A method of video processing is provided. The method includes: determining, for a conversion between a current video block of a video and a coded representation of the video, a mode of operation of an UMVE mode; and performing the conversion based on the determining, wherein the current video block is coded with an affine merge mode and motion vector differences in the affine UMVE mode, and wherein one or more fields in the coded representation correspond to the mode of operation, and wherein the one or more fields include: a list size field that indicates a size of a base affine merge candidate list for an affine merge mode with prediction offsets that is used by the UMVE mode, or a table field that signals a distance table or a direction table for the affine merge mode with prediction offsets.

The present disclosure provides a video decoding method. The method includes obtaining a bitstream that needs to be decoded, the bitstream that needs to be decoded comprising a current decoding block, the current decoding block using an intra string copy mode, and the current decoding block comprising a current string; determining a string length encoding resolution of the current string; decoding the bitstream that needs to be decoded to obtain an encoded string length corresponding to the current string; and obtaining a string length of the current string according to the string length encoding resolution of the current string and the corresponding encoded string length. The string length encoding resolution of the current string is at least one of the following: at least one preset value, each preset value being an integer pixel greater than or equal to 1, or a width or a height of the current decoding block.

The present disclosure provides a video decoding method. The method includes obtaining a bitstream that needs to be decoded, the bitstream that needs to be decoded comprising a current decoding block, the current decoding block using an intra string copy mode, and the current decoding block comprising a current string; determining a string length encoding resolution of the current string; decoding the bitstream that needs to be decoded to obtain an encoded string length corresponding to the current string; and obtaining a string length of the current string according to the string length encoding resolution of the current string and the corresponding encoded string length. The string length encoding resolution of the current string is at least one of the following: at least one preset value, each preset value being an integer pixel greater than or equal to 1, or a width or a height of the current decoding block.

Methods, system and apparatus for video processing are described. One example video processing method includes determining, for a conversion between a current video block of a video and a bitstream of the video, a usage of an identity transform mode for the conversion of the current video block according to a rule. The rule specifies that the usage is based on representative coefficients of one or more representative blocks of the video. The method also includes performing the conversion based on the determining.

An encoder includes circuitry and memory coupled to circuitry. In operation, circuitry: designs each of subpictures included in a picture in such a manner that at least one pixel included in the subpicture is included in a conformance cropping window; encodes arrangement information indicating an arrangement of each of the subpictures; and encodes each of the subpictures.

Disclosed is an image data encoding/decoding method and apparatus. A method for decoding a 360-degree image comprises the steps of: receiving a bitstream obtained by encoding a 360-degree image; generating a prediction image by making reference to syntax information obtained from the received bitstream; combining the generated prediction image with a residual image obtained by dequantizing and inverse-transforming the bitstream, so as to obtain a decoded image; and reconstructing the decoded image into a 360-degree image according to a projection format.

Disclosed is an image data encoding/decoding method and apparatus. A method for decoding a 360-degree image comprises the steps of: receiving a bitstream obtained by encoding a 360-degree image; generating a prediction image by making reference to syntax information obtained from the received bitstream; combining the generated prediction image with a residual image obtained by dequantizing and inverse-transforming the bitstream, so as to obtain a decoded image; and reconstructing the decoded image into a 360-degree image according to a projection format.

A method for decoding an image by a decoding device according to the present disclosure comprises the steps of: receiving a bit stream including residual information; deriving a quantized conversion factor of a current block on the basis of the residual information included in the bit stream; deriving a residual sample of the current block on the basis of the quantized conversion factor; and generating a reconstructed picture on the basis of the residual sample of the current block.

A method for decoding an image by a decoding device according to the present disclosure comprises the steps of: receiving a bit stream including residual information; deriving a quantized conversion factor of a current block on the basis of the residual information included in the bit stream; deriving a residual sample of the current block on the basis of the quantized conversion factor; and generating a reconstructed picture on the basis of the residual sample of the current block.

Embodiments provide methods and devices (encoder and/or decoder) of coding a picture. A History Based Motion Vector Prediction (HMVP) list for a current Coding Tree Unit (CTU) row within a tile of a picture is initialized and a CTU of the current CTU row is processed based on the initialized HMVP list.