Abstract: Methods and apparatus of for video coding using sub-block based affine mode are disclosed. In one method, if affine fallback is used or the control-point motion vectors are the same, the sub-block based affine mode is disabled in order to reduce computational complexity. According to another method for video coding using a coding tool belonging to a coding tool group comprising Prediction Refinement with Optical Flow (PROF) and Bi-Directional Optical Flow (BDOF), predictor refinement is derived for pixels of a target subblock of the current block, where a step to derive the predictor refinement comprises to derive gradients for the pixels of the target subblock of the current block and to right-shift the first gradients by a common shift.

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 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: 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 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: Methods and apparatus for video coding system utilizing Rate-Distortion Optimized Quantization (RDOQ) are provided. According to one method, a rate for a level belonging to a level set of a current quantized transform coefficient is estimated for a current coefficient group (CG) based on neighboring quantized coefficients of the current quantized transform coefficient and the current CG. A best level for the current quantized transform coefficient is selected from the level set for a best RD-cost. In another method, a TB is partitioned into M regions and M best regions are derived for the M regions according to RDOQ. At least two alternative region RD-costs are generated for each of the M best regions based on a relative position between each of the M best regions and a last significant region in the TB. TB RD-cost for the TB is selected according a last non-zero best region position.

Abstract: Various schemes for realizing JCCR mode decision in frequency domain are described. An apparatus receives first and second pixel data of a current block of a picture and transform the pixel data into first and second transformed data in frequency domain. The apparatus generates joint pixel data comprising a pixelwise linear combination of the first and second transformed data. The apparatus generates reconstructed joint pixel data based on the joint pixel data by quantization and inverse quantization operations. The apparatus derives first and second reconstructed pixel data based on the reconstructed joint pixel data. The apparatus accordingly calculates first and second distortion values in frequency domain, based on which a preferred mode may be determined to code the current block.

Abstract: Video processing methods comprise receiving input data of a current block in a current picture, constructing a candidate list for the current block by including one or more History-based Motion Vector Predictor (HMVP) candidates, selecting one candidate from the candidate list, locating a reference block according to motion information of the selected candidate, and encoding or decoding the current block by predicting the current block using the reference block. The one or more HMVP candidates are fetched from a normal HMVP table if the current block is to be processed by a normal inter prediction mode, and the one or more HMVP candidates are fetched form a Current Picture Referencing (CPR) HMVP table if the current block is to be processed by a CPR mode. The two HMVP tables are separately maintained and updated.

Abstract: A method for specifying layout of subpictures is provided. A video decoder receives data from a bitstream to be decoded as a current picture of a video. The video decoder parses the bitstream for positions and sizes of multiple subpictures of the current picture. A position of a first subpicture and a size of a last subpicture are skipped during the parsing. The video decoder reconstructs the current picture and the subpictures of the current picture according to the positions and the sizes of the subpictures.

Abstract: Aspects of the disclosure provide a method and an apparatus for video coding. A processing circuitry determines a process unit size for a decoder-side motion vector refinement (DMVR). Then, the processing circuitry enables an application of the DMVR on a current block when a size of the current block is smaller than or equal to the process unit size; and disables the application of the DMVR on the current block when the size of the current block is larger than the process unit size. In an example, the application of the DMVR refines the motion vectors with or without a template block.

Abstract: Methods and apparatus for video coding using non-adjacent affine candidates are provided. According to this method, one or more neighboring MVs (motion vectors) are determined from one or more non-adjacent affine-coded neighbors of the current block. CPMVs (Control-Point Motion Vectors) are determined based on said one or more neighboring MVs, wherein if a target neighboring block associated with one target neighboring MV (Motion Vector) is outside an available region, a derived CPMV) is generated to replace the target neighboring MV. An affine merge list or an affine AMVP (Advanced Motion Vector Prediction) list having said one or more neighboring MVs as one non-adjacent affine candidate is generated, wherein said one non-adjacent affine candidate generates a non-adjacent affine predictor using motion information according to the CPMVs. The current block is encoded or decoded using a motion candidate selected from the affine merge list or the affine AMVP list.

Abstract: Video encoding methods and apparatuses for frequency domain mode decision include receiving residual data of a current block, testing multiple coding modes on the residual data, calculating a distortion associated with each of the coding modes in a frequency domain, performing a mode decision to select a best coding mode from the tested coding modes according to the distortion calculated in the frequency domain, and encoding the current block based on the best coding mode.

Abstract: Methods and apparatus for loop-filter processing of reconstructed video are disclosed. According to this method, if a loop-filter is disallowed for a target boundary, the target loop filter is disabled at top, bottom, left and right of the target boundary. According to another method, CC-ALF (cross-component adaptive loop filter) shape is changed across a virtual boundary. According to yet another method, CC-ALF and luma ALF handle unavailable samples in a same way.

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 for video coding utilizing a current block, a maximum side of the transform block of the current block corresponds to 64. A scaling matrix is derived from elements of an 8×8 base scaling matrix, where the elements in a bottom-right 4×4 region of the 8×8 base scaling matrix are skipped, either not signaled or set to zero. According to another method, a current block belongs to a current picture in a first color format that has only a first color component. A first scaling matrix is signaled at the video encoder side or parsed at the video decoder side for the first color component of the current block. Signaling any second scaling matrix is disabled at the video encoder side or parsing any second scaling matrix is disabled at the video decoder side for a second or third color component of the current block.

Abstract: A video coding method using inter-layer prediction or referencing is provided. A video decoder receives data from a bitstream carrying data for video pictures in a plurality of different layers. At least one of the plurality of layers comprises temporal sublayers that correspond to levels in a hierarchical temporal prediction structure. Each temporal sublayer is associated with a temporal identifier. The video decoder receives an inter-layer prediction constraint parameter constraining a maximum temporal sublayer used in inter-layer prediction. The video decoder reconstructs a first picture in a first layer by referencing data of a second picture in a second layer. A temporal identifier of the referenced data satisfies the received inter-layer prediction constraint parameter.

Abstract: A method and apparatus of Inter prediction for video coding using UMVE (Ultimate Motion Vector Expression) are disclosed. According to this method, a base candidate is selected from an original Inter candidate list, where the base candidate has a base prediction direction. One or more extended candidates are derived by adding one or more offsets to the base candidate, where said one or more extended candidates have a same prediction direction as the base prediction direction. The extended candidates are then inserted into the original Inter candidate list to form an extended Inter candidate list for encoding or decoding. According to another method, the UMVE mode is treated as an additional AMVP (Advanced Motion Vector Prediction) mode.

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: Methods and apparatus for video coding are disclosed. According to this method, a bitstream corresponding to encoded data of the video sequence is generated at an encoder side or received at a decoder side, where the bitstream comprises a first syntax related to AMVR precision, and wherein the syntax related to the AMVR precision is coded by context coding bins with at least two contexts. One or motion vectors for the target block are encoded, at the encoder side, or decoded, at the decoder side, utilizing information comprising the AMVR precision.

Abstract: In one method, the current block is partitioned into multiple final sub-blocks using one or more stages of sub-tree partition comprising ternary tree partition and at least one other-type partition, where ternary partition tree is excluded from the sub-tree partition if a current sub-tree depth associated with a current sub-block is greater than a first threshold and the first threshold is an integer greater than or equal to 1. In another method, if a test condition is satisfied, the current block is encoded or decoded using a current Inter mode selected from a modified group of Inter tools, where the modified group of Inter tools is derived from an initial group of Inter tools by removing one or more first Inter tools from the initial group of Inter tools, replacing one or more second Inter tools with one or more complexity-reduced Inter tools, or both.