An image decoding method includes: splitting a first block included in an image on the basis of at least one of a split type and a split direction of the first block to determine at least one second block from the first block; determining one of a prediction mode of the at least one second block and whether to split the at least one second block on the basis of at least one of a size and a shape of the determined at least one second block; obtaining a prediction block of a block included in the at least one second block on the basis of one of the determined prediction mode and whether to split the at least one second block; and restoring the block included in the at least one second block on the basis of the prediction block of the block included in the at least one second block. Here, the split type represents one of binary-split, tri-split, and quad-split.

An image decoding method includes: splitting a first block included in an image on the basis of at least one of a split type and a split direction of the first block to determine at least one second block from the first block; determining one of a prediction mode of the at least one second block and whether to split the at least one second block on the basis of at least one of a size and a shape of the determined at least one second block; obtaining a prediction block of a block included in the at least one second block on the basis of one of the determined prediction mode and whether to split the at least one second block; and restoring the block included in the at least one second block on the basis of the prediction block of the block included in the at least one second block. Here, the split type represents one of binary-split, tri-split, and quad-split.

A method of video decoding performed in a video decoder includes receiving a coded video bitstream including a current block that is divided into a plurality of sub-blocks. The method includes performing sub-block based affine motion compensation on the current block to generate a sub-block prediction for each pixel in each sub-block of the current block. The method further includes determining one or more spatial gradients for each sub-block prediction. The method includes performing, for each sub-block prediction, prediction refinement with an optical flow process using the respective determined one or more spatial gradients and at least one constraint included in the coded video bitstream. The method further includes adding, for each sub-block prediction, an output of the respective prediction refinement to the respective sub-block prediction to generate a final prediction for each pixel in each sub-block of the current block.

A method of video decoding performed in a video decoder includes receiving a coded video bitstream including a current block that is divided into a plurality of sub-blocks. The method includes performing sub-block based affine motion compensation on the current block to generate a sub-block prediction for each pixel in each sub-block of the current block. The method further includes determining one or more spatial gradients for each sub-block prediction. The method includes performing, for each sub-block prediction, prediction refinement with an optical flow process using the respective determined one or more spatial gradients and at least one constraint included in the coded video bitstream. The method further includes adding, for each sub-block prediction, an output of the respective prediction refinement to the respective sub-block prediction to generate a final prediction for each pixel in each sub-block of the current block.

An encoding apparatus, includes a memory; and a processor coupled to the memory and configured to: perform intra-screen prediction encoding on an image of a region of a still image cut out from a first decoded image corresponding to a screen image before a predetermined region is switched from a video to a still image, generate a second decoded image obtained by decoding information for which the intra-screen prediction is performed, and when a first screen image after the predetermined region is switched from a video to a still image is received, perform inter-screen prediction encoding on an image of a region of a still image cut out from the first screen image after switching to a still image, by referring to the generated second decoded image.

Devices, systems and methods for palette mode coding are described. An exemplary method for video processing includes performing a conversion between a block of a video region of a video and a bitstream representation of the video. The bitstream representation is processed according to a first format rule that specifies whether a first indication of usage of a palette mode is signaled for the block and a second format rule that specifies a position of the first indication relative to a second indication of usage of a prediction mode for the block.

A method of video processing includes performing a conversion between a video and a bitstream of the video according to a rule, wherein the rule specifies that a sub-bitstream extraction process is implemented to generate a sub-bitstream for decoding, wherein the sub-bitstream extraction process is configured to extract, from the bitstream, a sub-bitstream with a target highest temporal identifier, and wherein, the rule specifies that, during the extracting, upon removing a video coding layer (VCL) network abstraction layer (NAL) unit, filler data units and filler supplemental enhancement information (SEI) messages in SEI NAL units that are associated with the VCL NAL unit are also removed.

A moving for transmitting a bitstream via network is provided. A first candidate is derived from a first motion vector that has been used to decode a first block. The first block is adjacent to a current block. A second candidate having a second motion vector that is a non-zero value vector based on an X-Y axis of a fixed offset value is derived. The second motion vector is not derived by decoding a block adjacent to the current block and the fixed offset value is a non-zero value. An index to select a candidate used for coding the current block from a plurality of candidates, including the first candidate and the second candidate, is determined. The current block is coded by including the determined index.

A moving for transmitting a bitstream via network is provided. A first candidate is derived from a first motion vector that has been used to decode a first block. The first block is adjacent to a current block. A second candidate having a second motion vector that is a non-zero value vector based on an X-Y axis of a fixed offset value is derived. The second motion vector is not derived by decoding a block adjacent to the current block and the fixed offset value is a non-zero value. An index to select a candidate used for coding the current block from a plurality of candidates, including the first candidate and the second candidate, is determined. The current block is coded by including the determined index.

A method of partitioning a video coding block for JVET, comprising representing a JVET coding tree unit as a root node in a quadtree plus binary tree (QTBT) structure that can have a quadtree branching from the root node and binary trees branching from each of the quadtree's leaf nodes using asymmetric binary partitioning to split a coding unit represented by a quadtree leaf node into two child coding units of unequal size, representing the two child coding units as leaf nodes in a binary tree branching from the quadtree leaf node and coding the child coding units represented by leaf nodes of the binary tree with JVET, wherein further partitioning of child coding units split from quadtree leaf nodes via asymmetric binary partitioning is disallowed.