Abstract: The present disclosure relates to intra- or inter-prediction for video encoding and decoding. For that purpose, an apparatus and methods obtain a reference sample and a subpixel offset value. A 4-tap interpolation filter is used to filter the reference sample to obtain a predicted sample value. The filter coefficients c0, c1, c2, and c3 of the 4-tap interpolation filter satisfy c 0 = 16 - p 2 , c 1 = 16 + 16 - p 2 , c 2 = 16 + p 2 , and ? ? c 3 = p 2 , with p being a fractional part of the value of the subpixel offset.

Abstract: A device for video decoding can be configured to obtain, from a syntax structure in a bitstream comprising an encoded representation of the video data, a syntax element indicating whether 6-parameter affine prediction is enabled for blocks corresponding to the syntax structure, wherein the blocks corresponding to the syntax structure comprise a first block; based on the syntax element indicating that the 6-parameter affine prediction is enabled for the blocks corresponding to the syntax structure, use the 6-parameter affine prediction to generate a predictive block for the first block; and use the predictive block and residual data to reconstruct the first block.

Abstract: Apparatuses and methods for intra predicting a block are described. The method of intra predicting a current block can include obtaining a predicted sample value from one or more reference sample values by using an intra prediction mode, obtaining at least one additional reference sample value in accordance with the intra prediction mode, and obtaining a thresholded additional reference sample value based on the additional reference sample value. The method can also include calculating an additional value from the thresholded additional reference sample value, multiplying the predicted sample value by a sample weighting factor, resulting in a weighted predicted sample value, adding the additional value to the weighted predicted sample value, resulting in a non-normalized predicted sample value, and normalizing the non-normalized predicted sample value, resulting in a normalized predicted sample values. The accuracy for the intra prediction is thus increased.

Abstract: The present disclosure relates to methods and apparatuses for encoding video data into a bitstream and for decoding video data received in a bitstream. A second control flag indicating whether or not to use multi-hypothesis prediction for intra and inter mode is generated and transmitted only conditionally, upon a determination whether or not separate merge list technique for subblock merge candidates is used. On the other hand, a decoder is capable of deciding usage of multi-hypothesis prediction for intra and inter mode and separate merge list technique for subblock merge candidates even though the second control flag is transmitted only conditionally.

Abstract: Devices and methods of intra prediction of a block of a picture are provided. The method includes obtaining reference samples of a block, and determining a value of a predicted sample based on the reference samples and an intra prediction mode. The method further includes obtaining a value of a multiplier based on at least one dimension of the block, and normalizing the value of the predicted sample based on the value of the multiplier and a value of a shift. The intra prediction mode is INTRA_DC, or INTRA_BI, or horizontal intra prediction mode. By normalizing the value of the predicted sample based on the value of the multiplier and a value of a shift without division operation, the method could increase intra prediction efficiency.

Abstract: Devices and methods of directional intra prediction for chroma component of a picture are provided. The method includes obtaining an initial intra prediction mode of the chroma component, and deriving a chroma intra prediction mode (intraPredModeC) from a look up table (LUT) by using the initial intra prediction mode of the chroma component. The chroma component has different subsampling ratios in horizontal and vertical directions. The method further includes performing wide-angle mapping on the chroma intra prediction mode (intraPredModeC) to obtain a modified intraPredModeC; obtaining an angle parameter for the chroma component based on the modified intraPredModeC; and obtaining predicted samples of the chroma component based on the angle parameter. The method provides the minimum number of entries in the LUT that is used to determine chroma intra prediction mode from the initial chroma intra prediction mode.

Abstract: A method of filtering a sample value of a picture is provided, with an integer t that is less than k and with an integer j in the range of 1 to m: generating, with an integer i in the range of 1 to k?t?1, a filtered sample value by applying a filter to the value of the sample p(i,j), wherein the filter is supported by a set of filter support samples, the set of filter support samples does not comprise any samples p(i?,j?) with row index i? greater than k?t?1, and/or generating, with an integer i in the range of k?t to k, a filtered sample value by applying a filter to the value of the sample p(i,j), the filter is supported by a set of filter support samples, wherein the set of filter support samples does not comprise any samples p(i?,j?) with row index i? less than k?t.

Abstract: 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.

Abstract: A method of decoding includes receiving a first picture parameter set and a second picture parameter set each referring to same sequence parameter set, the first picture parameter set and the second picture parameter set having same values of a conformance window when the first picture parameter set and the second picture parameter set have same values of picture width and picture height, and applying the conformance window to a current picture corresponding to the first picture parameter set or the second picture parameter set.

Abstract: A method of intra prediction of a block in a picture of a video is disclosed. The method comprises obtaining an intra prediction mode of the block; determining whether the intra prediction mode of the block is a wide-angle mode; filtering reference samples for the block based, at least in part, upon determining that the intra prediction mode of the block is the wide-angle mode; and generating predicted samples of the block based on filtered reference samples.

Abstract: Embodiments of this application disclose a bi-directional inter prediction method and apparatus. The method includes: determining a reference picture index i1 of a first reference picture list as a first reference picture index; determining a reference picture index i2 of a second reference picture list as a second reference picture index; and predicting the current block based on the first reference picture index and the second reference picture index. A POC corresponding to i1 is a POC, closest to a POC of a current picture, in all POCs that are in the first reference picture list and that are less than the POC of the current picture, a POC corresponding to i2 is a POC, closest to the POC of the current picture, in all POCs that are in the second reference picture list and that are greater than the POC of the current picture. Coding efficiency can be improved.

Abstract: A method of decoding a coded video bitstream implemented by a video decoder is provided. The method includes the video decoder determining whether a gradual decoding refresh (GDR) picture in the coded video bitstream is an initial picture in decoding order or the initial picture following an end of sequence (EOS) network abstraction layer (NAL) unit in the decoding order; setting a flag to a value to prevent the GDR picture from being output when the GDR picture is the initial picture in decoding order or the initial picture following the EOS NAL unit in the decoding order; decoding the GDR picture; and storing the GDR picture in a decoded picture buffer (DPB).

Abstract: A deblocking method is provided for deblocking a sub-partition boundary within a coding block during image encoding and/or image decoding process. The coding block is coded in an intra prediction mode and the coding block is partitioned into sub-partitions comprising a first sub-partition and a second sub-partition that is adjacent to the first sub-partition. The method comprises: determining a maximum filter length to be 1 for a first/second sub-partition when a width of the first or second sub-partition is 4 samples, or when a height of the first or second sub-partition is 4 samples; modifying a value of up to one sample of the first or second sub-partition, wherein the value of the up to one sample is obtained from a row or a column of the first or second sub-partition that is perpendicular to and adjacent to the sub-partitions boundary between the first sub-partition and the second sub-partition.

Abstract: A deblocking method is provided for deblocking a sub-partition boundary within a coding block during image encoding and/or image decoding process. The coding block is coded in an intra prediction mode and the coding block is partitioned into sub-partitions comprising a first sub-partition and a second sub-partition that is adjacent to the first sub-partition. The method comprises: determining a maximum filter length to be 1 for a first/second sub-partition when a width of the first or second sub-partition is 4 samples, or when a height of the first or second sub-partition is 4 samples; modifying a value of up to one sample of the first or second sub-partition, wherein the value of the up to one sample is obtained from a row or a column of the first or second sub-partition that is perpendicular to and adjacent to the sub-partitions boundary between the first sub-partition and the second sub-partition.

Abstract: An image prediction method, apparatus, and system, a device, and a storage medium are provided. The method includes: (401) obtaining a split mode of a current node, where the current node is an image block in a coding tree unit in a current image; (402) determining, based on the split mode of the current node and a size of the current node, whether the current node satisfies a first condition; and (403) when it is determined that the current node satisfies the first condition, performing intra prediction on all coding blocks belonging to the current node, to obtain predictors of all the coding blocks belonging to the current node.

Abstract: A method of intra prediction of a block, comprising obtaining two lines of reconstructed neighboring samples; deriving a set of reference samples based on the two lines of reconstructed neighboring samples; obtaining a set of MIP coefficients based on a intra prediction mode obtained from a bitstream, wherein a MIP coefficient CMIP of the set of MIP coefficients is obtained based on CMIP=vsgn·(q<<s), where q is a magnitude of the MIP coefficient, wherein s is a left shift value and vsgn is a sign value of the MIP coefficient; and obtaining a prediction block based on the set of reference samples and the set of MIP coefficients, wherein a reconstruct picture is obtained based on the prediction block.

Abstract: A deblocking method, for deblocking a transform block boundary within a coding block in an image encoding and/or an image decoding is provided, wherein the coding block comprising transform blocks is coded in inter prediction mode and the transform blocks comprises a first transform block and a second transform block; wherein the method comprises: determining, when the boundary between the first transform block and the second transform block is a transform block boundary and at least one of the first transform block and the second transform block has one or more non-zero transform coefficients, a value of a BS parameter for the boundary between the first transform block and the second transform block to be a first value; and performing de-blocking filtering process to the boundary between the first transform block and the second transform block at least based on the value of the boundary strength parameter.

Abstract: A method of video coding a block of a picture includes: obtaining a residual signal resulting from inter- or intra-picture prediction; inferring use of a DCT2 transform core for a sequence of the residual signal; processing the transformation of the block using the inferred transform core.

Abstract: Embodiments of this application relate to the field of video picture coding technologies, and disclose a bidirectional inter prediction method and apparatus, to improve coding efficiency. The method includes: obtaining a first motion vector difference of a current picture block; determining a second motion vector difference of the current picture block based on the first motion vector difference, where the first motion vector difference belongs to motion information of the current picture block in a first direction, and the second motion vector difference belongs to motion information of the current picture block in a second direction; and determining prediction samples of the current picture block based on the obtained first motion vector difference and the determined second motion vector difference.

Abstract: A method for inverse quantization of a current block of a picture is performed by a decoder, and the picture comprises a luminance component and a chrominance component, wherein the luminance component and the chrominance component are partitioned into multiple blocks. The method includes: obtaining one or more existing quantization parameter (QP) values from a received bitstream, wherein the one or more existing QP values relate to a current block in the chrominance component; determining a QP value for the current block in the chrominance component based on the one or more existing QP values; and performing inverse quantization on the current block in the chrominance component by using the determined QP value.