Abstract: Encoding methods and apparatuses include applying a Cross-Component Adaptive Loop Filter (CCALF) processing on a current picture based on CCALF coefficients signaled in one or more Adaptive Loop Filter (ALF) Adaptation Parameter Sets (APSs) to refine one or more chroma components according to a luma component, signaling two ALF signal flags and two CCALF signal flags in each ALF APS or parsing two ALF signal flags and two CCALF signal flags from each ALF APS, and encoding or decoding the current picture. Values of the two ALF signal flags and the two CCALF signal flags in each ALF APS are not all equal to 0 to ensure none of the ALF APS is an empty APS.

Abstract: Method and apparatus of Inter prediction for video coding are disclosed. When a sub-block motion compensation coding tool is selected for the current block, the method generates sub-block MVs (motion vectors) associated with multiple sub-blocks, which are included or contained in the current block, according to the sub-block motion compensation coding tool, constrains the sub-block MVs within a range to form constrained sub-block MVs, and applies motion compensation to the current block using the constrained sub-block MVs or applies motion compensation to the current block using one sub-block MV within the range around the primary MV in a second list if a corresponding sub-block MV in a first list is outside the range. In another method, motion compensation is applied to the current block only using reference pixels of reference sub-blocks within a primary reference block.

Abstract: A method for specifying layout of subpictures in video pictures is provided. A video decoder receives data from a bitstream to be decoded as a current picture of a video. For a current subpicture of a set of subpictures of the current picture, the video decoder determines a position of the current subpicture based on a width and a height of the current picture and a previously determined width and height of a particular subpicture in the set of subpictures. The video decoder reconstructs the current picture and the current subpicture based on the determined position.

Abstract: A method and apparatus of video encoding video coding for a video encoder or decoder using Neural Network (NN) are disclosed. According to this method, the multiple frames in a video sequence comprises multiple segments, where each of the multiple segments comprises a set of frames. The NN (Neural Network) processing is applied to a target signal in one or more encoded frames of a target segment in the encoder side or to the target signal in one or more decoded frames of the target segment in the decoder side using one NN parameter set for the target segment. The target signal may correspond to reconstructed residual, reconstructed output, de-blocked output, SAO (sample adaptive offset) output, ALF (adaptive loop filter) output, or a combination thereof. In another embodiment, the NN processing is applied to a target signal only in one or more specific encoded or decoded frames.

Abstract: Video processing methods and apparatuses for processing a current block in a current picture include receiving input data of the current block, determining a reference picture, determining whether picture sizes of the current and reference pictures are different, determining whether horizontal wraparound motion compensation is enabled for predicting the current block, performing motion compensation for the current block to obtain a reference block from the reference picture, and encoding or decoding the current block according to the reference block. Horizontal wraparound motion compensation is disabled when the picture sizes of the current and reference pictures are different.

Abstract: A video decoder determines whether the current block is coded by using intra block copy mode. The video decoder identifies a list of one or more prediction candidates for the current block. When the current block is not coded by using intra block copy mode, one or more spatial neighbors of the current block that are positioned in a same MER as the current block are excluded from the list of prediction candidates. When the current block is coded by using intra block copy mode and the list of prediction candidates belongs to a predefined subset of multiple different candidate lists, at least one of the identified prediction candidates is a spatial neighbor of the current block that is positioned in the MER. The video decoder reconstructs the current block by using a prediction candidate selected from the list of prediction candidates to generate a prediction of the current block.

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. 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: A method for multiple transform selection (MTS) is provided. A video decoder 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 decoder sets a zero-out indication based on one or more non-zero coefficient indications of subblocks of the current block. When the zero-out indication indicates that a zero-out region has no non-zero coefficient, the decoder parses the bitstream for an MTS index. When the zero-out indication indicates that the zero-out region has at least one non-zero coefficient, the decoder sets the MTS index to a default value without parsing the MTS index from the bitstream. The decoder selects a transform mode according to the MTS index for the current block. The decoder reconstructs the current block by using the selected transform mode.

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: A method and apparatus of entropy coding of coding symbols using Context-Based Adaptive Binary Arithmetic Coder (CABAC) are disclosed. According to the present invention, a math formula is used for calculating the LPS range for deriving rangeOne value and rangeZero value. For example, the LPS range is derived using one or more mathematical operations comprising calculating a multiplication of a first value and a second value, in which the first value is related to (2*the LPS probability index+1) or the LPS probability index, while the second value is related to (2*the range index+1) or the range index. Besides, the LPS range can be derived by using a look-up-table including table contents corresponding to values of LPS range associated with a set of LPS probability indexes and a set of range indexes for encoding or decoding a binary value of the current bin.

Abstract: Methods and apparatus for video coding are disclosed. According to one method, a bitstream is generated or received, where the bitstream includes a first syntax and a second syntax. The first syntax is related to a target number of bits used to represent a set of third syntaxes and each third syntax specifies one subpicture ID for one subpicture in a set of subpictures. The second syntax is related to a total number of subpictures in the set of subpicture, where a first number that can be represented by the target number of bits is equal to or greater than the total number of subpictures. According to another method, the subpicture ID syntaxes have different values for different subpictures.

Abstract: A method for adaptive MV precision is disclosed. According to one embodiment, whether to use or not to use the adaptive MV precision for a current block is determined according to a prediction mode/partition type of the current block. If the adaptive MV precision is used, a current MV precision is determined for a current MV of the current block, and the current MV is encoded or decoded at the current MV precision. If the adaptive MV precision is not used, the current MV is encoded or decoded at a finer MV precision. In another embodiment, a value of a current adaptive MV precision flag is selected for a current block to indicate whether to use or not to use the adaptive MV precision for a current block according to a prediction mode/partition type of the current block.

Abstract: Method and apparatus of using Bi-directional optical flow (BIO) for a true bi-direction predicted block are disclosed. According to one method of the present invention, a division-free BIO process is disclosed, where the x-motion offset and y-motion offset are derived using operations including right-shifting without any division operation. According to another method, a refined predictor is generated for the current block by applying BIO process to the reference blocks, where said applying the BIO process comprises applying a boundary-condition-dependent BIO process conditionally to boundary pixels associated with the reference blocks.

Abstract: Method and apparatus for a coding system with selectively refining an initial MV based on candidate characteristics of the initial MV are disclosed. The candidate characteristics of the initial MV may correspond to candidate position within the candidate list, association within interleaved candidate groups formed by candidates in the candidate list or restricted candidates belonging to a candidate group formed by excluding one or more spatial candidates, or one or more selected-type candidates from an original candidate group. According to another method, the search for candidate refinement is restricted to 8-connected locations around the target initial MV. In yet another method, the candidate refinement uses a reduced template of the current block and a reduced corresponding template of the reference block. In yet another method, the search for candidate refinement uses an adaptive search window.

Abstract: A method and apparatus for video coding incorporating enhanced multiple transform (EMT) are disclosed. According to one method, the number of candidates for EMT in the horizontal direction or vertical direction is reduced depending on the current block size. According to another method, an EMT flag, one or more EMT indices or both are signalled only if the total number of non-zero coefficients in at least a part of the 2D coefficient block is greater than a threshold, where the threshold is equal to 1 or larger. A method and apparatus for video coding using non-separable secondary transform (NSST) are disclosed. According to this method, a total number of non-zero first coefficients in a partial block of the 2D coefficient block is determined and used to determine whether to apply the NSST process.

Abstract: A method and apparatus provide adaptive interpolation filter for motion compensation with fractional-pixel accuracy. Embodiments of the present invention generate interpolated reference samples at non-integer locations based on existing reference samples in a reference block by using an interpolation filter set adaptively according to pixel location and/or pixel characteristics. A current block is then encoded or decoded using a temporal predictor including the interpolated reference samples. The adaptive interpolation filter can be applied to the prediction unit (PU). In one embodiment, the interpolation filter set consists of interpolation filters having different filter lengths. An interpolation filter with a longer tap length is applied to generate interpolated reference samples farther from the block boundary and an interpolation filter with a shorter tap length is applied to generate interpolated reference samples closer to the block boundary.

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 video coding using adaptive Inter prediction are disclosed. A selected Inter prediction process is determined, wherein the selected Inter prediction process selects an Inter prediction filter from multiple Inter prediction filters for the current block depending on first pixel data comprising neighbouring reconstructed pixels (NRP) of the current block. The selected Inter prediction process may be further determined depending on extra motion compensated pixels (EMCP) around a motion-compensated reference block corresponding to the current block. Distortion between the NRP and EMCP can be used to determine the selected Inter prediction filter. The distortion can be calculated using a sum of absolute differences or squared differences between the NRP and the EMCP.

Abstract: Method and apparatus of using Pattern-based MV derivation (PMVD), Bi-directional optical flow (BIO) or Decoder-side MV refinement (DMVR) to refine motion for a bi-direction predicted block are disclosed. According to one method of the present invention, a first and a second motion-compensated reference blocks associated with the current block in a first and a second reference pictures from reference picture list 0 and list 1 are determined respectively. The PMVD process, BIO process or DMVR process is applied to generate motion refinement for the current block using reference data corresponding to the first motion-compensated reference block and the second motion-compensated reference block without other reference data outside the first motion-compensated reference block and the second motion-compensated reference block so as to reduce required system memory bandwidth. Also an adaptive block size method for block-based BIO is disclosed.

Abstract: A method for signaling scaling matrices for transform coefficient quantization is provided. A decoder receives data from a bitstream to be decoded as a current picture of a video, the current picture to be decoded by using a plurality of scaling matrices. The decoder receives a reference index offset for a first scaling matrix of the plurality of scaling matrices. The decoder applies the reference index offset to a first index identifying the first scaling matrix to derive a second index identifying a second scaling matrix of the plurality of scaling matrices. The second scaling matrix is previously reconstructed. The decoder reconstructs the first scaling matrix by referencing the second scaling matrix. The decoder dequantizes transform coefficients of transform blocks of the current picture by using the plurality of scaling matrices and reconstructs the current picture by using the dequantized transform coefficients.