Abstract: Methods and apparatus of video coding using sub-block based affine mode are disclosed. According to this method, control-point motion vectors (MVs) associated with the affine mode are determined for a block. A sub-block MV is derived for a target sub-block of the block from the control-point MVs for the block. A prediction offset is determined for a target pixel of the target sub-block using information comprising a pixel MV offset from the sub-block MV for the target pixel according to Prediction Refinement with Optical Flow (PROF). The target pixel of the target sub-block is encoded or decoded using a modified predictor. The modified prediction is generated by clipping the prediction offset to a target range and combining the clipped prediction offset with an original predictor.

Abstract: Video processing methods and apparatuses implemented in a video encoding or decoding system with conditional secondary transform signaling. The video encoding system determines and applies a transform operation to residuals of a transform block to generate final transform coefficients, and adaptively signals a secondary transform index according to a position of a last significant coefficient in the transform block. A value of the secondary transform index is determined according to the transform operation.

Abstract: Video processing methods and apparatuses for coding a current block comprise receiving input data of a current block, partitioning the current block into multiple sub-blocks, deriving sub-block MVs for the current block according to a sub-block motion compensation coding tool, constraining the sub-block MVs to form constrained sub-block MVs, and encoding or decoding the current block using the constrained sub-block MVs, and applying motion compensation to the current block using the constrained sub-block MVs to encode or decode the current block. The sub-block MVs may be constrained according to a size, width, or height of the current block or a sub-block, an inter prediction direction of one of control point MVs of the current block, the current block, or current sub-block, the control point MVs, or a combination of the above.

Abstract: Method and apparatus of video coding are disclosed. According to one method, in the decoder side, a predefined Intra mode is assigned to a neighboring block adjacent to the current luma block when the neighboring block satisfies one or more conditions. An MPM (Most Probable Mode) list is derived based on information comprising at least one of neighboring Intra modes. A current Intra mode is derived utilizing the MPM list. The current luma block is decoded according to the current Intra mode According to another method, a predefined Intra mode is assigned to a neighboring block adjacent to the current luma block if the neighboring block is coded in BDPCM (Block-based Delta Pulse Code Modulation) mode, where the predefined Intra mode is set to horizontal mode or vertical mode depending on prediction direction used by the BDPCM mode.

Abstract: A method and apparatus of video coding, where according to one method, input data related to a current block in a current picture are received at a video encoder side or compressed data comprising the current block are received at a video decoder side. A first syntax at a high level in a video bitstream regarding residual coding type is signaled at the encoder side or parsed at the decoder side. A target coding mode is determined for the current block based on information comprising a value of the first syntax. The current block is encoded at the encoder side or decoded at the decoder side according to the target coding mode. The high level may correspond to a slice header or a picture header.

Abstract: Video processing methods and apparatuses implemented in a video encoding or decoding system with conditional secondary transform signaling. The video encoding system determines and applies a transform operation to residuals of one or more transform blocks to generate final transform coefficients, and skip signaling a secondary transform index if a position of a last significant coefficient in each considered transform block is less than or equal to a predefined position; otherwise, the video encoding system signals a secondary transform index according to the transform operation.

Abstract: A method and apparatus for block partition are disclosed. If a cross-colour component prediction mode is allowed, the luma block and the chroma block are partitioned into one or more luma leaf blocks and chroma leaf blocks. If a cross-colour component prediction mode is allowed, whether to enable an LM (Linear Model) mode for a target chroma leaf block is determined based on a first split type applied to an ancestor chroma node of the target chroma leaf block and a second split type applied to a corresponding ancestor luma node. According to another method, after the luma block and the chroma block are partitioned using different partition tress, determine whether one or more exception conditions to allow an LM for a target chroma leaf block are satisfied when the chroma partition tree uses a different split type, a different partition direction, or both from the luma partition tree.

Abstract: Methods and apparatus for video coding are disclosed. According to one method, First ALF (Adaptive Loop Filter) processing is applied to the reconstructed chroma samples for a target reconstructed chroma sample to generate a first filtered chroma sample. Second ALF processing is applied to the related reconstructed luma samples to generate a second filtered chroma sample for the target reconstructed chroma sample, where positions of the related reconstructed luma samples selected for the second ALF processing are determined according to the target chroma format. According to another method, the luma ALF and the cross-component ALF have the same filter coefficient precision.

Abstract: A video codec receives data for a block of pixels to be encoded or decoded as a current block of a current picture of a video. The video codec signals or parses a first syntax element for a first coding mode in a particular set of two or more coding modes. Each of coding mode of the particular set of coding modes modifies a merge candidate or an inter-prediction that is generated based on the merge candidate. The video codec enables the first coding mode and disables one or more other coding modes in the particular set of coding modes. The disabled one or more coding modes in the particular set of coding modes are disabled without parsing syntax elements for the disabled coding modes. The video codec encodes or decodes the current block by using the enabled first coding mode and bypassing the disabled coding modes.

Abstract: Method and apparatus for constrained de-blocking filter are disclosed. One method receives input data related to a current block in a current picture at a video encoder side or a video bitstream corresponding to compressed data including the current block in the current picture at a video decoder side, and determines a first boundary associated with the current block, wherein the first boundary corresponds to one vertical boundary or one horizontal boundary of the current block. The method then applies de-blocking process to a reconstructed current block corresponding to the current block to result in a filtered-reconstructed current block, using a plurality of first reference samples at a same side of the first boundary, and replaces a first set of the first reference samples by one or more padding values. The method then generates a filtered decoded picture including the filtered-reconstructed current block.

Abstract: A video system that applies constraints on block partitioning is provided. The system receives a partitioning control parameter from a bitstream specifying a maximum block size for enabling ternary-tree split that is constrained to be 64 or smaller. The system receives data from a bitstream for a block of pixels to be decoded as a current block of a current picture of a video. The system splits the current block into one or more partitions recursively, wherein ternary split is disallowed for a partition of the current block unless the partition is less than or equal to the maximum block size. The system reconstructs the one or more partitions of the current block.

Abstract: A method and apparatus of Inter prediction for video coding using Multi-hypothesis (MH) are disclosed. If an MH mode is used for the current block: at least one MH candidate is derived using reduced reference data by adjusting at least one coding-control setting; an Inter candidate list is generated, where the Inter candidate list comprises said at least one MH candidate; and current motion information associated with the current block is encoded using the Inter candidate list at the video encoder side or the current motion information associated with the current block is decoded at the video decoder side using the Merge candidate list. The coding control setting may correspond to prediction direction setting, filter tap setting, block size of reference block to be fetched, reference picture setting or motion limitation setting.

Abstract: Methods and apparatus for Adaptive Loop Filter (ALF) processing of reconstructed video are disclosed. According to one implementation, a method receives reconstructed pixels of a current block and determines one or more clipping values for the ALF processing, wherein a target clipping value is always signaled at an encoder side or parsed at a decoder side even if the target clipping value is zero. The method then derives a current ALF output for the current block, wherein the current ALF output has a weighted sum of clipped differences and each of the original differences is calculated between a first reconstructed pixel at a non-center filter location and a center reconstructed pixel at a center filter location, and each of the original differences is clipped according to a corresponding clipping value to form one clipped difference. The method then provides filtered-reconstructed pixels.

Abstract: Video processing methods and apparatuses for coding a current block and a adjacent block comprise receiving input data of the current and adjacent blocks in a current picture, determines the current and adjacent blocks are both coded in a BDPCM or RDPCM mode, performing a deblocking filtering operation on an edge between the current and adjacent blocks by de-activating deblocking filtering for a first color component and activating deblocking filtering for a second color component, and encoding or decoding the current and adjacent blocks. Each current pixel in a BDPCM coded block is predicted by one or more neighboring pixels of the current pixel. RDPCM is applied to process quantized residues of a RDPCM coded block according to a prediction direction of the RDPCM coded block.

Abstract: A method and apparatus of encoding or decoding for a coding system, where bi-directional CU (coding unit) weighting (BCW) is enabled for the coding system to allow using multiple pairs of weights, are disclosed. According to this method, a Merge candidate list is generated for the current block, where current bi-directional CU weights for a bi-directional predictor of the current block associated with a target Merge candidate in the Merge candidate list are set to a pre-define pair of weights when the target Merge candidate corresponds to a selected Merge candidate. In another method, current bi-directional CU weights for a bi-directional predictor associated with a target Merge candidate in the Merge candidate list are inherited from the target Merge candidate when the target Merge candidate corresponds to a selected Merge candidate.

Abstract: Video processing methods comprise receiving input data of a current block in a current picture having a plurality of Virtual Pipeline Data Units (VPDUs), wherein each VDPU is a fixed size, performing a decoding process to decode Coding Units (CUs) in the current VPDU and generate decoded samples of the current VPDU, wherein each CU coded in a Current Picture Referencing (CPR) mode is decoded by fetching decoded samples in a reference block stored in a CPR referring buffer, and updating the CPR referring buffer by storing the decoded samples of the current VPDU when finishing the decoding process of the current VPDU, wherein the CPR referring buffer is updated one VPDU by one VPDU.

Abstract: Exemplary video processing methods and apparatuses for encoding or decoding a current block by bi-directional prediction are disclosed. L0 and L1 reference blocks are determined for the current block, and a motion vector refinement is applied to refine the L0 and L1 reference blocks using a motion estimation search performed on each processing unit in the current block. A bi-directional optical flow operation is early terminated according to a cost of each processing unit in the current block. The processing units for cost calculation in the motion vector refinement and the bi-directional optical flow early termination are unified. The bi-directional optical flow operation is applied to the current block to further refine the L0 and L1 reference blocks if the bi-directional optical flow operation is not early terminated. A final inter predictor is derived from the refined L0 and L1 reference blocks for encoding or decoding the current block.

Abstract: Method and apparatus for signaling or parsing constrained active entries in reference picture lists for multi-layer coding are disclosed. For the decoder side, when the current picture is a RADL (Random Access Decodable Leading) picture, reference picture list 0 or reference picture list 1 of the current picture is mandatorily required to contain no active entry corresponding to a RASL (Random Access Skipped Leading) picture with pps_mixed_nalu_types_in_pic_flag equal to 0 or a picture that precedes an associated IRAP (Intra Random Access Point) picture in decoding order, and wherein an active entry in the reference picture list 0 or the reference picture list 1 of the RADL picture can refer to a RASL picture with the pps_mixed_nalu_types_in_pic_flag equal to 1 and a referenced RASL picture either belongs to the same layer or a different layer than a layer containing the current picture which is the RADL picture.

Abstract: According to one implementation, a method receives input data related to a current block in a current picture at a video encoder side or receiving a video bitstream comprising coded data of the current block at a video decoder side. When hen the MIP mode is applied to the current block, the method checks availability for a target reference boundary region comprising left reference boundary samples and top reference boundary samples, wherein the left reference boundary samples and the top reference boundary samples are checked jointly for the current block. The method further performs a padding process if an unavailable sample exists in the target reference boundary region, wherein the unavailable sample is padded with a default value or a sample value of an available sample and derives a reduced predictor, and encodes or decodes the current block using a MIP predictor derived from the reduced predictor.

Abstract: According to a method for Adaptive Loop Filter (ALF) processing of reconstructed video, multiple indicators are signaled in slice at an encoder side or parsed at a decoder side, where the multiple indicators are Adaptive Parameter Set (APS) indices associated with temporal ALF filter sets for the ALF processing. A current indicator is determined from the multiple indicators, where the current indicator is used to select a current ALF filter set. Filtered-reconstructed pixels are derived for the current block by applying the current ALF filter to the current block. In another method, if the ALF processing applied at a target sample requires an outside sample on other side of a target virtual boundary from the target sample, the outside sample is replaced by a padded sample.