Tencent America LLC

Madhu Peringassery Krishnan

Shan Liu

Xin Zhao

Liang Zhao

Yixin Du

Roman Chernyak

Biao Wang

Samruddhi Yashwant Kahu

Lien-Fei Chen

Xiang Li

Jing Ye

Han Gao

Xiang Yang Li

Xiaozhong Xu

Sehoon Yea

Yushin Cho

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.

Coefficient sign prediction for transform skip

The various implementations described herein include methods and systems for coding video. In one aspect, a method includes receiving a video bitstream that includes encoded video data; obtaining information indicating two or more different clipping ranges for the encoded video data; deriving the two or more different clipping ranges based on the obtained information; performing a first clipping operation on a first portion of the encoded video data based on a first clipping range of the two or more different clipping ranges; and performing a second clipping operation on a second portion of the encoded video data based on a second clipping range different from the first clipping range.

Different ranges for clipping processes for video and image compression

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.

Compound inter-intra prediction modes

Aspects of the disclosure provide a method and an apparatus including processing circuitry for video decoding. The processing circuitry decodes coded information for a transform block (TB) from a coded video bitstream. The coded information indicates one of intra prediction mode information that indicates an intra prediction mode used for the TB, a size of the TB, and a primary transform type used for the TB. The processing circuitry determines a context for entropy decoding a secondary transform index based on the one of the intra prediction mode information for the TB, the size of the TB, and the primary transform type used for the TB. The secondary transform index indicates a secondary transform in a set of secondary transforms that is to be performed on the TB. The processing circuitry entropy decodes the secondary transform index based on the context and performs the secondary transform.

Entropy coding a secondary transform index based on primary transform type

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 encoding a video block comprising a first transform block of a first color component and a second transform block of a second color component, wherein the first transform block and the second transform blocks are co-located blocks; encoding a first syntax element to signal whether a CCLR is applied to the first transform block, wherein, when CCLR is applied to the first transform block, a refinement process is required to be applied to the first transform block to obtain a refined first transform block on which an inverse transform is to be performed; and transmitting a bitstream comprising the video block and the first syntax element.

Primary transforms for cross-component level reconstruction

Systems and methods for encoding and decoding using syntax design for multi-symbol arithmetic coding are provided. A method includes receiving a coded video bitstream including a plurality of syntax elements; determining a first maximum alphabet size for arithmetic coding by an arithmetic coding engine, the first maximum alphabet size determined based on a hardware constraint; determining a second maximum alphabet size that is less than the first maximum alphabet size; and decoding the plurality of syntax elements included in the coded video bitstream, based on the determined second maximum alphabet size, wherein each of the plurality of syntax elements is entropy coded with an alphabet size less than or equal to the determined second maximum alphabet size.

Systems and methods including syntax design for multi-symbol arithmetic coding

In a method for video decoding in a decoder, transform coefficients associated with a coding block that is an L-shaped partition of a picture are decoded, by a processor and from a coded video bitstream. The L-shaped partition of the picture is partitioned into a plurality of rectangular sub-blocks when the coding block is the L-shaped partition, each corner of the L-shaped partition being a right angle. Residuals of each of the plurality of rectangular sub-blocks in the coding block are determined, by the processor, based on the transform coefficients of the respective rectangular sub-block. Samples of the coding block are reconstructed, by the processor, based on the residuals of the coding block.

Transform for L-shaped partition

The various implementations described herein include methods and systems for coding video. In one aspect, a method includes receiving a video bitstream that includes encoded video data and one or more syntax elements indicating one or more clipping ranges. The method includes deriving, based on the one or more syntax elements, the one or more clipping ranges for a portion of the encoded video data. Each of the one or more clipping ranges modifies a range of sample values of the received video bitstream. The method includes performing one or more clipping operations on the encoded video data using the derived one or more clipping ranges.

Adaptive range for clipping processes for video and image compression

The various embodiments described herein include methods and systems for encoding and decoding video. In one aspect, a method includes receiving a video bitstream that includes a plurality of blocks. The method also includes obtaining, from the video bitstream, respective values for one or more parameters associated with a block in the plurality of blocks, the one or more parameters corresponding to an arithmetic coder probability update rate, where the respective values for the one or more parameters are determined from a set of predefined values. The method further includes calculating the arithmetic coder probability update rate based on the respective values for the one or more parameters signaled in the video bitstream, and determining one or more coding contexts based on the calculated arithmetic coder probability update rate. The method also includes decoding the block in the plurality of blocks based on the one or more coding contexts.

Systems and methods for parameterizing arithmetic coder probability update rates

Methods, apparatus, and computer readable storage medium for implementation of entropy encoding of sign value of transform coefficient. The method includes receiving a first data block comprising a first transform coefficient from a coded video bitstream for the video data; and performing entropy decoding of a sign value of the first transform coefficient based on a context information, wherein the context information is derived based on a sign value of a second transform coefficient in a second data block in the video data, the second data block being co-located with the first data block, wherein co-located refers to two data blocks in different channels being located in a same spatial position.

Entropy coding of sign map for transform coefficients

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.

Method and apparatus for adaptive multi-hypothesis probability model for arithmetic coding

An example method of video coding includes receiving a video bitstream that includes a plurality of blocks and a plurality of quantized transform coefficients. The method includes deriving a dequantized transform coefficient for a first quantized transform coefficient of the plurality of quantized transform coefficients. The method also includes obtaining an adjusted transform value by applying an offset value to the dequantized transform coefficient, the adjusted transform value based on a quantized transform coefficient level and a current state of dequantization. The method further includes reconstructing a first block using the adjusted transform value.

Systems and methods for dependent quantization based on current dequantization states

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.

Sign coding for one-dimensional transform skip

This disclosure relates generally to video coding/decoding and particularly for a transform dictionary. A method includes receiving the coded video bitstream; determining, based on the coded video bitstream, a transform pile for the current block, the transform pile being one transform pile in a transform dictionary, the transform dictionary comprising a plurality of transform piles, and the transform pile comprising a plurality of transform sets; determining a transform set in the transform pile; determining a transform kernel in the transform set; performing an inverse transform for the current block based on the transform kernel for obtaining a residual block for the current block; and reconstructing the current block based on the residual block.

Dictionary of transforms

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.

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Mountain View, CA, United States of America

Madhu Peringassery Krishnan