Abstract: Difference calculation based on partial position is described. In a representative aspect, a method of video processing comprising: calculating, during a conversion between a current block of video and a bitstream representation of the current block, differences between two reference blocks associated with the current block or differences between two reference sub-blocks associated with a sub-block within the current block based on representative positions of the reference blocks or representative positions of the reference sub-blocks; and performing the conversion based on the differences.

Abstract: An example method of video processing includes performing a conversion between a picture of a video and a bitstream representation of the video. The picture includes one or more sub-pictures, and the bitstream representation conforms to a format rule that specifies that a length of a syntax element is equal to Ceil(Log 2(SS)) bits. SS is greater than 0, and the syntax element indicating a horizontal or a vertical position of a top-left corner of a coding tree unit of a sub-picture of the picture.

Abstract: A method, a video processing apparatus and computer-readable program medium for video process is disclosed. A method of video processing includes storing, during a conversion between a current block of video and a bitstream representation of the current block, affine model parameters for the current block; and performing the conversion using the affine model parameters, wherein the affine model parameters are derived at least from motion vectors of control points of the current block.

Abstract: A video processing method is provided, including: performing a conversion between a coded representation of a video including one or more video regions and the video, wherein the coded representation includes reshaping model information applicable for in-loop reshaping (ILR) of some of the one or more video regions, wherein the reshaping model information provides information for a reconstruction of a video unit of a video region based on a representation in a first domain and a second domain and/or scaling chroma residue of a chroma video unit, wherein the reshaping model information includes a parameter set that includes a first syntax element that derives a number of bits used to represent a second syntax element specifying an absolute delta codeword value from a corresponding bin, and wherein the first syntax element has a value smaller than a threshold.

Abstract: Methods and apparatus for video processing are described. The video processing may include video encoding, video decoding or video transcoding. One example video processing method includes performing a conversion between a video including one or more pictures including one or more slices and a coded representation of the video, wherein the coded representation conforms to a format rule that specifies that a condition of a field in the coded representation controls a constraint on a slice type or whether the slice type is included in the coded representation for a video slice, wherein the field includes a general constraint flag, a network abstraction layer unit type or whether the video slice is in a first video picture of an access unit.

Abstract: Methods and apparatus for video processing are described. The video processing may include video encoding, video decoding or video transcoding. One example video processing method includes performing a conversion between a video comprising a picture in a video unit and a bitstream of the video according to a format rule. The format rule specifies that, responsive to a width of a picture being equal to a maximum allowed picture width in the video unit and a height of the picture being equal to a maximum allowed picture height in the video unit, a conformance window flag in a picture parameter set corresponding to the picture is set to a zero value.

Abstract: Devices, systems and methods for specifying the syntax and semantics of the decoding parameter set (DPS) are described. One example method of video processing includes determining, for a conversion between a video and a bitstream of the video, that each output layer set (OLS) in a coded video sequence (CVS) in the bitstream conforms to at least one profile-tier-level (PTL) syntax structure included in a data structure associated with decoding parameter semantics in the bitstream, and performing, based on the determining, the conversion, wherein the PTL syntax structure indicates a profile, a tier, and a level of the bitstream.

Abstract: A method for video processing is provided. The method includes determining, for a conversion between a current video block of a video and a coded representation of the video, a context that is used to code a flag using arithmetic coding in the coded representation of the current video block, wherein the context is based on whether a top-left neighboring block of the current video block is coded using a cross-component linear model (CCLM) prediction mode; and performing the conversion based on the determining.

Abstract: Devices, systems and methods for digital video coding, which includes inter prediction with refinement, are described. An exemplary method of video processing includes determining to use, for a conversion between a current block of a video and a bitstream representation of the video, a first linear optimization model for the conversion using a first coding mode, the first linear optimization model being derived from a second linear optimization model that is used for the conversion using a second coding mode, and performing, based on the determining, the conversion. Another exemplary method of video processing includes determining to use, for a conversion between a current block of a video and a bitstream representation of the video, a gradient value computation algorithm for a bi-directional optical flow tool, and performing, based on the determining, the conversion.

Abstract: A method of video processing is provided to include determining, for a conversion between a video block of a video and a bitstream of the video, a parameter of a cross-component linear model (CCLM) for the video block according to a rule, and performing the conversion based on the determining, and wherein the rule specifies to use a variable representing a neighbouring luma sample in the determining of the parameter of the CCLM only in case that the variable has a certain value.

Abstract: Pruning method for History-based affine parameters is described. In an exemplary aspect, a method for video processing includes deriving, for a conversion between a current block of video and a bitstream representation of the current block, a first set of affine parameters associated with affine model for the current block; comparing the first set of affine parameters to one or more of sets of affine parameters stored in a buffer for storing affine parameters so as to determine whether the first set of affine parameters is same or similar to at least one set of affine parameters; and deciding whether or how to update the buffer for storing affine parameters based on the determination.

Abstract: An example method of video processing includes applying, in a conversion between a video comprising multiple components and a bitstream representation of the video, a deblocking filter to video blocks of the multiple components. A deblocking filter strength for the deblocking filter of each of the multiple components is determined according to a rule that specifies to use a different manner for determining the deblocking filter strength for the video blocks of each of the multiple components.

Abstract: The present disclosure relates to improvement on overlapped block motion compensation. A method for video processing comprises: determining, during a conversion between a current block and a bitstream representation of the current block, a motion vector for a first sub-block inside the current block; using overlapped block motion compensation (OBMC) mode to perform the conversion; wherein the OBMC mode uses intermediate prediction values of the first sub-block based on the motion vector of the first sub-block and prediction values of at least a second video unit that is neighboring the first sub-block to generate final prediction values for the first sub-block; wherein a sub-block size of the first sub-block is based on block size, block shape, motion information, or reference picture of the current block.

Abstract: History based motion vector prediction is disclosed. In one example method of video processing, initializing, for a conversion between a first region of video and a bitstream of the first region, a first history motion vector predictor (HMVP) table associated with the first region based on at least one of stored multiple HMVP tables, the multiple HMVP tables being used to store motion information associated with regions coded prior the first region; and performing the conversion by using the initialized first HMVP table which includes at least one motion candidate.

Abstract: Devices, systems and methods for coding video using one or more tables to store motion information and process subsequent blocks are described. In one aspect, a video coding method is provided to include deriving motion information for a first video block which is coded using an intra block copy mode, wherein one or more candidates of one or more tables are selectively checked during a motion candidate list construction process which is used to derive the motion information for the first video block, wherein each table of the one or more tables includes motion candidates derived from previously coded video blocks that are coded prior to the first video block; and coding, based on the motion information, the first video block.

Abstract: Devices, systems and methods for sub-block based prediction are described. In a representative aspect, a method for video encoding includes partitioning, based on a first rule, a luma component of a block of video data into a first set of sub-blocks. The method also includes partitioning, based on a second rule, a first chroma component of the block of video data into a second set of sub-blocks. The first and the second set of sub-blocks include different numbers of sub-blocks. The method also includes performing a subsequent motion prediction based on the first and the second set of sub-blocks.

Abstract: A computer-implemented method of generating a piece of music is disclosed. The method comprises: determining an initial sequence of notes for the piece of music; determining at least one probability distribution for selecting at least one subsequent note from a set of candidate notes; generating a biasing output based on data of the initial sequence of notes; and extending the initial sequence of notes with at least one subsequent note selected from the set of candidate notes according to the probability distribution and the biasing output, wherein the biasing output biases the selection so as to affect the likelihood of the selection resulting in a repeat of a musical element formed by the initial sequence of notes.

Abstract: Methods and apparatus for processing of video are described. The processing may include video encoding, decoding, or transcoding. One example video processing method includes performing a conversion between a video including one or more pictures including one or more subpictures and a bitstream of the video. The bitstream conforms to a format rule that specifies that a subpicture cannot be a random access type of subpicture in response to the subpicture not being a leading subpicture of an intra random access point subpicture. The leading subpicture precedes the intra random access point subpicture in output order.

Abstract: Gradient computation in Bi-directional optical flow are described. In a representative aspect, a method of video processing including: modifying temporal gradients in a motion vectors refinement process of a video block or sub-blocks within the video block; and performing the motion vectors refinement process of the video block or the sub-blocks within the video block based on the modified temporal gradients.

Abstract: Methods, systems, and apparatuses for video processing are described. A method for processing video includes performing a conversion between a video and a bitstream of the video according to a format rule, wherein the format rule specifies that values of one or more general constraint flags at a first level in the bitstream control occurrence of one or more syntax elements at a sequence parameter set (SPS) level or a picture header (PH) level or a slice header (SH) level.