Abstract: A method and apparatus for inter prediction in video coding system are disclosed. According to the method, one or more model parameters of one or more cross-color models for the second-color block are determined. Then, cross-color predictors for the second-color block are determined, wherein one cross-color predictor value for the second-color block is generated for each second-color pixel of the second-color block by applying said one or more cross-color models to corresponding reconstructed or predicted first-color pixels. The input data associated with the second-color block is encoded using prediction data comprising the cross-color predictors for the second-color block at the encoder side, or the input data associated with the second-color block is decoded using the prediction data comprising the cross-color predictors for the second-color block at the decoder side.

Abstract: A method and apparatus for inter prediction in video coding system are disclosed. According to the method, input data associated with a current block comprising at least one colour block are received. A blending predictor is determined according to a weighted sum of at least two candidate predictions generated based on one or more first hypotheses of prediction, one or more second hypotheses of prediction, or both. The first hypotheses of prediction are generated based on one or more intra prediction modes comprising a DC mode, a planar mode or at least one angular modes. The second hypotheses of prediction are generated based on one or more cross-component modes and a collocated block of said at least one colour block. The input data associated with the colour block is encoded or decoded using the blending predictor.

Abstract: A method for video encoding and decoding using Low-Frequency Non-Separable Transform (LFNST) mode and apparatus thereof are disclosed. The input data correspond to primary transformed data at the encoder and the input data correspond to coded data of the current CU at the decoder. A CU is partitioned into one or more transform blocks (TBs). An LFNST syntax is determined at an encoder side or at a decoder side if one or more conditions are satisfied. The LFNST syntax indicates whether the LFNST mode is applied to the current CU and/or which LFNST kernel is applied when the LFNST mode is applied. The conditions comprise the CBF indications for the target TBs being false. The current CU is encoded or decoded according to the LFNST mode as indicated by the LFNST syntax.

Abstract: A video coding system that uses multiple models to predict chroma samples is provided. The video coding system receives data for a block of pixels to be encoded or decoded as a current block of a current picture of a video. The system constructs two or more chroma prediction models based on luma and chroma samples neighboring the current block. The system applies the two or more chroma prediction models to incoming or reconstructed luma samples of the current block to produce two or more model predictions. The system computes predicted chroma samples by combining the two or more model predictions. The system uses the predicted chroma samples to reconstruct chroma samples of the current block or to encode the current block.

Abstract: A video coding system that uses multiple models to predict chroma samples is provided. The video coding system 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 coding system derives multiple prediction linear models based on luma and chroma samples neighboring the current block. The video coding system constructs a composite linear model based on the multiple prediction linear models. The video coding system applies the composite linear model to incoming or reconstructed luma samples of the current block to generate a chroma predictor of the current block. The video coding system uses the chroma predictor to reconstruct chroma samples of the current block or to encode the current block.

Abstract: A method and apparatus for video coding system that uses intra prediction based on cross-colour linear model are disclosed. According to the method, model parameters for a first-colour predictor model are determined and the first-colour predictor model provides a predicted first-colour pixel value according to a combination of at least two corresponding reconstructed second-colour pixel values. According to another method, the first-colour predictor model provides a predicted first-colour pixel value based on a second degree model or higher of one or more corresponding reconstructed second-colour pixel values. First-colour predictors for the current first-colour block are determined according to the first-colour prediction model. The input data are then encoded at the encoder side or decoded at the decoder side using the first-colour predictors.

Abstract: A video coding system that uses chroma prediction is provided. The system receives data for a block of pixels to be encoded or decoded as a current block of a current picture of a video. The system constructs a chroma prediction model based on luma and chroma samples neighboring the current block. The system signals a set of chroma prediction related syntax element and a refinement to the chroma prediction model. The system performs chroma prediction by applying the chroma prediction model to reconstructed luma samples of the current block to obtain predicted chroma samples of the current block. The system uses the predicted chroma samples to reconstruct 10 chroma samples of the current block or to encode the current block.

Abstract: A video encoder or a video decoder may perform operations to determine an initial motion vector (MV) such as a control point motion vector (CPMV) candidate according to an affine mode or an additional prediction signal representing an additional hypothesis motion vector, for a current sub-block in a current frame of a video stream; determine a current template associated with the current sub-block in the current frame; retrieve a reference template within a search area in a reference frame; and compute a difference between the reference template and the current template based on an optimization measurement. Additional operations performed may include iterating the retrieving and the computing the difference for a different reference template within the search area until a refinement MV, such as a refined CPMV or refined additional hypothesis motion vector, is found to minimize the difference according to the optimization measurement.

Abstract: A method and apparatus of prediction for video coding are disclosed. According to one method, a luma Intra prediction mode is determined for a corresponding luma block collocated with the current chroma block, where a predefined mode is assigned to the luma Intra prediction mode when the corresponding luma block collocated with the current chroma block satisfies one or more conditions. A chroma Intra prediction mode is determined for the current chroma block according to the luma Intra prediction mode. The current chroma block is then encoded or decoded according to the chroma Intra prediction mode. According to another method, a predefined mode is assigned to Intra prediction mode for the current block when the current block satisfies one or more conditions. The current block is then encoded or decoded according to the Intra prediction mode.

Abstract: A video coding system that uses template matching (TM) to improve signaling of coding modes is provided. The system receives data to be encoded or decoded as a current block of a current picture of a video. The system identifies a set of pixels neighboring the current block as a current template. The system identifies a reference template of each candidate coding mode in a plurality of candidate coding modes. The system computes a template matching (TM) cost for each candidate coding mode based on matching the current template with the reference template of the candidate coding mode. The system selects a candidate coding mode from the plurality of candidate coding modes based on the computed TM costs. The system reconstructs the current block or encoding the current block into a bitstream by using selected candidate coding mode.

Abstract: A method and apparatus for video coding system that utilizes low-latency template-matching motion-vector refinement are disclosed. According to this method, a current template for a current block is determined, where the current template includes an inside current template including inside prediction samples or inside partially reconstructed samples inside the current block. The inside partially reconstructed samples are derived by adding a DC value of the current block to the inside prediction samples. Corresponding candidate reference templates associated with the current block are determined at a set of candidate locations. A location of a target reference template among the candidate reference templates that achieves a best match between the current template and the candidate reference templates is determined. An initial motion vector (MV) is then refined according to the location of the target reference template.

Abstract: A method and apparatus for video coding system that utilizes low-latency template-matching motion-vector refinement are disclosed. According to this method, a current template for the current block is determined, where at least one of current above template and current left template is removed or is located away from a respective above edge or a respective left edge of the current block and the current template is generated using reconstructed samples. Candidate reference templates, corresponding to the current template at respective candidate locations, associated with the current block at a set of candidate locations in a reference picture are determined. A location of a target reference template among the candidate reference templates is determined, where the target reference template achieves a best match with the current template. A refined motion vector (MV) is determined by refining an initial MV according to the location of the target reference template.

Abstract: A video coding system generating candidates for Merge Mode with Motion Vector Difference (MMVD) with reduced resource usage is provided. The system receives data to be encoded or decoded as a current block of a current picture of a video. The system identifies multiple MMVD candidates for different offset positions based on a merge candidate of the current block. The system generates reference samples for the identified MMVD candidates. The system reconstructs the current block or encodes the current block into a bitstream by using the generated reference samples. The system processes the MMVD candidates in separate groups: a first group of vertical MMVD candidates and a second group of horizontal MMVD candidates. The system generates the reference samples for the identified MMVD candidates by applying a vertical filter to source reference samples of horizontal MMVD candidates and then applying a horizontal filter to outputs of the vertical filter.

Abstract: In a method and apparatus for video coding using Low-Frequency Non-Separable Transform (LFNST) mode, a coding unit (CU) is partitioned into one or more transform blocks (TBs). A syntax is determined at an encoder side or at a decoder side, where the determining step is performed by signaling the syntax at the encoder side or by parsing the syntax at the decoder side if one or more conditions are satisfied. The syntax indicates whether the LFNST mode is applied to the current CU and/or which LFNST kernel is applied when the LFNSF is applied, and the conditions comprise a target condition corresponding to that all target TBs in a target TB set have a TS mode indication as false, and the target TB set is selected from the TBs in the current CU. The current CU is encoded or decoded according to the LFNST mode.

Abstract: A method and apparatus of prediction for video coding are disclosed. According to one method, a block is partitioned into a first and second regions using a target partition selected from a partition set comprising triangle partition. A Merge candidate list is determined for a partitioned current block by including at least one HMVP (history-based motion vector prediction) candidate from an HMVP buffer, where the HMVP buffer stores motion information of previously coded blocks. The partitioned current block or current motion information associated with the partitioned current block are encoded or decoded using the Merge candidate list, where the Merge candidate list is used to derive a first candidate for the first region and a second candidate for the second region. In another method, whether to apply triangular CIIP (combined Inter/Intra prediction) to the current block is signaled at an encoder side or parsed at a decoder side.

Abstract: Video processing methods and apparatuses for coding a current block generate a final predictor by combining multiple predictors of the current block. One of the predictors for the current block is a motion compensated predictor, which is generated according to one candidate selected from a first candidate list. The construction of the first candidate list includes deriving an average candidate by averaging motion information of existing candidates in the first candidate list. A second predictor for the current block is another motion compensated predictor or an intra predictor.

Abstract: Video processing methods and apparatuses in a video encoding or decoding system for transforming residuals of transform blocks into final transform coefficients or inverse transforming final transform coefficients into residuals. In order to solve the latency issue, exemplary embodiments check if a width or height of a coding block is larger than a predefined threshold, and disable secondary transform or inverse secondary transform for any transform block within the coding block if the width or height of the coding block is larger than the predefined threshold. Another embodiment checks if there are multiple transform blocks in a coding block, and disables secondary transform or inverse secondary transform if the coding block contains multiple transform blocks.

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: 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: 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.