Abstract: An example method of decoding video data includes receiving encoded data for a current block. The method further includes determining whether single tree partitioning is enabled for the current block and decoding the encoded data to generate luma transform coefficients for the current block and chroma transform coefficients for the current block. The method further includes, in response to determining that the single tree partitioning is enabled for the current block, applying an inverse low-frequency non-separable transform (LFNST) to only the luma transform coefficients for the current block to produce a residual block for the current block. The method further includes reconstructing the current block of the video data using the residual block and a prediction block for the current block.

Abstract: An example device for decoding video data includes a memory configured to store the video data and one or more processors coupled to the memory. The one or more processors are configured to reorganize 2-D dequantized coefficients according to a first ordering. The one or more processors are configured to apply an inverse low-frequency non-separable transform (LFNST) to the reorganized 2-D dequantized coefficients to create inverse transformed coefficients. The one or more processors are configured to reorganize the inverse transformed coefficients according to a second ordering, the second ordering being based on an array including values, wherein each value in the array corresponds to a position in a 2-D block and the values in the array denote indices of the 2-D block in a defined order. The one or more processors are configured to decode the video data based on the second ordered inverse transformed coefficients.

Abstract: An example device for coding video data includes a 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 scaling matrices may be applied to a low-frequency non-separable transform (LFNST) coded block. The one or more processors are also configured to, based on a determination that scaling matrices may not be applied to the LFNST coded block, not applying the scaling matrices to the LFNST coded block. The one or more processors are also configured to code the video data without applying the scaling matrices to the LFNST coded block.

Abstract: A video decoder may be configured to determine whether a block of video data is to be further partitioned based on the size of the block of video data and a lossless coding flag. A video decoder may decode a lossless coding flag for a block of video data, wherein the block of video data is in a picture that includes both lossy coded blocks and lossless coded blocks, determine that the lossless coding flag indicates a lossless coding mode for the block, and partition the block into sub-blocks based on a size of the block and the determination of the lossless coding mode.

Abstract: An example coding device, such as a video coding (encoding or decoding) device is configured to determine a plurality of estimator functions to be used to calculate a probability of a symbol having a particular value, wherein the symbol is to be binary arithmetic coded according to the probability, and wherein the estimator functions do not include division operations; determine a plurality of weights for the plurality of estimator functions such that when the respective weights are applied to the estimator functions, a resulting sum of outputs of the plurality of estimator functions yields the probability; calculate the probability of the symbol having the particular value, including: execute the estimator functions without using the division operations to determine the outputs; and calculate a sum of the outputs as the probability; and binary arithmetic code the symbol according to the probability of the symbol having the particular value.

Abstract: A method of decoding video data includes receiving encoded data for a current block and decoding N bins for a low-frequency non-separable transform (LFNST) index from the encoded data. The N bins comprises a first bin and a second bin. Decoding the N bins comprises context decoding each bin of the N bins. The method further includes determining the LFNST index using the N bins and decoding the encoded data to generate transform coefficients. The method further includes applying an inverse LFNST to the transform coefficients using the LFNST index to produce a residual block for the current block and reconstructing the current block of the video data using the residual block and a prediction block for the current block.

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: Example techniques are described for coding video data by obtaining a block of video data, obtaining an adaptive parameter set, determining a set of adaptive loop filter parameters for a plurality of filters for the block of video data based on the adaptive parameter set, wherein a plurality of adaptive loop parameters of the set of adaptive loop filter parameters are signaled using the same signaling parameter for each of the plurality of filters of the adaptive parameter set, and coding the block of video data using the set of adaptive loop filter parameters. The example techniques can be performed as part of an encoding or decoding process and/or by an encoder or a decoder.

Abstract: A video coder may be configured to code video data by performing adaptive loop filtering processes. A video coder may decode a syntax element that indicates a manner in which to perform an adaptive loop filtering process, the syntax element indicating that a nonlinear operation is to be applied to the video data, where the nonlinear operation is configured to be applied in combination with a filtering operation of the adaptive loop filtering process. In addition, the video coder may perform the adaptive loop filtering process based on the syntax element.

Abstract: A video decoder determines, based on a block size of a current block and a low-frequency non-separable transform (LFNST) syntax element, a zero-out pattern of normatively defined zero-coefficients. The LFNST syntax element is signaled at a transform unit (TU) level. Additionally, the video decoder determines transform coefficients of the current block. The transform coefficients of the current block include transform coefficients in an LFNST region of the current block and transform coefficients outside the LFNST region of the current block. As part of determining the transform coefficients of the current block, the video decoder applies an inverse LFNST to determine values of one or more transform coefficients in the LFNST region of the current block. The video decoder also determines that transform coefficients of the current block in a region of the current block defined by the zero-out pattern are equal to 0.

Abstract: A video coder is configured to code an adaptive loop filter (ALF) clipping index as a fixed-length unsigned integer. The video coder may apply, based on the ALF clipping index, an ALF to a block of a picture of the video data.

Abstract: A method of decoding video data includes receiving, by processing circuitry, a video bitstream including encoded representations of one or more syntax elements of a coded unit and initializing, by the processing circuitry, a respective probability state for each bin of a plurality of bins for the one or more syntax elements based on a comparison of a parameter associated with the coded unit and a respective threshold of a plurality of thresholds. The method further includes performing, by the processing circuitry, inverse binary arithmetic coding on the encoded representations of the one or more syntax elements to obtain each bin of the plurality of bins using a respective probability state for the bin, inverse binarizing, by the processing circuitry, the plurality of bins to obtain the one or more syntax elements, and decoding, by the processing circuitry, the video data based on the one or more syntax elements.

Abstract: A device for decoding video data can be configured to perform a multi-pass inverse transformation on a plurality of values to derive residual data that represents pixel differences between a current block of video data and a predictive block of the video data, wherein to perform a pass of the multi-pass inverse transformation, the device is configured to determine at least two matrices, wherein the at least two matrices comprise a first matrix and a second matrix; determine at least two vectors, wherein the at least two vectors comprise a first vector and a second vector; and perform at least two matrix-vector computations, wherein the at least two matrix-vector computations comprise a first matrix-vector computation based on the first matrix and the first vector and a second matrix-vector computation based on the second matrix and the second vector.

Abstract: A video decoder is configured to determine a position of a last significant coefficient in a transform block of video data. The video decoder may then determine a value of a low-frequency non-separable transform (LFNST) index for the transform block based on the position of the last significant coefficient relative to a zero-out region of the transform block, wherein the zero-out region of the transform block includes both a first region within an LFNST region of the transform block and a second region of the transform block outside the LFNST region. The video decoder may then inverse transform the transform block in accordance with the value of the LFNST index.

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 first codeword representing a selected transform scheme of a set of transform candidates of a multiple transform selection (MTS) scheme for a current block of video data, the selected transform scheme being a secondary transform of a set of available secondary transforms to be applied in addition to a primary transform; code a second codeword representing the secondary transform from the set of available secondary transforms; and apply the primary transform and the secondary transform during coding of residual data for the current block. The second codeword may be a value for a low-frequency non-separable transform (LFNST) syntax element.

Abstract: A video coder may determine a filter set for a coding tree block (CTB) from a plurality of fixed filter sets. Based on the filter set for the CTB being from the fixed filter sets, the video coder may set clipping values to maximum supported values. Furthermore, the video coder may determine, based on the clipping values, clipped inputs to an adaptive loop filter (ALF) of the filter set, each of the inputs being an input sample minus a current sample. The video coder may then apply the ALF to the clipped inputs.

Abstract: A video decoder can be configured to generate a first bin stream by, for at least one bin of the first bin stream, determining a first probability estimation for the at least one bin of the first bin stream based on a first set of parameters and generate a second bin stream by, for at least one bin of the second bin stream, determining a second probability estimation for the at least one bin of the second bin stream based on a second set of parameters that are different parameters than the first set of parameters.

Abstract: An example method includes inferring, for a current transform block of a current video block, a transform type from a plurality of transform types that includes one or more discrete cosine transforms (DCTs) and one or more discrete sine transforms (DSTs), wherein inferring the transform type comprises: determining a size of the current transform block; determining whether the current video block is partitioned using intra-subblock partitioning (ISP); and responsive to determining that the size of the current transform block is less than a threshold and that the current video block is partitioned using ISP, selecting a particular DST of the one or more DSTs as the selected transform type; transforming, using the selected transform type, the current transform block to obtain a block of reconstructed residual data for the video block; and reconstructing, based on the reconstructed residual data for the video block, the video block.

Abstract: A video coder may apply a sub-block transform for blocks of video data. The video coder is configured to determine when to apply sub-block transforms to blocks of video data based on a ratio of the width and height (or ratio of height and width) of the block. The video coder may also determine when to use different transform kernels for different sub-blocks when applying sub-block transforms.

Abstract: A video decoder configured to determine a residual block by, for a first coefficient of a coefficient group, receiving a first instance of a flag, wherein the first instance of the flag is set to a first value; in response to the first instance of the flag being set to the first value, copying a coefficient value of a neighboring coefficient for the first coefficient; for a second coefficient of the coefficient group, receiving a second instance of the flag, wherein the second instance of the flag is set to a second value; in response to the second instance of the flag being set to the second value, receiving an index; determining, from a list of coefficient values, a value corresponding to the index; and set a value for the second coefficient to the value corresponding to the index.