Abstract: Example devices and techniques for multi-pass decoder-side motion vector refinement (DMVR) are disclosed. An example device includes memory configured to store video data and one or more processors coupled to the memory. The one or more processors are configured to apply a multi-pass DMVR to a motion vector for a block of the video data to determine at least one refined motion vector and decode the block based on the at least one refined motion vector. The multi-pass DMVR includes a block-based first pass, a sub-block-based second pass, and a sub-block-based third pass.

Abstract: A method of decoding video data includes determining that bi-directional optical flow (BDOF) is enabled for a block of the video data; dividing the block into a plurality of sub-blocks based on the determination that BDOF is enabled for the block, determining, for each sub-block of one or more sub-blocks of the plurality of sub-blocks, respective distortion values, determining that one of per-pixel BDOF is performed or BDOF is bypassed for each sub-block of the one or more sub-blocks of the plurality of sub-blocks based on the respective distortion values, determining prediction samples for each sub-block of the one or more sub-blocks based on the determination of per-pixel BDOF being performed or BDOF being bypassed, and reconstructing the block based on the prediction samples.

Abstract: Techniques are described herein for processing video data using enhanced interpolation filters for intra-prediction. For instance, a device can determine an intra-prediction mode for predicting a block of video data. The device can determine a type of smoothing filter to use for the block of video data, wherein the type of the smoothing filter is determined based at least in part on comparing at least one of a width of the block of video data and a height of the block of video data to a first threshold. The device can further perform intra-prediction for the block of video data using the determined type of smoothing filter and the intra-prediction mode.

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: Systems and techniques are provided for overlapped block motion compensation (OBMC). A method can include determining an OBMC mode is enabled for a current subblock of video data; for a neighboring subblock(s) adjacent to the current subblock, determining whether a first, second and third condition are met, the first condition comprising that all reference picture lists for predicting the current subblock are used to predict the neighboring subblock; the second condition comprising that identical reference pictures are used to determine motion vectors associated with the current subblock and the neighboring subblock, and the third condition comprising that a difference between motion vectors of the current subblock and the neighboring subblock do not exceed a threshold; and based on determining that the OBMC mode is enabled and the first, second, and third conditions are met, determining not to use motion information of the neighboring subblock for motion compensation of the current subblock.

Abstract: An example device for decoding video data includes one or more processors configured to: determine that a first weight and a second weight are specified for a bi-prediction mode predicted current block of video data; determine whether the current block is to be predicted using multi-hypothesis prediction (MHP) mode with the bi-prediction mode as a base mode; in response to determining that the current block is to be predicted using the MHP mode with the bi-prediction mode as the base mode, determine an additional inter-prediction mode of the MHP mode; generate a first prediction block according to the bi-prediction mode; generate a second prediction block according to the additional inter-prediction mode; generate a final prediction block for the current block according to the MHP mode using the first prediction block and the second prediction block; and decode the current block using the final prediction block.

Abstract: Techniques are described for adaptation parameter sets (APS) for adaptive loop filter (ALF) parameters. One example involves obtaining an APS ID value and an APS type value associated with a NAL unit from a bitstream. A first APS associated with at least a portion of at least one picture is identified, with the first APS being uniquely identified by a combination of the APS type value and the APS identifier value, and the APS identifier value of the first APS is in a range based on the APS type value. The portion of the at least one picture is then reconstructed using an adaptive loop filter with parameters defined by the first APS uniquely identified by the APS type value and the APS identifier value.

Abstract: A video decoder can be configured to decode a first syntax element indicating a size of a coding tree unit (CTU); after decoding the first syntax element indicating the size of the CTU, decode a second syntax element indicating a width of elements of a subpicture identifier grid; after decoding the first syntax element indicating the size of the CTU, decode a third syntax element indicating a height of the elements of the subpicture identifier grid; and determine a location of a subpicture within a picture based on the first syntax element, the second syntax element, and the third syntax element.

Abstract: Systems, methods, and computer-readable storage media for signaling filters for reference picture resampling are described. One example involves obtaining an encoded video bitstream associated with the video data, identifying a current picture and at least one reference picture from the encoded video bitstream, and identifying signaling data from the encoded video bitstream for the video data, the signaling data including a partial set of coefficient data for at least one filter. A complete set of coefficients (e.g., filter coefficients) is derived for the at least one filter from the partial set of coefficient data and characteristics of the at least one filter, and the current picture is processed using the complete set of coefficients for the at least one filter.

Abstract: A method of processing video data comprises obtaining a bitstream and locating intra random access pictures (IRAP) or Gradual Decoder Refresh (GDR) pictures among the encoded pictures in the bitstream. Locating the IRAP or GDR pictures may comprise obtaining, from a picture header Network Abstraction Layer (NAL) unit in the bitstream, a syntax element that indicates that a picture associated with the picture header NAL unit must be either an Intra Random Access Picture (IRAP) or a Gradual Decoder Refresh (GDR) picture. The picture header NAL unit contains syntax elements that apply to all slices of the picture associated with the picture header NAL unit.

Abstract: Systems, methods, and computer-readable media are provided for simplification of clipping value calculations for adaptive loop filtering. An example method can include obtaining video data including one or more pictures; obtaining a block of a picture from the one or more pictures; determining clipping values for a filter, the clipping values corresponding to a luma component in the picture and/or a chroma component in the picture, wherein each clipping value is determined by left shifting a first integer by a second integer, the second integer including a result of a bit depth value for a sample from the picture minus an offset value associated with a clipping index value; and applying the filter to the block.

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: An example method includes decoding a plurality of filter coefficients of a cross-component adaptive loop filter, wherein decoding a particular filter coefficient of the plurality of filter coefficients comprises: decoding, from an encoded video bitstream, a syntax element specifying an exponent value that represents a log base 2 of an absolute value of the particular filter coefficient as two raised to the power of the exponent value; and determining a value of the particular filter coefficient based on the exponent value; reconstructing samples of a block of video data; and cross-component adaptive loop filtering, based on the plurality of filter coefficients, the block of video data.

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: Methods incorporating extensions to copy-above mode for palette mode coding are disclosed. In one aspect, the method includes coding a current pixel of a current block of video data in copy-previous mode via coding a previous line index. The coding of the current pixel in copy-previous mode further including identifying a number of candidate values for the previous line index, identifying a number of escape pixels in a column of pixels above the current pixel in the current block, and reducing a number of candidate values of the previous line index by the number of identified escape pixels.

Abstract: An example device includes memory configured to store 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 picture of the video data is an intra random access picture (IRAP) and determine whether all layers of the picture are independent. Based on the picture being an IRAP and all layers of the picture being independent, the one or more processors are configured to determine a value of a first syntax element to be indicative of an inter slice not being allowed in the picture and code the picture without using inter slice prediction.

Abstract: In an example a method of processing video data includes determining a first palette for a first block of video data that is located in a first row of blocks, generating a predictor palette for constructing at least one second palette of at least one second block of video data in the first row of blocks coded, reinitializing the predictor palette for determining a third palette of a third block of video data that is located in a second row of blocks, wherein re-initializing the predictor palette comprises re-initializing the predictor palette based on the one or more palette entries of the first palette or an initial predictor palette generated after coding the first block, determining the third palette of the third block based on the re-initialized predictor palette, and coding the third block using the third palette.

Abstract: A video decoder may receive, in a bitstream that comprises an encoded representation of video data, information indicating whether a residual block is partitioned and information indicating a partition tree type for the residual block based on the residual block being partitioned, wherein the residual block is indicative of a difference between a current block and a prediction block. The video decoder may determine, based on the received information that the residual block is partitioned and the partition tree type for the residual block, a plurality of residual sub-blocks into which the residual block is partitioned according to the partition tree type. The video decoder may produce the residual data for the current block based at least in part on the residual block being partitioned according to the partition tree type into the plurality of residual sub-blocks and may decode the current block using the residual data.

Abstract: An example device for decoding video data includes a memory configured to store the video data and one or more processors implemented in circuitry and coupled to the memory. The one or more processors are configured to determine a first distance index associated with a first geometric partition mode (GEO) angle for a first prediction unit (PU) of the video data to be 4. The one or more processors are configured to determine a first displacement value based on the first distance index, the first displacement value being indicative of a distance from a center of the first PU to a GEO split. The one or more processors are configured to decode the first PU based on the first GEO angle and the first displacement value. The first displacement value is half of a displacement value associated with a distance index of 2.

Abstract: Systems, methods, and media are provided for video coding, including loop filtering. One example includes obtaining the video data comprising one or more pictures and determining a sample of the one or more pictures to be filtered using a loop filter. A shift variable associated with the sample is determined, and a rounding value is selected based on the shift variable. A modified sample is generated, the modified sample being generated at least in part by modifying a value of the sample using one or more filter coefficients, one or more clipping values of the loop filter, the rounding value, and the shift variable. The modified sample is then output.