Abstract: The disclosure describes examples for determining samples to use for DC intra mode prediction, such as where the samples are in a row or column that is not immediately above or immediately left of the current block. The samples may be aligned with the current block such that a last sample in the samples in a row above the current block is in same column as last column of the current block and such that a last sample in the samples in a column left of the current block is in the same row as the last row of the current block.

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 value of a syntax element for a block of the video data, the syntax element indicating whether the block is encoded using an intra-prediction mode using a zero reference line index, not encoded using intra sub-partition coding (ISP) partitioning mode, not encoded using matrix intra-prediction (MIP) mode, and not encoded using blurred differential pulse code modulation (BDPCM) mode; form a prediction block for the block according to the value of the syntax element; and code the block using the prediction block.

Abstract: A device for decoding video data determine that a current block of video data is encoded in an affine linear weighted intra prediction (ALWIP) mode; derives, based on a set of left edge neighboring samples of the current block and a set of top edge neighboring samples of the current block, a subset of left edge samples and a subset of top edge samples; applies an affine model to the subset of left edge samples and the subset of top edge samples to generate an intermediate block of intermediate samples; filters the intermediate samples to generate a final prediction block; decodes the current block of video data based on the final prediction block.

Abstract: A video coder performs a Most-Probable Mode (MPM) derivation process that derives one or more MPMs for a current block that is not coded using affine linear weighted intra prediction (ALWIP). As part of performing the MPM derivation process, the video coder determines whether a neighboring block of the current block is an ALWIP-coded neighboring block. Based on the neighboring block being an ALWIP-coded neighboring block, the video coder determines that a value of an intra prediction mode of the neighboring block is a value indicating a planar mode. The video coder codes the current block based on one of the MPMs for the current block.

Abstract: In some examples, a device includes a memory configured to store a current block of the video data and one or more processors coupled to the memory. The one or more processors may be configured to derive a reference sample position (RSP) for a current sample of a current block according to one or more RSP derivation models. The one or more RSP derivation models may include a circular model, an elliptical model, a piece-wise linear model, a table-based model, or a parametric model. The one or more processors may be further configured to determine a reference sample value for a reference sample at the RSP, determine a predicted value for the current sample using the reference sample value, and code the current sample using the predicted value.

Abstract: A method of decoding video data includes determining, by one or more processors implemented in circuitry, a partition of the video data into a plurality of blocks. The partition of the video data applies a block size restriction to prevent a splitting of a block of the plurality of blocks that would result in a small block comprising a block width and a block height when the block height times the block width is less than a threshold. The method further includes generating, by the one or more processors, prediction information for the block and determining, by the one or more processors, a predicted block for the block based on the prediction information. The method further includes decoding, by the one or more processors, a residual block for the block and combining, by the one or more processors, the predicted block and the residual block to decode the block.

Abstract: A video decoder may apply a first inverse residual modification function to first decoded modified chroma residual data to generate first inverse modified chroma residual data. Additionally, the video decoder may apply a second inverse residual modification function to second decoded modified chroma residual data to generate second inverse modified chroma residual data. The first decoded modified chroma residual data is associated with a first chroma component and the second decoded modified chroma residual data is associated with a second chroma component. The video decoder may reconstruct a block of video data based on the first inverse modified chroma residual data and the second inverse modified chroma residual data.

Abstract: A video coder may be configured to code video data by performing splitting of a coding unit (CU) of video data using intra sub-partition (ISP) to form a set of prediction blocks. The video coder may group a plurality of the prediction blocks from the set of prediction blocks into a first prediction block group (PBG). The video coder may reconstruct samples of prediction blocks included in the first PBG independently of samples of other prediction blocks included in the first PBG.

Abstract: An example device for coding (encoding or decoding) video data includes a memory configured to store video data; and one or more processors implemented in circuitry and configured to: partition a coding unit (CU) of video data into sub-blocks, the sub-blocks being arranged into a number of rows and a number of columns, the number of rows being greater than 1 and the number of columns being greater than 1; form intra-prediction blocks for each of the sub-blocks; and code the CU using the intra-prediction blocks.

Abstract: An example device for coding (encoding or decoding) video data includes a memory for storing video data and one or more processors implemented in circuitry and configured to form an inter-prediction block for a current chrominance block of the video data; form an intra-prediction block for the current chrominance block of the video data; determine a number of neighboring blocks to a luminance block corresponding to the current chrominance block that are intra-prediction coded; determine a first weight and a second weight according to the number of neighboring blocks that are intra-prediction coded; apply the first weight to the inter-prediction block and the second weight to the intra-prediction block; combine the first weighted inter-prediction block and the second weighted intra-prediction block to form a prediction block for the current chrominance block; and code the current chrominance block using the prediction block.

Abstract: Techniques are described for improving intra-subpartitioning (ISP) mode for splitting coding blocks into sub-blocks. In some cases, whether ISP mode is enabled for a coding block is based on size constraints pertaining to data units (e.g., VPDUs, transform blocks, among others). For instance, based on a size constraint related to a VPDU, the ISP mode can be disabled for coding blocks crossing VPDU boundaries. In some cases, whether to enable ISP mode may be based on comparison of the width and/or height of the coding block to size thresholds corresponding to one or more maximum transform block sizes. In some cases, where the ISP mode is enabled for a coding block, a value of a flag used for defining a type of split, horizontal or vertical, for the coding block, can be inferred based on the width and/or height of the coding block relative to one or more thresholds.

Abstract: A video coder is configured to determine a split type of a block of video data from an intra prediction mode associated with a neighboring block. The video coder may determine an intra prediction mode associated with a neighboring block of the current block of video data, determine a split type of the current block of video data based on the intra prediction mode associated with the neighboring block, split the current block of video data into a plurality of sub-partitions based on the determined split type, and code the plurality of sub-partitions.

Abstract: Systems and techniques for intra-block copy (IBC) prediction in processing video data include the use of one or more virtual search areas (VSAs) which can be generated to include one or more references to one or more pixels stored in a physical memory. The one or more VSAs can provide references to additional reconstructed sample values that are derived from previously decoded blocks without incurring physical memory use for storage of the additional reconstructed samples. A search area for performing the IBC prediction for a current block of the video data can be extended to include the one or more VSAs. Extending the search area to include the one or more VSAs provides the IBC prediction with additional search area for finding one or more prediction blocks or prediction samples without having to utilize physical memory to store the additional reconstructed samples from previously decoded blocks.

Abstract: An example device for coding (encoding or decoding) video data includes a memory configured to store video data; and one or more processors implemented in circuitry and configured to: determine a first number of neighboring blocks to a current block of the video data that are intra-predicted; determine a second number of the neighboring blocks that are inter-predicted; determine a first weight value to be applied to intra-prediction samples of an intra-prediction block for the current block; determine a second weight value to be applied to inter-prediction samples of an inter-prediction block for the current block; generate a prediction block for the current block as a weighted combination of the intra-prediction block to which the first weight value is applied and the inter-prediction block to which the second weight value is applied; and code the current block using the prediction block.

Abstract: A device for coding video data includes a processor configured to generate an inter-prediction block and an intra-prediction block for a current block of video data; for each sample of a prediction block to be generated: determine a first weight for the sample according to a position of the sample in the prediction block; determine a second weight for the sample according to the position of the sample in the prediction block; apply the first weight to a sample at the position in the inter-prediction block to generate a weighted inter-prediction sample; apply the second weight to a sample at the position in the intra-prediction block to generate a weighted intra-prediction sample; and calculate a value for the sample at the position in the prediction block using the weighted inter-prediction sample and the weighted intra-prediction sample; and code the current block using the prediction block.

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: 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: An example method includes obtaining a current block of video data in a current picture of video data; determining a search region for the current block within a reconstructed region of the current picture, wherein the search region includes less than all of the reconstructed region of the current picture; selecting, from within the search region, a predictor block for the current block; determining a vector that identifies the selected predictor block for the current block; and encoding, in a coded video bitstream, a representation of the vector.

Abstract: An example method includes obtaining values of control point motion vectors (CPMVs) for a current block of video data selected for coding using affine mode; determining whether a memory bandwidth needed for accessing samples of a plurality of reference blocks derived based on the values of the CPMVs satisfies a bandwidth threshold; selectively modifying, based on whether the determined memory bandwidth satisfies the bandwidth threshold, a motion compensation method used to predict samples of the current block of video data; and predicting, using the selectively modified motion compensation method, the samples of the current block of video data from the samples of the plurality of reference blocks.

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.