arrow "MV_U" pointing from the current block to the reference picture.
- the second correction of the predicted image is performed by superimposing the predicted image Pred_U on the predicted image (for example, Pred and Pred_L) subjected to the first correction. This has the effect of blending the boundaries between adjacent blocks.
- the predicted image obtained by the second correction is the final predicted image of the current block in which the boundaries with adjacent blocks are blended (smoothed).
- the above example is a two-pass correction method using the left and top neighboring blocks, but the correction method is three or more passes using also the right and/or bottom neighboring blocks. may be a correction method.
- the overlapping area may not be the pixel area of the entire block, but only a partial area near the block boundary.
- the predicted image correction processing of OBMC for obtaining one predicted image Pred by superimposing additional predicted images Pred_L and Pred_U from one reference picture has been described.
- similar processing may be applied to each of the multiple reference pictures.
- the obtained corrected predicted images are further superimposed. to get the final predicted image.
- the unit of the current block may be a unit of PU or a unit of sub-blocks obtained by further dividing the PU.
- encoding apparatus 100 may determine whether the current block belongs to an area with complex motion.
- the encoding apparatus 100 performs encoding by applying OBMC by setting a value of 1 as obmc_flag when it belongs to an area with complicated motion, and sets obmc_flag to Set the value 0 to encode the block without applying OBMC.
- the decoding device 200 decodes obmc_flag described in the stream, and performs decoding by switching whether to apply OBMC according to the value.
- BIO basic-directional optical flow
- BDOF bi-directional optical flow
- FIG. 63 is a diagram for explaining a model that assumes uniform linear motion.
- (vx, vy) indicates the velocity vector
- ⁇ 0 and ⁇ 1 respectively indicate the temporal distance between the current picture (Cur Pic) and the two reference pictures (Ref0, Ref1).
- (MVx0, MVy0) indicates the MV corresponding to the reference picture Ref0
- (MVx1, MVy1) indicates the MV corresponding to the reference picture Ref1.
- This optical flow equation is: (i) the time derivative of the luminance value, (ii) the product of 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 product of the vertical components of and is equal to zero.
- block-wise motion vectors obtained from the candidate MV list or the like may be corrected pixel-by-pixel.
- the MV may be derived on the decoding device 200 side by a method different from the motion vector derivation based on a model assuming uniform linear motion.
- a motion vector may be derived for each subblock based on MVs of a plurality of adjacent blocks.
- FIG. 64 is a flowchart showing an example of inter prediction according to BIO. Also, FIG. 65 is a diagram showing an example of the configuration of the inter prediction unit 126 that performs inter prediction according to the BIO.
- the inter prediction unit 126 includes, for example, a memory 126a, an interpolated image derivation unit 126b, a gradient image derivation unit 126c, an optical flow derivation unit 126d, a correction value derivation unit 126e, a predicted image correction and a portion 126f.
- the memory 126 a may be the frame memory 122 .
- the inter prediction unit 126 derives two motion vectors (M0, M1) using two reference pictures (Ref0, Ref1) different from the picture (Cur Pic) containing the current block.
- the inter prediction unit 126 then derives a predicted image of the current block using the two motion vectors (M0, M1) (step Sy_1).
- the motion vector M0 is the motion vector (MVx0, MVy0) corresponding to the reference picture Ref0
- the motion vector M1 is the motion vector (MVx1, MVy1) corresponding to the reference picture Ref1.
- the interpolated image deriving unit 126b refers to the memory 126a and derives the interpolated image I0 of the current block using the motion vector M0 and the reference picture L0.
- the interpolated image derivation unit 126b also refers to the memory 126a and derives the interpolated image I1 of the current block using the motion vector M1 and the reference picture L1 (step Sy_2 ).
- the interpolated image I0 is the image contained in the reference picture Ref0 derived for the current block
- the interpolated image I1 is the image contained in the reference picture Ref1 derived for the current block. It is an image.
- Interpolated image I0 and interpolated image I1 may each be the same size as the current block.
- interpolated image I0 and interpolated image I1 may each be images larger than the current block in order to properly derive the gradient images described below. Further, the interpolated images I0 and I1 may include prediction images derived by applying motion vectors (M0, M1) and reference pictures (L0, L1) and motion compensation filters.
- the gradient image derivation unit 126c also derives gradient images (Ix 0 , Ix 1 , Iy 0 , Iy 1 ) of the current block from the interpolation images I 0 and I 1 (step Sy_3). Note that the horizontal gradient image is (Ix 0 , Ix 1 ) and the vertical gradient image is (Iy 0 , Iy 1 ).
- the gradient image derivation unit 126c may derive the gradient image by, for example, applying a gradient filter to the interpolated image.
- the gradient image may be any image that indicates the amount of spatial variation in pixel values along the horizontal or vertical direction.
- the optical flow deriving unit 126d uses the interpolated images (I 0 , I 1 ) and the gradient images (Ix 0 , Ix 1 , Iy 0 , Iy 1 ) for each of a plurality of sub-blocks that make up the current block.
- An optical flow (vx, vy), which is the velocity vector described above, is derived (step Sy_4).
- Optical flow is a coefficient that corrects the amount of spatial movement of pixels, and may be called a local motion estimate, a corrected motion vector, or a corrected weight vector.
- a sub-block may be a sub-CU of 4x4 pixels.
- the derivation of the optical flow may be performed in other units such as pixel units instead of subblock units.
- the inter prediction unit 126 corrects the predicted image of the current block using the optical flow (vx, vy).
- the correction value deriving unit 126e derives the correction value of the pixel value included in the current block using the optical flow (vx, vy) (step Sy_5).
- the predicted image correction unit 126f may correct the predicted image of the current block using the correction value (step Sy_6).
- the correction value may be derived for each pixel, or may be derived for a plurality of pixels or sub-blocks.
- BIO processing flow is not limited to the processing disclosed in FIG. Only a part of the processes disclosed in FIG. 64 may be performed, different processes may be added or replaced, or the processes may be performed in a different order.
- FIG. 66A is a diagram for explaining an example of a predicted image generation method using luminance correction processing by LIC. Also, FIG. 66B is a flow chart showing an example of a predictive image generation method using the LIC.
- the inter prediction unit 126 derives the MV from the encoded reference picture and obtains the reference picture corresponding to the current block (step Sz_1).
- the inter prediction unit 126 extracts information indicating how the luminance value of the current block has changed between the reference picture and the current picture (step Sz_2). This extraction is based on the luminance pixel values of the coded left adjacent reference region (peripheral reference region) and the coded upper adjacent reference region (peripheral reference region) in the current picture, and the reference picture specified by the derived MV. luminance pixel values at equivalent positions.
- the inter prediction unit 126 then calculates a luminance correction parameter using information indicating how the luminance value has changed (step Sz_3).
- the inter prediction unit 126 generates a prediction image for the current block by performing luminance correction processing that applies the luminance correction parameter to the reference image in the reference picture specified by MV (step Sz_4). That is, correction based on the brightness correction parameter is performed on the predicted image, which is the reference image in the reference picture specified by the MV. In this correction, luminance may be corrected, and color difference may be corrected. That is, a color difference correction parameter may be calculated using information indicating how the color difference has changed, and color difference correction processing may be performed.
- the shape of the peripheral reference area in FIG. 66A is an example, and other shapes may be used.
- the prediction image may be generated after the brightness correction processing is performed by the same method as described above.
- lic_flag is a signal indicating whether to apply LIC.
- the encoding device 100 it is determined whether or not the current block belongs to an area in which luminance change occurs, and if it belongs to an area in which luminance change occurs, lic_flag A value of 1 is set and LIC is applied for encoding, and if it does not belong to an area where luminance change occurs, a value of 0 is set as lic_flag and encoding is performed without applying LIC.
- the decoding device 200 may decode lic_flag described in the stream, and perform decoding by switching whether to apply LIC according to the value.
- Another method of determining whether or not to apply LIC is, for example, a method of determining according to whether or not LIC has been applied to peripheral blocks.
- the inter prediction unit 126 applies LIC to the neighboring coded blocks selected when deriving the MV in merge mode. determine whether or not The inter prediction unit 126 performs encoding by switching whether to apply LIC according to the result. Note that the same processing is applied to the processing on the decoding device 200 side in this example as well.
- the LIC luminance correction processing
- the inter prediction unit 126 derives an MV for obtaining a reference image corresponding to the current block from a reference picture that is an encoded picture.
- the inter prediction unit 126 generates a predicted image for the current block by performing luminance correction processing on the reference image in the reference picture specified by the MV using the luminance correction parameter. For example, let p2 be the luminance pixel value in the reference image, and let p3 be the luminance pixel value of the predicted image after luminance correction processing.
- part of the peripheral reference area shown in FIG. 66A may be used.
- an area including a predetermined number of pixels thinned out from each of the upper adjacent pixels and the left adjacent pixels may be used as the peripheral reference area.
- the peripheral reference area is not limited to an area adjacent to the current block, and may be an area not adjacent to the current block.
- the surrounding reference area in the reference picture is the area specified by the MV of the current picture from the surrounding reference area in the current picture, but it is an area specified by another MV.
- the other MV may be the MV of the surrounding reference region within the current picture.
- LIC may be applied not only to luminance but also to color difference.
- correction parameters may be derived individually for each of Y, Cb, and Cr, or a common correction parameter may be used for any one of them.
- the LIC process may be applied on a sub-block basis.
- the correction parameter may be derived using the surrounding reference regions of the current sub-block and the surrounding reference regions of the reference sub-block in the reference picture specified by the MV of the current sub-block.
- the prediction control unit 128 selects either an intra-predicted image (image or signal output from the intra-prediction unit 124) or an inter-predicted image (image or signal output from the inter-prediction unit 126), and selects the selected predicted image. is output to subtraction section 104 and addition section 116 .
- the prediction parameter generating unit 130 may output information regarding intra prediction, inter prediction, selection of a predicted image in the prediction control unit 128, etc. to the entropy coding unit 110 as prediction parameters.
- the entropy coding unit 110 may generate a stream based on the prediction parameters input from the prediction parameter generation unit 130 and the quantization coefficients input from the quantization unit 108 .
- the prediction parameters may be used by the decoding device 200.
- the decoding device 200 may receive and decode the stream and perform the same prediction processing as the intra prediction section 124 , the inter prediction section 126 and the prediction control section 128 .
- the prediction parameters may be selected prediction signals (e.g., MV, prediction type, or prediction mode used by intra predictor 124 or inter predictor 126), or intra predictor 124, inter predictor 126 and prediction controller 128. may include any index, flag, or value based on or indicative of the prediction process performed in .
- FIG. 67 is a block diagram showing an example of the configuration of decoding device 200 according to the embodiment.
- the decoding device 200 is a device that decodes a stream, which is an encoded image, in units of blocks.
- decoding apparatus 200 includes entropy decoding section 202, inverse quantization section 204, inverse transform section 206, addition section 208, block memory 210, loop filter section 212, and frame memory 214. , an intra prediction unit 216 , an inter prediction unit 218 , a prediction control unit 220 , a prediction parameter generation unit 222 , and a partition determination unit 224 . Note that each of the intra prediction unit 216 and the inter prediction unit 218 is configured as part of the prediction processing unit.
- FIG. 68 is a block diagram showing an implementation example of the decoding device 200.
- the decoding device 200 comprises a processor b1 and a memory b2.
- a plurality of components of decoding device 200 shown in FIG. 67 are implemented by processor b1 and memory b2 shown in FIG.
- the processor b1 is a circuit that performs information processing and is a circuit that can access the memory b2.
- processor b1 is a dedicated or general purpose electronic circuit that decodes the stream.
- the processor b1 may be a processor such as a CPU.
- the processor b1 may be an assembly of a plurality of electronic circuits.
- the processor b1 may serve as a plurality of components of the decoding device 200 shown in FIG. 67 and the like, excluding a component for storing information.
- the memory b2 is a dedicated or general-purpose memory that stores information for the processor b1 to decode the stream.
- the memory b2 may be an electronic circuit and may be connected to the processor b1. Also, the memory b2 may be included in the processor b1. Also, the memory b2 may be an aggregate of a plurality of electronic circuits. Also, the memory b2 may be a magnetic disk, an optical disk, or the like, or may be expressed as a storage, recording medium, or the like. Also, the memory b2 may be a non-volatile memory or a volatile memory.
- the memory b2 may store an image or a stream.
- the memory b2 may also store a program for the processor b1 to decode the stream.
- the memory b2 may serve as a component for storing information among the plurality of components of the decoding device 200 shown in FIG. 67 and the like. Specifically, memory b2 may serve as block memory 210 and frame memory 214 shown in FIG. More specifically, the memory b2 may store reconstructed images (specifically, reconstructed blocks, reconstructed pictures, etc.).
- decoding device 200 may not implement all of the plurality of components shown in FIG. 67 and the like, and may not perform all of the plurality of processes described above. Some of the plurality of components shown in FIG. 67 and the like may be included in another device, and some of the plurality of processes described above may be executed by another device.
- each component included in the decoding device 200 will be described. It should be noted that, among the components included in the decoding device 200, those that perform the same processing as the components included in the encoding device 100 will not be described in detail.
- Unit 212 includes inverse quantization unit 112, inverse transform unit 114, addition unit 116, block memory 118, frame memory 122, intra prediction unit 124, inter prediction unit 126, prediction control unit 128, and the loop filter unit 120 perform the same processing.
- FIG. 69 is a flowchart showing an example of overall decoding processing by the decoding device 200.
- FIG. 69 is a flowchart showing an example of overall decoding processing by the decoding device 200.
- the partitioning determination unit 224 of the decoding device 200 determines a partitioning pattern for each of a plurality of fixed-size blocks (128 ⁇ 128 pixels) included in the picture based on the parameters input from the entropy decoding unit 202 ( Step Sp_1).
- This division pattern is a division pattern selected by encoding apparatus 100 .
- the decoding device 200 performs the processing of steps Sp_2 to Sp_6 for each of the plurality of blocks forming the division pattern.
- the entropy decoding unit 202 decodes (specifically, entropy decoding) the encoded quantization coefficients and prediction parameters of the current block (step Sp_2).
- the inverse quantization unit 204 and the inverse transform unit 206 restore the prediction residual of the current block by performing inverse quantization and inverse transform on the plurality of quantized coefficients (step Sp_3).
- the prediction processing unit consisting of the intra prediction unit 216, the inter prediction unit 218, and the prediction control unit 220 generates a prediction image of the current block (step Sp_4).
- the adding unit 208 reconstructs the current block into a reconstructed image (also referred to as a decoded image block) by adding the predicted image to the prediction residual (step Sp_5).
- the loop filter unit 212 filters the reconstructed image (step Sp_6).
- the decoding device 200 determines whether or not the decoding of the entire picture is completed (step Sp_7), and if it is determined that the decoding is not completed (No in step Sp_7), it repeats the processing from step Sp_1.
- steps Sp_1 to Sp_7 may be sequentially performed by the decoding device 200, some of the processes may be performed in parallel, and the order may be changed. good too.
- FIG. 70 is a diagram showing the relationship between the division determining section 224 and other components.
- the division determination unit 224 may perform the following processing.
- the division determination unit 224 collects block information from the block memory 210 or the frame memory 214, and further acquires parameters from the entropy decoding unit 202. Then, the division determination unit 224 may determine a division pattern for fixed-size blocks based on the block information and parameters. Then, the division determination section 224 may output information indicating the determined division pattern to the inverse transformation section 206 , the intra prediction section 216 and the inter prediction section 218 . The inverse transform section 206 may perform inverse transform on the transform coefficients based on the division pattern indicated by the information from the division determination section 224 . The intra prediction section 216 and the inter prediction section 218 may generate predicted images based on the division pattern indicated by the information from the division determination section 224 .
- FIG. 71 is a block diagram showing an example of the configuration of entropy decoding section 202. As shown in FIG.
- the entropy decoding unit 202 entropy-decodes the stream to generate quantization coefficients, prediction parameters, parameters related to division patterns, and the like.
- CABAC for example, is used for the entropy decoding.
- the entropy decoding unit 202 includes, for example, a binary arithmetic decoding unit 202a, a context control unit 202b, and a multi-level processing unit 202c.
- the binary arithmetic decoding unit 202a arithmetically decodes the stream into a binary signal using the context value derived by the context control unit 202b.
- context control section 202b derives a context value according to the features of syntax elements or the surrounding situation, that is, the probability of occurrence of a binary signal.
- the multi-value conversion unit 202c performs debinarization to convert the binary signal output from the binary arithmetic decoding unit 202a into a multi-value signal indicating the above-described quantization coefficient and the like. This multi-value conversion is performed according to the above-described binarization method.
- the entropy decoding unit 202 outputs the quantized coefficients to the inverse quantization unit 204 on a block basis.
- the entropy decoding unit 202 may output prediction parameters included in the stream (see FIG. 1) to the intra prediction unit 216, the inter prediction unit 218, and the prediction control unit 220.
- FIG. 1 The intra prediction unit 216, the inter prediction unit 218, and the prediction control unit 220 can execute the same prediction processing as the processing performed by the intra prediction unit 124, the inter prediction unit 126, and the prediction control unit 128 on the encoding device 100 side. .
- FIG. 72 is a diagram showing the flow of CABAC in entropy decoding section 202. As shown in FIG.
- CABAC in the entropy decoding unit 202 is initialized. In this initialization, initialization in the binary arithmetic decoding unit 202a and setting of initial context values are performed. Then, the binary arithmetic decoding unit 202a and the multi-value coding unit 202c execute arithmetic decoding and multi-value coding on, for example, CTU encoded data. At this time, the context control unit 202b updates the context value each time arithmetic decoding is performed. Then, the context control unit 202b saves the context value as post-processing. This saved context value is used, for example, for the initial context value for the next CTU.
- the inverse quantization unit 204 inversely quantizes the quantized coefficients of the current block that are input from the entropy decoding unit 202 . Specifically, the inverse quantization unit 204 inversely quantizes each quantized coefficient of the current block based on the quantization parameter corresponding to the quantized coefficient. The inverse quantization unit 204 then outputs the inversely quantized quantized coefficients (that is, transform coefficients) of the current block to the inverse transform unit 206 .
- FIG. 73 is a block diagram showing an example of the configuration of the inverse quantization section 204. As shown in FIG.
- the inverse quantization unit 204 includes, for example, a quantization parameter generation unit 204a, a predicted quantization parameter generation unit 204b, a quantization parameter storage unit 204d, and an inverse quantization processing unit 204e.
- FIG. 74 is a flowchart showing an example of inverse quantization by the inverse quantization unit 204.
- the inverse quantization unit 204 may perform inverse quantization processing for each CU based on the flow shown in FIG. Specifically, the quantization parameter generation unit 204a determines whether or not to perform inverse quantization (step Sv_11). Here, if it is determined to perform inverse quantization (Yes in step Sv_11), the quantization parameter generation unit 204a acquires the differential quantization parameter of the current block from the entropy decoding unit 202 (step Sv_12).
- the predicted quantization parameter generation unit 204b acquires a quantization parameter for a processing unit different from that of the current block from the quantization parameter storage unit 204d (step Sv_13).
- the predicted quantization parameter generation unit 204b generates the predicted quantization parameter of the current block based on the acquired quantization parameter (step Sv_14).
- the quantization parameter generation unit 204a adds the difference quantization parameter of the current block acquired from the entropy decoding unit 202 and the predicted quantization parameter of the current block generated by the prediction quantization parameter generation unit 204b. (Step Sv_15). This addition produces the quantization parameter for the current block. Also, the quantization parameter generation unit 204a stores the quantization parameter of the current block in the quantization parameter storage unit 204d (step Sv_16).
- the inverse quantization processing unit 204e inversely quantizes the quantization coefficients of the current block into transform coefficients using the quantization parameters generated in step Sv_15 (step Sv_17).
- differential quantization parameter may be decoded at the bit sequence level, picture level, slice level, brick level or CTU level.
- initial values of the quantization parameters may be decoded at the sequence level, picture level, slice level, brick level or CTU level.
- the quantization parameter may be generated using the initial value of the quantization parameter and the differential quantization parameter.
- the inverse quantization unit 204 may include a plurality of inverse quantizers, and may inversely quantize the quantized coefficients using an inverse quantization method selected from a plurality of inverse quantization methods.
- the inverse transform unit 206 restores the prediction residual by inverse transforming the transform coefficients input from the inverse quantization unit 204 .
- the inverse transform unit 206 converts the transform coefficients of the current block based on the information indicating the read transform type. to inverse transform.
- the inverse transform unit 206 applies inverse retransform to the transform coefficients.
- FIG. 75 is a flowchart showing an example of processing by the inverse transformation unit 206.
- the inverse transform unit 206 determines whether information indicating that orthogonal transform is not performed exists in the stream (step St_11). Here, if it is determined that the information does not exist (No in step St_11), the inverse transform unit 206 acquires the information indicating the transform type decoded by the entropy decoding unit 202 (step St_12). Next, inverse transform section 206 determines the transform type used for the orthogonal transform of encoding apparatus 100 based on the information (step St_13). Then, the inverse transform unit 206 performs inverse orthogonal transform using the determined transform type (step St_14).
- FIG. 76 is a flowchart showing another example of processing by the inverse transforming unit 206.
- FIG. 76 is a flowchart showing another example of processing by the inverse transforming unit 206.
- the inverse transform unit 206 determines whether the transform size is equal to or less than a predetermined value (step Su_11). Here, if it is determined that the value is equal to or less than the predetermined value (Yes in step Su_11), the inverse transform unit 206 selects which transform type among the one or more transform types included in the first transform type group is the encoding device. 100 is obtained from the entropy decoding unit 202 (step Su_12). Such information is decoded by entropy decoding section 202 and output to inverse transform section 206 .
- the inverse transform unit 206 determines the transform type used for the orthogonal transform in the encoding device 100 (step Su_13). Then, the inverse transform unit 206 inverse-orthogonal transforms the transform coefficients of the current block using the determined transform type (step Su_14). On the other hand, when the inverse transform unit 206 determines in step Su_11 that the transform size is not equal to or smaller than the predetermined value (No in step Su_11), the inverse transform unit 206 performs inverse orthogonal transform on the transform coefficients of the current block using the second transform type group (step Su_15).
- the inverse orthogonal transform by the inverse transform unit 206 may be performed according to the flow shown in FIG. 75 or 76 for each TU, as an example.
- the inverse orthogonal transform may be performed using a predefined transform type without decoding the information indicating the transform type used for the orthogonal transform.
- the transform type is specifically DST7 or DCT8, and the inverse orthogonal transform uses an inverse transform basis function corresponding to the transform type.
- the addition unit 208 adds the prediction residual input from the inverse transform unit 206 and the prediction image input from the prediction control unit 220 to reconstruct the current block. That is, a reconstructed image of the current block is generated.
- the adding section 208 then outputs the reconstructed image of the current block to the block memory 210 and the loop filter section 212 .
- the block memory 210 is a storage unit for storing blocks in the current picture that are referred to in intra prediction. Specifically, the block memory 210 stores the reconstructed image output from the adder 208 .
- a loop filter unit 212 applies a loop filter to the reconstructed image generated by the addition unit 208, and outputs the filtered reconstructed image to a frame memory 214, a display device, or the like.
- one filter is selected from among a plurality of filters based on the local gradient direction and activity, and is selected A filter is applied to the reconstructed image.
- FIG. 77 is a block diagram showing an example of the configuration of the loop filter section 212. As shown in FIG. Loop filter section 212 has the same configuration as loop filter section 120 of encoding apparatus 100 .
- the loop filter unit 212 includes a deblocking filter processing unit 212a, an SAO processing unit 212b, and an ALF processing unit 212c, as shown in FIG. 77, for example.
- the deblocking/filtering unit 212a performs the deblocking/filtering described above on the reconstructed image.
- the SAO processing unit 212b performs the above-described SAO processing on the reconstructed image after deblocking and filtering.
- the ALF processing unit 212c applies the above-described ALF processing to the reconstructed image after the SAO processing.
- the loop filter unit 212 may not include all the processing units disclosed in FIG. 77, and may include only some of the processing units.
- the loop filter unit 212 may be configured to perform each of the above processes in an order different from the process order disclosed in FIG. 77 .
- a frame memory 214 is a storage unit for storing reference pictures used for inter prediction, and is sometimes called a frame buffer. Specifically, the frame memory 214 stores the reconstructed image filtered by the loop filter unit 212 .
- FIG. 78 is a flowchart showing an example of processing performed by the prediction section of the decoding device 200.
- the prediction unit includes all or part of the intra prediction unit 216 , inter prediction unit 218 , and prediction control unit 220 .
- the prediction processing section includes, for example, an intra prediction section 216 and an inter prediction section 218 .
- the prediction unit generates a predicted image of the current block (step Sq_1).
- This predicted image is also called a predicted signal or a predicted block.
- the prediction signal includes, for example, an intra prediction signal or an inter prediction signal.
- the prediction unit predicts the current block using a reconstructed image already obtained by generating predicted images for other blocks, restoring prediction residuals, and adding predicted images. Generate an image.
- the prediction section of the decoding device 200 generates a predicted image that is the same as the predicted image generated by the prediction section of the encoding device 100 . In other words, the prediction image generation methods used by these prediction units are common or correspond to each other.
- the reconstructed image may be, for example, an image of a reference picture, or an image of a decoded block (that is, another block described above) in the current picture, which is the picture containing the current block.
- a decoded block in the current picture is, for example, a neighboring block of the current block.
- FIG. 79 is a flowchart showing another example of processing performed by the prediction unit of the decoding device 200.
- FIG. 79 is a flowchart showing another example of processing performed by the prediction unit of the decoding device 200.
- the prediction unit determines the method or mode for generating the predicted image (step Sr_1).
- the scheme or mode may be determined based on, for example, prediction parameters.
- the prediction unit determines the first method as the mode for generating the predicted image, it generates the predicted image according to the first method (step Sr_2a). Further, when the prediction unit determines the second method as the mode for generating the predicted image, it generates the predicted image according to the second method (step Sr_2b). Further, when the prediction unit determines the third method as the mode for generating the predicted image, it generates the predicted image according to the third method (step Sr_2c).
- the first method, the second method, and the third method are different methods for generating a predicted image, for example, an inter prediction method, an intra prediction method, and other prediction methods, respectively. There may be. These prediction schemes may use the reconstructed images described above.
- FIGS. 80A and 80B are flowcharts showing another example of processing performed by the prediction unit of the decoding device 200.
- FIG. 80A is a flowchart showing another example of processing performed by the prediction unit of the decoding device 200.
- the prediction unit may perform prediction processing according to the flow shown in FIGS. 80A and 80B as an example.
- the intra block copy shown in FIGS. 80A and 80B is one mode belonging to inter prediction, and is a mode in which blocks included in the current picture are referred to as reference images or reference blocks. In other words, intra-block copy does not refer to a picture different from the current picture.
- the PCM mode shown in FIG. 80A is one mode belonging to intra prediction, and is a mode in which transformation and quantization are not performed.
- the intra prediction unit 216 performs intra prediction with reference to blocks in the current picture stored in the block memory 210 based on the intra prediction mode read from the stream, thereby obtaining a prediction image of the current block (that is, an intra prediction image). generate a predicted image). Specifically, the intra prediction unit 216 generates an intra prediction image by performing intra prediction with reference to pixel values (for example, luminance values and color difference values) of blocks adjacent to the current block, and predicts the intra prediction image. Output to the control unit 220 .
- pixel values for example, luminance values and color difference values
- the intra prediction unit 216 may predict the chrominance component of the current block based on the luminance component of the current block.
- the intra prediction unit 216 corrects the pixel values after intra prediction based on the gradients of the reference pixels in the horizontal/vertical directions.
- FIG. 81 is a diagram showing an example of processing by the intra prediction unit 216 of the decoding device 200.
- FIG. 81 is a diagram showing an example of processing by the intra prediction unit 216 of the decoding device 200.
- the intra prediction unit 216 first determines whether an MPM flag indicating 1 exists in the stream (step Sw_11). Here, if it is determined that there is an MPM flag indicating 1 (Yes in step Sw_11), the intra prediction unit 216 transmits information indicating the intra prediction mode selected in the encoding device 100 from the entropy decoding unit 202, out of the MPM. obtain (step Sw_12). The information is decoded by entropy decoding section 202 and output to intra prediction section 216 . Next, the intra prediction unit 216 determines MPM (step Sw_13). MPM consists of six intra prediction modes, for example. Then, the intra prediction unit 216 determines the intra prediction mode indicated by the information acquired in step Sw_12 from among the intra prediction modes included in the MPM (step Sw_14).
- the intra prediction unit 216 determines in step Sw_11 that the MPM flag indicating 1 does not exist in the stream (No in step Sw_11), it acquires information indicating the intra prediction mode selected in the encoding device 100 ( Step Sw_15). That is, the intra prediction unit 216 acquires from the entropy decoding unit 202 information indicating the intra prediction mode selected in the encoding device 100 among one or more intra prediction modes not included in the MPM. The information is decoded by entropy decoding section 202 and output to intra prediction section 216 . Then, the intra prediction unit 216 determines an intra prediction mode indicated by the information acquired in step Sw_15 from one or more intra prediction modes not included in the MPM (step Sw_17).
- the intra prediction unit 216 generates a predicted image according to the intra prediction mode determined in step Sw_14 or step Sw_17 (step Sw_18).
- the inter prediction unit 218 refers to reference pictures stored in the frame memory 214 to predict the current block. Prediction is performed in units of the current block or sub-blocks within the current block. A sub-block is included in a block and is a smaller unit than the block. The sub-block size may be 4x4 pixels, 8x8 pixels, or any other size. The sub-block size may be switched in units of slices, bricks, pictures, or the like.
- the inter prediction unit 218 performs motion compensation using motion information (e.g., MV) read from a stream (e.g., prediction parameters output from the entropy decoding unit 202) to perform inter prediction of the current block or sub-block.
- motion information e.g., MV
- a stream e.g., prediction parameters output from the entropy decoding unit 202
- a predicted image is generated and an inter predicted image is output to the prediction control unit 220 .
- the inter prediction unit 218 When the information read from the stream indicates that the OBMC mode is applied, the inter prediction unit 218 performs inter prediction using not only the motion information of the current block obtained by motion search, but also the motion information of adjacent blocks. Generate an image.
- the inter prediction unit 218 performs motion search according to the pattern matching method (bilateral matching or template matching) read from the stream. to derive the motion information. Then, the inter prediction unit 218 performs motion compensation (prediction) using the derived motion information.
- the pattern matching method bilateral matching or template matching
- the inter prediction unit 218 derives the MV based on a model that assumes uniform linear motion. Also, when the information read from the stream indicates that the affine mode is applied, the inter prediction unit 218 derives MVs in units of subblocks based on MVs of a plurality of adjacent blocks.
- FIG. 82 is a flowchart showing an example of MV derivation in the decoding device 200.
- FIG. 82 is a flowchart showing an example of MV derivation in the decoding device 200.
- the inter prediction unit 218, determines whether to decode motion information (eg, MV). For example, the inter prediction unit 218 may make the determination according to the prediction mode included in the stream, or may make the determination based on other information included in the stream.
- the inter prediction unit 218 determines whether to decode the motion information. For example, the inter prediction unit 218 derives the MV of the current block in the mode of decoding the motion information.
- inter prediction section 218 determines not to decode motion information, it derives MV in a mode in which motion information is not decoded.
- MV derivation modes include normal inter mode, normal merge mode, FRUC mode, and affine mode, which will be described later.
- modes for decoding motion information include normal inter mode, normal merge mode, and affine mode (specifically, affine inter mode and affine merge mode).
- the motion information may include not only the MV but also predicted MV selection information, which will be described later.
- Modes in which motion information is not decoded include FRUC mode and the like.
- the inter prediction unit 218 selects a mode for deriving the MV of the current block from these multiple modes, and uses the selected mode to derive the MV of the current block.
- FIG. 83 is a flowchart showing another example of MV derivation in the decoding device 200.
- FIG. 83 is a flowchart showing another example of MV derivation in the decoding device 200.
- the inter prediction unit 218, determines whether to decode the difference MV. may be determined based on Here, when determining to decode the difference MV, the inter prediction unit 218 may derive the MV of the current block in the mode of decoding the difference MV. In this case, for example, the difference MV included in the stream is decoded as a prediction parameter.
- the inter prediction unit 218 determines not to decode the difference MV, it derives the MV in a mode in which the difference MV is not decoded. In this case, the coded differential MV is not included in the stream.
- MV derivation modes include normal inter, normal merge mode, FRUC mode, and affine mode, which will be described later.
- modes for encoding differential MVs include normal inter mode and affine mode (more specifically, affine inter mode).
- Modes in which differential MVs are not encoded include FRUC mode, normal merge mode, and affine mode (specifically, affine merge mode).
- the inter prediction unit 218 selects a mode for deriving the MV of the current block from these multiple modes, and uses the selected mode to derive the MV of the current block.
- the inter prediction unit 218 derives the MV in the normal merge mode based on the information read from the stream, and converts the MV to motion compensation (prediction).
- FIG. 84 is a flowchart showing an example of inter prediction in normal inter mode in decoding device 200.
- FIG. 84 is a flowchart showing an example of inter prediction in normal inter mode in decoding device 200.
- the inter prediction unit 218 of the decoding device 200 performs motion compensation on each block. At this time, the inter prediction unit 218 first acquires a plurality of candidate MVs for the current block based on information such as MVs of a plurality of decoded blocks temporally or spatially surrounding the current block. (Step Sg_11). That is, the inter prediction unit 218 creates a candidate MV list.
- the inter prediction unit 218 selects each of N (N is an integer equal to or greater than 2) candidate MVs from among the plurality of candidate MVs acquired in step Sg_11 as predicted motion vector candidates (also referred to as predicted MV candidates). , and extracted according to a predetermined priority (step Sg_12). The priority order is predetermined for each of the N predicted MV candidates.
- the inter prediction unit 218 decodes the prediction MV selection information from the input stream, and uses the decoded prediction MV selection information to select one prediction MV candidate from among the N prediction MV candidates. , as the prediction MV of the current block (step Sg_13).
- the inter prediction unit 218 decodes the difference MV from the input stream, and adds the difference value, which is the decoded difference MV, and the selected prediction MV, thereby deriving the MV of the current block. (step Sg_14).
- the inter prediction unit 218 generates a predicted image of the current block by performing motion compensation on the current block using the derived MV and the decoded reference picture (step Sg_15).
- the processing of steps Sg_11 to Sg_15 is performed for each block. For example, when the processing of steps Sg_11 to Sg_15 is executed for each of all blocks included in a slice, inter prediction using normal inter mode for that slice ends. Also, when the processing of steps Sg_11 to Sg_15 is executed for each of all the blocks included in the picture, the inter prediction using the normal inter mode for that picture ends.
- steps Sg_11 to Sg_15 are not performed for all blocks included in the slice, and if performed for some blocks, inter prediction using the normal inter mode for that slice ends. may Similarly, when the processing of steps Sg_11 to Sg_15 is performed on some blocks included in a picture, inter prediction using normal inter mode for that picture may end.
- the inter prediction unit 218 derives the MV in the normal merge mode and performs motion compensation (prediction) using the MV.
- FIG. 85 is a flowchart showing an example of inter prediction in normal merge mode in decoding device 200.
- the inter prediction unit 218 first obtains a plurality of candidate MVs for the current block based on information such as MVs of a plurality of decoded blocks temporally or spatially surrounding the current block (step Sh_11 ). That is, the inter prediction unit 218 creates a candidate MV list.
- the inter prediction unit 218 derives the MV of the current block by selecting one candidate MV from the plurality of candidate MVs acquired in step Sh_11 (step Sh_12). Specifically, the inter prediction unit 218 acquires MV selection information included in the stream as a prediction parameter, for example, and selects a candidate MV identified by the MV selection information as the MV of the current block.
- the inter prediction unit 218 generates a predicted image of the current block by performing motion compensation on the current block using the derived MV and the decoded reference picture (step Sh_13).
- the processing of steps Sh_11 to Sh_13 is executed for each block, for example. For example, when the processing of steps Sh_11 to Sh_13 is executed for each of all blocks included in a slice, inter prediction using normal merge mode for that slice ends. Also, when the processing of steps Sh_11 to Sh_13 is executed for each of all the blocks included in the picture, inter prediction using the normal merge mode for that picture ends. Note that the processing of steps Sh_11 to Sh_13 is not executed for all blocks included in the slice, and if it is executed for some blocks, inter prediction using the normal merge mode for that slice ends. may Similarly, when the processing of steps Sh_11 to Sh_13 is performed on some blocks included in a picture, inter prediction using the normal merge mode for that picture may end.
- the inter prediction unit 218 derives the MV in the FRUC mode and performs motion compensation (prediction) using the MV.
- the motion information is derived by the decoding device 200 side without being signaled from the encoding device 100 side.
- the decoding device 200 may derive motion information by performing motion search. In this case, the decoding device 200 performs motion search without using the pixel values of the current block.
- FIG. 86 is a flowchart showing an example of inter prediction in the FRUC mode in decoding device 200.
- the inter prediction unit 218 refers to the MVs of the decoded blocks that are spatially or temporally adjacent to the current block, and refers to a list indicating these MVs as candidate MVs (that is, a candidate MV list that is normal (which may be common with the merge mode candidate MV list) is generated (step Si_11).
- the inter prediction unit 218 selects the best candidate MV from among multiple candidate MVs registered in the candidate MV list (step Si_12). For example, the inter prediction unit 218 calculates the evaluation value of each candidate MV included in the candidate MV list, and selects one candidate MV as the best candidate MV based on the evaluation value.
- the inter predictor 218 then derives the MV for the current block based on the selected best candidate MV (step Si_14).
- the selected best candidate MV is directly derived as the MV for the current block.
- the MV for the current block may be derived by performing pattern matching in the region around the location in the reference picture corresponding to the selected best candidate MV. That is, the area around the best candidate MV is searched using pattern matching and evaluation value in the reference picture, and if there is an MV with a good evaluation value, the best candidate MV is set to that MV. It may be updated to make it the final MV of the current block. Updates to MVs with better evaluation values may not be performed.
- the inter prediction unit 218 generates a predicted image of the current block by performing motion compensation on the current block using the derived MV and the decoded reference picture (step Si_15).
- the processing of steps Si_11 to Si_15 is executed for each block, for example. For example, when the processing of steps Si_11 to Si_15 is executed for each of all the blocks included in the slice, inter prediction using the FRUC mode for that slice ends. Further, when the processing of steps Si_11 to Si_15 is executed for each of all the blocks included in the picture, inter prediction using the FRUC mode for that picture ends.
- Sub-block units may also be processed in the same manner as the block units described above.
- MV derivation > affine merge mode For example, if the information read from the stream indicates application of the affine merge mode, the inter prediction unit 218 derives the MV in the affine merge mode and performs motion compensation (prediction) using the MV.
- FIG. 87 is a flow chart showing an example of inter prediction in the affine merge mode in the decoding device 200.
- the inter prediction unit 218 first derives the MV of each control point of the current block (step Sk_11).
- the control points are the upper left and upper right corner points of the current block, as shown in FIG. 46A, or the upper left, upper right, and lower left corner points of the current block, as shown in FIG. 46B.
- the inter prediction unit 218 when using the MV derivation method shown in FIGS. 47A to 47C, the inter prediction unit 218 includes, as shown in FIG. 47A, decoded block A (left), block B (top), block C (upper right), We examine these blocks in order, block D (lower left) and block E (upper left), to identify the first valid block decoded in affine mode.
- Inter predictor 218 uses the first valid block decoded in the identified affine mode to derive the MV of the control points. For example, if block A is identified and block A has two control points, inter predictor 218 calculates motion vector v 3 for the upper left and upper right corners of the decoded block containing block A, as shown in FIG. 47B. and v4 onto the current block to compute the motion vector v0 of the upper left corner control point and the motion vector v1 of the upper right corner control point of the current block. This derives the MV of each control point.
- the inter prediction unit 218 may derive the MV of each control point of the current block using the MV selection information.
- the inter prediction unit 218 performs motion compensation on each of the multiple sub-blocks included in the current block. That is, the inter prediction unit 218 uses two motion vectors v 0 and v 1 and Equation (1A) above for each of the plurality of sub-blocks, or three motion vectors v 0 , v 1 and v 2 and equation (1B) above, the MV of the sub-block is calculated as an affine MV (step Sk_12). Then, the inter prediction unit 218 performs motion compensation on the sub-block using those affine MVs and decoded reference pictures (step Sk_13).
- the inter prediction using the affine merge mode for the current block ends. That is, motion compensation is performed on the current block to generate a predicted image of the current block.
- the aforementioned candidate MV list may be generated.
- the candidate MV list may be, for example, a list containing candidate MVs derived using multiple MV derivation methods for each control point. Multiple MV derivation methods, MV derivation method shown in FIGS. 47A to 47C, MV derivation method shown in FIGS. 48A and 48B, MV derivation method shown in FIGS. 49A and 49B, and other MV derivation Any combination of methods may be used.
- the candidate MV list may include candidate MVs for modes other than the affine mode that perform prediction in units of subblocks.
- a candidate MV list including affine merge mode candidate MVs having two control points and affine merge mode candidate MVs having three control points may be generated.
- a candidate MV list including affine merge mode candidate MVs with two control points and a candidate MV list including affine merge mode candidate MVs with three control points may be generated respectively.
- a candidate MV list including candidate MVs in one of the affine merge mode with two control points and the affine merge mode with three control points may be generated.
- the inter prediction unit 218 derives the MV in the affine inter mode and performs motion compensation (prediction) using the MV.
- FIG. 88 is a flowchart showing an example of inter prediction in affine inter mode in decoding device 200.
- the inter predictor 218 first derives predictions MV (v 0 ,v 1 ) or (v 0 ,v 1 ,v 2 ) for each of the two or three control points of the current block ( Step Sj_11).
- the control point is, for example, the upper left corner, upper right corner, or lower left corner point of the current block, as shown in FIG. 46A or 46B.
- the inter prediction unit 218 acquires prediction MV selection information included in the stream as a prediction parameter, and uses MVs identified by the prediction MV selection information to derive prediction MVs for each control point of the current block. For example, when using the MV derivation method shown in FIGS. 48A and 48B, the inter prediction unit 218 identifies by the prediction MV selection information among the decoded blocks near each control point of the current block shown in FIG. 48A or 48B. We derive the predicted MVs (v 0 ,v 1 ) or (v 0 ,v 1 ,v 2 ) of the control points of the current block by selecting the MVs of the blocks to be calculated.
- the inter prediction unit 218 acquires, for example, each difference MV included as a prediction parameter in the stream, and adds the prediction MV of each control point of the current block and the difference MV corresponding to the prediction MV (step Sj_12). This derives the MV of each control point of the current block.
- the inter prediction unit 218 performs motion compensation on each of the multiple sub-blocks included in the current block. That is, the inter prediction unit 218 uses two motion vectors v 0 and v 1 and Equation (1A) above for each of the plurality of sub-blocks, or three motion vectors v 0 , v 1 and v 2 and equation (1B) above, the MV of the sub-block is calculated as an affine MV (step Sj_13). Then, the inter prediction unit 218 performs motion compensation on the sub-block using those affine MVs and decoded reference pictures (step Sj_14).
- inter prediction using the affine merge mode for the current block ends. That is, motion compensation is performed on the current block to generate a predicted image of the current block.
- step Sj_11 the candidate MV list described above may be generated as in step Sk_11.
- the inter prediction unit 218 derives the MV in the triangle mode and performs motion compensation (prediction) using the MV.
- FIG. 89 is a flow chart showing an example of inter prediction in triangle mode in the decoding device 200.
- FIG. 89 is a flow chart showing an example of inter prediction in triangle mode in the decoding device 200.
- the inter prediction unit 218 divides the current block into a first partition and a second partition (step Sx_11). At this time, the inter prediction unit 218 may acquire partition information, which is information about division into partitions, from the stream as a prediction parameter. Then, the inter prediction unit 218 may divide the current block into a first partition and a second partition according to the partition information.
- the inter prediction unit 218 first acquires multiple candidate MVs for the current block based on information such as the MVs of multiple decoded blocks temporally or spatially surrounding the current block. (Step Sx_12). That is, the inter prediction unit 218 creates a candidate MV list.
- the inter prediction unit 218 selects the candidate MV for the first partition and the candidate MV for the second partition as the first MV and the second MV, respectively, from among the plurality of candidate MVs acquired in step Sx_11 (step Sx_13). .
- the inter prediction unit 218 may acquire MV selection information for identifying the selected candidate MV from the stream as a prediction parameter. Then, the inter prediction unit 218 may select the first MV and the second MV according to the MV selection information.
- the inter prediction unit 218 performs motion compensation using the selected first MV and the decoded reference picture to generate a first predicted image (step Sx_14). Similarly, the inter prediction unit 218 performs motion compensation using the selected second MV and the decoded reference picture to generate a second predicted image (step Sx_15).
- the inter prediction unit 218 generates a predicted image of the current block by weighted addition of the first predicted image and the second predicted image (step Sx_16).
- FIG. 90 is a flowchart showing an example of motion search by DMVR in the decoding device 200.
- FIG. 90 is a flowchart showing an example of motion search by DMVR in the decoding device 200.
- the inter prediction unit 218 first derives the MV of the current block in merge mode (step Sl_11). Next, the inter prediction unit 218 derives the final MV for the current block by searching the surrounding area of the reference picture indicated by the MV derived in step Sl_11 (step Sl_12). That is, DMVR determines the MV of the current block.
- FIG. 91 is a flowchart showing a detailed example of motion search by DMVR in the decoding device 200.
- FIG. 91 is a flowchart showing a detailed example of motion search by DMVR in the decoding device 200.
- the inter prediction unit 218 calculates the costs at the search position indicated by the initial MV (also referred to as the starting point) and the eight search positions surrounding it. Then, the inter prediction unit 218 determines whether or not the cost of search positions other than the starting point is the lowest. Here, if the inter prediction unit 218 determines that the search position other than the starting point has the lowest cost, it moves to the search position with the lowest cost, and performs the processing of Step 2 shown in FIG. 58A. On the other hand, if the cost of the starting point is the lowest, the inter prediction unit 218 skips the processing of Step 2 shown in FIG. 58A and performs the processing of Step 3.
- Step 2 shown in FIG. 58A the inter prediction unit 218 performs the same search as in Step 1 using the search position moved according to the processing result of Step 1 as a new starting point. Then, the inter prediction unit 218 determines whether or not the cost of search positions other than the starting point is the lowest. Here, the inter prediction unit 218 performs the processing of Step 4 if the cost of the search positions other than the starting point is the minimum. On the other hand, the inter prediction unit 218 performs the processing of Step 3 if the cost of the starting point is the minimum.
- Step 4 the inter prediction unit 218 treats the search position of the starting point as the final search position, and determines the difference between the position indicated by the initial MV and the final search position as a difference vector.
- the inter prediction unit 218 determines the decimal-precision pixel position with the lowest cost based on the costs at the four points above, below, and to the left and right of the starting point of Step 1 or Step 2, and uses that pixel position as the final pixel position. Search position.
- the decimal-precision pixel position is expressed by the four-point vectors ((0, 1), (0, -1), (-1, 0), (1, 0)) at the top, bottom, left, and right, respectively. is determined by weighted addition using the cost at the search position of .
- the inter prediction unit 218 determines the difference between the position indicated by the initial MV and its final search position as a difference vector.
- BIO/OBMC/LIC For example, if the information read from the stream indicates application of correction of the predicted image, the inter prediction unit 218 corrects the predicted image according to the mode of correction when generating the predicted image.
- the modes are, for example, BIO, OBMC, and LIC described above.
- FIG. 92 is a flowchart showing an example of predicted image generation in the decoding device 200.
- the inter prediction unit 218 generates a predicted image (step Sm_11), and corrects the predicted image according to one of the modes described above (step Sm_12).
- FIG. 93 is a flowchart showing another example of predicted image generation in the decoding device 200.
- FIG. 93 is a flowchart showing another example of predicted image generation in the decoding device 200.
- the inter prediction unit 218 derives the MV of the current block (step Sn_11). Next, the inter prediction unit 218 generates a predicted image using the MV (step Sn_12), and determines whether or not to perform correction processing (step Sn_13). For example, the inter prediction unit 218 acquires prediction parameters included in the stream, and determines whether or not to perform correction processing based on the prediction parameters. This prediction parameter is, for example, a flag indicating whether to apply each mode described above.
- the inter prediction unit 218 determines to perform correction processing (Yes in step Sn_13), it generates a final predicted image by correcting the predicted image (step Sn_14). Note that in LIC, the luminance and color difference of the predicted image may be corrected in step Sn_14.
- the inter prediction unit 218 determines not to perform correction processing (No in step Sn_13), it outputs the predicted image as a final predicted image without correcting it (step Sn_15).
- FIG. 94 is a flowchart showing an example of prediction image correction by OBMC in the decoding device 200.
- the inter prediction unit 218 acquires a predicted image (Pred) by normal motion compensation using the MV assigned to the current block, as shown in FIG.
- the inter prediction unit 218 applies (rides) the MV (MV_L) already derived for the decoded left adjacent block to the current block to acquire a predicted image (Pred_L). Then, the inter prediction unit 218 performs the first correction of the predicted image by overlapping the two predicted images Pred and Pred_L. This has the effect of blending the boundaries between adjacent blocks.
- the inter prediction unit 218 applies (rides) the MV (MV_U) already derived for the decoded upper adjacent block to the current block to obtain a predicted image (Pred_U). Then, the inter prediction unit 218 performs the second correction of the predicted image by superimposing the predicted image Pred_U on the predicted images (for example, Pred and Pred_L) that have undergone the first correction. This has the effect of blending the boundaries between adjacent blocks.
- the predicted image obtained by the second correction is the final predicted image of the current block in which the boundaries with adjacent blocks are blended (smoothed).
- BIO For example, if the information read from the stream indicates application of BIO, the inter prediction unit 218 corrects the predicted image according to BIO when generating the predicted image.
- FIG. 95 is a flowchart showing an example of predicted image correction by BIO in the decoding device 200 .
- the inter prediction unit 218 derives two motion vectors (M0, M1) using two reference pictures (Ref0, Ref1) different from the picture containing the current block (Cur Pic). .
- the inter prediction unit 218 then derives a predicted image of the current block using the two motion vectors (M0, M1) (step Sy_11).
- the motion vector M0 is the motion vector (MVx0, MVy0) corresponding to the reference picture Ref0
- the motion vector M1 is the motion vector (MVx1, MVy1) corresponding to the reference picture Ref1.
- the inter prediction unit 218 derives the interpolated image I0 of the current block using the motion vector M0 and the reference picture L0. Also, the inter prediction unit 218 derives the interpolated image I1 of the current block using the motion vector M1 and the reference picture L1 (step Sy_12 ).
- the interpolated image I0 is the image contained in the reference picture Ref0 derived for the current block
- the interpolated image I1 is the image contained in the reference picture Ref1 derived for the current block. It is an image.
- Interpolated image I0 and interpolated image I1 may each be the same size as the current block.
- interpolated image I0 and interpolated image I1 may each be images larger than the current block in order to properly derive the gradient images described below. Further, the interpolated images I0 and I1 may include prediction images derived by applying motion vectors (M0, M1) and reference pictures (L0, L1) and motion compensation filters.
- the inter prediction unit 218 also derives the gradient images (Ix 0 , Ix 1 , Iy 0 , Iy 1 ) of the current block from the interpolated images I 0 and I 1 (step Sy_13). Note that the horizontal gradient image is (Ix 0 , Ix 1 ) and the vertical gradient image is (Iy 0 , Iy 1 ). Inter-predictor 218 may derive the gradient image, for example, by applying a gradient filter to the interpolated image.
- the gradient image may be any image that indicates the amount of spatial variation in pixel values along the horizontal or vertical direction.
- the inter prediction unit 218 uses the interpolated images (I 0 , I 1 ) and the gradient images (Ix 0 , Ix 1 , Iy 0 , Iy 1 ) for each of a plurality of sub-blocks that make up the current block.
- An optical flow (vx, vy), which is a velocity vector of , is derived (step Sy_14).
- a sub-block may be a sub-CU of 4x4 pixels.
- the inter prediction unit 218 corrects the predicted image of the current block using the optical flow (vx, vy). For example, the inter prediction unit 218 uses the optical flow (vx, vy) to derive the correction value of the pixel value included in the current block (step Sy_15). Then, the inter prediction unit 218 may correct the predicted image of the current block using the correction value (step Sy_16). Note that the correction value may be derived for each pixel, or may be derived for a plurality of pixels or sub-blocks.
- BIO processing flow is not limited to the processing disclosed in FIG. Only a part of the processes disclosed in FIG. 95 may be performed, different processes may be added or replaced, or the processes may be performed in a different order.
- FIG. 96 is a flowchart showing an example of prediction image correction by LIC in the decoding device 200 .
- the inter prediction unit 218 uses MV to obtain a reference image corresponding to the current block from the decoded reference picture (step Sz_11).
- the inter prediction unit 218 extracts information indicating how the luminance value of the current block has changed between the reference picture and the current picture (step Sz_12). This extraction is specified by the luminance pixel values of the decoded left adjacent reference region (peripheral reference region) and the decoded upper adjacent reference region (peripheral reference region) in the current picture and the derived MV, as shown in FIG. 66A. This is done based on the luminance pixel value at the equivalent position in the reference picture. The inter prediction unit 218 then calculates a luminance correction parameter using information indicating how the luminance value has changed (step Sz_13).
- the inter prediction unit 218 generates a prediction image for the current block by performing luminance correction processing that applies the luminance correction parameter to the reference image in the reference picture specified by MV (step Sz_14). That is, correction based on the brightness correction parameter is performed on the predicted image, which is the reference image in the reference picture specified by the MV. In this correction, luminance may be corrected, and color difference may be corrected.
- the prediction control unit 220 selects either an intra-predicted image or an inter-predicted image, and outputs the selected predicted image to the adding unit 208 .
- the configurations, functions, and processes of prediction control section 220, intra prediction section 216, and inter prediction section 218 on the decoding device 200 side are similar to prediction control section 128, intra prediction section 124, and inter prediction section 128 on the encoding device 100 side. It may correspond to the configuration, function, and processing of unit 126 .
- VVC Very Video Coding subpicture
- a feature of VVC subpictures is that they are designed so that they can be easily extracted from and merged into the bitstream.
- FIG. 97 shows exemplary VVC sub-picture extraction.
- the first bitstream includes two subpictures: subpicture 971 with subpicture index 0 and subpicture 972 with subpicture index 1 .
- a sub-picture within a full-picture is identified by a sub-picture index.
- one subpicture can be extracted (S977) to create a new bitstream (second bitstream).
- each subpicture is assigned a unique subpicture identifier (subpicture ID) that can be mapped to the subpicture index of the subpicture within the full picture.
- subpicture ID subpicture identifier
- SPS Sequence Parameter Set
- PPS Picture Parameter Set
- unique refers to the unambiguous identification of sub-pictures within one or more video pictures to which SPS or PPS are applicable.
- the new bitstream now consists of a subpicture 975 corresponding to the extracted subpicture 972, but with a subpicture index of 0. This is because a subpicture index identifies a subpicture only within a full picture.
- the subpicture index is 0 (instead of 1, which subpicture 972 had in the first bitstream).
- the sub-picture ID of the sub-picture 975 is the same as that of the sub-picture 972, the sub-picture is uniquely identified.
- Subpictures were originally designed for immersive video. However, according to some aspects of this disclosure, subpictures may also be used in other applications.
- a content provider offers a mosaic of multiple pictures from which the user can select one or more pictures for display, as shown in FIG.
- Mosaic in this context refers to an arrangement of multiple sub-pictures that may be displayed to a user to allow the user to select one or more of the multiple sub-pictures.
- FIG. 98 An example of a personalization service is shown in FIG. 98, where a provider provides a mosaic picture 981 composed of multiple VVC subpictures (with subpicture IDs 0, 1, 2 and 3) from which the user can select which picture You can choose to display
- the mosaic has 4K resolution, while the sub-picture has HD (High Definition) resolution.
- a mosaic picture is a still image, which is a single picture, or a video, which is multiple pictures.
- the user selects one sub-picture, namely the sub-picture with sub-picture ID 1 (S983).
- Selection can be made in any known manner, such as entering a subpicture index via a remote control, keyboard or numeric keys.
- the input may be assisted by a graphical user interface that allows highlighting of the currently (preliminarily) selected subpicture 985 .
- a selection may then be made by confirming the preliminary selection, such as by pressing an OK button, enter, another confirmation input, or a voice command.
- a selected sub-picture 989 may then be extracted and decoded from the mosaic bitstream (S987) and displayed in HD resolution.
- extraction means that the sub-bitstreams of the sub-pictures are separated without necessarily decoding the sub-bitstreams carrying the remaining sub-pictures (0, 2 and 3) of the full (mosaic) picture 981 ( be deciphered).
- Decoding refers to reconstructing the sub-pictures from the bitstream, eg for the purpose of displaying them on a display device.
- 4K resolution generally refers to a picture resolution of approximately 8 megapixels, roughly corresponding to a vertical or horizontal size of 4000 pixels.
- the pixels correspond to luminance samples, for example.
- Pictures with 4K resolution are also referred to as 4K pictures.
- a 4K picture may have different vertical and horizontal sizes.
- 4K pictures may also have various different aspect ratios such as 4096x2160, 3996x2160, 3996x1716, 3840x2160 or 3840x2400. These numbers indicate the number of columns by the number of rows, or horizontal by vertical resolution in units of pixels (samples).
- HD resolution or full HD resolution typically refers to a picture resolution of 1920x1080, resulting in approximately 4 megapixels per picture. However, the term may also apply to other aspect ratios around 4 megapixels.
- Some known codec technologies such as VVC or HEVC, have mechanisms for dividing a picture into multiple regions, such as slices and/or tiles, for encoding and decoding. Slices and tiles are supported only if their size is an integer multiple of a certain preset coding unit size.
- Such preset coding unit size may be the size of a coding tree unit, may be fixed (defined in the standard), or may be for a sequence of pictures, or for pictures, etc. It may be configurable.
- sub-pictures are added with a mechanism that eliminates dependencies with other regions, making it possible to encode and decode multiple sub-pictures completely independently. be.
- VVC Video Coding Extension
- FIG. 99 shows difficulties in creating a 4K mosaic video 990 from 2 ⁇ 2 HD videos 991, 992, 993 and 994.
- Packing the 4 HD videos as a 2 ⁇ 2 array into a 4K Mosaic Video 990 the bottom border of the top HD video does not correspond to a CTU boundary and therefore cannot correspond to a subpicture boundary. This precludes the use of one sub-picture per HD video.
- CTU 998 placed across the boundary of HD videos 992 and 994 .
- the lower boundary of the HD video does not correspond to the CTU boundary means that the lower boundary of the HD video and the CTU boundary do not match.
- the HD pictures are video pictures.
- the present disclosure is equally applicable to still pictures. Codecs like VVC, HEVC or EVC support a still picture mode in which still pictures are encoded instead of video. In such mode no temporal prediction is applied. This disclosure is also equally applicable to any still image codec (including those that do not support video coding).
- Diagram 100 shows a specific non-limiting exemplary implementation that can be applied to address the above difficulties.
- Four HD videos 1001, 1002, 1003 and 1004 of 1920 ⁇ 1080 resolution are packed into a 4K mosaic video 1000 of 3840 ⁇ 2160 resolution encoded with a CTU size of 128 ⁇ 128.
- 72 padding pixel rows 1006 are added above the video signal to allow one subpicture per HD video.
- a padding pixel row 1006 is added above the mosaic picture 1000 so that subpictures 1001 and 1002 have a vertical size of 1152 pixels corresponding to 9 CTUs instead of an HD vertical size of 1080 pixels.
- the remaining subpictures 1003 and 1004 maintain the HD vertical size of 1080 pixels. This is possible because known codecs typically have some mechanism for handling full picture dimensions that do not align to integer multiples of the CTU size at the bottom and right edges of the picture.
- each of the four subpictures 1001, 1002, 1003 and 1004 can be encoded independently of the other subpictures, even though only the top subpictures 1001 and 1002 are integer multiples of the CTU size.
- padding pixel rows are similarly added to the lower side of the sub-pictures without using the above mechanism so that the sub-pictures are encoded after making the CTU size an integer multiple.
- the subpicture may be coded after adding a few rows of padding pixels to the bottom of the subpicture to a size that allows the above mechanism to work efficiently.
- the resulting mosaic picture may be larger than 4K and contain useless padding pixel rows. Therefore, in the decoding device the padding pixels may be removed before display or further processing.
- a VVC conformance cropping window may be used to remove padding pixels.
- cropping corresponds to trimming.
- VVC subpictures are designed to share the same conformance cropping window as full pictures.
- the VVC conformance cropping window is rewritten based on the position of the sub-picture within the full picture.
- FIG. 101 shows a table of examples of different settings for sub-pictures and mosaic video encoded with different CTU sizes.
- the picture has a 4:2:0 chroma format where the width in the chroma samples is half the width in the luma samples and the height in the chroma samples is half the height in the luma samples. be.
- This table also contains signaling information that may be associated with each configuration in the VVC SPS (Sequence Parameter Set).
- chrominance is subsampled, such signaling per chroma sample may offer advantages over signaling per luma sample. This narrows the range of values and makes the signaling more compact.
- the present disclosure is not limited to specific units indicating size (dimension). Signaling regarding luma samples may also be done, especially if chrominance is not sub-sampled.
- the first column of the table shows the syntax element name.
- the second column of the table shows the value settings for each syntax element name in a scenario where there is 2x2 HD video combined into one 4K mosaic picture and the CTU size is 128x128 as in Figure 100. indicates
- the third column of the table shows the value settings for each syntax element name in a scenario where there is 2x2 HD video combined into one 4K mosaic picture and the CTU size is 64x64.
- Column 4 of the table shows the value settings for each syntax element name in a scenario where there are 2 ⁇ 2 4K videos combined into one 8K mosaic picture and the CTU size is 128 ⁇ 128.
- the table in FIG. 101 shows the SPS elements described below.
- the parameter sps_pic_width_max_in_luma_samples indicates the maximum width in luma samples of each decoded full picture that references the SPS.
- the parameter sps_pic_height_max_in_luma_samples indicates the maximum height in luma samples of each decoded full picture that references the SPS.
- the parameter pps_pic_width_in_luma_samples indicates the width in luma samples of each decoded full picture that references the PPS and is less than or equal to sps_pic_width_max_in_luma_samples signaled in the referenced SPS.
- the parameter pps_pic_height_in_luma_samples indicates the height in luma samples of each decoded full picture referencing the PPS, less than or equal to sps_pic_height_max_in_luma_samples signaled in the referenced SPS.
- the parameter sps_conformance_window_flag when equal to 1, indicates that the conformance cropping window offset parameter follows in SPS.
- sps_conformance_window_flag if equal to 0, indicates that the conformance cropping window offset parameter is not present in the SPS.
- sps_conf_win_left_offset, sps_conf_win_right_offset, sps_conf_win_top_offset and sps_conf_win_bottom_offset indicate cropping windows.
- pps_pic_width_in_luma_samples equals sps_pic_width_max_in_luma_samples and pps_pic_height_in_luma_samples equals sps_pic_height_max_in_luma_samples indicates the cropping window in samples.
- the conformance cropping window offset parameter is applied only at the output. All internal decoding processes are applied to the uncropped picture size.
- sps_conf_win_top_offset not equal to 0 as in the example of FIG. 101
- the value of sps_conformance_window_flag is equal to 1.
- the parameter sps_num_subpics_minus1 plus 1 indicates the number of subpictures in each picture of the video sequence. If not present, the value of sps_num_subpics_minus1 is assumed to be equal to zero.
- the parameter sps_independent_subpics_flag if equal to 1, indicates that all sub-picture boundaries in the video sequence are treated as picture boundaries, there is no loop filtering across sub-picture boundaries, and sub-pictures in a picture can be decoded independently of each other. . If not present, the value of sps_independent_subpics_flag is assumed to be equal to one.
- sps_subpic_width_minus1[i] plus 1 indicates the width of the i-th subpicture in units of CtbSizeY, which is the CTU width in luma samples used in the bitstream.
- the parameter sps_subpic_height_minus1[i] plus 1 indicates the height of the i-th subpicture in CtbSizeY units, which is the CTU height in luma samples used in the bitstream.
- CTU is defined by a single size CtbSizeY both vertically and horizontally in luminance samples, as it is assumed to be square.
- the parameter sps_subpic_same_size_flag when equal to 1, indicates that all sub-pictures in the video sequence have the same width indicated by sps_subpic_width_minus1[0] plus 1 and the same height indicated by sps_subpic_height_minus1[0] plus 1. If sps_subpic_same_size_flag is equal to 0, no such constraint is imposed. If not present, the value of sps_subpic_same_size_flag is assumed to be equal to zero.
- the table in FIG. 101 shows exemplary settings that may be used to implement subpicture padding to multiples of the CTU size.
- the second column of the table shows a 4K mosaic picture (full picture) embedded with 4 HD videos arranged in 2 rows and 2 columns, with a CTU size of 128 ⁇ 128 (corresponding to the example in FIG. 100).
- the signaling by setting sps_num_subpics_minus1 to 3 (meaning 4 subpictures), sps_independent_subpics_flag to 1, and sps_subpic_same_size_flag to 1 (indicating that all subpictures have the same size) can be done.
- a mosaic picture before conformance cropping has a resolution of 3840 (width) x 2232 (height).
- the width 3840 is equal to 30 times the CTU size of 128 samples, but the height 2232 is not divisible by 128.
- a width of 30 CTUs per mosaic picture means 15 CTUs per subpicture, so a value of 14 is signaled by sps_subpic_width_minus1[0]. Based on sps_subpic_height_minus1[0] with a value of 8, the height of each subpicture is 9 CTU, resulting in a height of 2304 samples.
- the decoding device hierarchically divides the coding unit blocks at the bottom boundary of the image so that the blocks cover only the resolution height of 2232 luma samples. , so as not to cover more. This means that the 72 rows where there are no "pixels" of luma samples will not be decoded at the lower boundary.
- an upper conformance cropping window offset with a value of 36 is signaled. Therefore, 72 rows of luma samples (4:2:0 video in FIG. 101 is assumed, the number of luma samples is twice the number of chroma samples) and 36 rows of chroma samples are cropped at the decoder from the top of the picture. So, after applying conformance cropping, we have a decoded picture with a resolution of 3840 ⁇ 2160.
- a method for encoding a picture 1000 into a bitstream.
- This picture contains one or more subpictures 1001 , 1002 , 1003 , 1004 .
- the method is illustrated in Figure 102 and includes obtaining a first sub-picture from two or more sub-pictures of a (mosaic) picture (S1021).
- the size of the first sub-picture in at least one direction is not an integral multiple of the preset coding unit size.
- the height was not an integer multiple of the CTU size.
- the horizontal (width) direction may not be an integer multiple of the CTU size.
- the CTU in the above example was a square, so it was the same size in both dimensions, but similar processing is possible if the CTU is a rectangle with different widths and heights.
- the preset coding unit size is the CTU size, but it is not limited to this, and may be fixed (defined in the standard), or may be a sequence of pictures. , or may be settable for pictures or the like.
- the method further includes padding (1023) the first sub-picture in at least one direction (eg, width or height) to reach a size that is an integer multiple of the preset coding unit size.
- padding may be performed to achieve the size of the nearest integer multiple of the preset coding unit size. Padding is done before the actual encoding and may be understood as part of the encoding or as a kind of pre-processing before encoding, for example.
- the method employs a step S1025 of encoding one or more sub-pictures including the padded first sub-picture (eg 1001, 1002) into a bitstream.
- the padded first subpicture and the remaining subpictures of the picture are coded independently of each other.
- the bitstream has the advantageous property that the sub-pictures are also independently decodable, thus allowing parallel decoding to be employed.
- the method includes step S1027 of encoding cropping information indicating the amount of padding into the bitstream.
- the cropping information was indicated in the bitstream as a parameter of the cropping window, eg, as predicted in VVC.
- a parameter of the cropping window eg, as predicted in VVC.
- different syntax elements may be used and the method need not apply to codecs that already have cropping windows. Rather, syntax containing such cropping information may be added to any codec.
- the bitstream contains cropping information within the parameter set applicable to the picture.
- the parameter set was the SPS known from VVC and other codecs.
- the present disclosure is not limited to such specific parameter sets. Rather, any parameter set embedded in the bitstream in any manner may be used.
- a parameter set could be a PPS, or some hypothetical parameter set, or the parameters could be embedded within another structure.
- the first sub-picture is padded with the first number of top rows and/or the first number of left columns of samples.
- the number of padding rows is added (prepended) to the sub-picture above.
- the number of padding columns is added (prepended) to the left subpicture.
- additional rows of padding left and/or top non-border subpictures for each vertical or horizontal padding may not be required.
- the cropping information indicates the number of first upper sample rows and/or the number of first left sample columns in luminance sample units or chrominance sample units. For some implementations, this may be the same as indicating the number of first top rows of samples and/or the number of first left columns of samples that are padded.
- FIG. 103 shows an example of a method for decoding sub-pictures from a bitstream.
- the method includes decoding (S1031) cropping information from the bitstream indicating an amount of cropping in at least one direction (also called dimension, meaning, for example, vertical and/or horizontal).
- the method includes step S1033 of decoding the sub-pictures from the bitstream.
- a subpicture is the first subpicture of two or more subpictures of a (mosaic) picture contained in the bitstream. Two or more subpictures are independently decodable from each other.
- the size of the decoded first sub-picture in at least one direction is an integer multiple of the preset coding unit size.
- the method further includes cropping the decoded first sub-picture according to the indicated cropping amount in at least one direction S1035. Cropping may be implemented by simply discarding (deleting) padded rows and/or columns (during the encoding method as described with reference to FIG. 102) at the encoder side.
- the method may further comprise outputting the cropped sub-picture (S1037), eg, for display purposes or for further processing purposes.
- a bitstream contains cropping information in parameter sets applicable to pictures.
- the parameter set may be SPS, PPS, or any general parameter set.
- the cropping information indicates the number of first top rows and/or first left columns of samples to be removed from the first decoded sub-picture.
- FIG. 104 is a flowchart showing a more detailed processing example for creating a mosaic bitstream.
- width equals 1920 and height equals 1080.
- Other values may be, for example, 3840 for width and 2160 for height.
- the CTU size 'ctusize' is selected for mosaic encoding (S1042).
- One such value of ctusize may be equal to 128 for a CTU of size 128 ⁇ 128 pixels, for example.
- Another possible value might be 64 for a 64 ⁇ 64 pixel size CTU.
- selection steps S1041 and S1042 are exemplary and may, but do not necessarily include, actual selection based on criteria or conditions.
- sub-pictures eg, HD video
- S1041 sub-pictures
- they are inputs to processing as specified by the embodiments of this disclosure.
- selecting the CTU size may correspond to simply obtaining the CTU size.
- the CTU size may be fixed, for example given by the applied codec or the encoding application that uses the codec, or may be selected by the application or by the user of the encoding application.
- the CTU size, or the size of the basic coding unit may also differ in different directions, resulting in It may be non-square.
- steps S1043 and S1044 correspond to height processing.
- the variable "subpichgt" representing the height of the subpicture in CTU units
- the nearest integer value (floor function) less than the sum of height and ctusize minus 1 divided by ctusize is calculated as follows (S1043 ) is done.
- variable "padrows" representing the number of padding pixel rows to be added above the mosaic video is determined as follows by multiplying subpichgt by ctusize and subtracting height (S1044).
- variable subpichgt 9 and the variable padrows equals 72.
- subpicwdt floor ((width+ctusize-1) / ctusize)
- variable "padcols" representing the number of padding pixel columns to be added to the left of the mosaic video is determined as follows by multiplying subpicwdt by ctusize and subtracting width (S1046).
- padcols subpicwdt*ctusize-width
- variable subpicwdt 15 and the variable padcols equals zero.
- the mosaic video is then created by concatenating the four videos into a 2-by-2 grid and adding padrows padding pixel rows above the videos and padcols padding pixel columns to the left of the videos. (S1047).
- the mosaic video is encoded (S1048), eg, in VVC, and the associated SPS (Sequence Parameter Set) syntax elements are set to create a mosaic bitstream.
- sps_pic_width_max_in_luma_samples is set equal to the sum of double width and padcols.
- sps_pic_height_max_in_luma_samples is set equal to the sum of double height and padrows.
- the sps_conformance_window_flag is set to 1 to signal that there is a conformance cropping window with a non-zero offset.
- the top and left offsets of the conformance cropping window are set based on the padrows, padcols, and chrominance format of the video content.
- the number of subpictures in the mosaic video sps_num_subpics_minus1 is set equal to 3 to signal the presence of 4 subpictures corresponding to the 4 videos in the mosaic. Also, the sub-pictures are signaled as independently coded by setting sps_independent_subpic_flag equal to 1, which allows all sub-pictures to be decoded individually.
- the sps_subpic_same_size_flag is also set to 1 to signal that all four subpictures have the same size in CTU size units.
- the size of each subpicture is also signaled by setting sps_subpic_width_minus1[0] and sps_subpic_height_minus1[0] to subpicwdt minus 1 and subpichgt minus 1, respectively. Then, the resulting mosaic bitstream is output and the process ends.
- the (mosaic) picture has 4K resolution and the two or more sub-pictures are two or four sub-pictures, each with HD (High Definition) resolution.
- 4K resolution may correspond to dimensions of 3840 ⁇ 2160 samples
- HD resolution may correspond to dimensions of 1920 ⁇ 1080 samples.
- the present disclosure is not limited to 4K/HD. As shown in the last column of the table in FIG. 101, 8K or other resolutions may be used for mosaic pictures, and resolutions other than HD may be used for sub-pictures.
- the resolution of any picture and/or sub-picture may be signaled in the bitstream.
- both the encoder and decoder operate at a signaled resolution, e.g. given the width and height in samples or in some predefined units such as coding units. may be configured to
- the cropping information includes VVC conformance cropping window syntax elements such as sps_conformance_window_flag, sps_conf_win_top_offset and/or sps_conf_win_left_offset.
- VVC conformance cropping window tools This allows existing VVC conformance cropping window tools to be used for the specific purpose of providing sub-pictures (parts of the bitstream) that can be independently encoded and decoded. It may be advantageous to use SPS for conformance cropping window signaling.
- SPS conformance cropping window signaling
- this disclosure is not limited to SPS, nor is it limited to application in the context of VVC encoding and decoding in general.
- the same syntax element may be conveyed with different parameter sets (PPS, VPS, SEI, etc.). Codecs known or to be developed may implement the present disclosure.
- the subpictures may be encoded separately from each other. Therefore, they may be encoded in parallel, at least in part. This may speed up the encoding process.
- the encoding method includes including in the bitstream a parameter set that includes settings for two or more sub-pictures within a picture. Additionally, the method includes providing a subpicture identification for a subpicture within the bitstream such that the identification is associated with the encoded bitstream portion that includes the identified subpicture. As noted above, the encoding method also includes encoding the subpictures identified by their respective subpicture identifications into the bitstream.
- a bitstream generated by an encoding device may provide a subpicture identification in the bitstream so that a decoding device can retrieve portions of the bitstream containing the desired subpictures without having to decode portions of the bitstream containing other subpictures.
- bitstream is a Versatile Video Coding (VVC) compliant bitstream.
- VVC Versatile Video Coding
- a parameter set is a sequence parameter set (SPS) or a picture parameter set (PPS).
- the number of subpictures in a picture is given by sps_num_subpics_minus1. Whether the sizes of multiple subpictures of a picture are the same is given by sps_subpic_same_size_flag.
- the size of multiple subpictures in at least one direction is given by sps_subpic_width_minus1 and/or sps_subpic_height_minus1.
- the size of the picture in at least one direction is given by the parameters described above: sps_pic_width_max_in_luma_samples and/or sps_pic_height_max_in_luma_samples.
- This disclosure is not limited to using features of VVCs or sub-pictures within VVCs. In general, it may be advantageous to provide at least one of the following indicators to support subpictures.
- two or more decoded sub-pictures have the same size in at least one direction, and in at least one direction the pictures are consecutive It may be advantageous to ensure that the first sub-picture and the second sub-picture that are aligned consist. No padding or cropping is applied to the decoded second subpicture.
- sub-pictures at the bottom and/or right boundary of a picture are aligned in the vertical and/or horizontal direction (dimension ) need not be an integer multiple of the CTU size.
- Such boundary subpictures may be processed by other mechanisms, such as existing mechanisms of existing codecs.
- One such existing mechanism is hierarchical partitioning of CTUs at picture boundaries (ie, partitioning).
- the second subpicture (eg, 1003 and/or 1004) is included in the bitstream according to the bitstream syntax and is segmented in at least one direction as follows.
- the remaining coding units are further hierarchically segmented into smaller coding units.
- Some smaller coding units may be square or rectangular. Such segmentation is hierarchically repeated until picture boundaries and coding unit boundaries coincide. Note that additional padding to the bottom/right of the second sub-picture may reduce the number of hierarchically repeated segmentations.
- the size of the second sub-picture is an integral multiple of the CTU size by padding the bottom/right of the second sub-picture without using the above mechanism at the bottom/right boundary of the picture.
- the values of sps_conf_win_bottom_offset and sps_conf_win_right_offset may be set according to the number of padding pixel rows added. Also, in this case, values may be added to sps_pic_width_max_in_luma_samples and sps_pic_height_max_in_luma_samples.
- all subpictures in a picture have the same size in at least one direction.
- a picture consists of two or more subpictures arranged in succession. Padding (at the encoder) and corresponding cropping (at the decoder) are applied to all two or more subpictures in at least one direction. This implementation works independently regardless of the specific handling of picture boundaries by the codec to which it applies.
- bitstream structure that allows independent encoding and decoding of sub-pictures.
- independent encodability and decodability may be achieved in synergy with existing frameworks such as independently encodable and decodable bitstream structures provided by existing codecs. good.
- a bitstream includes pictures encoded with multiple slices and multiple tiles.
- Each slice and each tile contains data corresponding to only one subpicture.
- slices and tiles are parts of a picture that can be encoded independently, ie the entropy encoder/decoder is restarted at least for each new slice or tile.
- each sub-picture of a picture is encoded into a single slice and a single tile. Since there is only one slice/tile per subpicture, such encoding and corresponding decoding is efficient and reduces syntax overhead. Moreover, such a setting simplifies the operation of the decoding device when extracting one sub-picture from the mosaic bitstream into the sub-bitstream and decoding the sub-picture, as described below.
- the slicing and tiling settings may be provided within the bitstream, particularly within a parameter set such as the PPS.
- the parameter pps_no_pic_partition_flag when equal to 1, indicates that no picture partitioning is applied to each picture referencing the PPS.
- the parameter pps_no_pic_partition_flag when equal to 0, indicates that each picture referencing the PPS may be partitioned into multiple tiles or multiple slices.
- pps_num_exp_tile_columns_minus1 plus 1 indicates the number of tile column widths explicitly provided.
- the value of pps_num_exp_tile_columns_minus1 ranges from 0 to PicWidthInCtbsY-1. If pps_no_pic_partition_flag is equal to 1, the value of pps_num_exp_tile_columns_minus1 is assumed to be equal to 0.
- PicWidthInCtbsY is a variable that indicates the size (width) of the picture in multiples of CTU in the horizontal direction.
- a CTU is referred to herein as a CTB (coding tree block).
- pps_num_exp_tile_rows_minus1 plus 1 indicates the number of tile row heights explicitly provided.
- the value of pps_num_exp_tile_rows_minus1 should range from 0 to PicHeightInCtbsY-1. If pps_no_pic_partition_flag is equal to 1, the value of num_tile_rows_minus1 is assumed to be equal to 0.
- PicHeightInCtbsY is a variable that indicates the size (height) of the picture in multiples of CTU in the vertical direction.
- the parameter pps_tile_column_width_minus1[i] plus 1 indicates the width in CTB units of the i-th tile column for i ranging from 0 to pps_num_exp_tile_columns_minus1.
- the parameter pps_tile_column_width_minus1 [pps_num_exp_tile_columns_minus1] is also used to derive the width of the tile column whose index is greater than pps_num_exp_tile_columns_minus1.
- pps_tile_column_width_minus1[i] ranges from 0 to PicWidthInCtbsY-1. If not present, the value of pps_tile_column_width_minus1[0] is assumed to be equal to PicWidthInCtbsY-1.
- the parameter pps_tile_row_height_minus1[0] plus 1 indicates the height of the i-th tile row for i ranging from 0 to pps_num_exp_tile_rows_minus1 in CTB units.
- the parameter pps_tile_row_height_minus1 [pps_num_exp_tile_rows_minus1] is also used to derive the height of the tile row whose index is greater than pps_num_exp_tile_rows_minus1.
- pps_tile_row_height_minus1[i] ranges from 0 to PicHeightInCtbsY-1. If not present, the value of pps_tile_row_height_minus1[0] is assumed to be equal to PicHeightInCtbsY-1.
- pps_loop_filter_across_tiles_enabled_flag when equal to 1, indicates that in-loop filtering across tile boundaries is enabled for pictures referencing PPS.
- pps_loop_filter_across_tiles_enabled_flag if equal to 0, indicates that in-loop filtering across tile boundaries is disabled for pictures referencing PPS.
- In-loop filter operations include deblocking filter, SAO and ALF operations. If pps_loop_filter_across_tiles_enabled_flag is not present, the value of pps_loop_filter_across_tiles_enabled_flag is assumed to be equal to 0.
- the parameter pps_rect_slice_flag when equal to 0, indicates that raster scan slice mode is used for each picture referencing the PPS and slice layout is not signaled in the PPS.
- pps_rect_slice_flag when equal to 1, indicates that rectangular slice mode is used for each picture referencing the PPS and the slice layout is signaled in the PPS. If not present, the value of pps_rect_slice_flag is assumed to be equal to one.
- pps_single_slice_per_subpic_flag when equal to 1, indicates that each subpicture consists of only one rectangular slice.
- pps_single_slice_per_subpic_flag if equal to 0, indicates that each subpicture may consist of one or more rectangular slices. If pps_no_pic_partition_flag is equal to 1, then the value of pps_single_slice_per_subpic_flag is assumed to be equal to 1.
- pps_single_slice_per_subpic_flag 1 means that there is only one slice per picture.
- the parameter pps_loop_filter_across_slices_enabled_flag when equal to 1, indicates that in-loop filtering across slice boundaries is enabled for pictures referencing PPS.
- the parameter pps_loop_filter_across_slice_enabled_flag if equal to 0, indicates that in-loop filtering across slice boundaries is disabled for pictures referencing PPS.
- In-loop filter operations include deblocking filter, SAO and ALF operations. If pps_loop_filter_across_slices_enabled_flag is not present, the value of pps_loop_filter_across_slices_enabled_flag is assumed to be equal to 0.
- the above parameters are exemplary and based on VVC. They allow different settings of slices and tiles to match different possible sizes of the sub-pictures that make up the mosaic picture. They show that subpictures of arbitrary size and shape may be encoded and decoded independently using slices and tiles.
- each subpicture consists of only one tile and one slice as described above. It may be useful to indicate that Thus, an encoder may set the relevant PPS (Picture Parameter Set) syntax elements for the examples of FIGS. 100 and 101 as follows.
- PPS Picture Parameter Set
- pps_no_pic_partition_flag 0
- pps_num_exp_tile_columns_minus1 0
- pps_num_exp_tile_rows_minus1 0
- pps_tile_column_width_minus1[0] sps_subpic_width_minus1[0]
- pps_tile_row_height_minus1[0] sps_subpic_height_minus1[0]
- pps_loop_filter_across_tiles_enabled_flag 0
- pps_rect_slice_flag 1
- pps_single_slice_per_subpic_flag 1 (9)
- pps_loop_filter_across_slices_enabled_flag 0
- the PPS corresponding to the extracted sub-pictures can be rewritten very simply by simply setting the syntax element pps_no_pic_partition_flag equal to 1 and simply discarding the remaining parameters from the PPS. good.
- PPS rewriting refers to the procedure performed when separating a sub-bitstream corresponding to a sub-picture from a bitstream of a mosaic picture for the purpose of decoding only the sub-bitstream corresponding to the sub-picture at a decoding device.
- Another possibility that simplifies the rewriting of the PPS when extracting one of the sub-pictures may be to indicate that each sub-picture consists of only one tile.
- the PPS syntax would be the same as above, except that pps_single_slice_per_subpic_flag would be equal to 0, and there would be syntax in the PPS to signal the slice size and location.
- the decoding device can use information from the PPS of the entire bitstream to determine and decode the tiles/slices contained within the sub-pictures. PPS may not be rewritten.
- the present disclosure is not limited to codecs that support VVC or one or both of slices and tiles.
- FIG. 105 shows a flowchart for receiving, deciphering/decoding a mosaic bitstream on the decoding device side.
- a mosaic bitstream is a bitstream containing an encoded picture (still or video) consisting of multiple subpictures that can be decoded independently of the decoding of other subpictures of the picture.
- the user can select one of the sub-pictures that make up the mosaic as the preferred picture for display. This may be done by an application that includes a graphical user interface that provides the user with a selection of sub-pictures, or may be done based on previously captured user preferences or the like.
- subpictures for display may not be selected.
- embodiments of the present disclosure are also applicable to some intermediate encoding or recording, etc., in which case immediate display may not occur, while one or more subpictures ( (not all) substreams may be decoded and/or stored.
- decoding may simply be extracting the relevant part belonging to the selected (one or more) sub-pictures from the bitstream and rewriting the corresponding parameter sets, etc., or such extraction and May include rewriting.
- the selection for example, decodes and displays the entire mosaic video (not necessarily all frames of the video, but possibly one or more mosaic picture frames, etc.), and displays the mosaic to the user. It is presented to the user by asking him to select one of the videos to compose.
- the variable selID represents the subpicture identifier corresponding to this preferred (selected) subpicture.
- the variables are obtained by the method of associating displayed subpictures with subpicture indices, as described above with reference to FIGS.
- step S1054 the subpicture index spIdx is determined such that selID is equal to sps_subpic_id[spIdx] if the subpicture identifier is signaled in the SPS. Also, if a sub-picture identifier is signaled in the PPS, the sub-picture index spIdx is determined such that selID is equal to pps_subpic_id[spIdx].
- the sub-picture index spIdx is determined such that selID is equal to spIdx.
- the sub-picture (spIdx) is sub-picture sub-bitstream extraction processing as described in, for example, the VVC specification (see Annex C.7 (non-patent document) of ITU-T H.266 (08/2020)) is extracted from the mosaic bitstream using spIdx as input.
- the SPS and PPS for the sub-picture bitstream are rewritten according to the extraction process based on the SPS and PPS for the entire mosaic bitstream.
- step S1058 the extracted sub-picture bitstream containing only the NAL units corresponding to the sub-picture with identifier selID is decoded and the resulting video selected by the user is displayed instead of the mosaic video. Then the process ends.
- Arrangements according to some aspects may employ VVC sub-pictures for user personalization of video content, thereby allowing the user to select several different videos for display, aggregated within the mosaic video. is presented. If the bitstream is correctly encoded with sub-pictures as in this disclosure, it is possible to extract and decode only the sub-pictures intended for display at the receiver and thereby not intended for display. To avoid wasting computing resources by not decoding an image.
- the exemplary embodiment described with reference to FIG. 105 offers the advantage of being easily applicable within the VVC framework.
- the present disclosure is not limited to such developments of encoding and decoding methods and apparatus.
- methods for decoding subpictures from a bitstream generally take input from a user that includes a subpicture selection that selects subpictures of a picture without decoding another one or more subpictures of the picture. , decoding the first sub-picture from the bitstream according to the sub-picture selection.
- another one or more subpictures may not necessarily be all of the rest.
- the user may select multiple sub-pictures.
- Decoding in an exemplary implementation parses from the bitstream a parameter set that includes settings for two or more subpictures in the picture and determines subpicture identities for selected subpictures according to the parsed settings. Including.
- the method decodes from the bitstream a portion of a picture corresponding to a selected subpicture identified by the determined subpicture identification and decodes a portion corresponding to at least one subpicture other than the selected subpicture of the same picture. It may further include not doing.
- Interpreted settings include, for example, the number of subpictures in a picture, whether the subpictures of a picture are the same size, the size of the subpictures in at least one direction, and the size of the subpictures in at least one direction. Contains at least one of the picture sizes.
- a picture portion may be one or more NAL units (NALUs), or any bitstream portion that generally corresponds to one or more desired sub-pictures, or the like.
- NALUs NAL units
- bitstream generated on the encoding device side may be decoded by the decoding device side, the above features related to the bitstream related to the encoding device side can also be applied to the decoding device side.
- the mosaic picture Eight padding pixel rows may be added below the .
- a 4K mosaic picture encoded with a CTU size of 128 ⁇ 128 consists of 4 HD sub-pictures
- 72 padding pixel rows may be added below the mosaic picture.
- only 8 padding pixel rows may be added below the mosaic picture to avoid automatic splitting into very narrow rectangular CTUs at the bottom borders of the two bottom subpictures.
- each sub-picture may be padded to the top and/or left of the sub-picture.
- Implementations are possible in which the padding is split and some of the multiple lines are added to the top and/or left and the remaining padding lines are added to the bottom and/or right.
- Some aspects support using conformance cropping windows to enable creation of mosaic video from VVC sub-pictures of sizes that do not correspond to multiples of the CTU size used for encoding.
- the encoding device is a mosaic bitstream from multiple smaller videos encoded with padding pixel rows that may be above the mosaic or padding pixel columns that may be to the left of the mosaic, one subpicture per video. to create Padding rows or columns are signaled using conformance cropping offsets.
- the decoding device then extracts the relevant subpictures for the user from the mosaic bitstream, decodes them, and displays only the relevant subpictures, whereby the padding pixels are subdivided according to the signaled conformance cropping offsets. Cropped from picture.
- the decoding device reduces wastage of computational resources by decoding only sub-pictures intended for display.
- a row of padding pixels is added to shift the bottom boundary of the video to correspond to the CTU boundary within the mosaic video, allowing sub-picture boundaries to exist at the bottom boundary.
- padding pixel columns are added to allow sub-picture boundaries to exist at the right boundary.
- Each sub-picture may contain only one tile to simplify PPS rewriting during sub-picture extraction, or each sub-picture may contain one tile to simplify PPS rewriting during sub-picture extraction. It may contain only slices and one tile.
- One or more aspects disclosed herein may be implemented in combination with at least some of the other aspects of the present disclosure. Also, part of the processing, part of the configuration of the device, part of the syntax, etc. described in the flowcharts of one or more aspects disclosed herein may be implemented in combination with other aspects.
- a decoding device for decoding sub-pictures from a bitstream.
- the decoding device includes processing circuitry.
- the processing circuitry of the decoding device is configured to decode from the bitstream cropping information indicating the amount of cropping in at least one direction.
- the processing circuitry is further configured to decode the subpictures from the bitstream.
- a subpicture is the first subpicture of two or more subpictures of a picture included in the bitstream. Two or more subpictures are independently decodable from each other.
- the size of the decoded first sub-picture is an integer multiple of the preset coding unit size.
- the processing circuitry of the decoding device is further configured to crop the decoded first sub-picture according to the indicated cropping amount in at least one direction.
- a device for encoding a picture including sub-pictures into a bitstream.
- the apparatus may comprise processing circuitry configured to obtain a first sub-picture of the two or more sub-pictures of the picture. In at least one direction, the size of the first sub-picture is not an integer multiple of the preset coding unit size.
- the processing circuitry of the encoding device is further configured to pad the first sub-picture in at least one direction to reach a size that is an integral multiple of the preset coding unit size.
- the processing circuitry is further configured to encode the padded first sub-picture into the bitstream, wherein the padded first sub-picture and the remaining sub-pictures of the picture are encoded independently of each other.
- the processing circuitry is configured to encode cropping information indicative of the amount of padding into the bitstream.
- the processing circuitry in the encoding device and/or in the decoding device may be any combination of software and hardware.
- the processing circuitry may be one or more processors configured by software (code instructions) retrieved from memory.
- the encoder and/or decoder may include memory. Exemplary implementations of the encoder and decoder are described further below.
- the processing circuitry of the encoding device and decoding device may be further configured to perform any of the steps described herein for the method.
- an encoding device may comprise modules implemented in any hardware. Such modules may, for example, be:
- An input terminal to which at least one image is input (2) A block divider that divides a first image included in at least one image into a plurality of blocks (3) Using a reference image included in the first image , an intra predictor that predicts a block included in the first image; (4) an inter predictor that predicts a block included in the first image using a reference block included in the second image that is different from the first image; ) a loop filter that filters the blocks contained in the first image; (7) a quantizer that quantizes the transform coefficients to generate quantized coefficients; (8) an entropy encoder that variable-length codes the quantized coefficients to generate an encoded bitstream; An output terminal where the coded bitstream containing the quantization coefficients and control information is output.
- a mosaic bitstream is created from a small video that is encoded with one subpicture per video, including padding pixel rows that can be above the mosaic or padding pixel columns that can be to the left of the mosaic. be.
- a padding row or padding column is signaled using a conformance cropping offset.
- the decoding device may include the following modules.
- Input terminal to which encoded bitstream is input (2) Decoder (entropy decoder, etc.) that decodes encoded bitstream and outputs quantization coefficients (3) An inverse quantizer that inversely quantizes the quantized coefficients and outputs transform coefficients (4) An inverse transformer that inverse transforms the transform coefficients and outputs prediction errors (5) A reference picture included in the first image (6) an inter predictor that predicts a block included in the first image using a reference block included in the second image that is different from the first image; ) A loop filter that filters blocks included in the first image. (8) An output terminal to which a picture including the first image is output.
- the input terminal extracts the sub-pictures to be decoded that are relevant to the user from the mosaic bitstream, and the output terminal displays only the relevant sub-pictures, whereby the padding pixels are the signaled conformance cropping offsets. are cropped from subpictures according to
- padding pixel rows are added and the lower boundary of the video in the mosaic video is shifted to correspond to the CTU boundary, thereby allowing sub-picture boundaries to exist at the lower boundary.
- a padding pixel column is added to shift the right boundary of the video in the mosaic video to correspond to the CTU boundary, thereby allowing subpicture boundaries to exist at the right boundary.
- each subpicture may contain only one tile.
- each subpicture may contain only one slice and one tile.
- a program includes code instructions stored on a computer-readable, non-transitory medium.
- the code instructions when executed by one or more processors, cause the one or more processors to perform any of the methods described above.
- the bitstream includes cropping information in the parameter set applicable to the picture, and the cropping information is removed from the first decoded subpicture. indicates the first top row number of samples and/or the first left sample column number.
- the cropping information includes VVC conformance cropping window syntax elements sps_conformance_window_flag, sps_conf_win_top_offset, and/or sps_conf_win_left_offset.
- the encoder-side method and corresponding encoder further take input from a user including a sub-picture selection that selects a first sub-picture of a picture, without decoding other sub-pictures of the picture. , decoding the first sub-picture according to the sub-picture selection from the bitstream.
- decoding reads from the bitstream a parameter set that includes settings for two or more subpictures in the picture, determines a subpicture identity for the selected first subpicture according to the settings that are read, and determines decoding from the bitstream of the picture a portion corresponding to the selected first subpicture identified by the selected subpicture identification, and decoding a portion corresponding to at least one subpicture other than the selected first subpicture of the same picture; Including what not to do.
- the settings read may be the number of subpictures in a picture, whether subpictures of a picture are the same size, the size of subpictures in at least one direction, and the size of subpictures in at least one direction. Contains at least one of the picture sizes.
- the bitstream is a VVC (Versatile Video Coding) compliant bitstream
- the parameter set is a sequence parameter set (SPS) or a picture parameter set (PPS).
- SPS sequence parameter set
- PPS picture parameter set
- the number of subpictures in a picture is given by sps_num_subpics_minus1, and whether or not the sizes of a plurality of subpictures in a picture are the same is given by sps_subpic_same_size_flag.
- the size of multiple subpictures in at least one direction is given by sps_subpic_width_minus1 and/or sps_subpic_height_minus1. Also, the size of the picture in at least one direction is given by sps_pic_width_max_in_luma_samples and/or sps_pic_height_max_in_luma_samples.
- two or more decoded sub-pictures have the same size in at least one direction, and a picture consists of a first sub-picture and a second sub-picture arranged consecutively in at least one direction. And no cropping is applied to the decoded second sub-picture.
- the two or more decoded sub-pictures have the same size in at least one direction, and the pictures are arranged consecutively in at least one direction. consists of pictures. Cropping is then applied to all two or more subpictures in at least one direction.
- a bitstream includes pictures encoded into multiple slices and multiple tiles.
- Each slice and each tile contains data corresponding to only one subpicture.
- each sub-picture of two or more sub-pictures is encoded into a single slice and a single tile.
- encoding according to some exemplary aspects includes padding pixel rows, which may be, for example, on top of the mosaic, or padding pixel columns, which may be, for example, to the left of the mosaic, in one subpicture per video.
- padding pixel rows which may be, for example, on top of the mosaic
- padding pixel columns which may be, for example, to the left of the mosaic, in one subpicture per video.
- decoding includes extracting sub-pictures of interest to a user or application from the mosaic bitstream, and decoding and displaying only the sub-pictures of interest, thereby , padding pixels are cropped from the sub-picture according to the signaled conformance cropping offset.
- Such encoding or decoding makes it possible to waste less computational resources by decoding only sub-pictures for display purposes.
- FIG. 106 is a flowchart showing operations performed by the encoding device 100.
- the encoding device 100 comprises circuitry and memory coupled to the circuitry.
- the circuits and memories included in the encoding device 100 may correspond to the processor a1 and the memory a2 shown in FIG. In operation, the circuitry of encoding device 100 does the following.
- the circuit of the encoding device 100 pads the first subpicture (S1061).
- the first subpicture is included in a plurality of subpictures forming a picture.
- at least one of the top and left edges of the first sub-picture is included in at least one of the top and left edges of the picture.
- at least one subpicture is adjacent to the opposite side of at least one edge of the first subpicture.
- the circuitry of the encoding device 100 pads the first sub-picture at at least one edge of the first sub-picture with padding at at least one edge of the picture. Also, at that time, the circuitry of the encoding apparatus 100 pads the first sub-picture so that the size of the first sub-picture reaches an integral multiple of the preset coding unit size in at least one direction.
- the circuit of the encoding device 100 encodes cropping information indicating the cropping amount corresponding to the padding amount of the first sub-picture into the bitstream (S1062). Also, the circuitry of the encoding apparatus 100 independently encodes a plurality of sub-pictures including the padded first sub-picture into a bitstream (S1063).
- the cropping information indicates at least one of the number of upper sample rows and the number of left sample columns added to the first sub-picture by padding the first sub-picture as a cropping amount corresponding to the padding amount.
- encoding device 100 may be able to pad subpictures so that the subpicture size corresponds to an integral multiple of the preset coding unit size. Encoding apparatus 100 may then encode cropping information for cropping sub-pictures according to the amount of padding. Accordingly, encoding apparatus 100 may be able to encode information for matching the size of a sub-picture to the size of the video corresponding to the sub-picture.
- a picture may correspond to 4K resolution.
- each sub-picture may correspond to HD resolution.
- the encoding device 100 may be able to encode a plurality of sub-pictures included in a picture corresponding to 4K resolution and corresponding to HD resolution.
- encoding device 100 may be able to encode, for example, multiple videos with HD resolution into a bitstream as videos with 4K resolution.
- a picture may correspond to 8K resolution.
- Each sub-picture may also support 4K resolution.
- the encoding device 100 may be able to encode a plurality of sub-pictures that are included in a picture that supports 8k resolution and that support 4K resolution.
- encoding device 100 may be able to encode, for example, videos with 4K resolution into a bitstream as videos with 8K resolution.
- the cropping information may include at least one of sps_conformance_window_flag, sps_conf_win_top_offset and sps_conf_win_left_offset. where each parameter is a syntax element for the VVC conformance cropping window.
- encoding device 100 may be able to encode cropping information for cropping sub-pictures according to the syntax element regarding the cropping window.
- the circuitry of the encoding device 100 may encode settings of multiple sub-pictures into a bitstream.
- the bitstream may then include settings for multiple sub-pictures within the parameter set applicable to the picture.
- bitstream may conform to VVC.
- parameter set may be SPS or PPS.
- the setting of multiple sub-pictures may include the total number of multiple sub-pictures.
- the setting of multiple sub-pictures may also include whether or not the multiple sub-pictures have the same size.
- the settings for multiple sub-pictures may include one or more sizes that apply to multiple sub-pictures for one or more directions.
- the sub-picture settings may also include one or more sizes applied to the picture in one or more directions.
- a setting of multiple subpictures may include at least one of these items.
- the total number of multiple subpictures may be given by sps_num_subpics_minus1. Also, whether multiple subpictures have the same size may be given by sps_subpic_same_size_flag. The one or more sizes applied to multiple subpictures may be given by at least one of sps_subpic_width_minus1 and sps_subpic_height_minus1.
- the one or more sizes applied to the picture may be given by at least one of sps_pic_width_max_in_luma_samples and sps_pic_height_max_in_luma_samples.
- each parameter is a VVC syntax element.
- the encoding device 100 may be able to encode settings for determining regions of each sub-picture in a picture according to multiple syntax elements in SPS or PPS of VVC.
- the first sub-picture and the second sub-picture may be arranged spatially continuously in one direction. Then, for one direction, the total size of the first sub-picture and the second sub-picture may correspond to the size of the picture. And for one direction, the first sub-picture may be padded and the second sub-picture may not be padded.
- encoding device 100 may be able to pad only the first sub-picture of the first sub-picture and the second sub-picture that are spatially consecutively arranged. Therefore, encoding device 100 may be able to reduce processing.
- the first sub-picture and the second sub-picture may be arranged spatially continuously in one direction. Then, for one direction, the total size of the first sub-picture and the second sub-picture may correspond to the size of the picture. Then, for one direction, both the first sub-picture and the second sub-picture may be padded.
- encoding device 100 may be able to pad both the first sub-picture and the second sub-picture that are spatially consecutively arranged. Therefore, encoding apparatus 100 may be able to apply similar processing to both the first sub-picture and the second sub-picture. Therefore, the encoding device 100 may be able to reduce complexity of processing.
- the cropping information may include at least one of sps_conf_win_bottom_offset and sps_conf_win_right_offset as information indicating the cropping amount of the second sub-picture.
- each parameter is a syntax element for the VVC conformance cropping window.
- encoding device 100 may be able to encode cropping information for cropping the second sub-picture according to the syntax element regarding the cropping window.
- a picture includes at least a plurality of slices that spatially equally correspond to a plurality of subpictures on a one-to-one basis, and a plurality of tiles that spatially correspond equally to a plurality of subpictures on a one-to-one basis. You may include one.
- encoding device 100 may be able to simplify the relationship between subpictures and slices or tiles. Therefore, encoding device 100 may be able to reduce complexity of processing.
- the entropy encoding unit 110 of the encoding device 100 may perform the above-described operation as a circuit of the encoding device 100.
- Entropy coding section 110 may also cooperate with other components to perform the operations described above.
- FIG. 107 is a flowchart showing operations performed by the decoding device 200.
- the decoding device 200 comprises circuitry and memory coupled to the circuitry.
- the circuit and memory included in the decoding device 200 may correspond to the processor b1 and memory b2 shown in FIG. In operation, the circuitry of decoding device 200 does the following.
- the circuit of the decoding device 200 may decode cropping information indicating the cropping amount corresponding to the padding amount of the first sub-picture from the bitstream (S1071).
- the first sub-picture is included in a plurality of independently decodable sub-pictures forming a picture. Also, at least one of the top and left edges of the first sub-picture is included in at least one of the top and left edges of the picture. Also, at least one subpicture is adjacent to the opposite side of at least one edge of the first subpicture.
- the first sub-picture is padded on at least one edge of the first sub-picture with padding on at least one edge of the picture. Also, the first sub-picture is padded such that the size of the first sub-picture reaches an integral multiple of a preset coding unit size in at least one direction.
- the circuit of the decoding device 200 decodes the first subpicture from the bitstream (S1072). Then, the circuit of the decoding device 200 crops the first sub-picture at at least one edge of the first sub-picture according to the cropping amount (S1073).
- the cropping information indicates, as a cropping amount, at least one of the number of upper sample rows and the number of left sample columns removed from the first sub-picture by cropping the first sub-picture.
- the decoding apparatus 200 can crop the sub-picture according to the cropping amount corresponding to the padding amount after decoding the sub-picture that has been padded so that the size reaches an integral multiple of the preset coding unit size. Sometimes. Therefore, after decoding the sub-picture, the decoding device 200 may be able to match the size of the sub-picture to the size of the video corresponding to the sub-picture.
- a picture may correspond to 4K resolution.
- each sub-picture may correspond to HD resolution.
- decoding device 200 may be able to decode one of a plurality of sub-pictures that are included in a picture that corresponds to 4K resolution and that corresponds to HD resolution.
- the decoding device 200 may be able to decode one video with HD resolution, for example, from a bitstream in which multiple videos with HD resolution are encoded as videos with 4K resolution.
- a picture may correspond to 8K resolution.
- Each sub-picture may also support 4K resolution.
- decoding device 200 may be able to decode one of a plurality of sub-pictures that are included in a picture that supports 8K resolution and that support 4K resolution.
- the decoding device 200 may be able to decode one video with 4K resolution, for example, from a bitstream in which multiple videos with 4K resolution are encoded as videos with 8K resolution.
- the cropping information may include at least one of sps_conformance_window_flag, sps_conf_win_top_offset and sps_conf_win_left_offset. where each parameter is a syntax element for the VVC conformance cropping window.
- the circuitry of the decoding device 200 may obtain an input from the user for selecting the first sub-picture among the plurality of sub-pictures. Then, according to the input, the circuit of the decoding device 200 may decode the first sub-picture from the bitstream without decoding one or more sub-pictures other than the first sub-picture among the plurality of sub-pictures. .
- a bitstream may contain settings for multiple sub-pictures within a parameter set applicable to a picture.
- the circuitry of the decoding device 200 may then decode multiple sub-picture settings from the bitstream. Further, the circuitry of the decoding device 200 may derive sub-picture identification information for the first sub-picture according to the settings and inputs. The circuitry of decoding device 200 may then decode the first sub-picture identified by the sub-picture identification information from the bitstream.
- the decoding apparatus 200 derives sub-picture identification information (sub-picture index or sub-picture identifier, etc.) of the sub-picture to be decoded according to the parameter set applicable to the picture and the input obtained from the user. may be possible. Decoding apparatus 200 may then be able to efficiently decode sub-pictures identified according to the sub-picture identification information.
- sub-picture identification information sub-picture index or sub-picture identifier, etc.
- bitstream may conform to VVC.
- a parameter set may be an SPS or a PPS.
- the setting of multiple sub-pictures may include the total number of multiple sub-pictures.
- the setting of multiple sub-pictures may also include whether or not the multiple sub-pictures have the same size.
- the settings for multiple sub-pictures may include one or more sizes that apply to multiple sub-pictures for one or more directions.
- the sub-picture settings may also include one or more sizes applied to the picture in one or more directions.
- a multiple subpicture setting may include at least one of these items.
- the total number of multiple subpictures may be given by sps_num_subpics_minus1. Also, whether multiple subpictures have the same size may be given by sps_subpic_same_size_flag. Also, the one or more sizes applied to the multiple subpictures may be given by at least one of sps_subpic_width_minus1 and sps_subpic_height_minus1.
- the one or more sizes applied to the picture may be given by at least one of sps_pic_width_max_in_luma_samples and sps_pic_height_max_in_luma_samples.
- each parameter is a VVC syntax element.
- the decoding device 200 may be able to decode the setting for determining the area of each sub-picture in the picture according to multiple syntax elements in the SPS or PPS of VVC. Then, the decoding device 200 may be able to derive sub-picture identification information or the like corresponding to the region selected as the sub-picture.
- the first sub-picture and the second sub-picture may be arranged spatially continuously in one direction. Also, for one direction, the total size of the first sub-picture and the second sub-picture may correspond to the size of the picture. And for one direction, the first sub-picture may be cropped and the second sub-picture may not be cropped.
- the decoding device 200 may be able to crop only the first sub-picture out of the first sub-picture and the second sub-picture that are spatially consecutively arranged. Therefore, it may be possible to reduce processing.
- the first sub-picture and the second sub-picture may be arranged spatially continuously in one direction. Also, for one direction, the total size of the first sub-picture and the second sub-picture may correspond to the size of the picture. Also, for one direction, both the first sub-picture and the second sub-picture may be cropped.
- decoding device 200 may be able to crop both the first sub-picture and the second sub-picture that are spatially consecutively arranged. Therefore, decoding device 200 may be able to apply similar processing to both the first sub-picture and the second sub-picture. Therefore, decoding device 200 may be able to reduce complexity of processing.
- the cropping information may include at least one of sps_conf_win_bottom_offset and sps_conf_win_right_offset as information indicating the cropping amount of the second sub-picture.
- each parameter is a syntax element for the VVC conformance cropping window.
- a picture includes at least a plurality of slices that spatially equally correspond to a plurality of subpictures on a one-to-one basis, and a plurality of tiles that spatially correspond equally to a plurality of subpictures on a one-to-one basis. You may include one.
- decoding device 200 may be able to simplify the relationship between subpictures and slices or tiles. Therefore, decoding device 200 may be able to reduce complexity of processing.
- the entropy decoding unit 202 of the decoding device 200 may perform the above-described operation as a circuit of the decoding device 200.
- the entropy decoding unit 202 may also cooperate with other components to perform the operations described above.
- division of pictures, etc. may mean the division of frameworks such as pictures, and division of pictures, etc. is possible even before decoding. Similarly, it is possible to allocate various areas even before decoding.
- the encoding device 100 and the decoding device 200 in each example described above may be used as an image encoding device and an image decoding device, respectively, or may be used as a video encoding device and a video decoding device. .
- the encoding device 100 and the decoding device 200 may be used as an entropy encoding device and an entropy decoding device, respectively. That is, encoding device 100 and decoding device 200 may correspond only to entropy encoding section 110 and entropy decoding section 202, respectively. And other components may be included in other devices.
- the encoding device 100 may include an input section and an output section. For example, one or more pictures are input to the input unit of the encoding device 100 and an encoded bitstream is output from the output unit of the encoding device 100 .
- the decoding device 200 may also comprise an input and an output. For example, an encoded bitstream is input to the input unit of the decoding device 200 and one or more pictures are output from the output unit of the decoding device 200 .
- the coded bitstream may include quantized coefficients to which variable length coding is applied and control information.
- encoding the information may be including the information in a bitstream.
- encoding information into a bitstream may mean encoding the information to produce a bitstream containing the encoded information.
- decoding information may be obtaining information from a bitstream.
- decoding information from a bitstream may mean decoding the bitstream to obtain information contained in the bitstream.
- dividing each region into one or more sub-regions corresponds to assigning one or more sub-regions to each region, and may be expressed as dividing each region into one or more sub-regions. . Dividing various regions into one or more sub-regions, assigning one or more sub-regions to various regions, and dividing various regions into one or more sub-regions can be read interchangeably.
- each of the examples described above may be used as an encoding method, may be used as a decoding method, may be used as an entropy encoding method, or may be used as an entropy decoding method. It may be used, or may be used as another method.
- each component may be configured with dedicated hardware or realized by executing a software program suitable for each component.
- Each component may be realized by reading and executing a software program recorded in a recording medium such as a hard disk or a semiconductor memory by a program execution unit such as a CPU or processor.
- each of the encoding device 100 and the decoding device 200 includes a processing circuit and a storage device electrically connected to the processing circuit and accessible from the processing circuit.
- the processing circuit corresponds to processor a1 or b1
- the storage device corresponds to memory a2 or b2.
- a processing circuit includes at least one of dedicated hardware and a program execution unit, and executes processing using a storage device. Also, if the processing circuit includes a program execution unit, the storage device stores a software program executed by the program execution unit.
- the software that implements the encoding device 100 or the decoding device 200 described above is the following program.
- this program may cause a computer to: (i) be a sub-picture among a plurality of sub-pictures constituting a picture; and the left end, and (iii) a sub-picture adjacent to at least one of the plurality of sub-pictures on the opposite side of the at least one end of the sub-picture.
- one sub-picture such that padding at the at least one edge of the picture causes the size of the first sub-picture in at least one direction to reach an integer multiple of a preset coding unit size; padding at the at least one edge; encoding cropping information into a bitstream indicating a cropping amount corresponding to the padding amount of the first sub-picture; and the plurality of padded first sub-pictures.
- An encoding method may be performed in which at least one of the numbers of sample sequences is indicated as the cropping amount corresponding to the padding amount.
- this program provides a computer with (i) a sub-picture among a plurality of independently decodable sub-pictures constituting a picture, and (ii) one of the upper end and the left end of the sub-picture.
- a decoding method may be performed in which at least one of the number of upper rows of samples and the number of left columns of samples to be removed from a picture is indicated as the cropping amount.
- each component may be a circuit as described above. These circuits may form one circuit as a whole, or may be separate circuits. Also, each component may be realized by a general-purpose processor or by a dedicated processor.
- the encoding/decoding device may include encoding device 100 and decoding device 200 .
- ordinal numbers such as first and second used in the explanation may be replaced as appropriate.
- ordinal numbers may be newly given to the components and the like, or may be removed.
- these ordinal numbers may be attached to the elements to identify them and may not correspond to a meaningful order.
- the expression “greater than or equal to the threshold” and the expression “greater than the threshold” may be read interchangeably. Also, the expression “below the threshold” and the expression “smaller than the threshold” may be read interchangeably.
- aspects of the encoding device 100 and the decoding device 200 have been described above based on multiple examples, but the aspects of the encoding device 100 and the decoding device 200 are not limited to these examples. As long as it does not deviate from the spirit of the present disclosure, the scope of aspects of the encoding device 100 and the decoding device 200 includes various modifications that a person skilled in the art can think of, and configurations constructed by combining components in different examples. may be included within
- One or more aspects disclosed herein may be implemented in combination with at least some of the other aspects of the present disclosure. Also, part of the processing, part of the configuration of the device, part of the syntax, etc. described in the flowcharts of one or more aspects disclosed herein may be implemented in combination with other aspects.
- each functional or operational block can usually be implemented by an MPU (micro processing unit), memory, or the like.
- the processing by each of the functional blocks may be implemented as a program execution unit such as a processor that reads and executes software (program) recorded in a recording medium such as a ROM.
- the software may be distributed.
- the software may be recorded in various recording media such as semiconductor memory.
- each functional block can also be realized by hardware (dedicated circuit).
- each embodiment may be implemented by centralized processing using a single device (system), or may be implemented by distributed processing using multiple devices. Also, the number of processors executing the above program may be singular or plural. That is, centralized processing may be performed, or distributed processing may be performed.
- Such a system may be characterized by having an image encoding device using an image encoding method, an image decoding device using an image decoding method, or an image encoding/decoding device comprising both. Other configurations of such systems may be appropriately modified from time to time.
- FIG. 108 is a diagram showing the overall configuration of a suitable content supply system ex100 that implements the content distribution service.
- a communication service providing area is divided into desired sizes, and base stations ex106, ex107, ex108, ex109 and ex110, which are fixed radio stations in the illustrated example, 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 are connected to the internet ex101 via an internet service provider ex102 or a communication network ex104 and base stations ex106 to ex110. is connected.
- the content supply system ex100 may connect any one of the above devices in combination.
- each device may be directly or indirectly connected to each other via a telephone network, short-range radio, or the like, without going through the base stations ex106-ex110.
- the streaming server ex103 may be connected to 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 or the like.
- Streaming server ex103 may also be connected to a terminal or the like in a hotspot inside airplane ex117 via satellite ex116.
- a wireless access point, hotspot, or the like may be used instead of the base stations ex106 to ex110.
- 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 such as a digital camera that can shoot still images and movies.
- the smartphone ex115 is a smartphone, mobile phone, PHS (Personal Handyphone System), or the like that is compatible with mobile communication systems called 2G, 3G, 3.9G, 4G, and 5G in the future.
- PHS Personal Handyphone System
- the home appliance ex114 is a refrigerator or a device included in a household fuel cell cogeneration system.
- a terminal having a shooting function is connected to the streaming server ex103 through the base station ex106 or the like, enabling live distribution and the like.
- the terminals (computer ex111, game machine ex112, camera ex113, home appliance ex114, smartphone ex115, terminal in airplane ex117, etc.) perform the above-described
- the encoding process described in each embodiment may be performed, video data obtained by encoding may be multiplexed with audio data obtained by encoding sound corresponding to the video, and the obtained data may be streamed. It may be transmitted to the server ex103. That is, each terminal functions as an image coding device according to one aspect of the present disclosure.
- the streaming server ex103 streams the transmitted content data to the requesting client.
- the client is a computer ex111, a game machine ex112, a camera ex113, a home appliance ex114, a smartphone ex115, a terminal in an airplane ex117, or the like, which can decode the encoded data.
- Each device that has received the distributed data decodes and reproduces the received data. That is, each device may function as an image decoding device according to one aspect of the present disclosure.
- 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 implemented by a CDN (Contents Delivery Network), and content delivery may be implemented by a network connecting a large number of edge servers distributed around the world.
- CDN Contents Delivery Network
- the CDN dynamically allocates edge servers that are physically close to each client. Delays can be reduced by caching and distributing content to the edge server.
- processing can be distributed among multiple edge servers, the distribution entity can be switched to another edge server, and failures can occur. Since it is possible to bypass the network portion and continue distribution, high-speed and stable distribution can be achieved.
- the encoding processing of the captured data may be performed by each terminal, may be performed by the server side, or may be shared by each other.
- the encoding process typically involves two processing loops. In the first loop, the image complexity or code amount is detected for each frame or scene. Also, in the second loop, processing for maintaining image quality and improving encoding efficiency is performed.
- the terminal performs the first encoding process
- the server side that receives the content performs the second encoding process, thereby reducing the processing load on each terminal and improving the quality and efficiency of the content. can.
- it is possible for other terminals to receive and play back the data that has already been encoded for the first time enabling more flexible real-time distribution. Become.
- the camera ex 113 or the like extracts a feature amount from an image, compresses data related to the feature amount as metadata, and transmits it to the server.
- the server performs compression according to the meaning of the image (or the importance of the content), such as judging the importance of the object from the feature amount and switching the quantization accuracy.
- Feature amount data is particularly effective in improving the accuracy and efficiency of motion vector prediction during recompression in the server.
- the terminal may perform simple encoding such as VLC (Variable Length Coding), and the server may perform encoding with a large processing load such as CABAC (Context Adaptive Binary Arithmetic Coding).
- the server may manage and/or give instructions so that the video data shot by each terminal can be referred to each other.
- the encoded data from each terminal may be received by the server and re-encoded by changing the reference relationship among a plurality of data or by correcting or replacing the picture itself. This makes it possible to generate streams with improved quality and efficiency for 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 MPEG-based encoding to VP-based (for example, VP9). 264 to H.264. H.265 may be converted.
- the encoding process can be performed by a terminal or one or more servers. Therefore, in the following description, “server” or “terminal” is used as an entity that performs processing. Part or all may be performed at the server. In addition, regarding these, the same applies to decoding processing.
- the server not only encodes a two-dimensional moving image, but also automatically encodes a still image based on scene analysis of the moving image or at a time designated by the user, and transmits the image to the receiving terminal. good too. Furthermore, when the relative positional relationship between shooting terminals can be acquired, the server can determine the three-dimensional shape of the scene based on not only two-dimensional moving images but also videos of the same scene shot from different angles. can be generated.
- the server may separately encode three-dimensional data generated by a point cloud or the like, or based on the results of recognizing or tracking a person or object using three-dimensional data, may transmit a plurality of images to the receiving terminal. may be generated by selecting or reconstructing from the video shot by the terminal.
- the user can arbitrarily select each video corresponding to each shooting terminal and enjoy the scene, or select video from a selected viewpoint from three-dimensional data reconstructed using a plurality of images or videos. You can also enjoy the clipped content. Further, along with the video, sound is also collected from multiple different angles, and the server may multiplex the sound from a particular angle or space with the corresponding video and send the multiplexed video and sound. good.
- 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. It may be encoded as another stream without reference.
- MVC Multi-View Coding
- the server superimposes virtual object information in virtual space on camera information in real space based on the three-dimensional position or movement of the user's viewpoint.
- the decoding device may acquire or hold the virtual object information and the three-dimensional data, generate a two-dimensional image according to the movement of the user's viewpoint, and create the superimposed data by connecting them smoothly.
- the decoding device may transmit the motion of the user's viewpoint to the server in addition to the request for the virtual object information.
- the server may create superimposed data according to the movement of the viewpoint received from the three-dimensional data held in the server, encode the superimposed data, and distribute the encoded data to the decoding device.
- the superimposed data has an ⁇ value indicating transparency in addition to RGB. , may be encoded.
- the server may generate data in which predetermined RGB values are set as the background, like chromakey, and the background color is used for portions other than the object.
- the decryption processing of the distributed data may be performed by each client terminal, by the server side, or by each other.
- a certain terminal once sends a reception request to the server, another terminal receives and decodes the content corresponding to the request, and the decoded signal is transmitted to the device having the display.
- Data with good image quality can be reproduced by distributing the processing and selecting appropriate content regardless of the performance of the communicable terminal itself.
- a partial area such as a tile into which a picture is divided may be decoded and displayed on a viewer's personal terminal. As a result, while sharing the overall picture, it is possible to check at hand the field in which the user is in charge or an area that the user wants to check in more detail.
- IPsec Dynamic Adaptive Streaming over HTTP
- the user may switch in real time while freely selecting the user's terminal, decoding device or display device such as a display placed indoors or outdoors.
- decoding can be performed while switching between a terminal for decoding and a terminal for displaying, using its own position information and the like. This allows information to be mapped and displayed on a wall or part of the ground of a neighboring building embedded with a displayable device while the user is moving to the destination.
- access to encoded data over a network such as the encoded data being cached on a server that can be accessed in a short time from the receiving terminal, or being copied to an edge server in a content delivery service. It is also possible to switch the bit rate of the received data based on ease.
- FIG. 109 is a diagram showing an example of a display screen of a web page on the computer ex111 or the like.
- FIG. 110 is a diagram showing a display screen example of a web page on the smartphone ex115 or the like.
- a web page may contain a plurality of link images that are links to image content, and the appearance differs depending on the viewing device.
- the display device decoding device
- the display device When the user selects a link image, the display device performs decoding while giving top priority to the base layer.
- the display device may decode up to the enhancement layer.
- the display device decodes only forward reference pictures (I pictures, P pictures, forward reference only B pictures). and display, it is possible to reduce the delay between the decoding time and the display time of the first picture (the delay from the start of decoding of the content to the start of display).
- the display device may purposely ignore the reference relationships of pictures, refer to all B pictures and P pictures as forward references, perform rough decoding, and perform normal decoding as the number of received pictures increases over time. .
- the receiving terminal when transmitting/receiving still images or video data such as two-dimensional or three-dimensional map information for automatic driving or driving support of a vehicle, the receiving terminal, in addition to image data belonging to one or more layers, adds meta data.
- Information such as weather or construction information may be received as information and decoded in association with them.
- Meta information may belong to a layer or may be simply multiplexed with image data.
- the receiving terminal since a car, drone, or airplane including the receiving terminal moves, the receiving terminal transmits the position information of the receiving terminal, thereby seamlessly performing reception and decoding while switching between the base stations ex106 to ex110. realizable.
- the receiving terminal dynamically switches how much meta information is received or how much map information is updated according to user selection, user status and/or communication band status. becomes possible.
- the encoded information transmitted by the user can be received, decoded, and reproduced by the client in real time.
- the content supply system ex100 enables unicast or multicast distribution of not only high-quality, long-time content by video distributors, but also low-quality, short-time content by individuals. Such personal contents are expected to increase in the future.
- the server may perform the editing process before the encoding process. This can be realized, for example, using the following configuration.
- the server performs recognition processing such as shooting errors, scene search, semantic analysis, and object detection from the original image data or encoded data in real time at the time of shooting or after shooting. Then, the server manually or automatically corrects out-of-focus or camera shake based on the recognition result, or selects less important scenes such as scenes with lower brightness than other pictures or out-of-focus scenes. Make edits such as deleting, emphasizing the edges of objects, or changing their hues.
- the server encodes the edited data based on the edited result. It is also known that if the filming time is too long, the audience rating will decrease. Scenes with few images may be automatically clipped based on the result of image processing. Alternatively, the server may generate and encode a digest based on the results of semantic analysis of the scene.
- personal content may contain content that infringes on copyright, author's moral rights, portrait rights, etc., and it is inconvenient for the individual, such as the scope of sharing exceeding the intended scope.
- the server may intentionally change the image of a person's face or the inside of a house on the periphery of the screen into an out-of-focus image for encoding.
- the server recognizes whether or not the face of a person other than the person registered in advance appears in the image to be encoded, and if so, performs processing such as applying a mosaic to the face portion.
- the user may designate a person or background area to be processed in the image from the viewpoint of copyright or the like.
- the server may perform processing such as replacing the designated area with another image or blurring the focus.
- it is possible to track the person in the moving image and replace the image of the person's face.
- the decoding device first receives the base layer with the highest priority and decodes and reproduces it.
- the decoding device may receive the enhancement layer during this period, and may reproduce the high-definition video including the enhancement layer when reproduction is performed twice or more, such as when the reproduction is looped.
- the stream is scalable encoded in this way, it is possible to provide an experience in which the video is rough when it is not selected or at the beginning of viewing, but the stream gradually becomes smarter and the image becomes better.
- the same experience can be provided even if the coarse stream played the first time and the second stream encoded with reference to the first video are configured as one stream. .
- these encoding or decoding processes are generally processed in the LSI ex 500 that each terminal has.
- the LSI (large scale integration circuit) ex500 may be of a one-chip configuration or may be composed of multiple 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 a computer ex111, etc., and encoding or decoding is performed using that software. good too.
- the smartphone ex115 is equipped with a camera, the video data acquired by the camera may be transmitted. The video data at this time is data encoded by the LSI ex500 of the smartphone ex115.
- the LSI ex 500 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 the execution capability of the specific service. If the terminal does not support the coding scheme of the content or does not have the ability to perform the specific service, the terminal downloads the codec or application software, and then acquires and plays the content.
- a digital broadcasting system can employ at least the video encoding device (image encoding device) or the video decoding device (image decoding device) of each of the above-described embodiments.
- the content supply system ex100 has a configuration that facilitates unicasting, but the difference is that it is suitable for multicasting.
- similar applications are possible with respect to the encoding process and the decoding process.
- FIG. 111 is a diagram showing further details of the smartphone ex115 shown in FIG.
- FIG. 112 is a diagram illustrating a configuration example of the smartphone ex115.
- the smartphone ex115 has an antenna ex450 for transmitting and receiving radio waves to and from the base station ex110, a camera unit ex465 capable of capturing video and still images, and receiving images captured by the camera unit ex465 and the antenna ex450. and a display unit ex458 for displaying data obtained by decoding video or the like.
- the smartphone ex115 further includes an operation unit ex466 such as a touch panel, an audio output unit ex457 such as a speaker for outputting voice or sound, an audio input unit ex456 such as a microphone for inputting voice, and a camera.
- a memory unit ex467 capable of storing received video or still images, recorded audio, received video or still images, encoded data such as e-mails, or decoded data; It has a slot part ex464 which is an interface part with SIM (Subscriber Identity Module) ex468 for authenticating access to various data. Note that an external memory may be used instead of the memory unit ex467.
- SIM Subscriber Identity Module
- a main control unit ex460 that controls the display unit ex458 and the operation unit ex466, etc., 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, modulation/demodulation A section ex452, a multiplexing/separating section ex453, an audio signal processing section ex454, a slot section ex464, and a memory section ex467 are connected via a synchronous bus ex470.
- the power supply circuit unit ex461 activates the smartphone ex115 in an operable state and supplies power from the battery pack to each unit.
- the smartphone ex115 performs processes such as phone calls and data communication under the control of the main control unit ex460, which has a CPU, ROM, RAM, and the like.
- the main control unit ex460 which has a CPU, ROM, RAM, and the like.
- an audio signal picked up by the audio input unit ex456 is converted into a digital audio signal by the audio signal processing unit ex454, spread spectrum processing is performed by the modulation/demodulation unit ex452, and digital-to-analog conversion processing is performed by the transmission/reception unit ex451. and frequency conversion processing, and the resulting signal is transmitted via the antenna ex450.
- the received data is amplified, subjected to frequency conversion processing and analog-to-digital conversion processing, subjected to spectrum despreading processing by the modulation/demodulation unit ex452, converted to an analog audio signal by the audio signal processing unit ex454, and then output to the audio output unit ex457.
- Output from In the data communication mode text, still image, or video data is sent to the main control unit ex460 via the operation input control unit ex462 based on the operation of the operation unit ex466 of the main unit. Similar transmission/reception processing is performed.
- the video signal processing unit ex455 converts the video signal stored in the memory unit ex467 or the video signal input from the camera unit ex465 to each of the above implementations.
- the video data is compression-encoded by the moving image encoding method shown in the form, and the encoded video data is sent to the multiplexing/demultiplexing unit ex453.
- the audio signal processing unit ex454 encodes an audio signal picked up by the audio input unit ex456 while a video or still image is captured by the camera unit ex465, and sends the encoded audio data to the multiplexing/separating unit ex453.
- a multiplexing/demultiplexing unit ex453 multiplexes the encoded video data and the encoded audio data by a predetermined method, and a modulation/demodulation unit (modulation/demodulation circuit unit) ex452 and a transmission/reception unit ex451 perform modulation processing and conversion. After being processed, it is transmitted via the antenna ex450.
- a modulation/demodulation unit modulation/demodulation circuit unit
- a transmission/reception unit ex451 perform modulation processing and conversion. After being processed, it is transmitted via the antenna ex450.
- the multiplexing/demultiplexing unit ex453 By separating the encoded data, the multiplexed data is divided into a video data bit stream and an audio data bit stream, and the encoded video data is supplied to the video signal processing unit ex455 via the synchronization bus ex470, The encoded 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 each of the above embodiments, and the video signal is linked from the display unit ex458 via the display control unit ex459.
- a video or still image included in the moving image file is displayed.
- the audio signal processing unit ex454 decodes the audio signal, and audio is output from the audio output unit ex457.
- Real-time streaming is becoming more and more popular, so depending on the user's situation, audio playback may not be socially appropriate. Therefore, as an initial value, it is preferable to play only the video data without playing the audio signal, and the audio may be played in synchronization only when the user performs an operation such as clicking the video data. .
- the smartphone ex115 has been described as an example here, as a terminal, in addition to a transmission/reception type terminal having both an encoder and a decoder, a transmission terminal having only an encoder and a reception terminal having only a decoder Three other implementation types of terminals are possible. It has been described that the digital broadcasting system receives or transmits multiplexed data in which audio data is multiplexed with video data. However, the multiplexed data may be multiplexed with text data related to video in addition to the audio data. Also, video data itself may be received or transmitted instead of multiplexed data.
- main control unit ex460 including the CPU controls the encoding or decoding process
- various terminals are often equipped with a GPU (Graphics Processing Unit). Therefore, a memory shared by the CPU and the GPU or a memory whose addresses are managed so that they can be used in common may be used to collectively process a wide area by utilizing the performance of the GPU. This makes it possible to shorten the encoding time, ensure real-time performance, and achieve low delay.
- motion search, deblocking filter, SAO (Sample Adaptive Offset), and transformation/quantization processing are more efficient if they are collectively performed by the GPU instead of the CPU in units of pictures.
- the present disclosure can be used, for example, in television receivers, digital video recorders, car navigation systems, mobile phones, digital cameras, digital video cameras, video conference systems, electronic mirrors, and the like.
- encoding device 102 division unit 102a block division determination unit 104 subtraction unit 106 transformation unit 108 quantization unit 108a differential quantization parameter generation unit 108b, 204b predicted quantization parameter generation unit 108c, 204a quantization parameter generation unit 108d, 204d quantization quantization parameter storage unit 108e quantization processing unit 110 entropy coding unit 110a binarization unit 110b, 202b context control unit 110c binary arithmetic coding unit 112, 204 inverse quantization unit 114, 206 inverse transform unit 116, 208 addition unit 118, 210 block memory 120, 212 loop filter unit 120a, 212a deblocking filter processing unit 120b, 212b SAO processing unit 120c, 212c ALF processing unit 122, 214 frame memory 124, 216 intra prediction unit 126, 218 inter prediction unit 126a , a2, b2 memory 126b interpolation image derivation unit 126c gradient image derivation unit 126d optical flow derivation unit
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Abstract
Description
例えば、ピクチャ内の各サブピクチャは、矩形領域として定められる。そして、ピクチャ内の各コーディングユニットは、ピクチャ内の複数のサブピクチャのうちのいずれか1つのみに属する。また、ピクチャ内の複数のサブピクチャは、それぞれ、複数のビデオに対応していてもよい。具体的には、まず、複数のビデオに対応する複数のサブピクチャを含むピクチャが復号されて表示され、その後、複数のビデオの中から選択された1つのビデオのみがピクチャとして復号されて表示されてもよい。
各用語は一例として以下のような定義であってもよい。
画素の集合によって構成されたデータの単位であり、ピクチャやピクチャより小さいブロックからなり、動画の他、静止画も含む。
画素の集合によって構成される画像の処理単位であり、フレームやフィールドと呼ばれる場合もある。
特定数の画素を含む集合の処理単位であり、以下の例に挙げる通り、名称は問わない。また、形状も問わず、例えば、M×N画素からなる長方形、M×M画素からなる正方形はもちろん、三角形、円形、その他の形状も含む。
・スライス/タイル/ブリック
・CTU/スーパーブロック/基本分割単位
・VPDU/ハードウェアの処理分割単位
・CU/処理ブロック単位/予測ブロック単位(PU)/直交変換ブロック単位(TU)/ユニット
・サブブロック
画像を構成する最小単位の点であって、整数位置の画素のみならず整数位置の画素に基づいて生成された小数位置の画素も含む。
画素が有する固有の値であって、輝度値、色差値、RGBの階調はもちろん、depth値、又は0、1の2値も含む。
1ビットの他、複数ビットの場合も含み、例えば、2ビット以上のパラメータやインデックスであってもよい。また、二進数を用いた2値のみならず、その他の進数を用いた多値であってもよい。
情報を伝達するために記号化、符号化したものであって、離散化されたデジタル信号の他、連続値を取るアナログ信号も含む。
デジタルデータのデータ列又はデジタルデータの流れをいう。ストリーム/ビットストリームは、1本のストリームの他、複数の階層に分けられ複数のストリームにより構成されてもよい。また、単数の伝送路でシリアル通信により伝送される場合の他、複数の伝送路でパケット通信により伝送される場合も含む。
スカラー量の場合、単純差(x-y)の他、差の演算が含まれていれば足り、差の絶対値(|x-y|)、二乗差(x^2-y^2)、差の平方根(√(x-y))、重み付け差(ax-by:a、bは定数)、オフセット差(x-y+a:aはオフセット)を含む。
スカラー量の場合、単純和(x+y)の他、和の演算が含まれていれば足り、和の絶対値(|x+y|)、二乗和(x^2+y^2)、和の平方根(√(x+y))、重み付け和(ax+by:a、bは定数)、オフセット和(x+y+a:aはオフセット)を含む。
基づく対象となる要素以外を加味する場合も含む。また、直接結果を求める場合の他、中間的な結果を経由して結果を求める場合も含む。
用いる対象となる要素以外を加味する場合も含む。また、直接結果を求める場合の他、中間的な結果を経由して結果を求める場合も含む。
許されないと言い換えることができる。また、禁止していないこと又は許可されることは、必ずしも義務を意味するものではない。
許されないと言い換えることができる。また、禁止していないこと又は許可されることは、必ずしも義務を意味するものではない。さらに、量的又は質的に一部が禁止されていれば足り、全面的に禁止する場合も含まれる。
サンプル配列または単一のサンプルが、原色に関連する2つの色差(colour difference)信号の1つを表すことを指定する、記号CbおよびCrで表される形容詞である。chromaという用語の代わりに、chrominanceという用語を使用することもできる。
サンプル配列または単一のサンプルが原色に関連するモノクロ信号を表すことを指定する、記号または下付きのYまたはLで表される形容詞である。lumaという用語の代わりに、luminanceという用語を使用することもできる。
図面において、同一の参照番号は同一または類似の構成要素を示す。また、図面における構成要素のサイズおよび相対位置は、必ずしも一定の縮尺で描かれていない。
図1は、本実施の形態に係る伝送システムの構成の一例を示す概略図である。
図2は、ストリームにおけるデータの階層構造の一例を示す図である。ストリームは、例えばビデオシーケンスを含む。このビデオシーケンスは、例えば図2の(a)に示すように、VPS(Video Parameter Set)と、SPS(Sequence Parameter Set)と、PPS(Picture Parameter Set)と、SEI(Supplemental Enhancement Information)と、複数のピクチャとを含む。
ピクチャを並列にデコードするために、ピクチャはスライス単位またはタイル単位で構成される場合がある。
図5および図6は、スケーラブルなストリームの構成の一例を示す図である。
次に、実施の形態に係る符号化装置100を説明する。図7は、実施の形態に係る符号化装置100の構成の一例を示すブロック図である。符号化装置100は、画像をブロック単位で符号化する。
図8は、符号化装置100の実装例を示すブロック図である。符号化装置100は、プロセッサa1およびメモリa2を備える。例えば、図7に示された符号化装置100の複数の構成要素は、図8に示されたプロセッサa1およびメモリa2によって実装される。
図9は、符号化装置100による全体的な符号化処理の一例を示すフローチャートである。
分割部102は、原画像に含まれる各ピクチャを複数のブロックに分割し、各ブロックを減算部104に出力する。例えば、分割部102は、まず、ピクチャを固定サイズ(例えば128x128画素)のブロックに分割する。この固定サイズのブロックは、符号化ツリーユニット(CTU)と呼ばれることがある。そして、分割部102は、例えば再帰的な四分木(quadtree)および/または二分木(binary tree)ブロック分割に基づいて、固定サイズのブロックの各々を可変サイズ(例えば64x64画素以下)のブロックに分割する。すなわち、分割部102は、分割パターンを選択する。この可変サイズのブロックは、符号化ユニット(CU)、予測ユニット(PU)あるいは変換ユニット(TU)と呼ばれることがある。なお、種々の実装例では、CU、PUおよびTUは区別される必要はなく、ピクチャ内の一部またはすべてのブロックがCU、PU、またはTUの処理単位となってもよい。
減算部104は、分割部102から入力され、分割部102によって分割されたブロック単位で、原画像から予測画像(予測制御部128から入力される予測画像)を減算する。つまり、減算部104は、カレントブロックの予測残差を算出する。そして、減算部104は、算出された予測残差を変換部106に出力する。
変換部106は、空間領域の予測残差を周波数領域の変換係数に変換し、変換係数を量子化部108に出力する。具体的には、変換部106は、例えば空間領域の予測残差に対して予め定められた離散コサイン変換(DCT)または離散サイン変換(DST)を行う。
量子化部108は、変換部106から出力された変換係数を量子化する。具体的には、量子化部108は、カレントブロックの複数の変換係数を所定の走査順序で走査し、走査された変換係数に対応する量子化パラメータ(QP)に基づいて当該変換係数を量子化する。そして、量子化部108は、カレントブロックの量子化された複数の変換係数(以下、量子化係数という)をエントロピー符号化部110および逆量子化部112に出力する。
図20は、エントロピー符号化部110の構成の一例を示すブロック図である。
逆量子化部112は、量子化部108から入力された量子化係数を逆量子化する。具体的には、逆量子化部112は、カレントブロックの量子化係数を所定の走査順序で逆量子化する。そして、逆量子化部112は、カレントブロックの逆量子化された変換係数を逆変換部114に出力する。
逆変換部114は、逆量子化部112から入力された変換係数を逆変換することにより予測残差を復元する。具体的には、逆変換部114は、変換係数に対して、変換部106による変換に対応する逆変換を行うことにより、カレントブロックの予測残差を復元する。そして、逆変換部114は、復元された予測残差を加算部116に出力する。
加算部116は、逆変換部114から入力された予測残差と予測制御部128から入力された予測画像とを加算することによりカレントブロックを再構成する。その結果、再構成画像が生成される。そして、加算部116は、再構成画像をブロックメモリ118およびループフィルタ部120に出力する。
ブロックメモリ118は、例えば、イントラ予測で参照されるブロックであってカレントピクチャ内のブロックを格納するための記憶部である。具体的には、ブロックメモリ118は、加算部116から出力された再構成画像を格納する。
フレームメモリ122は、例えば、インター予測に用いられる参照ピクチャを格納するための記憶部であり、フレームバッファと呼ばれることもある。具体的には、フレームメモリ122は、ループフィルタ部120によってフィルタされた再構成画像を格納する。
ループフィルタ部120は、加算部116から出力される再構成画像にループフィルタ処理を施し、そのフィルタ処理された再構成画像をフレームメモリ122に出力する。ループフィルタとは、符号化ループ内で用いられるフィルタ(インループフィルタ)であり、例えば、アダプティブループフィルタ(ALF)、デブロッキング・フィルタ(DFまたはDBF)、およびサンプルアダプティブオフセット(SAO)などを含む。
ALFでは、符号化歪みを除去するための最小二乗誤差フィルタが適用され、例えばカレントブロック内の2x2画素のサブブロックごとに、局所的な勾配(gradient)の方向および活性度(activity)に基づいて複数のフィルタの中から選択された1つのフィルタが適用される。
図23Dは、Yサンプル(第1成分)がCbのCCALFおよびCrのCCALF(第1成分とは異なる複数の成分)に使用される例を示す図である。図23Eは、ダイヤモンド形状フィルタを示す図である。
図23Fは、JC-CCALFの例を示す図である。図23Gは、JC-CCALFのweight_index候補の例を示す図である。
デブロッキング・フィルタ処理では、ループフィルタ部120は、再構成画像のブロック境界にフィルタ処理を行うことによって、そのブロック境界に生じる歪みを減少させる。
q’1=(p0+q0+q1+q2+2)/4
q’2=(p0+q0+q1+3×q2+2×q3+4)/8
図28は、符号化装置100の予測部で行われる処理の一例を示すフローチャートである。なお、一例として予測部は、イントラ予測部124、インター予測部126、および予測制御部128の全てまたは一部の構成要素からなる。予測処理部は、例えばイントラ予測部124およびインター予測部126を含む。
イントラ予測部124は、ブロックメモリ118に格納されたカレントピクチャ内のブロックを参照してカレントブロックのイントラ予測(画面内予測ともいう)を行うことで、カレントブロックの予測画像(すなわちイントラ予測画像)を生成する。具体的には、イントラ予測部124は、カレントブロックに隣接するブロックの画素値(例えば輝度値、色差値)を参照してイントラ予測を行うことでイントラ予測画像を生成し、イントラ予測画像を予測制御部128に出力する。
インター予測部126は、フレームメモリ122に格納された参照ピクチャであってカレントピクチャとは異なる参照ピクチャを参照してカレントブロックのインター予測(画面間予測ともいう)を行うことで、予測画像(インター予測画像)を生成する。インター予測は、カレントブロックまたはカレントブロック内のカレントサブブロックの単位で行われる。サブブロックはブロックに含まれていて、ブロックより小さい単位である。サブブロックのサイズは、4x4画素であっても、8x8画素であっても、それ以外のサイズであってもよい。サブブロックのサイズは、スライス、ブリック、またはピクチャなどの単位で切り替えられてもよい。
図33は、各参照ピクチャの一例を示す図であり、図34は、参照ピクチャリストの一例を示す概念図である。参照ピクチャリストは、フレームメモリ122に記憶されている1つ以上の参照ピクチャを示すリストである。なお、図33において、矩形はピクチャを示し、矢印はピクチャの参照関係を示し、横軸は時間を示し、矩形中のI、PおよびBは各々、イントラ予測ピクチャ、単予測ピクチャおよび双予測ピクチャを示し、矩形中の数字は復号順を示す。図33に示すように、各ピクチャの復号順は、I0、P1、B2、B3、B4であり、各ピクチャの表示順は、I0、B3、B2、B4、P1である。図34に示すように、参照ピクチャリストは、参照ピクチャの候補を表すリストであり、例えば1つのピクチャ(またはスライス)が1つ以上の参照ピクチャリストを有してもよい。例えば、カレントピクチャが、単予測ピクチャであれば1つの参照ピクチャリストを用い、カレントピクチャが双予測ピクチャであれば2つの参照ピクチャリストを用いる。図33および図34の例では、カレントピクチャcurrPicであるピクチャB3は、L0リストおよびL1リストの2つの参照ピクチャリストを持つ。カレントピクチャcurrPicがピクチャB3の場合、そのカレントピクチャcurrPicの参照ピクチャの候補は、I0、P1およびB2であり、各参照ピクチャリスト(すなわちL0リストおよびL1リスト)はこれらのピクチャを示す。インター予測部126または予測制御部128は、各参照ピクチャリスト中のどのピクチャを実際に参照するか否かを参照ピクチャインデックスrefIdxLxによって指定する。図34では、参照ピクチャインデックスrefIdxL0およびrefIdxL1により参照ピクチャP1およびB2が指定されている。
図35は、インター予測の基本的な流れを示すフローチャートである。
図36は、MV導出の一例を示すフローチャートである。
図38Aおよび図38Bは、MV導出の各モードの分類の一例を示す図である。例えば図38Aに示すように、動き情報を符号化するか否か、および、差分MVを符号化するか否かに応じて、MV導出のモードは大きく3つのモードに分類される。3つのモードは、インターモード、マージモード、およびFRUC(frame rate up-conversion)モードである。インターモードは、動き探索を行うモードであって、動き情報および差分MVを符号化するモードである。例えば図38Bに示すように、インターモードは、アフィンインターモードおよびノーマルインターモードを含む。マージモードは、動き探索を行わないモードであって、周辺の符号化済みブロックからMVを選択し、そのMVを用いてカレントブロックのMVを導出するモードである。このマージモードは、基本的に、動き情報を符号化し、差分MVを符号化しないモードである。例えば図38Bに示すように、マージモードは、ノーマルマージモード(通常マージモードまたはレギュラーマージモードと呼ぶこともある)、MMVD(Merge with Motion Vector Difference)モード、CIIP(Combined inter merge/intra prediction)モード、トライアングルモード、ATMVPモード、およびアフィンマージモードを含む。ここで、マージモードに含まれる各モードのうちのMMVDモードでは、例外的に、差分MVが符号化される。なお、上述のアフィンマージモードおよびアフィンインターモードは、アフィンモードに含まれるモードである。アフィンモードは、アフィン変換を想定して、カレントブロックを構成する複数のサブブロックそれぞれのMVを、カレントブロックのMVとして導出するモードである。FRUCモードは、符号化済み領域間で探索を行うことによって、カレントブロックのMVを導出するモードであって、動き情報および差分MVの何れも符号化しないモードである。なお、これらの各モードの詳細については、後述する。
ノーマルインターモードは、候補MVによって示される参照ピクチャの領域から、カレントブロックの画像に類似するブロックを見つけ出すことによって、カレントブロックのMVを導出するインター予測モードである。また、このノーマルインターモードでは、差分MVが符号化される。
ノーマルマージモードは、候補MVリストから候補MVをカレントブロックのMVとして選択することによって、そのMVを導出するインター予測モードである。なお、ノーマルマージモードは、狭義のマージモードであって、単にマージモードと呼ばれることもある。本実施の形態では、ノーマルマージモードとマージモードとを区別し、マージモードを広義の意味で用いる。
図42は、HMVPモードによるカレントピクチャのMV導出処理の一例について説明するための図である。
動き情報は、符号化装置100側から信号化されずに、復号装置200側で導出されてもよい。例えば、復号装置200側で動き探索を行うことにより動き情報が導出されてもよい。この場合、復号装置200側では、カレントブロックの画素値を用いずに動き探索が行われる。このような復号装置200側で動き探索を行うモードには、FRUC(frame rate up-conversion)モードまたはPMMVD(pattern matched motion vector derivation)モードなどがある。
第1パターンマッチングでは、異なる2つの参照ピクチャ内の2つのブロックであってカレントブロックの動き軌道(motion trajectory)に沿う2つのブロックの間でパターンマッチングが行われる。したがって、第1パターンマッチングでは、上述した候補MVの評価値の算出のための所定の領域として、カレントブロックの動き軌道に沿う他の参照ピクチャ内の領域が用いられる。
第2パターンマッチング(テンプレートマッチング)では、カレントピクチャ内のテンプレート(カレントピクチャ内でカレントブロックに隣接するブロック(例えば上および/または左隣接ブロック))と参照ピクチャ内のブロックとの間でパターンマッチングが行われる。したがって、第2パターンマッチングでは、上述した候補MVの評価値の算出のための所定の領域として、カレントピクチャ内のカレントブロックに隣接するブロックが用いられる。
アフィンモードは、affine変換を用いてMVを生成するモードであり、例えば、複数の隣接ブロックのMVに基づいてサブブロック単位でMVを導出してもよい。このモードは、アフィン動き補償予測(affine motion compensation prediction)モードと呼ばれることがある。
図47A,図47Bおよび図47Cは、アフィンモードにおける制御ポイントのMV導出の一例を説明するための概念図である。
図50は、アフィンマージモードの一例を示すフローチャートである。
図51は、アフィンインターモードの一例を示すフローチャートである。
インター予測部126は、上述の例では、矩形のカレントブロックに対して1つの矩形の予測画像を生成する。しかし、インター予測部126は、その矩形のカレントブロックに対して矩形と異なる形状の複数の予測画像を生成し、それらの複数の予測画像を結合することによって、最終的な矩形の予測画像を生成してもよい。矩形と異なる形状は、例えば三角形であってもよい。
図54は、サブブロック単位にMVが導出されるATMVPモードの一例を示す図である。
図55は、マージモードおよびDMVRの関係を示す図である。
動き補償では、予測画像を生成し、その予測画像を補正するモードがある。そのモードは、例えば、後述のBIO、OBMC、およびLICである。
動き探索により得られたカレントブロックの動き情報だけでなく、隣接ブロックの動き情報も用いて、インター予測画像が生成されてもよい。具体的には、(参照ピクチャ内の)動き探索により得られた動き情報に基づく予測画像と、(カレントピクチャ内の)隣接ブロックの動き情報に基づく予測画像と、を重み付け加算することにより、カレントブロック内のサブブロック単位でインター予測画像が生成されてもよい。このようなインター予測(動き補償)は、OBMC(ovulerlapped block motion compensation)またはOBMCモードと呼ばれることがある。
次に、MVを導出する方法について説明する。まず、等速直線運動を仮定したモデルに基づいてMVを導出するモードについて説明する。このモードは、BIO(bi-directional optical flow)モードと呼ばれることがある。また、このbi-directional optical flowは、BIOの代わりに、BDOFと表記されてもよい。
次に、LIC(local illumination compensation)を用いて予測画像(予測)を生成するモードの一例について説明する。
予測制御部128は、イントラ予測画像(イントラ予測部124から出力される画像または信号)およびインター予測画像(インター予測部126から出力される画像または信号)のいずれかを選択し、選択した予測画像を減算部104および加算部116に出力する。
予測パラメータ生成部130は、イントラ予測、インター予測、および予測制御部128における予測画像の選択などに関する情報を予測パラメータとしてエントロピー符号化部110に出力してもよい。エントロピー符号化部110は、予測パラメータ生成部130から入力されるその予測パラメータ、量子化部108から入力される量子化係数に基づいて、ストリームを生成してもよい。予測パラメータは復号装置200に使用されてもよい。復号装置200は、ストリームを受信して復号し、イントラ予測部124、インター予測部126および予測制御部128において行われる予測処理と同じ処理を行ってもよい。予測パラメータは、選択予測信号(例えば、MV、予測タイプ、または、イントラ予測部124またはインター予測部126で用いられた予測モード)、または、イントラ予測部124、インター予測部126および予測制御部128において行われる予測処理に基づく、あるいはその予測処理を示す、任意のインデックス、フラグ、もしくは値を含んでいてもよい。
次に、上記の符号化装置100から出力されたストリームを復号可能な復号装置200について説明する。図67は、実施の形態に係る復号装置200の構成の一例を示すブロック図である。復号装置200は、符号化された画像であるストリームをブロック単位で復号する装置である。
図68は、復号装置200の実装例を示すブロック図である。復号装置200は、プロセッサb1およびメモリb2を備える。例えば、図67に示された復号装置200の複数の構成要素は、図68に示されたプロセッサb1およびメモリb2によって実装される。
図69は、復号装置200による全体的な復号処理の一例を示すフローチャートである。
図70は、分割決定部224と他の構成要素との関係を示す図である。分割決定部224は、一例として以下の処理を行ってもよい。
図71は、エントロピー復号部202の構成の一例を示すブロック図である。
図72は、エントロピー復号部202におけるCABACの流れを示す図である。
逆量子化部204は、エントロピー復号部202からの入力であるカレントブロックの量子化係数を逆量子化する。具体的には、逆量子化部204は、カレントブロックの量子化係数の各々について、当該量子化係数に対応する量子化パラメータに基づいて当該量子化係数を逆量子化する。そして、逆量子化部204は、カレントブロックの逆量子化された量子化係数(つまり変換係数)を逆変換部206に出力する。
逆変換部206は、逆量子化部204からの入力である変換係数を逆変換することにより予測残差を復元する。
加算部208は、逆変換部206からの入力である予測残差と予測制御部220からの入力である予測画像とを加算することによりカレントブロックを再構成する。つまり、カレントブロックの再構成画像が生成される。そして、加算部208は、カレントブロックの再構成画像をブロックメモリ210およびループフィルタ部212に出力する。
ブロックメモリ210は、イントラ予測で参照されるブロックであって、カレントピクチャ内のブロックを格納するための記憶部である。具体的には、ブロックメモリ210は、加算部208から出力された再構成画像を格納する。
ループフィルタ部212は、加算部208によって生成された再構成画像にループフィルタを施し、フィルタが施された再構成画像をフレームメモリ214および表示装置等に出力する。
フレームメモリ214は、インター予測に用いられる参照ピクチャを格納するための記憶部であり、フレームバッファと呼ばれることもある。具体的には、フレームメモリ214は、ループフィルタ部212によってフィルタが施された再構成画像を格納する。
図78は、復号装置200の予測部で行われる処理の一例を示すフローチャートである。なお、一例として予測部は、イントラ予測部216、インター予測部218、および予測制御部220の全てまたは一部の構成要素からなる。予測処理部は、例えばイントラ予測部216およびインター予測部218を含む。
イントラ予測部216は、ストリームから読み解かれたイントラ予測モードに基づいて、ブロックメモリ210に格納されたカレントピクチャ内のブロックを参照してイントラ予測を行うことで、カレントブロックの予測画像(すなわちイントラ予測画像)を生成する。具体的には、イントラ予測部216は、カレントブロックに隣接するブロックの画素値(例えば輝度値、色差値)を参照してイントラ予測を行うことでイントラ予測画像を生成し、イントラ予測画像を予測制御部220に出力する。
インター予測部218は、フレームメモリ214に格納された参照ピクチャを参照して、カレントブロックを予測する。予測は、カレントブロックまたはカレントブロック内のサブブロックの単位で行われる。なお、サブブロックはブロックに含まれていて、ブロックより小さい単位である。サブブロックのサイズは、4x4画素であっても、8x8画素であっても、それ以外のサイズであってもよい。サブブロックのサイズは、スライス、ブリック、またはピクチャなどの単位で切り替えられてもよい。
図82は、復号装置200におけるMV導出の一例を示すフローチャートである。
例えば、ストリームから読み解かれた情報がノーマルインターモードを適用することを示す場合、インター予測部218は、ストリームから読み解かれた情報に基づいて、ノーマルマージモードでMVを導出し、そのMVを用いて動き補償(予測)を行う。
例えば、ストリームから読み解かれた情報がノーマルマージモードの適用を示す場合、インター予測部218は、ノーマルマージモードでMVを導出し、そのMVを用いて動き補償(予測)を行う。
例えば、ストリームから読み解かれた情報がFRUCモードの適用を示す場合、インター予測部218は、FRUCモードでMVを導出し、そのMVを用いて動き補償(予測)を行う。この場合、動き情報は、符号化装置100側から信号化されずに、復号装置200側で導出される。例えば、復号装置200は、動き探索を行うことにより動き情報を導出してもよい。この場合、復号装置200は、カレントブロックの画素値を用いずに動き探索を行う。
例えば、ストリームから読み解かれた情報がアフィンマージモードの適用を示す場合、インター予測部218は、アフィンマージモードでMVを導出し、そのMVを用いて動き補償(予測)を行う。
例えば、ストリームから読み解かれた情報がアフィンインターモードの適用を示す場合、インター予測部218は、アフィンインターモードでMVを導出し、そのMVを用いて動き補償(予測)を行う。
例えば、ストリームから読み解かれた情報がトライアングルモードの適用を示す場合、インター予測部218は、トライアングルモードでMVを導出し、そのMVを用いて動き補償(予測)を行う。
例えば、ストリームから読み解かれた情報がDMVRの適用を示す場合、インター予測部218は、DMVRで動き探索を行う。
例えば、ストリームから読み解かれた情報が予測画像の補正の適用を示す場合、インター予測部218は、予測画像を生成すると、その補正のモードにしたがって予測画像を補正する。そのモードは、例えば、上述のBIO、OBMC、およびLICなどである。
例えば、ストリームから読み解かれた情報がOBMCの適用を示す場合、インター予測部218は、予測画像を生成すると、OBMCにしたがって予測画像を補正する。
例えば、ストリームから読み解かれた情報がBIOの適用を示す場合、インター予測部218は、予測画像を生成すると、BIOにしたがって予測画像を補正する。
例えば、ストリームから読み解かれた情報がLICの適用を示す場合、インター予測部218は、予測画像を生成すると、LICにしたがって予測画像を補正する。
予測制御部220は、イントラ予測画像およびインター予測画像のいずれかを選択し、選択した予測画像を加算部208に出力する。全体的に、復号装置200側の予測制御部220、イントラ予測部216およびインター予測部218の構成、機能、および処理は、符号化装置100側の予測制御部128、イントラ予測部124およびインター予測部126の構成、機能、および処理と対応していてもよい。
VVC(Versatile Video Coding)サブピクチャは、画像の矩形領域であって、1つ以上のスライスで構成される。VVCのサブピクチャの特徴は、サブピクチャを簡単にビットストリームから抽出したりビットストリームにマージしたりすることができるように設計されていることである。
図100は、上記の難点に対処するために適用され得る特定の非限定的かつ例示的な実装を示す。解像度1920×1080の4つのHDビデオ1001、1002、1003及び1004は、128×128のCTUサイズで符号化された解像度3840×2160の4Kモザイクビデオ1000にパッキングされる。CTUサイズに整合させるために、72個のパディング画素行1006がビデオシグナルの上に追加され、HDビデオ毎に1つのサブピクチャを用いることが可能になる。
実施の形態によれば、ピクチャ1000をビットストリームに符号化するための方法が提供される。このピクチャは、1つ以上のサブピクチャ1001、1002、1003、1004を含む。この方法は、図102に示され、(モザイク)ピクチャの2つ以上のサブピクチャから第1サブピクチャを取得すること(S1021)を含む。
(2)ピクチャの複数のサブピクチャのサイズが同じであるか否か
(3)少なくとも1つの方向における複数のサブピクチャのサイズ、及び、少なくとも1つの方向におけるピクチャのサイズ
(2)少なくとも1つの方向においてコーディングツリーユニットよりも小さいサイズを有する残りのコーディングユニット
(2)pps_num_exp_tile_columns_minus1 = 0
(3)pps_num_exp_tile_rows_minus1 = 0
(4)pps_tile_column_width_minus1[0] = sps_subpic_width_minus1[0]
(5)pps_tile_row_height_minus1[0] = sps_subpic_height_minus1[0]
(6)pps_loop_filter_across_tiles_enabled_flag = 0
(7)pps_rect_slice_flag = 1
(8)pps_single_slice_per_subpic_flag = 1
(9)pps_loop_filter_across_slices_enabled_flag = 0
本開示は、VVCコンフォーマンスクロッピングウィンドウの他の態様と組み合わせられ得る。例えば、モザイクビデオの下にパディング画素行、又は、モザイクビデオの右にパディング画素列を追加して、CTU単位だけでなく、輝度サンプル単位でも、全てのサブピクチャについて同じサイズを有することが望ましい場合がある。
上記の方法に対応して、ビットストリームからサブピクチャを復号するための復号装置が提供される。復号装置は処理回路を含む。
(2)少なくとも1つの画像に含まれる第1画像を複数のブロックに分割するブロック分割器
(3)第1画像に含まれる参照画像を用いて、第1画像に含まれるブロックを予測するイントラ予測器
(4)第1画像とは異なる第2画像に含まれる参照ブロックを用いて、第1画像に含まれるブロックを予測するインター予測器
(5)第1画像に含まれるブロックをフィルタリングするループフィルタ
(6)原信号と、イントラ予測器又はインター予測器によって生成された予測信号との間の予測誤差を変換して、変換係数を生成する変換器
(7)変換係数を量子化して量子化係数を生成する量子化器
(8)量子化係数を可変長符号化して、符号化ビットストリームを生成するエントロピー符号化器
(9)符号化された量子化係数及び制御情報が含まれる符号化ビットストリームが出力される出力端子
(2)符号化ビットストリームを復号して量子化係数を出力する復号器(エントロピー復号器等)
(3)量子化係数を逆量子化して変換係数を出力する逆量子化器
(4)変換係数を逆変換して予測誤差を出力する逆変換器
(5)第1画像に含まれる参照ピクチャを用いて、画像に含まれるブロックを予測するイントラ予測器
(6)第1画像とは異なる第2画像に含まれる参照ブロックを用いて、第1画像に含まれるブロックを予測するインター予測器
(7)第1画像に含まれるブロックをフィルタリングするループフィルタ
(8)第1画像を含むピクチャが出力される出力端子
上記に示された符号化装置100及び復号装置200の構成及び処理の代表例を以下に示す。
上述された各例における符号化装置100及び復号装置200は、それぞれ、画像符号化装置及び画像復号装置として利用されてもよいし、動画像符号化装置及び動画像復号装置として利用されてもよい。
以上の各実施の形態において、機能的又は作用的なブロックの各々は、通常、MPU(micro proccessing unit)及びメモリ等によって実現可能である。また、機能ブロックの各々による処理は、ROM等の記録媒体に記録されたソフトウェア(プログラム)を読み出して実行するプロセッサなどのプログラム実行部として実現されてもよい。当該ソフトウェアは、配布されてもよい。当該ソフトウェアは、半導体メモリなどの様々な記録媒体に記録されてもよい。なお、各機能ブロックをハードウェア(専用回路)によって実現することも可能である。
図108は、コンテンツ配信サービスを実現する適切なコンテンツ供給システムex100の全体構成を示す図である。通信サービスの提供エリアを所望の大きさに分割し、各セル内にそれぞれ、図示された例における固定無線局である基地局ex106、ex107、ex108、ex109、ex110が設置されている。
また、ストリーミングサーバex103は複数のサーバ又は複数のコンピュータであって、データを分散して処理したり記録したり配信するものであってもよい。例えば、ストリーミングサーバex103は、CDN(Contents Delivery Network)により実現され、世界中に分散された多数のエッジサーバとエッジサーバ間をつなぐネットワークによりコンテンツ配信が実現されていてもよい。CDNでは、クライアントに応じて物理的に近いエッジサーバが動的に割り当てられる。そして、当該エッジサーバにコンテンツがキャッシュ及び配信されることで遅延を減らすことができる。また、いくつかのタイプのエラーが発生した場合又はトラフィックの増加などにより通信状態が変わる場合に複数のエッジサーバで処理を分散したり、他のエッジサーバに配信主体を切り替えたり、障害が生じたネットワークの部分を迂回して配信を続けることができるので、高速かつ安定した配信が実現できる。
互いにほぼ同期した複数のカメラex113及び/又はスマートフォンex115などの端末により撮影された異なるシーン、又は、同一シーンを異なるアングルから撮影した画像或いは映像を統合して利用することが増えてきている。各端末で撮影した映像は、別途取得した端末間の相対的な位置関係、又は、映像に含まれる特徴点が一致する領域などに基づいて統合される。
図109は、コンピュータex111等におけるwebページの表示画面例を示す図である。図110は、スマートフォンex115等におけるwebページの表示画面例を示す図である。図109及び図110に示すようにwebページが、画像コンテンツへのリンクであるリンク画像を複数含む場合があり、閲覧するデバイスによってその見え方は異なる。画面上に複数のリンク画像が見える場合には、ユーザが明示的にリンク画像を選択するまで、又は画面の中央付近にリンク画像が近付く或いはリンク画像の全体が画面内に入るまで、表示装置(復号装置)は、リンク画像として各コンテンツが有する静止画又はIピクチャを表示してもよいし、複数の静止画又はIピクチャ等でgifアニメのような映像を表示してもよいし、ベースレイヤのみを受信し、映像を復号及び表示してもよい。
また、車の自動走行又は走行支援のため2次元又は3次元の地図情報などのような静止画又は映像データを送受信する場合、受信端末は、1以上のレイヤに属する画像データに加えて、メタ情報として天候又は工事の情報なども受信し、これらを対応付けて復号してもよい。なお、メタ情報は、レイヤに属してもよいし、単に画像データと多重化されてもよい。
また、コンテンツ供給システムex100では、映像配信業者による高画質で長時間のコンテンツのみならず、個人による低画質で短時間のコンテンツのユニキャスト、又はマルチキャスト配信が可能である。このような個人のコンテンツは今後も増加していくと考えられる。個人コンテンツをより優れたコンテンツにするために、サーバは、編集処理を行ってから符号化処理を行ってもよい。これは、例えば、以下のような構成を用いて実現できる。
また、これらの符号化又は復号処理は、一般的に各端末が有するLSIex500において処理される。LSI(large scale integration circuitry)ex500(図108参照)は、ワンチップであっても複数チップからなる構成であってもよい。なお、動画像符号化又は復号用のソフトウェアをコンピュータex111等で読み取り可能な何らかの記録メディア(CD-ROM、フレキシブルディスク、又はハードディスクなど)に組み込み、そのソフトウェアを用いて符号化又は復号処理を行ってもよい。さらに、スマートフォンex115がカメラ付きである場合には、そのカメラで取得した動画データを送信してもよい。このときの動画データはスマートフォンex115が有するLSIex500で符号化処理されたデータである。
図111は、図108に示されたスマートフォンex115のさらに詳細を示す図である。また、図112は、スマートフォンex115の構成例を示す図である。スマートフォンex115は、基地局ex110との間で電波を送受信するためのアンテナex450と、映像及び静止画を撮ることが可能なカメラ部ex465と、カメラ部ex465で撮像した映像、及びアンテナex450で受信した映像等が復号されたデータを表示する表示部ex458とを備える。スマートフォンex115は、さらに、タッチパネル等である操作部ex466と、音声又は音響を出力するためのスピーカ等である音声出力部ex457と、音声を入力するためのマイク等である音声入力部ex456と、撮影した映像或いは静止画、録音した音声、受信した映像或いは静止画、メール等の符号化されたデータ、又は、復号化されたデータを保存可能なメモリ部ex467と、ユーザを特定し、ネットワークをはじめ各種データへのアクセスの認証をするためのSIM(Subscriber Identity Module)ex468とのインタフェース部であるスロット部ex464とを備える。なお、メモリ部ex467の代わりに外付けメモリが用いられてもよい。
102 分割部
102a ブロック分割決定部
104 減算部
106 変換部
108 量子化部
108a 差分量子化パラメータ生成部
108b、204b 予測量子化パラメータ生成部
108c、204a 量子化パラメータ生成部
108d、204d 量子化パラメータ記憶部
108e 量子化処理部
110 エントロピー符号化部
110a 二値化部
110b、202b コンテキスト制御部
110c 二値算術符号化部
112、204 逆量子化部
114、206 逆変換部
116、208 加算部
118、210 ブロックメモリ
120、212 ループフィルタ部
120a、212a デブロッキング・フィルタ処理部
120b、212b SAO処理部
120c、212c ALF処理部
122、214 フレームメモリ
124、216 イントラ予測部
126、218 インター予測部
126a、a2、b2 メモリ
126b 補間画像導出部
126c 勾配画像導出部
126d オプティカルフロー導出部
126e 補正値導出部
126f 予測画像補正部
128、220 予測制御部
130、222 予測パラメータ生成部
200 復号装置
202 エントロピー復号部
202a 二値算術復号部
202c 多値化部
204e 逆量子化処理部
224 分割決定部
971、972、975、985、989、991、992、993、994、1001、1002、1003、1004 サブピクチャ(HDビデオ)
981、990、1000 モザイクピクチャ(4Kモザイクビデオ)
1006 パディング画素行
1201 境界判定部
1202、1204、1206 スイッチ
1203 フィルタ判定部
1205 フィルタ処理部
1207 フィルタ特性決定部
1208 処理判定部
a1、b1 プロセッサ
Claims (14)
- (i)ピクチャを構成する互いに独立して復号可能な複数のサブピクチャのうちのサブピクチャであり、(ii)当該サブピクチャの上端及び左端のうちの少なくとも1つの端が前記ピクチャの上端及び左端のうちの少なくとも1つの端に含まれ、(iii)当該サブピクチャの前記少なくとも1つの端の反対側に前記複数のサブピクチャのうちの少なくとも1つのサブピクチャが隣接し、(iv)前記ピクチャの前記少なくとも1つの端におけるパディングによって少なくとも1つの方向において当該サブピクチャのサイズが予め設定されたコーディングユニットサイズの整数倍に到達するように当該サブピクチャの前記少なくとも1つの端においてパディングされたサブピクチャである第1サブピクチャのパディング量に対応するクロッピング量を示すクロッピング情報をビットストリームから復号することと、
前記第1サブピクチャを前記ビットストリームから復号することと、
前記クロッピング量に従って前記第1サブピクチャを前記第1サブピクチャの前記少なくとも1つの端においてクロッピングすることとを含み、
前記クロッピング情報は、前記第1サブピクチャをクロッピングすることにより前記第1サブピクチャから取り除かれる上側サンプル行数及び左側サンプル列数のうちの少なくとも1つを前記クロッピング量として示す
復号方法。 - 前記ピクチャは、4K解像度に対応し、
前記複数のサブピクチャのそれぞれは、HD(High Definition)解像度に対応する
請求項1に記載の復号方法。 - 前記ピクチャは、8K解像度に対応し、
前記複数のサブピクチャのそれぞれは、4K解像度に対応する
請求項1に記載の復号方法。 - 前記クロッピング情報は、それぞれがVVC(Versatile Video Coding)のコンフォーマンスクロッピングウィンドウに関するシンタックス要素であるsps_conformance_window_flag、sps_conf_win_top_offset及びsps_conf_win_left_offsetのうちの少なくとも1つを含む
請求項1~3のいずれか1項に記載の復号方法。 - 前記復号方法は、さらに、
前記複数のサブピクチャのうちの前記第1サブピクチャを選択するための入力をユーザから取得することと、
前記入力に従って、前記ビットストリームから、前記複数のサブピクチャのうち前記第1サブピクチャ以外の1つ以上のサブピクチャを復号せずに、前記第1サブピクチャを復号することとを含む
請求項1~4のいずれか1項に記載の復号方法。 - 前記ビットストリームは、前記ピクチャに適用可能なパラメータセット内に前記複数のサブピクチャの設定を含み、
前記復号方法は、さらに、
前記ビットストリームから、前記設定を復号することと、
前記設定及び前記入力に従って、前記第1サブピクチャのサブピクチャ識別情報を導出することと、
前記ビットストリームから、前記サブピクチャ識別情報によって識別される前記第1サブピクチャを復号することとを含む
請求項5に記載の復号方法。 - 前記ビットストリームは、VVC(Versatile Video Coding)に準拠し、
前記パラメータセットは、SPS(Sequence Parameter Set)又はPPS(Picture Parameter Set)であり、
前記設定は、前記複数のサブピクチャの総数と、前記複数のサブピクチャが同じサイズを有するか否かと、1つ以上の方向に関して前記複数のサブピクチャに適用される1つ以上のサイズと、前記1つ以上の方向に関して前記ピクチャに適用される1つ以上のサイズとのうちの少なくとも1つを含み、
前記複数のサブピクチャの総数は、VVCのシンタックス要素であるsps_num_subpics_minus1によって与えられ、
前記複数のサブピクチャが同じサイズを有するか否かは、VVCのシンタックス要素であるsps_subpic_same_size_flagによって与えられ、
前記複数のサブピクチャに適用される前記1つ以上のサイズは、それぞれがVVCのシンタックス要素であるsps_subpic_width_minus1及びsps_subpic_height_minus1のうちの少なくとも1つによって与えられ、
前記ピクチャに適用される前記1つ以上のサイズは、それぞれがVVCのシンタックス要素であるsps_pic_width_max_in_luma_samples及びsps_pic_height_max_in_luma_samplesのうちの少なくとも1つによって与えられる
請求項6に記載の復号方法。 - 前記少なくとも1つの方向に対応する1つの方向に関して、前記第1サブピクチャと、前記少なくとも1つのサブピクチャに対応する第2サブピクチャとが、空間的に連続して配置され、
前記1つの方向に関して、前記第1サブピクチャと前記第2サブピクチャとの合計サイズは、前記ピクチャのサイズに対応し、
前記1つの方向に関して、前記第1サブピクチャがクロッピングされ、前記第2サブピクチャがクロッピングされない
請求項1~7のいずれか1項に記載の復号方法。 - 前記少なくとも1つの方向に対応する1つの方向に関して、前記第1サブピクチャと、前記少なくとも1つのサブピクチャに対応する第2サブピクチャとが、空間的に連続して配置され、
前記1つの方向に関して、前記第1サブピクチャと前記第2サブピクチャとの合計サイズは、前記ピクチャのサイズに対応し、
前記1つの方向に関して、前記第1サブピクチャと前記第2サブピクチャとの両方がクロッピングされる
請求項1~7のいずれか1項に記載の復号方法。 - 前記クロッピング情報は、前記第2サブピクチャのクロッピング量を示す情報として、それぞれがVVCのコンフォーマンスクロッピングウィンドウに関するシンタックス要素であるsps_conf_win_bottom_offset及びsps_conf_win_right_offsetのうちの少なくとも1つを含む
請求項9に記載の復号方法。 - 前記ピクチャは、前記複数のサブピクチャにそれぞれ空間的に等しく一対一に対応する複数のスライスと、前記複数のサブピクチャにそれぞれ空間的に等しく一対一に対応する複数のタイルとのうちの少なくとも一方を含む
請求項1~10のいずれか1項に記載の復号方法。 - (i)ピクチャを構成する複数のサブピクチャのうちのサブピクチャであり、(ii)当該サブピクチャの上端及び左端のうちの少なくとも1つの端が前記ピクチャの上端及び左端のうちの少なくとも1つの端に含まれ、(iii)当該サブピクチャの前記少なくとも1つの端の反対側に前記複数のサブピクチャのうちの少なくとも1つのサブピクチャが隣接するサブピクチャである第1サブピクチャを、前記ピクチャの前記少なくとも1つの端におけるパディングによって少なくとも1つの方向において前記第1サブピクチャのサイズが予め設定されたコーディングユニットサイズの整数倍に到達するように前記第1サブピクチャの前記少なくとも1つの端においてパディングすることと、
前記第1サブピクチャのパディング量に対応するクロッピング量を示すクロッピング情報をビットストリームに符号化することと、
パディングされた前記第1サブピクチャを含む前記複数のサブピクチャを互いに独立して前記ビットストリームに符号化することとを含み、
前記クロッピング情報は、前記第1サブピクチャをパディングすることにより前記第1サブピクチャに付加される上側サンプル行数及び左側サンプル列数のうちの少なくとも1つを前記パディング量に対応する前記クロッピング量として示す
符号化方法。 - 回路と、
前記回路に接続されたメモリとを備え、
前記回路は、動作において、
(i)ピクチャを構成する互いに独立して復号可能な複数のサブピクチャのうちのサブピクチャであり、(ii)当該サブピクチャの上端及び左端のうちの少なくとも1つの端が前記ピクチャの上端及び左端のうちの少なくとも1つの端に含まれ、(iii)当該サブピクチャの前記少なくとも1つの端の反対側に前記複数のサブピクチャのうちの少なくとも1つのサブピクチャが隣接し、(iv)前記ピクチャの前記少なくとも1つの端におけるパディングによって少なくとも1つの方向において当該サブピクチャのサイズが予め設定されたコーディングユニットサイズの整数倍に到達するように当該サブピクチャの前記少なくとも1つの端においてパディングされたサブピクチャである第1サブピクチャのパディング量に対応するクロッピング量を示すクロッピング情報をビットストリームから復号し、
前記第1サブピクチャを前記ビットストリームから復号し、
前記クロッピング量に従って前記第1サブピクチャを前記第1サブピクチャの前記少なくとも1つの端においてクロッピングし、
前記クロッピング情報は、前記第1サブピクチャをクロッピングすることにより前記第1サブピクチャから取り除かれる上側サンプル行数及び左側サンプル列数のうちの少なくとも1つを前記クロッピング量として示す
復号装置。 - 回路と、
前記回路に接続されたメモリとを備え、
前記回路は、動作において、
(i)ピクチャを構成する複数のサブピクチャのうちのサブピクチャであり、(ii)当該サブピクチャの上端及び左端のうちの少なくとも1つの端が前記ピクチャの上端及び左端のうちの少なくとも1つの端に含まれ、(iii)当該サブピクチャの前記少なくとも1つの端の反対側に前記複数のサブピクチャのうちの少なくとも1つのサブピクチャが隣接するサブピクチャである第1サブピクチャを、前記ピクチャの前記少なくとも1つの端におけるパディングによって少なくとも1つの方向において前記第1サブピクチャのサイズが予め設定されたコーディングユニットサイズの整数倍に到達するように前記第1サブピクチャの前記少なくとも1つの端においてパディングし、
前記第1サブピクチャのパディング量に対応するクロッピング量を示すクロッピング情報をビットストリームに符号化し、
パディングされた前記第1サブピクチャを含む前記複数のサブピクチャを互いに独立して前記ビットストリームに符号化し、
前記クロッピング情報は、前記第1サブピクチャをパディングすることにより前記第1サブピクチャに付加される上側サンプル行数及び左側サンプル列数のうちの少なくとも1つを前記パディング量に対応する前記クロッピング量として示す
符号化装置。
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