Abstract: An example device for coding video data includes memory configured to store the video data and one or more processors communicatively coupled to the memory. The one or more processors are configured to reduce a bit length of one or more input variables for a linear regression operation to generate one or more reduced bit length input variables, the input variables including at least one of a) one or more delta coordinates, b) one or more delta motion vectors, or c) a value representing a number of subblocks. The one or more processors are configured to perform the linear regression operation and derive an affine motion model based on the performing the linear regression on the one or more reduced bit length input variables. The one or more processors are configured to code a current block of the video data based on the affine motion model.

Abstract: An example device for decoding video data includes a memory configured to store video data; and a processing system comprising one or more processors implemented in circuitry, the processing system being configured to: inverse transform a block of transform coefficients of a block of the video data using an inverse non-separable primary transform (NSPT), without using an inverse separable transform, to reconstruct a residual block of the block of the video data; and decode the block using the residual block.

Abstract: A video coder may be configured to partition a coding block into subblocks, and generate initial subblock motion vectors for a plurality of the subblocks. The video coder may further refine the initial subblock motion vectors for the plurality of the subblocks using decoder side motion vector refinement to produce refined subblock motion vectors for the plurality of the subblocks, and perform a linear regression on the refined subblock motion vectors and coordinates of the plurality of the subblocks to derive an affine motion model. The video coder may then code the coding block using the derived affine motion model.

Abstract: An example device for decoding video data includes: a memory configured to store video data; and a processing system comprising one or more processors implemented in circuitry, the processing system being configured to: determine whether motion information of a block of video data is for sub-blocks of the block larger than individual pixels of the block or for the individual pixels, the block being associated with data indicating that the block is to be predicted using affine motion compensation; in response to determining that the motion information of the block is for the sub-blocks, perform sub-block-based affine motion compensation to form a prediction block for the block; in response to determining that the motion information is for the individual pixels, perform pixel-based affine motion compensation to form the prediction block for the block; and decode the block using the prediction block.

Abstract: A method coding video data includes receiving a block of video data, wherein chroma samples of the block of video data are subsampled relative to luma samples of the block of video data (e.g., 4:2:0 or 4:2:2 video content). A video coder may determine a subsampling technique, from a plurality of subsampling techniques, for the luma samples of the block of video data for a cross-component prediction mode, and may code the block of video data using the subsampling technique and the cross-component prediction mode. A first subsampling technique of the plurality of subsampling techniques includes not applying subsampling to the luma samples of the block of video data, and a second subsampling technique of the plurality of subsampling techniques includes a combination of downsampling filters to be applied to the luma samples of the block.

Abstract: Encoding and decoding video data using an affine decoder side motion vector derivation (DMVR) mode includes receiving a block of video data to be decoded using the affine DMVR mode, and dividing the block into a plurality of subblocks. A video encoder and video decoder may determine a final offset for the affine DMVR mode using a first subset of the plurality of subblocks. The video encoder and decoder may code the block of video data using the final offset to generate a coded block of video data.

Abstract: An example device for decoding video data includes a memory configured to store video data; and a processing system comprising one or more processors implemented in circuitry, the processing system being configured to: refine a first control point motion vector (CPMV) of a current block of the video data using a first decoder-side motion vector refinement (DMVR) process to form a first refined CPMV for the current block; refine a second CPMV of the current block of video data using a second DMVR process, independently of the first DMVR process, to form a second refined CPMV for the current block; form a prediction block for the current block using the first refined CPMV and the second refined CPMV; and decode the current block using the prediction block. In some examples, the CPMVs may each be decoded using a respective merge index and a respective motion vector difference (MVD).

Abstract: A device and method for coding video data is described. The device may generate filtered samples by performing, in a predicted samples domain, interpolation filtering and a second filtering from a group of one or more of: an adaptive filter, a domain transform filter, a scaler, or a local illumination compensation (LIC). The device may generate one or more of: residual data based on the filtered samples, or reconstructed samples based on the filtered samples; and code the video data based on one or more of the residual data or the reconstructed samples.

Abstract: A video decoder can be configured to determine a number of allowed non-zero coefficients for a block of video data based on a size of the block; obtain a set of dequantized coefficients for the block, wherein the set of dequantized coefficients comprises a first subset of dequantized coefficients that includes non-zero dequantized coefficients and a second subset of dequantized coefficients that includes all zero coefficients, wherein a number of coefficients in the first subset of dequantized coefficients is equal to the number of allowed non-zero coefficients for the block of video data; apply an inverse low-frequency non-separable transform (LFNST) to the first subset of dequantized coefficients to determine a first intermediate subset of coefficients; and apply an inverse separable transform to the first intermediate subset of coefficients and at least a portion of the second subset of coefficients to determine a block of reconstructed residual values.

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.

Abstract: An example method includes determining a color component of a unit of video data; determining, based at least on the color component, a context for context-adaptive binary arithmetic coding (CABAC) a syntax element that specifies a value of a low-frequency non-separable transform (LFNST) index for the unit of video data; CABAC decoding, based on the determined context and via a syntax structure for the unit of video data, the syntax element that specifies the value of the LFNST index for the unit of video data; and inverse-transforming, based on a transform indicated by the value of the LFNST index, transform coefficients of the unit of video data.

Abstract: An example device for coding video data 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 whether a sequence parameter set of the video data refers to a video parameter set. Based on the sequence parameter set not referring to the video parameter set, the one or more processors are configured to determine a value of a first syntax element to be indicative of a profile-tier-layer structure being signaled in the sequence parameter set and code the video data based on the profile-tier-layer structure.

Abstract: A video decoder may be configured to determine that a block of video data is encoded using an intra prediction process that utilizes multiple intra prediction predictors; determine a set of reference lines for the intra prediction process; determine a first set of intra prediction predictors based on the set of reference lines; determine a second set of intra prediction predictors based on the set of reference lines; generate a fusion of predictors from the first set of intra prediction predictors and the second set of intra prediction predictors; and decode the block of video data using the fusion of predictors.

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 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 video decoder configured to set a context index variable to a first value, wherein the first value for the context index variable is associated with a first context; context decode a first bin for a syntax element indicating a transform using the first context; determine a new value for the context index variable based on a value of the first bin; context decode a second bin for the syntax element indicating the transform using a context associated with the new value; determine an inverse transform from a set of inverse transform candidates based on the first bin and the second bin; and apply the inverse transform to a set of coefficients to determine a block of residual data.

Abstract: An example device for decoding video data includes one or more processors implemented in circuitry and configured to: generate an inter-prediction block for a current block of video data; generate an intra-prediction block for the current block of video data; generate a final prediction block for the current block of video data from the inter-prediction block and the intra-prediction block, including performing each of combined inter/intra prediction (CIIP) mode, overlapped block motion compensation (OBMC), and luma mapping with chroma scaling (LMCS) while generating the final prediction block; and decode the current block of video data using the final prediction block. To generate the final prediction block, the processors may perform LMCS on a first inter-prediction sub-block, combine the LMCS-mapped first inter-prediction sub-block with the intra-prediction block using CIIP, and perform OBMC between the first CIIP prediction block and a second inter-prediction sub-block.

Abstract: An example method includes decoding, via a first syntax level of a video bitstream, a first deblocking filter control syntax element with a value that specifies whether deblocking filter information is present in a second syntax level of the bitstream; decoding, via the first syntax level of the bitstream, a second deblocking filter control syntax element with a value that specifies whether deblocking override is enabled; responsive to the first deblocking filter control syntax element specifying that the deblocking filter information is present in the second syntax level of the bitstream and regardless of the value of the second deblocking filter control syntax element, decoding, via the second syntax level, one or more syntax elements that specify deblocking filter information; and applying, based on the deblocking filter information, a deblocking filter to a block of the video data.

Abstract: Systems, methods, and computer-readable storage media are provided for decoded picture buffer (DPB) operations and rewriting access unit delimiters (AUDs) after bitstream extractions. An example method can include storing one or more pictures associated with an access unit (AU) in a decoded picture buffer (DPB), the AU including a first plurality of pictures, the first plurality of pictures corresponding to a plurality of video coding layers; after each picture of a second plurality of pictures associated with the AU is removed from a coded picture buffer (CPB), removing at least one picture of the one or more pictures from the DPB; and storing, in the DPB, each picture of the second plurality of pictures removed from the CPB.

Abstract: A video encoder and/or video decoder are configured to apply an adaptive loop filter to a reconstructed block of video data. The video encoder and/or video decoder may be configured to determine a value of a gradient for a sample in the reconstructed block of video data, including performing a gradient calculation for the sample using an available sample that corresponds to an unavailable sample that is outside of one of: a picture, a slice, a tile, or a tile group that includes the reconstructed block of samples, determine an adaptive loop filter for the reconstructed block of video data based at least in part on the determined value of the gradient for the sample, and apply the determined adaptive loop filter to the reconstructed block of video data to generate a filtered block of video data.