Tencent America LLC

Lien-Fei Chen

Shan Liu

Guichun Li

Xiang Li

Xin Zhao

Xiang Yang Li

Ling Li

Xiaozhong Xu

Han Gao

Roman Chernyak

Biao Wang

A video bitstream is received. The video bitstream includes a current block comprising a plurality of subblocks and a template region of the current block comprising a plurality of template subblocks adjacent to at least one of a top side and a left side of the current block. A motion vector (MV) located in a center position of the current block is determined. The MV is determined based on at least one MV of the plurality of subblocks of the current block. A MV for each of the plurality of template subblocks is determined based on the MV located in the center position of the current block and a respective MV of a corresponding subblock of the plurality of subblocks that is adjacent to the respective template subblock. The current block is reconstructed based on the determined MVs for the plurality of template subblocks.

Motion vector derivation of subblock-based template-matching for subblock based motion vector predictor

Aspects of the disclosure provide methods and apparatuses for video encoding/decoding. In some examples, an apparatus for video decoding includes receiving circuitry and processing circuitry. The processing circuitry extracts, from a bitstream, a signal indicative of an application of a template matching based block vector refinement for coding a current block in a current picture referencing (CPR) mode. The processing circuitry derives a first refined block vector associated with the current block according to the template matching based block vector refinement. The first refined block vector includes a first block vector refinement offset applied on a first block vector associated with the current block. The processing circuitry reconstructs the current block according to a first reference block in a same picture as the current block, the first reference block being indicated by the first refined block vector.

Block vector refinement method for intra block copy

Aspects of the disclosure include methods and an apparatus for video coding. The apparatus includes processing circuitry that receives coded information of a current block in a current picture. The current block is coded with a first intra prediction mode that is different from a plurality of intra prediction modes including a DC mode, a Planar mode, and angular intra prediction modes. A candidate block in the current picture coded by an intra prediction mode different from the plurality of intra prediction modes is selected. If the candidate block is located within a pre-defined region, a second intra prediction mode is derived from the plurality of intra prediction modes for the candidate block. The second intra prediction mode is associated with the current block and is used to select a transform for the current block and/or to construct a most probable mode (MPM) list for another block.

Intra prediction mode derivation for coding blocks

Processing circuitry receives a coded video bitstream comprising coded information of a current block in a current picture, the coded information is indicative of an AMVP-merge mode, the AMVP-merge mode uses a bi-directional predictor including an AMVP predictor in a first direction and a merge predictor in a second direction. The processing circuitry constructs an AMVP candidate list that includes a plurality of AMVP candidates for the AMVP predictor and constructs a merge candidate list that includes a plurality of merge candidates for the merge predictor. The merge candidate list includes an SbTMVP candidate. The processing circuitry determines the AMVP predictor from the AMVP candidate list, determines the merge predictor from the merge candidate list, and reconstructs the current block according to a combination of a first prediction according to the AMVP predictor in the first direction and a second prediction according to the merge predictor in the second direction.

AMVP-merge mode with SBTMVP

Processing circuitry for video decoding receives coded information of a current block in a current picture from a coded video bitstream, the coded information is indicative of applying local illumination compensation (LIC) on the current block in the current picture. The processing circuitry derives, parameters of an LIC model, according to a first template of a current block and a second template of a reference block in a reference picture. The reference block is pointed based on a motion vector for the current block. The first template includes a subset of reconstructed neighboring samples that are above and left to the current block, and the second template includes collocated samples to the subset of the reconstructed neighboring samples. The processing circuitry applies the LIC model on the current block according to the reference block to generate compensated samples of the current block.

Local illumination compensation

Processing circuitry receives coded information of a current block indicative of applying LIC on the current block according to at least a first reference block in a first reference picture. The processing circuitry determines, for a sample in the current block, at least a first reference sample in the first reference block, the first reference sample is co-located to the sample in the current block. The processing circuitry calculates a weighted sum of a plurality of terms and an offset for the LIC according to a plurality of parameter values for a plurality of parameters used in the LIC, and reconstructs the sample accordingly. The plurality of parameter values includes at least a first weighting value for a first weighting that is applied to a non-linear term of the first reference sample of a kth power, k is a power index value and is not equal to 1.

Local illumination compensation for bi-prediction

A method and an apparatus are provided. The apparatus includes processing circuitry that receives a coded video bitstream comprising a current picture that includes a current block. The processing circuitry determines, based on a syntax element in the coded video bitstream, that the current block including a plurality of subblocks is coded in a subblock-based temporal motion vector prediction (SbTMVP) mode. The processing circuitry determines a plurality of displacement vector (DV) predictor (DVP) candidates and receives a base index indicating a DVP in the plurality of DVP candidates and a DV offset of the current block. The processing circuitry determines a DV based on the DVP and the DV offset. The DV indicates a block collocated with the current block in a collocated reference picture. The processing circuitry reconstructs a subblock in the plurality of subblocks based on motion information of a corresponding subblock in the collocated block.

Subblock level temporal motion vector prediction with multiple displacement vector predictors and an offset

Aspects of the disclosure provide a method and an apparatus including processing circuitry that adds merge candidates into a merge candidate list of a current block in a current picture. The merge candidates include available merge candidates including one or more of spatial motion vector predictors (MVP(s)), temporal MVP(s), non-adjacent MVP(s), history-based MVP(s), and pairwise average MVP(s). Whether the merge candidate list includes all available SMVP, TMVP, NA-MVP, HMVP, and PAMVP, and no merge candidate in the merge candidate list has a zero motion vector (zero MV) are determined. If the merge candidate list includes all available SMVP, TMVP, NA-MVP, HMVP, and PAMVP, and no merge candidate in the merge candidate list has the zero MV, the merge candidate having the zero MV is added to the merge candidate list. Merge candidates in the merge candidate list including the merge candidate having the zero MV are reordered using template matching.

Zero motion vector in adaptive reordering of merge candidates (ARMC)

A current block is partitioned into a first partition and a second partition. Template samples of the current block are split into a first template region adjacent to the first partition and a second template region adjacent to the second partition. A plurality of first candidate reference blocks is determined for the first partition. A plurality of second candidate reference blocks is determined for the second partition. At least one of the plurality of first candidate reference blocks and the plurality of second candidate reference blocks is reordered based on a size of the first template region of the template samples and a size of the second template region of the template samples. The current block is reconstructed based on a received index value and based on the reordered at least one of the plurality of first candidate reference blocks and the plurality of second candidate reference blocks.

Template-matching based merge index reordering for geometric partition mode (GPM)

In a method, a first area and a second area of a current frame is determined when the current frame is a GDR frame. The first area is independently coded and the second area is coded with dependency. When a current block in the current frame is coded by an intraTMP mode or an IBC mode, a search range of the intraTMP mode or the IBC mode is determined such that the search range is only in the first area of the current frame. A reference block is determined from a plurality of candidate reference blocks in the search range. The current block is encoded in a bitstream based on the determined reference block.

Intra template matching prediction in GDR pictures

In some examples, an apparatus for video decoding includes receiving circuitry and processing circuitry. The processing circuitry receives coded information of a current block in a current picture from a coded video bitstream. The coded information includes a syntax element with a value indicative of a merge with motion vector difference (MMVD) mode being applied on the current block. The processing circuitry determines, in response to a motion vector predictor of a merge candidate being a bi-predictor, whether the merge candidate for the current block satisfies a requirement for applying a bi-prediction motion refinement. The processing circuitry can constrain the merge candidate for use in the MMVD mode when the merge candidate for the current block satisfies the requirement. Then, the processing circuitry reconstructs the current block in the MMVD mode with the merge candidate being constrained for use in the MMVD mode.

Merge with motion vector difference

A reference block is determined from a plurality of candidate reference blocks for a current block in a current picture based on template matching (TM) costs of the plurality of candidate reference blocks. The TM costs indicate differences between a template of the current block and respective reference templates of the plurality of candidate reference blocks. Samples of the determined reference block are classified into a plurality of classes of samples. A partitioning pattern of the current block is derived based on the determined reference block from a predetermined plurality of partitioning patterns. The derived partitioning pattern indicates a plurality of partitions of the current block. Each of the plurality of classes of the samples of the determined reference block corresponds to a respective partition of the plurality of partitions of the current block. The current block is reconstructed based on the derived partitioning pattern of the current block.

Template matching based partitioning pattern derivation

Aspects of the disclosure provide a method and an apparatus including processing circuitry that obtaining prediction information indicating whether a current block is coded in a subblock-based temporal motion vector prediction (SbTMVP) mode. If the current block is coded in the SbTMVP mode, whether a subblock in a plurality of subblocks of the current block is bi-predicted is determined. If the subblock is bi-predicted, motion information of the subblock is determined based on the SbTMVP mode. At least one of (i) a bilateral matching (BM)-based motion vector (MV) refinement and (ii) a bi-directional optical flow (BDOF) mode is applied to the subblock to refine the motion information of the subblock. The current block is reconstructed based on refined motion information corresponding to one or more subblocks in the plurality of subblocks. The refined motion information corresponding to the one or more subblocks includes the refined motion information of the subblock.

Decoder-side motion vector refinement and bi-directional optical flow in subblock-based temporal motion vector prediction (SBTMVP)

Processing circuitry determines an initial affine model with bi-prediction for a current block in an affine motion inter prediction mode, the initial affine model predicts the current block based on a first reference picture and a second reference picture. The processing circuitry performs a multi-stage bilateral matching motion refinement with at least a first stage and a second stage on the initial affine model to derive a refined affine model, one of the first stage and the second stage applies a first bilateral matching motion refinement on a translational component of the initial affine model, and the other of the first stage and the second stage applies a second bilateral matching motion refinement on a non-translational component of the initial affine model. The processing circuitry reconstructs the current block using the refined affine model based on the first reference picture and the second reference picture.

Method and apparatus for affine motion refinement

Aspects of the disclosure provide a method and an apparatus including processing circuitry that performs template matching (TM) on motion vector resolution (MVR) pairs of a current block by determining a TM cost corresponding to each one of the MVR pairs. The current block is predicted with an affine adaptive motion vector prediction (ΔMVP) mode. Each MVR pair includes a first MVR in a first plurality of MVRs corresponding to a first reference picture and a second MVR in a second plurality of MVRs corresponding to a second reference picture. Each TM cost is determined based on a current template of the current block and a bi-predictor of the respective MVR pair. The bi-predictor is based on a first reference template in the first reference picture and a second reference template in the second reference picture. An MVR pair is selected based on the determined corresponding TM costs.

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Taipei, Taiwan

Lien-Fei Chen