Abstract: An encoder encodes a video, and includes: circuitry; and memory coupled to the circuitry. Using the memory, the circuitry: obtains at least two items of prediction information for a first partition included in the video; derives at least one template from neighboring samples which neighbor the first partition; calculates at least two costs, using the at least one template and the at least two items of prediction information; using the at least two costs, (i) determines at least one splitting direction for the first partition or (ii) assigns one of the at least two items of prediction information to a second partition split from the first partition according to the splitting direction, and another thereof to a third partition split from the first partition according to the splitting direction; and encodes the first partition according to the splitting direction and the at least two items of prediction information.

Abstract: An encoder according to one aspect of the present disclosure encodes a block of an image, and includes a processor and memory connected to the processor. Using the memory, the processor partitions a block into a plurality of sub blocks and encodes a sub block included in the plurality of sub blocks in an encoding process including at least a transform process or a prediction process. The block is partitioned using a multiple partition including at least three odd-numbered child nodes and each of a width and a height of each of the plurality of sub blocks is a power of two.

Abstract: During video encoding or decoding, cross-component prediction can be used to predict a chroma sample from collocated reconstructed luma samples. The prediction can be based on a gradient of the collocated reconstructed luma samples, a down-sampled value of the collocated reconstructed luma samples, or a combination thereof. An exemplary method includes: determining a first value associated with a chroma sample, by applying a first gradient pattern to reconstructed values of a first plurality of luma samples; determining a second value associated with the chroma sample, by applying a down-sampling filter to reconstructed values of a second plurality of luma samples; and predicting the chroma sample based on the first value and the second value.

Abstract: An encoder includes circuitry and memory connected to the circuitry. In operation, the circuitry corrects a base motion vector using a correction value in a fixed direction; and encodes a current partition by using the corrected base motion vector corrected. The correction value is specified by an index indicating one of correction values included in a table. The table is selected from among a plurality of tables, wherein the correction values in one of the plurality of tables have different increments from the correction values in another one of the plurality of tables.

Abstract: The present disclosure provides a computer-implemented method for decoding video. The method includes receiving a bitstream including a coding unit of a video frame, the coding unit being coded in a skip mode or a direct mode; determining whether the coding units has a width greater than a threshold width or a height greater than a threshold height; in response to the coding unit having the width greater than the threshold width or the height greater than the threshold height, enabling a motion vector angular prediction process to store one or more motion vector angular prediction candidates in a candidate list storing a plurality of motion candidates associated with the coding unit; and performing an inter prediction to the coding unit according to the candidate list and an index parsed from the bitstream.

Abstract: An encoder includes circuitry and memory coupled to the circuitry. The circuitry, in operation, determines whether a first block is available and whether a second block is available, the first block and the second block being defined relative to a current block to be processed; selects a context model based on whether the first block is available, whether the second block is available, which of inter prediction and intra prediction is to be applied to the first block, and which of inter prediction and intra prediction is to be applied to the second block; and encodes, using the context model selected, a parameter indicating which of intra prediction and inter prediction is to be applied to the current block.

Abstract: Methods are provided for optical flow-based motion refinement. An exemplary method includes: receiving a bitstream; and decoding, using coded information of the bitstream, one or more pictures, wherein the decoding includes: determining whether a current block is coded by partitioning into multiple parts; and in response to the current block being partitioned into multiple parts that are inter predicted according to respective reference blocks, determining whether to apply a local illumination compensation (LIC) process to the multiple parts based on whether a coded block applies the LIC process.

Abstract: Methods and apparatuses are provided for subblock-based temporal motion vector prediction (SbTMVP). An exemplary decoding method includes: decoding a target coding unit (CU) based on a SbTMVP mode, wherein the target CU is divided into a plurality of subblocks; determining a same reference picture index for the plurality of subblocks; selecting, based on the determined reference picture index, a reference picture from a list of reference pictures; generating a plurality of predicted subblocks based on the selected reference picture; and reconstructing the target CU based on the plurality of predicted subblocks.

Abstract: Methods and apparatuses are provided for motion template-matching-based motion refinement. An exemplary method includes: dividing a target coding block into a plurality of subblocks; determining a first plurality of templates associated with the plurality of subblocks; determining a plurality of reference templates based on the first plurality of templates; performing motion compensation to the target coding block based on an affine merge candidate; and refining the motion compensation by matching the first plurality of templates and the plurality of reference templates.

Abstract: An encoder which includes circuitry and memory. Using the memory, the circuitry generates a list which includes candidates for a first motion vector for a first partition. The list has a maximum list size and an order of the candidates, and at least one of the maximum list size or the order of the candidates is dependent on at least one of a partition size or a partition shape of the first partition. The circuitry selects the first motion vector from the candidates included in the list; encodes an index indicating the first motion vector among the candidates in the list into the bitstream based on the maximum list size; and generates the predicted image for the first partition using the first motion vector.

Abstract: The present disclosure provides a computer-implemented method for encoding video. The method includes: determining whether a coded video sequence (CVS) contains equal number of profile, tier and level (PTL) syntax structures and output layer sets (OLSs); and in response to the CVS containing equal number of PTL syntax structures and OLSs, coding the bitstream without signaling a first PTL syntax element specifying an index, to a list of PTL syntax structures in the VPS, of a PTL syntax structure that applies to a corresponding OLS in the VPS.

Abstract: The present disclosure provides a video data processing method. The method includes: receiving a bitstream; decoding a first index from the bitstream; determining a maximum number of an adaptive loop filter (ALF) for a component of a picture based on the first index; and processing pixels in the picture with the ALF.

Abstract: The present disclosure provides a video data processing method for cross-component sample adaptive offset (CCSAO). The method includes determining an index based on a vertical coordinate of a chroma sample within a picture; determining a luma sample based on the index; classifying the chroma sample based on a reconstructed value associated with the luma sample; determining an offset based on the classification; and adding the offset to a reconstructed value associated with the chroma sample.

Abstract: An image encoder includes circuitry and a memory, wherein the circuitry, in operation, obtains a current block from a coding tree unit (CTU); determines whether inter prediction is to be applied to the current block; in response to determining that the inter prediction is to be applied, performs a partition prediction process; and, in response to determining that the inter prediction is not to be applied, encodes the current block without using the partition prediction process. The partition prediction process includes predicting first values of a set of pixels between a first partition and a second partition in the current block, using a first motion vector for the first partition; predicting second values of the set of pixels, using a second motion vector for the second partition; weighting the first values and the second values; and generating a prediction image for the current block using the weighted first and second values.

Abstract: An image encoder writes a first parameter and a second parameter to a bitstream, and derives a partition mode based on the first and second parameters. Responsive to the derived partition mode being a first partition mode, the image encoder executes the first partition mode including: splitting a block of a picture into a plurality of first blocks including a N×2N block sized N pixels by 2N pixels; splitting the N×2N block, wherein a ternary split is allowed to split the N×2N block in a vertical direction, which is a direction along the 2N pixels, into a plurality of sub blocks including at least one sub block sized N/4×2N, while a binary split is not allowed to split the N×2N block in the vertical direction into two sub blocks that are equally sized N/2×2N; and encoding the plurality of sub blocks.

Abstract: An encoder according to one aspect of the present disclosure encodes a block of an image, and includes a processor and memory connected to the processor. Using the memory, the processor partitions a block into a plurality of sub blocks and encodes a sub block included in the plurality of sub blocks in an encoding process including at least a transform process or a prediction process. The block is partitioned using a multiple partition including at least three odd-numbered child nodes and each of a width and a height of each of the plurality of sub blocks is a power of two.

Abstract: An encoder includes circuitry and memory. Using the memory, the circuitry, in operation, selects an encoding mode from among candidates including a decoder-side motion vector refinement (DMVR) encoding mode and a partition encoding mode. When the DMVR encoding mode is selected, the circuitry: obtains a first motion vector for a first image block; derives a second motion vector from the first motion vector using motion search; and generates a prediction image for the first image block using the second motion vector. When the partition encoding mode is selected, the circuitry: determines a plurality of partitions in a second image block; obtains a third motion vector for each partition; and generates a prediction image for the second image block using the third motion vector, without deriving a fourth motion vector from the third motion vector using motion search.

Abstract: The present disclosure provides methods for picture processing. The method can include: receiving a bitstream comprising a set of pictures; determining, according to the received bitstream, whether a virtual boundary is signaled at a sequence level for the set of pictures; in response to the virtual boundary being signaled at the sequence level, determining a position of the virtual boundary for the set of pictures, the position being bounded by a range signaled in the received bitstream; and disabling in-loop filtering operations across the virtual boundary.

Abstract: An encoder includes: circuitry; and memory coupled to the circuitry. In operation, the circuitry: derives a base motion vector to be used in predicting a current block to be encoded; derives a first motion vector different from the base motion vector; derives a motion vector difference based on a difference between the base motion vector and the first motion vector; determines whether the motion vector difference is greater than a threshold; modifies the first motion vector when the motion vector difference is determined to be greater than the threshold, and does not modify the first motion vector when the motion vector difference is determined not to be greater than the threshold; and encodes the current block using the first motion vector modified or the first motion vector not modified.

Abstract: A method for video data processing includes: determining a category index of a target chroma sample, wherein the category index is determined based on a first reconstructed value associated with a co-located luma sample and a second reconstructed value associated with the target chroma sample; determining an offset based on the category index; and adding the offset to a third reconstructed value associated with the target chroma sample.