Abstract: The various embodiments described herein include methods and systems for coding video. In one aspect, a method includes obtaining video data including a syntax element with a corresponding alphabet of M elements, a first set of respective probabilities of occurrence for the M elements of the syntax element; and a second set of respective probabilities of occurrence for the M elements of the syntax element. The method further includes entropy coding a first portion of the video data in accordance with an aggregation of the first and second sets; and, while entropy coding the first portion of the video data, encountering a first syntax element. The method also includes updating the first set at a first rate and updating the second set at a second rate, faster than the first rate. The method further includes adaptively entropy coding a second portion of the video data.

Abstract: The various implementations described herein include methods and systems for coding video. In one aspect, a method includes determining whether multiple transform units are within the video block in accordance with a determination that the inter-prediction mode is enabled; and in accordance with a determination that multiple transform units are within the video block: determining a transform unit of the multiple transform units to apply a secondary transform based on a relative location of the transform unit within the video block, applying the secondary transform to the transform unit, and reconstructing/processing the video block based at least on the secondary transform.

Abstract: The various embodiments described herein include methods and systems for coding video. In one aspect, a method includes obtaining video data that includes a first syntax element with a corresponding alphabet of M elements, and obtaining respective probabilities of occurrence for the M elements. The method further includes entropy coding a first portion of the video data using the respective probabilities of occurrence, and, while entropy coding, encountering the first syntax element. The method also includes updating probabilities of occurrence based on the first syntax element, and, in accordance with at least one of the updated probabilities being less than a threshold probability value, determining regularized probabilities of occurrence by applying a probability regularization to the updated probabilities of occurrence, where the probability regularization does not include a division operation.

Abstract: A method performed by at least one processor of a video decoder includes receiving a coded video bitstream including at least one picture and one or more syntax elements encoded in accordance with multi-hypothesis arithmetic coding. The method further includes decoding each syntax element from the one or more syntax elements based on the multi-hypothesis arithmetic coding. The method further includes selecting a probability update rate from a plurality of probability update rates based on a predetermined condition, the plurality of probability update rates including a first probability update rate that is higher than a second probability update rate. The method further includes updating at least one probability model utilized in the multi-hypothesis arithmetic coding based on the selected probability update rate. The method further includes decoding at least one block in the at least one picture based on the decoded one or more syntax elements.

Abstract: A method for applying adaptive weightings on intra prediction and inter prediction parts in compound inter-intra prediction modes includes defining a template area of neighboring reconstruction or prediction samples, applying one or more adaptive weighting candidates to the template area to generate one or more prediction samples using compound inter-intra prediction, calculating a cost value for each of the one or more adaptive weighting candidates, selecting the adaptive weighting candidate that provides the lowest cost as the weighting used for decoding a block with compound inter-intra prediction mode, and decoding the block based on the selected adaptive weighting.

Abstract: Aspects of the present disclosure provide methods and apparatuses for video encoding/decoding. In some examples, an apparatus includes processing circuitry that is configured to receive a coded video stream including a current block that is associated with a transform block, and determine whether a transform skip is used in the transform block. In response to a determination that the transform skip is not used in the transform block, the processing circuitry is configured to perform a first transform coefficient sign prediction in which (i) first signs of a first plurality of transform coefficients are predicted based on a first plurality of neighboring samples, and (ii) second signs of a second plurality of transform coefficients are predicted based on a second plurality of neighboring samples. The processing circuitry is further configured to reconstruct the current block based on the first plurality of transform coefficients and the second plurality of transform coefficients.

Abstract: A system includes code including first obtaining code to obtain a first syntax element that indicates a first quantization index value for an AC coefficient of an image; second obtaining code to obtain at least one second syntax element that indicates an offset value; third obtaining code to obtain a second quantization index value for another coefficient of the image; fourth obtaining code to obtain a quantization step size that corresponds to the second quantization index value that is obtained; and determining code to determine whether a mode in which the image is to be coded is a lossy mode or a lossless mode based on determining whether the first quantization index value is equal to a quantization index value associated with lossless coding, and based on determining whether the offset value is less than or equal to the quantization index value associated with the lossless coding.

Abstract: This disclosure relates to video coding with a block-level window size update for arithmetic coding. A probability update rate may be a function of count of appearances for the associated syntax/context when parsing a bitstream. It may also be a function of a number of different symbol values for the associated syntax/context. The value of the count is restarted with a pre-defined value at block-level. The probability or cumulative distribution function (CDF) update rate for a particular syntax/context may be reinitialized with a pre-defined value at block level.

Abstract: Methods, apparatus, and computer readable storage medium for multi-symbol arithmetic coding in video decoding. The method includes receiving a coded video bitstream; obtaining an array of cumulative distribution functions and corresponding M symbols, wherein M is an integer larger than 1; and performing, based on the array of cumulative distribution functions, arithmetic decoding on the coded video bitstream to extract at least one symbol by: for each extracted symbol, updating the array of cumulative distribution functions according to the extracted symbol based on at least one probability update rate, and continuing, based on the updated array of cumulative distribution functions, arithmetic decoding on the coded video bitstream to extract next symbol.

Abstract: Methods, apparatus, and computer readable storage medium for implementation of signaling EOC/EOR. The method includes receiving a video bitstream comprising a transform block having two dimensions, the transform block being entropy encoded; determining whether a one-dimensional transform skip is applied to the transform block based on a syntax element in the video bitstream; in response to the one-dimensional transform skip being applied to the transform block, obtaining, from the video bitstream, an end position value associated with the transform block, the end position value indicating only one of a horizontal coordinate end position in the transform block and a vertical coordinate end position in the transform block; and retrieving the transform block from the video bitstream according to the end position value.

Abstract: A method, computer program, and computer system is encoding or decoding video data. Video data may include a syntax element indicating a quantization index, wherein a range of the quantization index is extended by an offset value. The syntax element may be parsed to determine the quantization index, a quantization step size may be obtained from a lookup table based on the quantization index and the offset value; and the video data may be encoded or decoded based on the quantization step size.

Abstract: Aspects of the disclosure provide a method and an apparatus including processing circuitry for video decoding. The processing circuitry can decode coding information of a transform block (TB) from a coded video bitstream. The coding information can indicate a transform skip in one direction for the TB. The processing circuitry can decode a sign value of a current transform coefficient in the TB based on a previously decoded sign value of a previous transform coefficient. The current transform coefficient and the previous transform coefficient can be in one of a same row and a same column in the TB. The one of the same row and the same column can be along the one direction of the transform skip. The processing circuitry can determine the current transform coefficient in the TB based on the decoded sign value of the current transform coefficient.

Abstract: Systems and methods for coding and decoding of a coded bitstream is provided. A method comprises decoding a block of a picture from a coded bitstream. The decoding includes selecting a transform set based on at least one neighboring reconstructed sample from one or more previously decoded neighboring blocks or from a previously decoded picture and inverse transforming coefficients of the block using a transform from the transform set.

Abstract: Aspects of the disclosure provide a method and an apparatus including processing circuitry for video decoding. The processing circuitry can decode coding information of a transform block (TB) from a coded video bitstream. The coding information can indicate a transform skip in one direction for the TB. The processing circuitry can decode a sign value of a current transform coefficient in the TB based on a previously decoded sign value of a previous transform coefficient. The current transform coefficient and the previous transform coefficient can be in one of a same row and a same column in the TB. The one of the same row and the same column can be along the one direction of the transform skip. The processing circuitry can determine the current transform coefficient in the TB based on the decoded sign value of the current transform coefficient.

Abstract: This disclosure relates to adaptive loop filtering (ALF) for cross-component sample offset (CCSO) and local sample offset (LSO). ALF uses reconstructed samples of a first color component as input (e.g., Y or Cb or Cr). For CCSO, the output is applied on a second color component which is a different color component of the first color component. For LSO, the output is applied on the first color component. A combined ALF may be generalized for CCSO and LSO by considering a delta value between neighboring samples of a collocated (or current) sample and also considering a level value of the collocated (or current) sample.

Abstract: This disclosure relates to adaptive loop filtering (ALF) for cross-component sample offset (CCSO), local sample offset (LSO), and generalized sample offset (GSO). ALF uses reconstructed samples of a first color component as input (e.g., Y or Cb or Cr). At least one of the GSO, LSO, or CCSO is determined to be enabled for a frame based on a syntax value in a coded video stream. The coded video stream is decoded by applying the at least one of the GSO, the LSO, or the CCSO at a block level.

Abstract: This disclosure relates generally to video coding and particularly to cross component level reconstruction. For example, a method is disclosed for processing video data which may include extracting a first transform block of a first color component and a second transform block of a second color component from a bitstream of a video block; determining that transform coefficients in the first transform block are all zero; determining that a CCLR is applied to the first transform block; refining one or more of the transform coefficients in the first transform block, to obtain a refined first transform block; determining a target transform kernel for the refined first transform block; performing a reverse transform on the refined first transform block based on the target transform kernel to obtain a target block; and reconstructing the first color component of the video block based on at least the target block.

Abstract: This disclosure relates transform configuration and signaling for a compound inter-intra prediction modes. In one example, a method for decoding a video block in a video stream is disclosed. The method may include determining that the current block is predicted under a CIIP mode; generating a set of secondary transform coefficients for the current block from the video bitstream; applying a combined inter intra secondary transform by: performing an inverse separable or non-separable secondary transform on the set of secondary transform coefficients to obtain a set of primary transform coefficients of the current block; and performing an inverse primary transform on the set of primary transform coefficients to obtain a residual block of the current block; and decoding, under the CIIP mode, the current block from the residual block.

Abstract: This disclosure relates generally to video coding and particularly to methods and systems for deriving offsets in cross-component transform coefficient level reconstruction. An example method for decoding a current video block of a video bitstream is disclosed. The method includes receiving a coded video bitstream; extracting, from the coded video bitstream, a first transform coefficient of a first color component for a current video block; determining a second transform coefficient of a second color component for the current video block; deriving an offset value based on at least one of the following: a quantization step size, or the first transform coefficient; adding the offset value to the second transform coefficient to generate a modified second transform coefficient for the second color component; and decoding the current video block based on the first transform coefficient and the modified second transform coefficient of the second color component.

Abstract: This disclosure relates transform configuration and signaling for a compound inter intra prediction modes. In one example, a method for decoding a video block in a video stream is disclosed. The method may include determining that the video block is predicted in a Compound Inter Intra Prediction (CIIP) mode, wherein the video block is derived as a combination of an intra prediction and an inter prediction in the CIIP mode.