Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/50—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding
  • H04N19/59—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding involving spatial sub-sampling or interpolation, e.g. alteration of picture size or resolution
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
  • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
  • H04N19/119—Adaptive subdivision aspects, e.g. subdivision of a picture into rectangular or non-rectangular coding blocks
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
  • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
  • H04N19/12—Selection from among a plurality of transforms or standards, e.g. selection between discrete cosine transform [DCT] and sub-band transform or selection between H.263 and H.264
  • H04N19/122—Selection of transform size, e.g. 8x8 or 2x4x8 DCT; Selection of sub-band transforms of varying structure or type
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
  • H04N19/134—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or criterion affecting or controlling the adaptive coding
  • H04N19/146—Data rate or code amount at the encoder output
  • H04N19/152—Data rate or code amount at the encoder output by measuring the fullness of the transmission buffer
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
  • H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
  • H04N19/17—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object
  • H04N19/172—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object the region being a picture, frame or field
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
  • H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
  • H04N19/184—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being bits, e.g. of the compressed video stream
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/60—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using transform coding
  • H04N19/63—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using transform coding using sub-band based transform, e.g. wavelets
  • H04N19/64—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using transform coding using sub-band based transform, e.g. wavelets characterised by ordering of coefficients or of bits for transmission
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/70—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals characterised by syntax aspects related to video coding, e.g. related to compression standards

Definitions

• This patent document relates to image and video coding and decoding.
• Digital video accounts for the largest bandwidth use on the internet and other digital communication networks. As the number of connected user devices capable of receiving and displaying video increases, it is expected that the bandwidth demand for digital video usage will continue to grow.
• the present document discloses techniques that can be used by video encoders and decoders to signal picture buffer levels as part of performing video encoding or decoding.
• a video processing method includes performing a conversion between a video and a bitstream of the video according to a rule, wherein the bitstream includes one or more bitstream parts that are independently decodable, each bitstream part corresponding to one or more coded video pictures of the video, and wherein the rule specifies that a maximum decoded picture buffer size required for decoding the bitstream or the one or more bitstream parts is determined based on a maximum allowed picture size for the one or more coded video pictures corresponding to the bitstream or the one or more bitstream parts.
• another video processing method includes performing a conversion between a video comprising a video unit and a bitstream of the video comprising one or more coded layer video sequences, wherein the bitstream conforms to a rule, and wherein the rule specifies that a maximum buffer size of a decoded picture of a coded layer video sequence is constrained to be less than or equal to a maximum picture size selected from pictures in the coded layer video sequence.
• another video processing method includes performing a conversion between a video and a bitstream of the video according to a rule, wherein the bitstream includes one or more bitstream parts that are independently decodable, each bitstream part corresponding to one or more coded video pictures of the video, and wherein the rule specifies at least one of a maximum allowed picture size, a maximum allowed picture width, and a maximum allowed picture height for the conversion.
• another video processing method includes performing a conversion between a video and a bitstream of the video, wherein the bitstream includes one or more output layer sets, wherein at least one output layer set includes multiple video layers, and wherein the bitstream conforms to a rule that specifies a constraint on an overall size of a decoded picture buffer for the at least one output layer set comprising the multiple video layers.
• another video processing method includes performing a conversion between a video and a bitstream of the video, wherein the bitstream is organized into one or more access units according to a rule, and wherein the rule specifies that one or more constraints for an access unit on at least one of a coded picture buffer (CPB) removal time, a nominal CPB removal time, a decoded picture buffer (DPB) output time, or a sum of a number of bytes in a network abstract layer (NAL) unit are based on a sum of a picture size of each of a plurality of pictures of the access unit.
• CPB coded picture buffer
• DPB decoded picture buffer
• NAL network abstract layer
• another video processing method includes performing a conversion between a video and a bitstream of the video, wherein the bitstream is organized into one or more access units according to a rule, and wherein the rule specifies a limit on a maximum number of slices in an access unit.
• a video encoder apparatus comprising a processor configured to implement above-described methods.
• a video decoder apparatus comprising a processor configured to implement above-described methods.
• a computer readable medium having code stored thereon is disclose. The code embodies one of the methods described herein in the form of processor- executable code.
• FIG. 1 is a block diagram showing an example video processing system in which various techniques disclosed herein may be implemented.
• FIG. 2 is a block diagram of an example hardware platform used for video processing.
• FIG. 3 is a block diagram that illustrates an example video coding system that can implement some embodiments of the present disclosure.
• FIG. 4 is a block diagram that illustrates an example of an encoder that can implement some embodiments of the present disclosure.
• FIG. 5 is a block diagram that illustrates an example of a decoder that can implement some embodiments of the present disclosure.
• FIGS. 6-9 show flowcharts for example methods of video processing.
• Section headings are used in the present document for ease of understanding and do not limit the applicability of techniques and embodiments disclosed in each section only to that section.
• H.266 terminology is used in some description only for ease of understanding and not for limiting scope of the disclosed techniques. As such, the techniques described herein are applicable to other video codec protocols and designs also.
• This document is related to video coding technologies. Specifically, it is about defining levels for a video codec that supports both single-layer video coding and multi-layer video coding. It may be applied to any video coding standard or non-standard video codec that supports single layer video coding and multi-layer video coding, e.g., Versatile Video Coding (VVC) that is being developed.
• VVC Versatile Video Coding
• Video coding standards have evolved primarily through the development of the well- known ITU-T and ISO/IEC standards.
• the ITU-T produced H.261 and H.263, ISO/IEC produced MPEG-1 and MPEG-4 Visual, and the two organizations jointly produced the H.262/MPEG-2 Video and H.264/MPEG-4 Advanced Video Coding (AVC) and H.265/HEVC standards.
• AVC H.264/MPEG-4 Advanced Video Coding
• H.265/HEVC High Efficiency Video Coding
• JEM Joint Exploration Model
• Video coding standards usually specify profiles and levels. Some video coding standards also specify tiers, e.g., HEVC and the being-developed VVC.
• Profiles, tiers, and levels specify restrictions on bitstreams and hence limits on the capabilities needed to decode the bitstreams. Profiles, tiers and levels may also be used to indicate interoperability points between individual decoder implementations.
• Each profile specifies a subset of algorithmic features and limits that is supported by all decoders conforming to that profile. Note that encoders are not required to make use of all coding tools or features supported in a profile, while decoders conforming to a profile are required to support all coding tools or features.
• Each level of a tier specifies a set of limits on the values that may be taken by the bitstream syntax elements.
• the same set of tier and level definitions is usally used with all profiles, but individual implementations may support a different tier and within a tier a different level for each supported profile.
• a level of a tier generally corresponds to a particular decoder processing load and memory capability.
• Capabilities of video decoders conforming to a video codec specification are specified in terms of the ability to decode video streams conforming to the constraints of profiles, tiers and levels specified in the video codec specifiation. When expressing the capabilities of a decoder for a specified profile, the tier and level supported for that profile should also be expressed.
• the tier with general tier flag equal to 0 is considered to be a lower tier than the tier with general tier flag equal to 1.
• a particular level of a specific tier is considered to be a lower level than some other level of the same tier when the value of the general level idc or sublayer_level_idc[ i ] of the particular level is less than that of the other level.
• access unit n be the n-th access unit in decoding order, with the first access unit being access unit 0 (i.e., the 0-th access unit).
• bitstreams conforming to a profile at a specified tier and level shall obey the following constraints for each bitstream conformance test as specified in Annex C: a) PicSizelnSamplesY shall be less than or equal to MaxLumaPs, where MaxLumaPs is specified in Table A.1. b) The value of pic width in luma samples shall be less than or equal to
• Table A.1 specifies the limits for each level of each tier for levels other than level 8.5.
• a tier and level to which a bitstream conforms are indicated by the syntax elements general tier flag and general level idc, and a level to which a sublayer representation conforms are indicated by the syntax element sublayer_level_idc[ i ], as follows:
• general tier flag indicates conformance to the Main tier
• general tier flag indicates conformance to the High tier
• general tier flag shall be equal to 0 for levels below level 4 (corresponding to the entries in Table A.l marked with Otherwise (the specified level is level 8.5)
• variable fR be set equal to 1 ⁇ 300.
• variable HbrF actor is defined as follows:
• HbrF actor is set equal to 1.
• the variable BrVclFactor which represents the VCL bit rate scale factor, is set equal to CpbVclF actor * HbrF actor.
• the variable BrNalFactor which represents the NAL bit rate scale factor, is set equal to CpbNalF actor * HbrF actor.
• the variable MinCr is set equal to MinCrBase * MinCrScaleFactor ⁇ HbrFactor.
• MaxDpbSize Min( ( 4 * maxDpbPicBuf ) / 3, 16 ) else
• MaxDpbSize maxDpbPicBuf where MaxLumaPs is specified in Table A.l, and maxDpbPicBuf is equal to 8.
• Bitstreams conforming to the Main 10 or Main 4:4:4 10 profile at a specified tier and level shall obey the following constraints for each bitstream conformance test as specified in Annex C: a) The nominal removal time of access unit n (with n greater than 0) from the CPB, as specified in clause C.2.3, shall satisfy the constraint that
• AuNominalRemovalTime[ n ] - AuCpbRemovalTime[ n - 1 ] is greater than or equal to Max( PicSizelnSamplesY ⁇ MaxLumaSr, fR ) for the value of PicSizelnSamplesY of picture n - 1, where MaxLumaSr is the value specified in that applies to picture n - 1.
• BitRate[Htid][ i ] shall be less than or equal to BrVclFactor * MaxBR for at least one value of i in the range of 0 to hrd cpb cnt minusl, inclusive, where BitRate[Htid][ i ] is specified in clause 7.4.6.3 based on parameters selected as specified in clause C.l and MaxBR is specified in Table A.2 in units of BrVclFactor bits/s.
• BitRate[Htid][ i ] shall be less than or equal to BrNalFactor * MaxBR for at least one value of i in the range of 0 to hrd cpb cnt minusl, inclusive, where BitRate[Htid][ i ] is specified in clause 7.4.6.3 based on parameters selected as specified in clause C.l and MaxBR is specified in Table A.2 in units of BrNalFactor bits/s.
• the sum of the NumBytesInNalUnit variables for access unit 0 shall be less than or equal to FormatCapabilityF actor * ( Max( PicSizelnSamplesY, fR * MaxLumaSr ) + MaxLumaSr * ( AuCpbRemovalTime[ 0 ] - AuNominalRemovalTime[ 0 ] ) ) ⁇ MinCr for the value of PicSizelnSamplesY of picture 0, where MaxLumaSr and FormatCapabilityF actor are the values specified in Table A.2 and Table A.3, respectively, that apply to picture 0. h)
• the sum of the NumBytesInNalUnit variables for access unit n shall be less than or equal to FormatCapabilityF actor * MaxLumaSr *
• Equation (A.l) uses the variable PicSizelnSamplesY, which is the picture size of a particular picture.
• the picture size can change from picture to picture within a coded layer video sequence (CL VS). Therefore, the maximum picture size among pictures within a CLVS should be used for the derivation of MaxDpbSize instead.
• MaxDpbSize derived for each layer.
• a limit on the maximum number of slices per picture instead of specifying a limit on the maximum number of slices per picture for each level and use the limit in specifying some constraints for an AU on CPB removal times, i.e., items c and d in Section A.1.2 above, a limit on the maximum number of slices per AU should be specified and used in specifying those constraints.
• the equation for the derivation of the variable MaxDpbSize is updated to use the maximum picture size among pictures within a CL VS instead of using the variable PicSizelnSamplesY, and a value of MaxDpbSize is derived for each layer.
• the specific instance of the max dec pic buffering minusl [ ] syntax element is the max dec _pic_buffering_minusl [ i ] for the highest value of i in the dpb_parameters( ) syntax structure that is determined as the follows: if the layer is an output layer of the OLS, the dpb _parameters( ) syntax structure is the one that applies to the layer when the layer is an output layer in an OLS; otherwise, the dpb _parameters( ) syntax structure is the one that applies to the layer when the layer is not an output layer in an OLS.
• the definitions of the constraints on picture size, picture width, and picture height use the maximum picture size, picture width, and picture height instead of the variable PicSizelnSamplesY and the syntax elements pic width in luma samples and pic height in luma samples. Furthermore, the constraints are specified separately for each layer or each SPS referenced by the layers.
• a constraint on the overall DPB size for an OLS containing multiple layers is specified. a.
• the constraint is specified as follows:
• numDecPics be the number of decoded pictures in the DPB
• picSizeInSamplesY[ i ] for i in the range of 0 to numDecPics - 1, inclusive be the value of PicSizelnSamplesY of the i-th decoded picture in the DPB
• the value pi c sizeInSamplesY[ i ] shall be less than or equal to maxDpbPicBuf* MaxLumaPs, where maxDpbPicBuf is equal to 8 and MaxLumaPs is specified in Table A.l. b.
• the constraint is specified as follows:
• numLayers be the number of layers in the OLS
• maxDecBuff[ i ] and picSizeMaxInSamplesY[ i ] for i in the range of 0 to numLayers - 1, inclusive be the values of max dec pic buffering minus l [ maxTid ] and PicSizeMaxInSamplesY, respectively, of the i-th layer
• PicSizeMaxInSamplesY is equal to pic width max in luma samples * pic height max in luma samples for a layer
• ax dec pi c bufferi ng_m i nus l [ maxTid ] for layer is the value of m ax dec pi c bufferi ng_m i nus l [ i ] for the highest value of i in the dpb_parameters( ) syntax structure that is determined as the follows: if the layer is an output layer of the OLS, the dpb _parameters(
• a limit on the maximum number of slices per picture for each level instead of specifying a limit on the maximum number of slices per picture for each level and use the limit in specifying some constraints for an AU on CPB removal times, a limit on the maximum number of slices per AU is specified and used in specifying those constraints.
• Profiles, tiers and levels specify restrictions on bitstreams and hence limits on the capabilities needed to decode the bitstreams. Profiles, tiers and levels may also be used to indicate interoperability points between individual decoder implementations.
• Each profile specifies a subset of algorithmic features and limits that shall be supported by all decoders conforming to that profile.
• Each level of a tier specifies a set of limits on the values that may be taken by the syntax elements of this Specification.
• the same set of tier and level definitions is ⁇ usally ⁇ used with all profiles, but individual implementations may support a different tier and within a tier a different level for each supported profile.
• a level of a tier generally corresponds to a particular decoder processing load and memory capability.
• the tier with general tier flag equal to 0 is considered to be a lower tier than the tier with general tier flag equal to 1.
• a particular level of a specific tier is considered to be a lower level than some other level of the same tier when the value of the general level idc or sublayer_level_idc[ i ] of the particular level is less than that of the other level.
• the following is specified for expressing the constraints in this annex:
• AU n be the n-th AU in decoding order, with the first AU being AU 0 (i.e., the 0-th AU).
• MaxDpbSize Min( ( 4 * maxDpbPicBuf ) / 3, 16 ) else
• MaxDpbSize maxDpbPicBuf where MaxLumaPs is specified in Table A.l, and maxDpbPicBuf is equal to 8.
• bitstreams conforming to a profile at a specified tier and level shall obey the following constraints for each bitstream conformance test as specified in Annex C: a) ⁇ PicSizeMaxInSamplesY for each referenced SPS ⁇ shall be less than or equal to MaxLumaPs, where MaxLumaPs is specified in Table A.L b) The value of pic_width_ ⁇ max_ ⁇ in_luma_samples ⁇ for each referenced SPS ⁇ shall be less than or equal to Sqrt( MaxLumaPs * 8 ).
• CpbSize[Htid][ i ] shall be less than or equal to CpbNalFactor * MaxCPB for at least one value of i in the range of 0 to hrd cpb cnt minusl, inclusive, where CpbSize[Htid][ i ] is specified in clause 7.4.6.3 based on parameters selected as specified in clause C.l, CpbNalFactor is specified in Table A.3, and MaxCPB is specified in Table A.1 in units of CpbNalFactor bits.
• the value of max dec _pic_buffering_minusl [ maxTid ] + 1 shall be less than or equal to MaxDpbSize for the layer, where max dec pic buffering minus l [ maxTid ] is the value of max_dec_pic_buffering_minusl [ i ] for the highest value of i in the dpb_parameters( ) syntax structure that is determined as the follows: if the layer is an output layer of the OLS, the dpb _parameters( ) syntax structure is the one that applies to the layer when the layer is an output layer in an OLS; otherwise, the dpb _parameters( ) syntax structure is the one that applies to the layer when the layer is not an output layer in an OLS.
• numDecPics be the number of decoded pictures in the DPB
• picSizelnSamplesYf i ] for i in the range of 0 to numDecPics - 1, inclusive be the value of PicSizelnSamplesY of the i-th decoded picture in the DPB
• the value of - 1 picSizelnSamplesYf i ] shall be less than or equal to maxDpbPicBuf* MaxLumaPs, where maxDpbPicBuf is equal to 8 and MaxLumaPs is specified in Table A.1.
• Table A.1 specifies the limits for each level of each tier for levels other than level 8.5.
• a tier and level to which a bitstream conforms are indicated by the syntax elements general tier flag and general level idc, and a level to which a sublayer representation conforms are indicated by the syntax element sublayer_level_idc[ i ], as follows:
• general tier flag indicates conformance to the Main tier
• general tier flag indicates conformance to the High tier
• general tier flag shall be equal to 0 for levels below level 4 (corresponding to the entries in Table A.l marked with Otherwise (the specified level is level 8.5)
• level idc and sublay er_level_idc[ i ] shall be set equal to a value of 30 times the level number specified in Table A.l.
• variable fR be set equal to 1 ⁇ 300.
• HbrF actor is defined as follows:
• HbrF actor is set equal to 1.
• the variable BrVclFactor which represents the VCL bit rate scale factor, is set equal to CpbVclF actor * HbrF actor.
• the variable BrNalFactor which represents the NAL bit rate scale factor, is set equal to CpbNalF actor * HbrF actor.
• MinCr is set equal to MinCrBase * MinCrScaleFactor ⁇ HbrFactor.
• the variable AuSizeInSamplesY[ n ] is set equal to - 1 picSizelnSamplesY[ i ], where numDecPics is the number of pictures in AU n, picSizelnSamplesYf i ] for i in the range of 0 to numDecPics - 1, inclusive, is the value of PicSizelnSamplesY for the i-th picture in AU n. ⁇
• Bitstreams conforming to the Main 10 or Main 4:4:4 10 profile at a specified tier and level shall obey the following constraints for each bitstream conformance test as specified in Annex C: a) The nominal removal time of AU n (with n greater than 0) from the CPB, as specified in clause C.2.3, shall satisfy the constraint that
• AuNominalRemovalTime[ n ] - AuCpbRemovalTime[ n - 1 ] is greater than or equal to Max( ⁇ AuSizeInSamplesY[ n - 1 ] ⁇ ⁇ MaxLumaSr, fR ), where MaxLumaSr is the value specified in Table A.2 that applies to AU n - 1.
• BitRate[Htid][ i ] shall be less than or equal to BrVclFactor * MaxBR for at least one value of i in the range of 0 to hrd cpb cnt minusl, inclusive, where BitRate[Htid][ i ] is specified in clause 7.4.6.3 based on parameters selected as specified in clause C.l and MaxBR is specified in Table A.2 in units of BrVclFactor bits/s.
• BitRate[Htid][ i ] shall be less than or equal to BrNalFactor * MaxBR for at least one value of i in the range of 0 to hrd cpb cnt minusl, inclusive, where BitRate[Htid][ i ] is specified in clause 7.4.6.3 based on parameters selected as specified in clause C.l and MaxBR is specified in Table A.2 in units of BrNalFactor bits/s.
• the removal time of AU 0 shall satisfy the constraint that the number of tiles in each picture in AU 0 is less than or equal to Min( Max( 1, MaxTileCols * MaxTileRows * 120 * ( AuCpbRemovalTime[ 0 ] - AuNominalRemovalTime[ 0 ] ) + MaxTileCols * MaxTileRows * ⁇ AuSizeInSamplesY[ 0 ] ⁇ / MaxLumaPs ), MaxTileCols * MaxTileRows ), where MaxTileCols and MaxTileRows are the values specified in Table A.l that apply to AU 0.
• FIG. 1 is a block diagram showing an example video processing system 1000 in which various techniques disclosed herein may be implemented.
• the system 1000 may include input 1002 for receiving video content.
• the video content may be received in a raw or uncompressed format, e.g., 8 or 10 bit multi-component pixel values, or may be in a compressed or encoded format.
• the input 1002 may represent a network interface, a peripheral bus interface, or a storage interface. Examples of network interface include wired interfaces such as Ethernet, passive optical network (PON), etc. and wireless interfaces such as Wi-Fi or cellular interfaces.
• the system 1000 may include a coding component 1004 that may implement the various coding or encoding methods described in the present document.
• the coding component 1004 may reduce the average bitrate of video from the input 1002 to the output of the coding component 1004 to produce a coded representation of the video.
• the coding techniques are therefore sometimes called video compression or video transcoding techniques.
• the output of the coding component 1004 may be either stored, or transmitted via a communication connected, as represented by the component 1006.
• the stored or communicated bitstream (or coded) representation of the video received at the input 1002 may be used by the component 1008 for generating pixel values or displayable video that is sent to a display interface 1010.
• the process of generating user-viewable video from the bitstream representation is sometimes called video decompression.
• certain video processing operations are referred to as “coding” operations or tools, it will be appreciated that the coding tools or operations are used at an encoder and corresponding decoding tools or operations that reverse the results of the coding will be performed by
• Examples of a peripheral bus interface or a display interface may include universal serial bus (USB) or high definition multimedia interface (HDMI) or Displayport, and so on.
• Examples of storage interfaces include SATA (serial advanced technology attachment), PCI, IDE interface, and the like.
• FIG. 2 is a block diagram of a video processing apparatus 2000.
• the apparatus 2000 may be used to implement one or more of the methods described herein.
• the apparatus 2000 may be embodied in a smartphone, tablet, computer, Internet of Things (IoT) receiver, and so on.
• the apparatus 2000 may include one or more processors 2002, one or more memories 2004 and video processing hardware 2006.
• the processor(s) 2002 may be configured to implement one or more methods described in the present document (e.g., in FIGS. 6-9).
• the memory (memories) 2004 may be used for storing data and code used for implementing the methods and techniques described herein.
• the video processing hardware 2006 may be used to implement, in hardware circuitry, some techniques described in the present document.
• FIG. 3 is a block diagram that illustrates an example video coding system 100 that may utilize the techniques of this disclosure.
• video coding system 100 may include a source device 110 and a destination device 120.
• Source device 110 generates encoded video data which may be referred to as a video encoding device.
• Destination device 120 may decode the encoded video data generated by source device 110 which may be referred to as a video decoding device.
• Source device 110 may include a video source 112, a video encoder 114, and an input/output (EO) interface 116.
• EO input/output
• Video source 112 may include a source such as a video capture device, an interface to receive video data from a video content provider, and/or a computer graphics system for generating video data, or a combination of such sources.
• the video data may comprise one or more pictures.
• Video encoder 114 encodes the video data from video source 112 to generate a bitstream.
• the bitstream may include a sequence of bits that form a coded representation of the video data.
• the bitstream may include coded pictures and associated data.
• the coded picture is a coded representation of a picture.
• the associated data may include sequence parameter sets, picture parameter sets, and other syntax structures.
• I/O interface 116 may include a modulator/demodulator (modem) and/or a transmitter.
• modem modulator/demodulator
• the encoded video data may be transmitted directly to destination device 120 via I/O interface 116 through network 130a.
• the encoded video data may also be stored onto a storage medium/server 130b for access by destination device 120.
• Destination device 120 may include an I/O interface 126, a video decoder 124, and a display device 122.
• I/O interface 126 may include a receiver and/or a modem. I/O interface 126 may acquire encoded video data from the source device 110 or the storage medium/ server 130b. Video decoder 124 may decode the encoded video data. Display device 122 may display the decoded video data to a user. Display device 122 may be integrated with the destination device 120, or may be external to destination device 120 which be configured to interface with an external display device.
• Video encoder 114 and video decoder 124 may operate according to a video compression standard, such as the High Efficiency Video Coding (HEVC) standard, Versatile Video Coding(VVM) standard and other current and/or further standards.
• HEVC High Efficiency Video Coding
• VVM Versatile Video Coding
• FIG. 4 is a block diagram illustrating an example of video encoder 200, which may be video encoder 114 in the system 100 illustrated in FIG. 3.
• Video encoder 200 may be configured to perform any or all of the techniques of this disclosure.
• video encoder 200 includes a plurality of functional components. The techniques described in this disclosure may be shared among the various components of video encoder 200.
• a processor may be configured to perform any or all of the techniques described in this disclosure.
• the functional components of video encoder 200 may include a partition unit 201, a predication unit 202 which may include a mode select unit 203, a motion estimation unit 204, a motion compensation unit 205 and an intra prediction unit 206, a residual generation unit 207, a transform unit 208, a quantization unit 209, an inverse quantization unit 210, an inverse transform unit 211, a reconstruction unit 212, a buffer 213, and an entropy encoding unit 214.
• a partition unit 201 may include a mode select unit 203, a motion estimation unit 204, a motion compensation unit 205 and an intra prediction unit 206, a residual generation unit 207, a transform unit 208, a quantization unit 209, an inverse quantization unit 210, an inverse transform unit 211, a reconstruction unit 212, a buffer 213, and an entropy encoding unit 214.
• video encoder 200 may include more, fewer, or different functional components.
• predication unit 202 may include an intra block copy(IBC) unit.
• the IBC unit may perform predication in an IBC mode in which at least one reference picture is a picture where the current video block is located.
• motion estimation unit 204 and motion compensation unit 205 may be highly integrated, but are represented in the example of FIG. 4 separately for purposes of explanation.
• Partition unit 201 may partition a picture into one or more video blocks.
• Video encoder 200 and video decoder 300 may support various video block sizes.
• Mode select unit 203 may select one of the coding modes, intra or inter, e.g., based on error results, and provide the resulting intra- or inter-coded block to a residual generation unit 207 to generate residual block data and to a reconstruction unit 212 to reconstruct the encoded block for use as a reference picture.
• Mode select unit 203 may select a combination of intra and inter predication (CUP) mode in which the predication is based on an inter predication signal and an intra predication signal.
• Mode select unit 203 may also select a resolution for a motion vector (e.g., a sub-pixel or integer pixel precision) for the block in the case of inter predication.
• a motion vector e.g., a sub-pixel or integer pixel precision
• motion estimation unit 204 may generate motion information for the current video block by comparing one or more reference frames from buffer 213 to the current video block.
• Motion compensation unit 205 may determine a predicted video block for the current video block based on the motion information and decoded samples of pictures from buffer 213 other than the picture associated with the current video block.
• Motion estimation unit 204 and motion compensation unit 205 may perform different operations for a current video block, for example, depending on whether the current video block is in an I slice, a P slice, or a B slice.
• motion estimation unit 204 may perform uni-directional prediction for the current video block, and motion estimation unit 204 may search reference pictures of list 0 or list 1 for a reference video block for the current video block. Motion estimation unit 204 may then generate a reference index that indicates the reference picture in list 0 or list 1 that contains the reference video block and a motion vector that indicates a spatial displacement between the current video block and the reference video block. Motion estimation unit 204 may output the reference index, a prediction direction indicator, and the motion vector as the motion information of the current video block. Motion compensation unit 205 may generate the predicted video block of the current block based on the reference video block indicated by the motion information of the current video block.
• motion estimation unit 204 may perform bi-directional prediction for the current video block, motion estimation unit 204 may search the reference pictures in list 0 for a reference video block for the current video block and may also search the reference pictures in list 1 for another reference video block for the current video block. Motion estimation unit 204 may then generate reference indexes that indicate the reference pictures in list 0 and list 1 containing the reference video blocks and motion vectors that indicate spatial displacements between the reference video blocks and the current video block. Motion estimation unit 204 may output the reference indexes and the motion vectors of the current video block as the motion information of the current video block. Motion compensation unit 205 may generate the predicted video block of the current video block based on the reference video blocks indicated by the motion information of the current video block.
• motion estimation unit 204 may output a full set of motion information for decoding processing of a decoder.
• motion estimation unit 204 may do not output a full set of motion information for the current video. Rather, motion estimation unit 204 may signal the motion information of the current video block with reference to the motion information of another video block. For example, motion estimation unit 204 may determine that the motion information of the current video block is sufficiently similar to the motion information of a neighboring video block. [0063] In one example, motion estimation unit 204 may indicate, in a syntax structure associated with the current video block, a value that indicates to the video decoder 300 that the current video block has the same motion information as the another video block.
• motion estimation unit 204 may identify, in a syntax structure associated with the current video block, another video block and a motion vector difference (MVD).
• the motion vector difference indicates a difference between the motion vector of the current video block and the motion vector of the indicated video block.
• the video decoder 300 may use the motion vector of the indicated video block and the motion vector difference to determine the motion vector of the current video block.
• video encoder 200 may predictively signal the motion vector. Two examples of predictive signaling techniques that may be implemented by video encoder 200 include advanced motion vector predication (AMVP) and merge mode signaling.
• AMVP advanced motion vector predication
• merge mode signaling merge mode signaling
• Intra prediction unit 206 may perform intra prediction on the current video block. When intra prediction unit 206 performs intra prediction on the current video block, intra prediction unit 206 may generate prediction data for the current video block based on decoded samples of other video blocks in the same picture.
• the prediction data for the current video block may include a predicted video block and various syntax elements.
• Residual generation unit 207 may generate residual data for the current video block by subtracting (e.g., indicated by the minus sign) the predicted video block(s) of the current video block from the current video block.
• the residual data of the current video block may include residual video blocks that correspond to different sample components of the samples in the current video block.
• residual generation unit 207 may not perform the subtracting operation.
• Transform processing unit 208 may generate one or more transform coefficient video blocks for the current video block by applying one or more transforms to a residual video block associated with the current video block.
• quantization unit 209 may quantize the transform coefficient video block associated with the current video block based on one or more quantization parameter (QP) values associated with the current video block.
• QP quantization parameter
• Inverse quantization unit 210 and inverse transform unit 211 may apply inverse quantization and inverse transforms to the transform coefficient video block, respectively, to reconstruct a residual video block from the transform coefficient video block.
• Reconstruction unit 212 may add the reconstructed residual video block to corresponding samples from one or more predicted video blocks generated by the predication unit 202 to produce a reconstructed video block associated with the current block for storage in the buffer 213.
• loop filtering operation may be performed reduce video blocking artifacts in the video block.
• Entropy encoding unit 214 may receive data from other functional components of the video encoder 200. When entropy encoding unit 214 receives the data, entropy encoding unit 214 may perform one or more entropy encoding operations to generate entropy encoded data and output a bitstream that includes the entropy encoded data.
• FIG. 5 is a block diagram illustrating an example of video decoder 300 which may be video decoder 114 in the system 100 illustrated in FIG. 3.
• the video decoder 300 may be configured to perform any or all of the techniques of this disclosure.
• the video decoder 300 includes a plurality of functional components.
• the techniques described in this disclosure may be shared among the various components of the video decoder 300.
• a processor may be configured to perform any or all of the techniques described in this disclosure.
• video decoder 300 includes an entropy decoding unit 301, a motion compensation unit 302, an intra prediction unit 303, an inverse quantization unit 304, an inverse transformation unit 305 , and a reconstruction unit 306 and a buffer 307.
• Video decoder 300 may, in some examples, perform a decoding pass generally reciprocal to the encoding pass described with respect to video encoder 200 (FIG. 4).
• Entropy decoding unit 301 may retrieve an encoded bitstream.
• the encoded bitstream may include entropy coded video data (e.g., encoded blocks of video data).
• Entropy decoding unit 301 may decode the entropy coded video data, and from the entropy decoded video data, motion compensation unit 302 may determine motion information including motion vectors, motion vector precision, reference picture list indexes, and other motion information. Motion compensation unit 302 may, for example, determine such information by performing the AMVP and merge mode.
• Motion compensation unit 302 may produce motion compensated blocks, possibly performing interpolation based on interpolation filters. Identifiers for interpolation filters to be used with sub-pixel precision may be included in the syntax elements.
• Motion compensation unit 302 may use interpolation filters as used by video encoder 20 during encoding of the video block to calculate interpolated values for sub-integer pixels of a reference block. Motion compensation unit 302 may determine the interpolation filters used by video encoder 200 according to received syntax information and use the interpolation filters to produce predictive blocks.
• Motion compensation unit 302 may uses some of the syntax information to determine sizes of blocks used to encode frame(s) and/or slice(s) of the encoded video sequence, partition information that describes how each macroblock of a picture of the encoded video sequence is partitioned, modes indicating how each partition is encoded, one or more reference frames (and reference frame lists) for each inter-encoded block, and other information to decode the encoded video sequence.
• Intra prediction unit 303 may use intra prediction modes for example received in the bitstream to form a prediction block from spatially adjacent blocks.
• Inverse quantization unit 303 inverse quantizes, i.e., de-quantizes, the quantized video block coefficients provided in the bitstream and decoded by entropy decoding unit 301.
• Inverse transform unit 303 applies an inverse transform.
• Reconstruction unit 306 may sum the residual blocks with the corresponding prediction blocks generated by motion compensation unit 202 or intra-prediction unit 303 to form decoded blocks. If desired, a deblocking filter may also be applied to filter the decoded blocks in order to remove blockiness artifacts.
• the decoded video blocks are then stored in buffer 307, which provides reference blocks for subsequent motion compensation/intra predication and also produces decoded video for presentation on a display device.
• FIGS. 6-9 show example methods that can implement the technical solution described above in, for example, the embodiments shows in FIGS. 1-5.
• FIG. 6 shows a flowchart for an example method 600 of video processing.
• the method 600 includes, at operation 610, performing a conversion between a video and a bitstream of the video according to a rule, the bitstream including one or more bitstream parts that are independently decodable, each bitstream part corresponding to one or more coded video pictures of the video, and the rule specifying that a maximum decoded picture buffer size required for decoding the bitstream or the one or more bitstream parts is determined based on a maximum allowed picture size for the one or more coded video pictures corresponding to the bitstream or the one or more bitstream parts.
• FIG. 7 shows a flowchart for an example method 700 of video processing.
• the method 700 includes, at operation 710, performing a conversion between a video comprising a video unit and a bitstream of the video comprising one or more coded layer video sequences, the bitstream conforming to a rule that specifies that a maximum buffer size of a decoded picture of a coded layer video sequence is constrained to be less than or equal to a maximum picture size selected from pictures in the coded layer video sequence.
• FIG. 8 shows a flowchart for an example method 800 of video processing.
• the method 800 includes, at operation 810, performing a conversion between a video and a bitstream of the video according to a rule, the bitstream including one or more bitstream parts that are independently decodable, each bitstream part corresponding to one or more coded video pictures of the video, and the rule specifying at least one of a maximum allowed picture size, a maximum allowed picture width, and a maximum allowed picture height for the conversion.
• FIG. 9 shows a flowchart for an example method 900 of video processing.
• the method 900 includes, at operation 910, performing a conversion between a video and a bitstream of the video, the bitstream including one or more output layer sets, at least one output layer set including multiple video layers, and the bitstream conforming to a rule that specifies a constraint on an overall size of a decoded picture buffer for the at least one output layer set comprising the multiple video layers.
• a method of video processing comprising performing a conversion between a video and a bitstream of the video according to a rule, wherein the bitstream includes one or more bitstream parts that are independently decodable, each bitstream part corresponding to one or more coded video pictures of the video, and wherein the rule specifies that a maximum decoded picture buffer size required for decoding the bitstream or the one or more bitstream parts is determined based on a maximum allowed picture size for the one or more coded video pictures corresponding to the bitstream or the one or more bitstream parts.
• A2 The method of solution Al, further comprising refraining from determining the maximum picture buffer size based on a picture size in luma samples (denoted PicSizelnSamplesY).
• A3. The method of solution A1 or A2, wherein the maximum decoded picture buffer size is denoted MaxDpbSize, a maximum luma picture size is denoted MaxLumaPs, the maximum allowed picture size is denoted PicSizeMaxInSamplesY, and a default maximum decoded picture buffer size is denoted maxDpbPicBuf, and wherein MaxDpbSize is determined as follows: if( PicSizeMaxInSamplesY £ ( MaxLumaPs » 2 ) )
• MaxDpbSize Min( 4 * maxDpbPicBuf, 16 ) else if( PicSizeMaxInSamplesY £ ( MaxLumaPs » 1 ) )
• MaxDpbSize Min( 2 * maxDpbPicBuf, 16 ) else if( PicSizeMaxInSamplesY £ ( ( 3 * MaxLumaPs ) » 2 ) )
• MaxDpbSize Min( ( 4 * maxDpbPicBuf ) / 3, 16 ) else
• MaxDpbSize maxDpbPicBuf.
• A5. The method of any of solutions A1 to A4, wherein the maximum decoded picture buffer size is derived on a per-CLVS basis.
• a method of video processing comprising performing a conversion between a video and a bitstream of the video according to a rule, wherein the bitstream includes one or more bitstream parts that are independently decodable, each bitstream part corresponding to one or more coded video pictures of the video, and wherein the rule specifies at least one of a maximum allowed picture size, a maximum allowed picture width, and a maximum allowed picture height for the conversion.
• each of the one or more bitstream parts that is independently decodable is a coded layer video sequence (CLVS).
• CLVS coded layer video sequence
• A8 The method of solution A7, wherein one or more of the maximum allowed picture size, the maximum allowed picture width, and the maximum allowed picture height are specified on a per-CLVS basis.
• A12 The method of any of solutions A6 to Al l, wherein the rule specifies that the maximum allowed picture height (denoted pic height max in luma samples) for each referenced sequence parameter set (SPS) is less than or equal to Sqrt( 8 x MaxLumaPs ), wherein MaxLumaPs is a maximum luma picture size.
• SPS referenced sequence parameter set
• a method of video processing comprising performing a conversion between a video and a bitstream of the video comprising one or more coded layer video sequences, wherein the bitstream conforms to a rule, and wherein the rule specifies that a maximum buffer size of a decoded picture of a coded layer video sequence is constrained to be less than or equal to a maximum picture size selected from pictures in the coded layer video sequence.
• A14 The method of solution A13, wherein the maximum buffer size of the decoded picture is selected based on a maximum buffer size from a decoded picture buffer (DPB) parameter set.
• DPB decoded picture buffer
• A15 The method of solution A14, wherein the DPB parameter set corresponds to a DPB parameter set for a coding layer that is an outer layer of an output layer set (OLS).
• OLS output layer set
• A16 The method of solution A14, wherein the DPB parameter set corresponds to a DPB parameter set for a coding layer that is not an outer layer of an output layer set (OLS).
• OLS output layer set
• a method of video processing comprising performing a conversion between a video and a bitstream of the video, wherein the bitstream includes one or more output layer sets, wherein at least one output layer set includes multiple video layers, and wherein the bitstream conforms to a rule that specifies a constraint on an overall size of a decoded picture buffer for the at least one output layer set comprising the multiple video layers.
• A18 The method of solution A17, wherein the decoded picture buffer comprises a plurality of decoded pictures after a decoding of each access unit, wherein each of the plurality of decoded pictures has a width in luma samples, and wherein the constraint specifies that a sum of the widths of the plurality of decoded pictures is less than or equal to a predetermined value.
• the predetermined value is based on an index of a corresponding coding layer of the multiple coding layers.
• each of the multiple coding layers is associated with each of a plurality of decoded pictures, wherein each of the plurality of decoded pictures has a maximum width, and wherein the constraint specifies that a sum of the maximum widths of the plurality of decoded pictures is less than or equal to a predetermined value.
• A21 The method of solution A20, wherein the maximum width is a product of a maximum picture width in luma samples and a maximum picture height in luma samples for the corresponding layer of the multiple coding layers.
• A22 The method of any of solutions A1 to A21, wherein the conversion comprises decoding the video from the bitstream.
• A23 The method of any of solutions A1 to A21, wherein the conversion comprises encoding the video into the bitstream.
• a video processing apparatus comprising a processor configured to implement a method recited in any one or more of solutions A1 to A24.
• A26 A non-transitory computer-readable recording medium configured to store a bitstream of a video generated by a method recited in any one or more of solutions A1 to A24.
• A27 A non-transitory computer-readable recording medium configured to store instructions that cause a processor to implement a method recited in any one or more of solutions A1 to A24.
• a video processing apparatus for storing a bitstream comprising generating a bitstream from the video according to a rule; and storing the bitstream in a non-transitory computer-readable recording medium, wherein the bitstream includes one or more bitstream parts that are independently decodable, each bitstream part corresponding to one or more coded video pictures of the video, and wherein the rule specifies that a maximum decoded picture buffer size required for decoding the bitstream or the one or more bitstream parts is determined based on a maximum allowed picture size for the one or more coded video pictures corresponding to the bitstream or the one or more bitstream parts.
• a method for storing a bitstream of a video comprising generating a bitstream from the video according to a rule; and storing the bitstream in a non-transitory computer-readable recording medium, wherein the bitstream includes one or more bitstream parts that are independently decodable, each bitstream part corresponding to one or more coded video pictures of the video, and wherein the rule specifies at least one of a maximum allowed picture size, a maximum allowed picture width, and a maximum allowed picture height for the conversion.
• a method of video processing comprising performing a conversion between a video and a bitstream of the video, wherein the bitstream is organized into one or more access units according to a rule, and wherein the rule specifies that one or more constraints for an access unit on at least one of a coded picture buffer (CPB) removal time, a nominal CPB removal time, a decoded picture buffer (DPB) output time, or a sum of a number of bytes in a network abstract layer (NAL) unit are based on a sum of a picture size of each of a plurality of pictures of the access unit.
• CPB coded picture buffer
• DPB decoded picture buffer
• NAL network abstract layer
• DpbOutputInterval[ n ] Max( AuSizeInSamplesY[ n - 1 ] ⁇ MaxLumaSr, fR ), wherein DpbOutputInterval[ n ] is the DPB output time of an n-th AU, MaxLumaSr is a maximum luma sample rate (in samples per second), AuSizeInSamplesY[ n - 1 ] is a size of the (n-l)-th AU in samples, and fR is a variable equal to 1 ⁇ 300, and wherein n is an integer greater than zero.
• NumBytesInNalUnit[ 0 ] is the sum of the number of bytes in the NAL unit for a first access unit (AU)
• AuSizelnSamplesYf 0 ] is a size of the first AU in samples
• MaxLumaSr is a maximum luma sample rate (in samples per second)
• AuCpbRemovalTime[ 0 ] is the CPB removal time for the first AU
• AuNomi nal Removal Time[ 0 ] is the nominal CPB removal time for the first AU
• MinCr is a minimum compression level
• fR is a variable equal to 1 ⁇ 300.
• a method of video processing comprising performing a conversion between a video and a bitstream of the video, wherein the bitstream is organized into one or more access units according to a rule, and wherein the rule specifies a limit on a maximum number of slices in an access unit.
• BIO The method of solution B7, wherein the rule further specifies that a constraint on a coded picture buffer (CPB) removal time (denoted AuCpbRemovalTime) for each access unit is based on the limit on the maximum number of slices in the access unit.
• CPB coded picture buffer
• NumSlicesPerAu[ 0 ] Min( Max( 1, MaxSlicesPerAu x MaxLumaSr / MaxLumaPs x ( AuCpb Rem oval Time[ 0 ] - AuNomi nal Removal Time[ 0 ] ) + MaxSlicesPerAu x AuSizelnSamplesYf 0 ] / MaxLumaPs ), MaxSlicesPerAu ), wherein MaxSlicesPerAu is the maximum number of slices in the access unit, NumSlicesPerAu[ 0 ] is a number of slices in the first access unit (AU), MaxLumaPs is a maximum luma picture size, MaxLumaSr is a maximum luma sample rate (in samples per second), AuCpb Rem oval Time[ 0 ] is the CPB removal time for the first AU, and AuNomi nal Removal Time[ 0 ] is the nominal CPB removal time
• MaxSlicesPerAu is the maximum number of slices in the access unit
• NumSlicesPerAu[ n ] is a number of slices in an n-th access unit (AU)
• MaxLumaPs is a maximum luma picture size
• MaxLumaSr is a maximum luma sample rate (in samples per second)
• AuCpb Rem oval Time[ n ] is the CPB removal time for the n-th AU
• AuCpb Removal Time[ n-1 ] is the CPB removal time for an (n-l)-th AU, and wherein n is an integer greater than zero.
• B15 The method of any of solutions B1 to B13, wherein the conversion comprises encoding the video into the bitstream.
• B16 The method of any of solutions B1 to B13, wherein the performing the conversion comprises encoding the video into the bitstream; and storing the bitstream in a non-transitory computer-readable recording medium.
• a video processing apparatus comprising a processor configured to implement a method recited in any one or more of solutions B1 to B16.
• B18 A non-transitory computer-readable recording medium configured to store a bitstream of a video generated by a method recited in any one or more of solutions B1 to B16.
• B19 A non-transitory computer-readable recording medium configured to store instructions that cause a processor to implement a method recited in any one or more of solutions B1 to B16.
• a video processing apparatus for storing a bitstream comprising generating a bitstream from the video according to a rule; and storing the bitstream in a non-transitory computer-readable recording medium, wherein the bitstream is organized into one or more access units according to the rule, and wherein the rule specifies that one or more constraints for an access unit on at least one of a coded picture buffer (CPB) removal time, a nominal CPB removal time, a decoded picture buffer (DPB) output time, or a sum of a number of bytes in a network abstract layer (NAL) unit are based on a sum of a picture size of each of a plurality of pictures of the access unit.
• CPB coded picture buffer
• DPB decoded picture buffer
• B22 A method for storing a bitstream of a video, comprising generating a bitstream from the video according to a rule; and storing the bitstream in a non-transitory computer-readable recording medium, wherein the bitstream is organized into one or more access units according to the rule, and wherein the rule specifies a limit on a maximum number of slices in an access unit.
• a method of video processing comprising performing a conversion between a video unit of a video and a coded representation of the video wherein a maximum picture buffer size used during the conversion is determined from a maximum picture size among pictures in a coding layer of the video unit, wherein the maximum picture buffer size is specific to the coding layer.
• P2 The method of solution PI, wherein the maximum picture buffer size is determined independent of a variable defining picture size associated with the coding layer.
• a method of video processing comprising performing a conversion between a video unit of a video and a coded representation of the video, wherein the coded representation conforms to a format rule that specifies a constraint related to a maximum buffer size of a decoded picture is applicable to only a single-layer coded representation.
• a method of video processing comprising performing a conversion between a video unit of a video and a coded representation of the video, wherein the coded representation conforms to a format rule that specifies that, in case that the coded representation includes multiple layers, values of a maximum picture size, a picture width, and a picture height among pictures are individually specifies within each coded layer of the coded representation of the video.
• a video decoding apparatus comprising a processor configured to implement a method recited in one or more of solutions PI to P8.
• a video encoding apparatus comprising a processor configured to implement a method recited in one or more of solutions PI to P8.
• PI 1 A computer program product having computer code stored thereon, the code, when executed by a processor, causes the processor to implement a method recited in any of solutions PI to P8.
• video processing may refer to video encoding, video decoding, video compression or video decompression.
• video compression algorithms may be applied during conversion from pixel representation of a video to a corresponding bitstream representation or vice versa.
• the bitstream representation (or simply, the bitstream) of a current video block may, for example, correspond to bits that are either co-located or spread in different places within the bitstream, as is defined by the syntax.
• a macroblock may be encoded in terms of transformed and coded error residual values and also using bits in headers and other fields in the bitstream.
• the disclosed and other solutions, examples, embodiments, modules and the functional operations described in this document can be implemented in digital electronic circuitry, or in computer software, firmware, or hardware, including the structures disclosed in this document and their structural equivalents, or in combinations of one or more of them.
• the disclosed and other embodiments can be implemented as one or more computer program products, i.e., one or more modules of computer program instructions encoded on a computer readable medium for execution by, or to control the operation of, data processing apparatus.
• the computer readable medium can be a machine-readable storage device, a machine-readable storage substrate, a memory device, a composition of matter effecting a machine-readable propagated signal, or a combination of one or more them.
• data processing apparatus encompasses all apparatus, devices, and machines for processing data, including by way of example a programmable processor, a computer, or multiple processors or computers.
• the apparatus can include, in addition to hardware, code that creates an execution environment for the computer program in question, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of them.
• a propagated signal is an artificially generated signal, e.g., a machine-generated electrical, optical, or electromagnetic signal, that is generated to encode information for transmission to suitable receiver apparatus.
• a computer program (also known as a program, software, software application, script, or code) can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment.
• a computer program does not necessarily correspond to a file in a file system.
• a program can be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code).
• a computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network.
• Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read only memory or a random-access memory or both.
• the essential elements of a computer are a processor for performing instructions and one or more memory devices for storing instructions and data.
• a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto optical disks, or optical disks.
• mass storage devices for storing data, e.g., magnetic, magneto optical disks, or optical disks.
• Computer readable media suitable for storing computer program instructions and data include all forms of non-volatile memory, media and memory devices, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto optical disks; and CD ROM and DVD-ROM disks.
• the processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.

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