Abstract: Example techniques are described to illustrate multiple transform applied for Intra prediction residual. It may be used in the context of advanced video codecs, such as extensions of HEVC or the next generation of video coding standards. A video encoder and a video decoder may select transform subsets that each identify one or more candidate transforms. The video encoder and the video decoder may determine transforms from the selected transform subsets.

Abstract: An example device for decoding video data includes one or more processors implemented in circuitry and configured to: decode a coding tree unit (CTU) of video data, the CTU including a luminance (luma) block and a chrominance (chroma) block, to produce a decoded luma block and a decoded chroma block; determine that a chroma sample of the decoded chroma block is on a first side of an adaptive loop filter (ALF) virtual boundary and that a co-located luma sample of the decoded luma block is on a second side of the ALF virtual boundary, the co-located luma sample being co-located with the chroma sample, the first side being different than the second side; and in response to determining that the chroma sample is on the first side and the luma sample is on the second side, disable cross-component adaptive loop filtering (CC-ALF) for the chroma sample.

Abstract: An example method includes determining, for each respective coding block of a plurality of coding blocks of a current coding tree unit (CTU) of video data in a current picture of video data, a respective search area of a plurality of respective search areas, wherein at least one of the plurality of search areas includes samples of the current picture located outside of the current CTU, and wherein at least one of the plurality of search areas does not include samples of the current picture located outside of the current CTU; selecting, for each respective coding block and from within the respective search area for the respective coding block, a respective predictor block of a plurality of predictor blocks; and reconstructing samples of each respective coding block based on samples included in a corresponding predictor block in the plurality of predictor blocks.

Abstract: Methods and apparatuses for encoding and decoding an intra prediction mode of a prediction unit of a chrominance component based on an intra prediction mode of a prediction unit of a luminance component are provided. When an intra prediction mode of a prediction unit of a luminance component is the same as an intra prediction mode in an intra prediction mode candidate group of a prediction unit of a chrominance component, reconstructing the intra prediction mode candidate group of the prediction unit of the chrominance component by excluding or replacing an intra prediction mode of the prediction unit of the chrominance component which is same as an intra prediction mode of the prediction unit of the luminance component from the intra prediction mode candidate group, and encoding the intra prediction mode of the prediction unit of the chrominance component by using the reconstructed intra prediction mode candidate group.

Abstract: A video decoder may be configured to receive, in response to receiving a first syntax element indicating that reference picture list information is included in a picture header syntax structure, a second syntax element in the picture header syntax structure indicating whether a collocated picture used for temporal motion vector prediction is to be derived from a first reference picture list or a second reference picture list; receive a slice of the video data that refers to the picture header syntax structure; and in response to the slice being a P slice, set a value for a third syntax element associated with the slice to a first value for the third syntax element, with the first value for the third syntax element indicating that the collocated picture used for temporal motion vector prediction is to be derived from the first reference picture list.

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 determine a maximum possible value for a secondary transform syntax element for a block of video data, entropy decode a value for the secondary transform syntax element of the block to form a binarized value representative of the secondary transform for the block, reverse binarize the value for the secondary transform syntax element using a common binarization scheme regardless of the maximum possible value to determine the secondary transform for the block, and inverse-transform transform coefficients of the block using the determined secondary transform.

Abstract: A video decoder can be configured to determine that a first subpicture of a current picture has associated scaling parameters; receive the associated scaling parameters for the first subpicture of the current picture in response to determining that the first subpicture of the current picture has the associated scaling parameters; determine motion information, for a block of the first subpicture of the current picture, that identifies a subpicture of a reference picture; locate a prediction block for the block of the first subpicture of the current picture in the subpicture of the reference picture; and scale the prediction block based on the associated scaling parameters for the first subpicture of the current picture.

Abstract: An example method includes obtaining values of luma motion vectors for a plurality of luma sub-blocks of a current block of the video data selected for coding using affine motion compensation; determining, based on values of luma motion vectors of a sub-set of the plurality of luma sub-blocks, a value of a chroma motion vector for a chroma sub-block that corresponds to the plurality of luma sub-blocks; predicting, using affine motion compensation, respective samples of each luma sub-block of the plurality of luma sub-blocks based on respective values of the luma motion vectors; and predicting, using affine motion compensation, sample the chroma sub-block based on the value of the chroma motion vector.

Abstract: A video decoder can be configured to determine that a current block in a current picture of the video data is coded in an affine prediction mode; determine one or more control-point motion vectors (CPMVs) for the current block; identify an initial prediction block for the current block in a reference picture using the one or more CPMVs; determine a current template for the current block in the current picture; and determine an initial reference template for the initial prediction block in the reference picture; and perform a motion vector refinement process to determine a modified prediction block based on a comparison of the current template to the initial reference template.

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: determine a size of a current block of video data; determine an intra-prediction mode for the current block of video data; determine a mode group including the determined intra-prediction mode, the mode group being one of a plurality of mode groups, each including respective sets of intra-prediction modes; determine a set of available multiple transform selection (MTS) schemes for the current block according to the size and the intra-prediction mode for the current block; determine an MTS scheme from the set of available MTS schemes according to the determined mode group; apply transforms of the MTS scheme to a transform block of the current block to produce a residual block for the current block; and decode the current block using the residual block.

Abstract: A device for decoding video data includes memory configured to store the video data and processing circuitry. The processing circuitry is configured to determine that a current block of the video data is inter-predicted in a combined inter-intra prediction (CIIP) mode or a geometric partitioning mode (GPM), determine that template matching is enabled for the current block, generate a motion vector for the current block based on template matching; determine a prediction block for the current block based on the motion vector in accordance with the CIIP mode or the GPM, and reconstruct the current block based on the prediction block.

Abstract: An example device for coding video data includes a memory configured to store video data; and one or more processing units implemented in circuitry and configured to: store motion information for a first coding tree unit (CTU) line of a picture in a first history motion vector predictor (MVP) buffer of the memory; reset a second history MVP buffer of the memory; and after resetting the second history MVP buffer, store motion information for a second CTU line of the picture in the second history MVP buffer, the second CTU line being different than the first CTU line. Separate threads of a video coding process executed by the one or more processors may process respective CTU lines, in some examples.

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: determine that a transform block of video data has a size of 8×8 coefficients and that the transform block is transformed using a low-frequency non-separable transform (LFNST); decode at least nine non-zero transform coefficients of the transform block; inverse transform the transform block using an inverse LFNST to reproduce a residual block corresponding to the transform block; and reconstruct a block of the video data using the residual block.

Abstract: Techniques for processing video data are described. The techniques include determining a first partition and a second partition for a current block coded in geometric partition mode, determining a first and second prediction block based on a first and second motion vector, blending the first prediction block and the second prediction block based on weights indicative of an amount to scale samples in the first prediction block and the second prediction block to generate a final prediction block, dividing the current block into a plurality of sub-blocks, determining a set of sub-blocks that each include at least one sample that corresponds to a prediction sample in the final prediction block that was generated based on equal weighting of a sample in the first prediction block and a sample in the second prediction block, and storing respective bi-prediction motion vectors for each sub-block in the determined set of sub-blocks.

Abstract: An example device for decoding video data includes one or more processors configured to: generate a first prediction block for a current block of video data using a base inter-prediction mode; code a merge mode syntax element for a second prediction block representing an additional prediction hypothesis, the merge mode syntax element indicating whether motion information for the second prediction block is coded using merge mode; code the motion information for the second prediction block according to the merge mode syntax element, wherein to code the motion information, the one or more processors are configured to form a merge candidate list including merge candidates representing respective sets of uni-prediction motion information; generate the second prediction block for the current block of video data using the motion information; form a multi-hypothesis prediction block from the first and second prediction blocks; and decode the current block using the multi-hypothesis prediction block.

Abstract: A video coder may code a sign prediction syntax element that indicates whether a sign prediction hypothesis is correct for a transform coefficient. The video coder may code the sign prediction syntax element using a context-based coding process. The video coder may determine a context for coding the sign prediction syntax element based on a position of the transform coefficient in the block of video data. The context may be further based on a coding mode used to code the block.

Abstract: 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 determine at least one of a temporal candidate or a history-based candidate and determine at least one non-adjacent candidate, wherein the at least one non-adjacent candidate is from a unit that is not adjacent to a current prediction unit (PU). The one or more processors are configured to determine an advanced motion vector predictor (AMVP) candidate list including the at least one of the temporal candidate or the history-based candidate and the at least one non-adjacent candidate. The at least one non-adjacent candidate is added to the AMVP candidate list after the temporal candidate or before the history-based candidate. The one or more processors are configured to code the current PU based on the AMVP candidate list.

Abstract: A method of decoding video data includes decoding, from a coded video bitstream and as an unsigned integer 0-th order Exp-Golomb-coded syntax element with the left bit first, a value that specifies a target recovery point picture for a current picture of a current sequence of pictures, wherein the target recovery point picture is located at or after the current picture in display order; and recovering decoding of the current sequence of pictures at the target recovery point picture.

Abstract: A video encoder and video decoder may determine a set of adaptive loop filters, from among a plurality of sets of adaptive loop filters, on a per-block basis. Each set of adaptive loop filters may include filters from a previous picture, filters signaled for the current picture, and/or pre-trained filter. By varying the set of adaptive loop filters on a per-block basis, the adaptive loop filters available for each block of video data may be more adapted to local statistics of the video data.

Abstract: Systems, methods, and media are provided for loop filtering across raster scan slices. One example includes obtaining the video data comprising one or more pictures and a first block of a picture having a pixel subject to filtering. A second block is determined to be located in the first slice in a particular relation to the second block. A third block that includes pixels for filtering the pixel is determined to be in a second slice at a diagonal corner of the first block, with filtering across slice boundaries disabled. First one or more pixels of the second block are identified as available for performing loop filtering of the pixel and second one or more pixels of the third block identified as unavailable for performing the loop filtering of the pixel of the first block. The first one or more pixels and the second one or more pixels are padded.