Abstract: A down-sample video coding system is provided. A decoding system receives to be decoded data from a bitstream for one or more pictures of a video. Each picture includes pixels having different color components. The decoding system receives up-down-sampling parameters that are applicable to a current video unit in the received data. The up-down-sampling parameters include different subsets for different color components. The decoding system decodes the data to reconstruct the current video unit. The decoding system up-samples the reconstructed current video unit according to the up-down-sampling parameters. The different color components of the current video unit are up-sampled according to different subsets of the up-down-sampling parameters.

Abstract: For each prediction candidate of a set of one or more prediction candidates of the current block, a video coder computes a matching cost between a set of reference pixels of the prediction candidate in a reference picture and a set of neighboring pixels of a current block in a current picture. The video coder identifies a subset of the reference pictures as major reference pictures based on a distribution of the prediction candidates among the reference pictures of the current picture. A bounding block is defined for each major reference picture, the bounding block encompassing at least portions of multiple sets of reference pixels for multiple prediction candidates. The video coder assigns an index to each prediction candidate based on the computed matching cost of the set of prediction candidates. A selection of a prediction candidate is signaled by using the assigned index of the selected prediction candidate.

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: Video processing methods and apparatuses for processing a current block in a current picture by reference picture resampling include receiving input data of the current block, determining a scaling window of the current picture and a scaling window of a reference picture. The current picture and reference picture may have different scaling window sizes. A ratio between a scaling window width, height, or size of the current picture and a scaling window width, height, or size of the reference picture is constrained to be within a ratio constraint. A reference block is generated from the reference picture according to the ratio, and used to encode or decode the current block.

Abstract: A method for signaling adaptive loop filter (ALF) settings 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 video decoder parses whether to use adaptive parameter set (APS) for filtering the current block without determining whether to select a particular APS from a plurality of APSs. When the APS is used to filter the current block, the video decoder parses a first filter selection index for selecting a filter from a set of filters in the APS. When the APS is not used to filter the current block, the video decoder signals a second filter selection index for selecting a filter from a set of default fixed filters. The video decoder filters the current block based on the selected filter. The video decoder outputs the filtered current block.

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: 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 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: A method and apparatus of prediction for video coding using MH (Multiple Hypothesis) mode are disclosed. According to this method, a block is partitioned into a first partition and a second partition. A first candidate and a second candidate are derived for the first and second partitions respectively. At least one of the first candidate and the second candidate is derived using a candidate list derived for a regular Merge mode (or also called as normal Merge mode). An MH prediction generated by blending a first prediction corresponding to a first candidate and a second prediction corresponding to a second candidate, and the MH prediction is applied to a part of the current block.

Abstract: Method and apparatus of coding VR360 video sequence are disclosed, wherein wraparound motion compensation is included as a coding tool. According to the method, a bitstream corresponding to encoded data of the VR360 video sequence is generated at an encoder side or received at a decoder side, where the bitstream comprises one or more PPS syntaxes related to wraparound motion compensation information in a PPS (Picture Parameter Set). The VR360 video sequence is encoded at the encoder side or decoded at the decoder side based on the wraparound motion compensation information.

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: 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: 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.

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: 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 and apparatus for block partition in video encoding and decoding are disclosed. According to one method of the present invention, input data associated with a current block in a current picture are received, wherein the current block comprises a luma block and a chroma block to be encoded or decoded, and wherein a minimum block size is constrained to be no greater than a constrained minimum size for the luma block regardless of whether a dual partition tree or a single partition tree is used for the current block. The luma block is partitioned into one or more luma leaf blocks and the chroma block into one or more chroma leaf blocks using the dual partition tree or the single partition tree. Said one or more luma leaf blocks and said one or more chroma leaf blocks are encoded or decoded.

Abstract: Method and apparatus for coding system using affine motion model are disclosed. According to one method, a neighbouring block set of the current block comprising multiple spatial neighbouring blocks and one or more collocated blocks is determined for the current block. One or more constructed affine MVP candidates are derived for an affine MVP candidate list based on CP (control-point) MVs (motion vectors) at multiple spatial neighbouring blocks and said one or more collocated blocks. One constructed affine MVP candidate without one temporal MV is checked and inserted into the affine MVP candidate list before any constructed affine MV with one temporal MV. The current block or motion information of the current block is then encoded or decoded based on the affine MVP candidate list.

Abstract: A method and apparatus of Inter prediction for video coding are disclosed. According to one method, a sub-block motion vector prediction (MVP) mode is turned off for small size coding units (CUs). In another method, if the neighbouring reference block for a current coding unit (CU) is in a root CU region, the neighbouring reference block is not used to derive a Merge candidate or a modified neighbouring reference block on the shared boundary of the root CU is used to derive the Merge candidate for the current block. In yet another method, a shared sub-block Merge candidate list is derived for sub-CUs within a root CU region or an MER (Merge estimation region). If a neighbouring reference block is within the same MER as a current sub-CU, the neighbouring reference block is not used for deriving a candidate for the shared sub-CU Merge list.