Huawei Technologies Co., Limited

Xiang Ma

Haitao Yang

Jianle Chen

Yin Zhao

Huanbang Chen

Lian Zhang

Alexey Konstantinovich Filippov

Vasily Alexeevich Rufitskiy

Xu Chen

Shan Gao

Fan Mu

Jue Mao

Nan Song

Apparatuses and methods for encoding and decoding are provided. The method for intra predicting a chroma sample of a block by applying cross-component linear model includes: obtaining reconstructed luma samples; determining maximum and minimum luma sample values based on the reconstructed luma samples; obtaining a difference of the maximum and minimum luma sample values. The method also includes: fetching a value out of a lookup table (LUT) by using a set of bits as an index, the set of bits following a position of the most-significant bit; obtaining linear model parameters based on the fetched value; and calculating a predicted chroma sample value by using the obtained linear model parameters. The efficiency to fetch the value out of the LUT is increased.

Method and apparatus of cross-component linear modeling for intra prediction

The technology of this application relates to an entropy encoding method that includes obtaining base layer information of a to-be-encoded picture block, where the base layer information corresponds to M samples in the picture block, and M is a positive integer, obtaining K elements corresponding to enhancement layer information of the picture block, where the enhancement layer information corresponds to N samples in the picture block, both K and N are positive integers, and N≥M, inputting the base layer information into a neural network to obtain K groups of probability values, where the K groups of probability values correspond to the K elements, and any group of probability values is for representing probabilities of a plurality of candidate values of a corresponding element, and performing entropy encoding on the K elements based on the K groups of probability values.

Entropy encoding/decoding method and apparatus

A method for decoding a coded video bitstream is provided. The method includes: obtaining a reference layer syntax element by parsing the coded video bitstream, wherein a value of the reference layer syntax element specifying whether a layer with index k is a direct reference layer for a layer with index i; determining whether the layer with index j is a reference layer for the layer with index i based on the value of the reference layer syntax element; and when a condition is satisfied, predicting a picture of the layer with index i based on the layer with index j, wherein the value of a chroma format related syntax element applied to the layer with index i is the same as the value of a chroma format related syntax element applied to the layer with index j.

Encoder, decoder and corresponding methods and apparatus

This application provides a video picture prediction method and apparatus, to resolve a problem in a conventional technology that a length of a coded video sequence is increased. The first type of identifier may be added to a bitstream. The first type of identifier is used to indicate whether an affine motion model-based inter prediction mode is enabled for a video picture. For a video picture or a picture block included in the slice for which the affine motion model does not need to be used, a parameter, related to the affine motion model, of the picture block may not need to be transmitted. On a decoder side, during decoding of the picture block, the parameter related to the affine motion model does not need to be parsed. This can reduce load of a decoder, increase a processing speed, and decrease a processing time.

Video picture prediction method and apparatus

An intra prediction method includes obtaining respective intra prediction modes or texture distributions of P reconstructed picture blocks in a surrounding region of a current block; obtaining, based on the respective intra prediction modes or texture distributions of the P reconstructed picture blocks, Q priori candidate intra prediction modes of the current block and Q probability values; obtaining, based on M probability values corresponding to M priori candidate intra prediction modes, M weighting factors corresponding to the M priori candidate intra prediction modes; separately performing intra prediction based on the M priori candidate intra prediction modes to obtain M predicted values; and obtaining a predicted value of the current block based on a weighted summation of the M predicted values and the corresponding M weighting factors.

Intra prediction method and apparatus

This application provides a chroma block prediction method and apparatus. The method includes: obtaining chroma values of chroma samples; obtaining, luma values of luma samples corresponding to the chroma samples; obtaining, from the luma values, a first luma set and a second luma set; grouping the chroma values into a first chroma set and a second chroma set; determining a scaling coefficient in a linear model based on an average value of luma values in the first luma set, an average value of luma values in the second luma set, an average value of chroma values in the first chroma set, and an average value of chroma values in the second chroma set; determining, based on the scaling coefficient, an offset factor in the linear model; and determining prediction information of the chroma block based on the scaling coefficient and the offset factor.

Chroma block prediction method and apparatus

This application discloses a method for constructing an MPM list, a method for obtaining an intra prediction mode of a chroma block, and an apparatus. In a specific implementation, a MIP mode is used for a current block, and the method for constructing an MPM list includes: obtaining intra prediction mode information of a neighboring block; determining, based on the intra prediction mode information of the neighboring block, whether an intra prediction mode of the neighboring block is the MIP mode; and skipping using the intra prediction mode of the neighboring block for MPM list construction of the current block if the intra prediction mode of the neighboring block is not the MIP mode; or using the intra prediction mode of the neighboring block for MPM list construction of the current block if the intra prediction mode of the neighboring block is the MIP mode.

Method for constructing MPM list, method for obtaining intra prediction mode of chroma block, and apparatus

Techniques are described of a linear model prediction mode. A set of reconstructed neighboring luma samples are determined. Two pairs of luma value and chroma value are determined according to N reconstructed neighboring luma samples, N reconstructed neighboring chroma samples, M reconstructed neighboring luma samples, and M reconstructed neighboring chroma samples. The minimum value of the N reconstructed neighboring luma samples is not less than the maximum luma value of the remaining reconstructed neighboring luma samples of the set of reconstructed neighboring luma samples. The maximum value of the M reconstructed neighboring luma samples is not larger than the minimum luma value of the remaining reconstructed neighboring luma samples of the set of reconstructed neighboring luma samples. M>1 and N>1. Linear model parameters are determined based on the two pairs of luma value and chroma value, and a predictive block is determined based on the linear model parameters.

Video encoder, video decoder, and corresponding encoding and decoding methods

An intra prediction method by using cross component liner prediction mode (CCLM), includes: determining a luma block corresponding to a current chroma block; obtaining luma reference samples of the luma block based on determining L available chroma reference samples of the current chroma block, wherein the obtained luma reference samples of the luma block are down-sampled luma reference samples; calculating linear model coefficients based on the luma reference samples and chroma reference samples that correspond to the luma reference samples; and obtaining a prediction for the current chroma block based on the linear model coefficients and values of a down-sampled luma block of the luma block.

Intra prediction method and device

This application provides a chroma block prediction method and apparatus. The method includes: obtaining a maximum luma value and a minimum luma value based on luma samples corresponding to neighboring samples of a target chroma block, and calculating a first difference between the maximum luma value and the minimum luma value; if the first difference is not equal to 0, processing the first difference based on a quantity of significant bits of the first difference and a first preset bit depth to obtain a second difference; and determining, based on a first chroma value, a second chroma value, and the second difference, an intra prediction model parameter corresponding to the target chroma block, and determining prediction information of the target chroma block based on the intra prediction model parameter and luma reconstruction information corresponding to the target chroma block.

A picture prediction method is provided, which includes: obtaining initial motion information of a current picture block; determining, based on a matching cost criterion, that positions of a pair of reference blocks are a position of a target forward reference block of the current picture block and a position of a target backward reference block of the current picture block, where positions of each pair of reference blocks include a position of a forward reference block and a position of a backward reference block; and for the positions of each pair of reference blocks, a first position offset and a second position offset are in a mirror relationship; and obtaining a predicted value of a pixel value of the current picture block based on a pixel value of the target forward reference block and a pixel value of the target backward reference block.

Picture prediction method and apparatus, and codec

The present disclosure provides a method of decoding a coded video bitstream, the method comprising: obtaining a picture-level syntax element included in a picture header of the current picture by parsing the video bitstream, wherein the picture-level syntax element is used to specify whether an adaptive loop filter (ALF) is enabled for the current picture; in case that the picture-level syntax element specifies the adaptive loop filter is enabled for the current picture, obtaining a parameter set identifier included in the picture header, wherein the parameter set identifier is used to indicate a first parameter set comprising a set of ALF parameters, and wherein a temporal identifier of the first parameter set is less than or equal to a temporal identifier of the current picture; performing the adaptive loop filter on at least one slice of the current picture based on the first parameter set.

Encoder, a decoder and corresponding methods

The present application disclose a picture processing method and apparatus, which are applicable to a video picture processing scenario. The method includes: obtaining at least two transform coefficient blocks, where each of the at least two transform coefficient blocks includes at least two transform coefficients that correspond to different frequency points; determining, according to a preset frequency point scanning order, the transform coefficients that are in the at least two transform coefficient blocks and that correspond to a selected frequency point; and encoding, according to a preset coefficient scanning order, each transform coefficient corresponding to the selected frequency point, to obtain picture encoded information.

Picture processing method and apparatus

A method of decoding a coded video bitstream includes obtaining a sequence parameter set (SPS)-level syntax element from the bitstream, wherein that the SPS-level syntax element equaling a preset value specifies that no video parameter set (VPS) is referred to by a SPS, and wherein the SPS-level syntax element being greater than the preset value specifies that the SPS refers to a VPS. The method further includes obtaining, when the SPS-level syntax element is greater than the preset value, an inter-layer enabled syntax element specifying whether one or more inter-layer reference pictures (ILRPs) are enabled to be used for the inter prediction of one or more coded pictures, and predicting one or more coded pictures based on the value of the inter-layer enabled syntax element.

Apparatuses and methods for encoding and decoding based on syntax element values

The present disclosure provides a chroma block prediction method and a device. The method includes: parsing a bitstream to obtain first indication information; downsampling a first luma block by a first filter when a value of the first indication information is a first value or by using a second filter when a value of the first indication information is a second value, to obtain a second luma block; obtaining a plurality of chroma samples and a plurality of luma samples; obtaining linear model coefficients based on the plurality of chroma samples and the plurality of luma samples; and obtaining a prediction value of the current chroma block based on the second luma block and the linear model coefficients.

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Moscow, Russia

Xiang Ma