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: The disclosure describes generating a prediction block for matrix intra prediction (MIP) tool. A video coder (e.g., video encode or video decoder) may generate intra prediction samples based on reference samples, where the intra prediction samples are a subsampled set of samples of the prediction block. The video coder may clip the intra prediction samples, and after clipping the intra prediction samples, generate one or more remaining samples of the prediction block.

Abstract: Techniques are described for improving video coding. For example, a first block of a picture included in an encoded video bitstream can be obtained. A second block of the picture can be determined as being coded (e.g., encoded) using a type of block-based quantized residual domain pulse code modulation (BDPCM) mode, such as vertical BDPCM mode or horizontal BDPCM mode. In the event the second block is coded using the vertical BDPCM mode, a vertical intra-prediction mode can be determined for an intra-prediction mode list for the first block. The vertical intra-prediction mode can be added to the intra-prediction mode list for the first block. In the event the second block is coded using the horizontal BDPCM mode, a horizontal intra-prediction mode can be determined for the intra-prediction mode list for the first block and the horizontal intra-prediction mode can be added to the intra-prediction mode list.

Abstract: A method of decoding 360-degree video, including receiving video data indicative of a 360-degree video picture projected onto a 2D picture, the 2D picture being divided into a plurality of blocks, predicting a first of the blocks of the 2D picture, and deblock filtering pixels along a border of the first of the blocks based on the position of the border between the first of the blocks and a second of the blocks in the 360-degree video picture.

Abstract: A video coder selects a set of wide-angle intra prediction directions based on a size of a luma block of a picture having a YUV 4:2:2 chroma sampling format. Additionally, the video coder determines an intra prediction direction for the luma block. The intra prediction direction for the luma block is in the set of wide-angle intra prediction directions. The video coder also determines an intra prediction direction for a chroma block. The luma block is collocated in the picture with the chroma block. The chroma block has a different width/height ratio than the luma block. The intra prediction direction for the chroma block is guaranteed to have the intra prediction direction for the luma block. The video coder uses the intra prediction directions for the luma and chroma blocks to generate prediction blocks for the luma and chroma blocks, respectively.

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: This disclosure describes techniques for signaling 360-degree video information in syntax structures. As one example, this disclosure describes examples for signaling projection types and related information for 360-degree video in syntax structures that include one or more syntax elements. In some examples, the same syntax structures may include non-360-degree video information as well. Accordingly, the syntax structure may be used for encoding and decoding a bitstream carrying only non-360-degree video data, only 360-degree video data, or both non-360-degree video data and 360-degree video data.

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: Provided are systems and methods for processing 360-degree video data by obtaining a 360-degree rectangular formatted projected picture, the 360-degree rectangular formatted projected picture including a first region with a region boundary and a first region area; identifying coding tree units (CTUs) within the first region area; selectively identifying a first coding unit (CU) and a second CU from within the CTUs; determining an initial QP value for the first CU; determining an initial QP value for the second CU; identifying the first CU as a region boundary CU; identifying the second CU as a non-region boundary CU; reducing the initial QP value for the first CU to a final first QP value in response to identifying the first CU as a region boundary CU, and generating an encoded video bitstream comprising: the final QP value for the first CU, and the initial QP value for the second CU.

Abstract: A video coder may determine reference samples based on a location of a current block of a current picture of the 360-degree video data and a packing arrangement that defines an arrangement of a plurality of regions in the current picture. The current picture is in a projected domain and each respective region of the plurality of regions is a respective face defined by a projection of 360-degree video data. The regions are arranged in the current picture according to the packing arrangement. Based on the location of the current block being at a border of the first region that is adjacent to the second region and there being a discontinuity at the border due to the packing arrangement, the reference samples are samples of the current picture that spatially neighbor the current block in a spherical domain and not in the projected domain.

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: 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: 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 device for decoding 360-degree video data is configured to store a decoded picture of 360-degree video as a reference frame; derive an extended reference frame from the stored reference frame based on a padding amount by extending a first cube face in the reference frame; inter-predict a block of a current picture from a block of the extended reference frame by determining a motion vector for the block of the current picture; in response to a determination that the motion vector points to a cube face in the extended reference frame other than the first cube face, clipping the motion vector such that the motion vector points to a location in the first cube face; and locating a prediction block for a current block using the clipped motion vector.

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: In various implementations, computing systems and computer-implemented methods can be used for correcting the distortion present in a fisheye image, and rendering the image for display as 360-degree video. In various implementations, a computing device can receive 2-dimensional video data captured by an omnidirectional camera. The computing device can map an image from each video frame to a 3-dimensional hemispherical representation. In various implementations, this mapping can be executed using a polynomial model. The 3-dimensional hemispherical representation can then be used in a 360-degree video presentation, to provide a virtual reality experience.

Abstract: A video decoder configured to determine a block of video data is intra predicted using an angular intra prediction mode, wherein the angular intra prediction mode is one of a bottom-left intra prediction mode or a top-right intra prediction mode; determine an aspect ratio of the block; locate one or more reference samples corresponding to the angular intra prediction mode; apply position dependent intra prediction combination to the reference samples to determine modified reference samples based on the aspect ratio of the block; and generate a predictive block for the block based on the modified reference samples.