Abstract: An example device includes a memory and one or more processors implemented in circuitry and communicatively coupled to the memory. The one or more processors are configured to determine a value of a first syntax element indicative of a number of subpictures in a picture of video data. The one or more processors are configured to determine, for each subpicture among the subpictures in the picture, a value of a respective second syntax element indicative of an identification of a respective subpicture. The one or more processors are also configured to code the respective subpicture identified by the respective second syntax element.

Abstract: A device capable of compressing video data includes a memory configured to store a luma new filter value, a chroma new filter value, a cross component Cb new filter value, and a cross component Cr new filter value. The device may also include one or more processors, coupled to the memory, configured to set a joint constraint on the luma new filter value, the chroma new filter value, the cross component Cb new filter value, and the cross component Cr new filter value, such that each of the luma new filter value, the chroma new filter value, the cross component Cb new filter value, and the cross component Cr new filter value are not disabled in a unit associated with an adaptation parameter set having a first adaptation parameter set identification (APS ID).

Abstract: A method of encoding or decoding video data includes determining that geometric partition mode is enabled for a current block of the video data, the geometric partition mode comprising a plurality of split modes that each defines an edge for partitioning; for each split mode among at least two of the plurality of split modes, determining a respective cost associated with a respective split mode; constructing, based on the respective costs associated with the respective split modes, a mapping list including index values respectively associated with values indicative of the respective split modes, where a lower index value is associated with a first split mode having a lower cost than a second split mode with a higher index value; determining a split mode amongst the plurality of split modes within the mapping list; and reconstructing a current block of the video data based on the split mode.

Abstract: A video decoder may be configured to receive a block of video data, and determine a value of a multiple transform set index for the block of video data based on a presence of non-zero transform coefficients in the block of video data other than a DC coefficient. The video decoder may then apply a transform to the block of video data based on the determined value of the multiple transform set index.

Abstract: A video decoder is configured to receive bin values according to a context model, wherein the context model includes one or more probability states and the bin values correspond to one or more syntax elements of the video data; determine a first shift value based on the received bin values; determine a second shift value based on the received bin values; update a first state variable based on the first shift value; update a second state variable based on the second shift value; determine, for a next bin to be decoded, a probability state for the context model based on the first state variable and the second state variable; context decode the next bin to be decoded based on the probability state; and determine values for the one or more syntax elements based on the received bin values and the context decoded next bin value.

Abstract: A video decoder may be configured to generate a first ordering of reference pictures in a reference picture list for a first block of a slice, wherein generating the first ordering of the reference pictures for the first block comprises assigning indexes to the reference pictures; and generate a second ordering of the reference pictures in the reference picture list for a second block of the slice based on an adaptive reference picture reordering process, wherein the first ordering is different than the second ordering and generating the second ordering of reference pictures for the second block comprises assigning at least some of the indexes to different reference pictures than in the first ordering; decode the first block using the first ordering of the reference pictures; and decode the second block using the second ordering of the reference pictures.

Abstract: A video decoder determines, based on a block size of a current block and a low-frequency non-separable transform (LFNST) syntax element, a zero-out pattern of normatively defined zero-coefficients. The LFNST syntax element is signaled at a transform unit (TU) level. Additionally, the video decoder determines transform coefficients of the current block. The transform coefficients of the current block include transform coefficients in an LFNST region of the current block and transform coefficients outside the LFNST region of the current block. As part of determining the transform coefficients of the current block, the video decoder applies an inverse LFNST to determine values of one or more transform coefficients in the LFNST region of the current block. The video decoder also determines that transform coefficients of the current block in a region of the current block defined by the zero-out pattern are equal to 0.

Abstract: A video coder may determine a motion vector of a non-adjacent block of a current picture of the video data. The non-adjacent block is non-adjacent to a current block of the current picture. Furthermore, the video coder determines, based on the motion vector of the non-adjacent block, a motion vector predictor (MVP) for the current block. The video coder may determine a motion vector of the current block. The video coder may also determine a predictive block based on the motion vector of the current block.

Abstract: A video encoder and video decoder may determine to enable or disable a template-based inter prediction technique based on whether reference picture resampling or weighted prediction are used. A video encoder and video decoder may determine that a reference picture resampling mode is enabled. determine not to apply a template-based inter prediction technique to the video data based on the reference picture resampling mode being enabled, and code the video data using inter prediction without applying the template-based inter prediction technique.

Abstract: Example techniques and devices for decoding video data are disclosed. An example device includes memory configured to store the video data and one or more processors implemented in circuitry and communicatively coupled to the memory. The one or more processors are configured to extract a current sub-picture from a bitstream of the video data and parse virtual boundary syntax elements indicative of virtual boundaries for a current picture, wherein the current sub-picture is associated with the current picture. The one or more processors are configured to update the virtual boundaries based at least in part on the virtual boundary syntax elements and decode the current sub-picture based on the updated virtual boundaries.

Abstract: A method of decoding video data including decoding, from a video bitstream for which adaptive loop filtering is enabled for luma blocks of one or more of a picture, a slice, a tile, or a tile group, a first syntax element indicating a number of adaptive parameter sets for the luma blocks, decoding a plurality of first adaptive parameter set indices for the luma blocks based on the number of adaptive parameter sets for the luma blocks, and decoding, from the video bitstream for which adaptive loop filtering is enabled for chroma blocks of the one or more of the picture, the slice, the tile, or the tile group, a second adaptive parameter set index for the chroma blocks.

Abstract: A method of decoding video data includes determining that a current block of the video data is coded in palette mode, determining, between single tree or dual tree partitioning, that the current block is coded with single tree partitioning enabled, determining that the current block is coded in monochrome format, when the current block is coded with single tree partitioning enabled and when the current block is coded in monochrome format, determining that a number of color components used for palette mode decoding the current block is equal to one, and palette mode decoding the current block based on the determined number of color components used for palette mode decoding the current block being equal to one.

Abstract: An example device for coding video data includes a memory configured to store video data; and one or more processors implemented in circuitry and configured to: code a first codeword representing a selected transform scheme of a set of transform candidates of a multiple transform selection (MTS) scheme for a current block of video data, the selected transform scheme being a secondary transform of a set of available secondary transforms to be applied in addition to a primary transform; code a second codeword representing the secondary transform from the set of available secondary transforms; and apply the primary transform and the secondary transform during coding of residual data for the current block. The second codeword may be a value for a low-frequency non-separable transform (LFNST) syntax element.

Abstract: A method of decoding video data may comprise decoding data from an encoded bitstream to generate motion vectors and performing a decoder-side motion vector refinement (DMVR) process on one or more of the motion vectors. Performing the DMVR process may include determining one or more characteristics of current video block being decoded and determining a search area for the DMVR process for the current video block based on the determined one or more characteristics of the current video block.

Abstract: A method of decoding video data includes receiving encoded data for a current block and decoding N bins for a low-frequency non-separable transform (LFNST) index from the encoded data. The N bins comprises a first bin and a second bin. Decoding the N bins comprises context decoding each bin of the N bins. The method further includes determining the LFNST index using the N bins and decoding the encoded data to generate transform coefficients. The method further includes applying an inverse LFNST to the transform coefficients using the LFNST index to produce a residual block for the current block and reconstructing the current block of the video data using the residual block and a prediction block for the current block.

Abstract: An example device applies a primary transform to a current block of video data to create primary transform coefficients. The device determines whether intra sub-partitioning is applied to the current block of video data. The device applies a primary transform to the current block. The device also determines whether a primary transform size for the current block of video data is at least a predetermined size. Based on intra sub-partitioning being applied and the primary transform size being at least the predetermined size, the device applies a secondary transform to primary transform coefficients and codes the current block of video data based on the secondary transform.

Abstract: An method of decoding video data includes deriving, for a current block of video data and using decoder side intra mode derivation (DIMD), a list of intra modes using reconstructed samples of neighboring blocks; constructing, for the current block, a most probable mode (MPM) list, wherein constructing the MPM list comprises inserting, into the MPM list, at least one intra mode from the derived list of intra modes; and predicting, using a candidate selected from the constructed MPM list, the current block.

Abstract: An example device for decoding video data includes a memory configured to store video data; and one or more processors implemented in circuitry and configured to: generate an intra-prediction block for a current block of video data using an angular intra-prediction mode, the angular intra-prediction mode being an upper-right angular intra-prediction mode or a lower-left angular intra-prediction mode; determine a prediction direction of the angular intra-prediction mode; for at least one sample of the intra-prediction block for the current block: calculate a gradient term for the at least one sample along the prediction direction; and combine a value of an intra-predicted sample of the intra-prediction block at a position of the at least one sample of the intra-prediction block with the gradient term to produce a value of the at least one sample of the intra-prediction block; and decode the current block using the intra-prediction block.

Abstract: Systems, methods, and computer-readable storage media for calculating scaling ratios are described. An example method can include obtaining a current picture of video data and one or more scaling windows associated with the current picture and/or a reference picture selected for use in coding the current picture; determining a first size of the current picture and/or a second size of the reference picture, the first size including a first height and a first width and the second size including a second height and a second width; based on the one or more scaling windows and the first size and/or the second size, determining one or more scaling ratios associated with the current picture and/or the reference picture.

Abstract: An example method includes decoding, from a coded video bitstream, a first syntax element that specifies a constraint for a second syntax element that specifies whether subpicture information is present in the coded video bitstream and whether more than one subpicture is allowed to be present in the coded video bitstream; and decoding, based on the constraint specified by the first syntax element, the second syntax element.