Provided is a video decoding method including: generating a merge candidate list including neighboring blocks referred to predict a motion vector of a current block in a skip mode or a merge mode; when a merge motion vector difference is used according to merge difference mode information indicating whether the merge motion vector difference and a motion vector determined from the merge candidate list are used, determining a base motion vector from a candidate determined among the merge candidate list based on merge candidate information; determining the motion vector of the current block by using the base motion vector and a merge motion vector difference of the current block, the merge motion vector difference being determined by using a distance index and direction index of the merge motion vector difference of the current block; and reconstructing the current block by using the motion vector of the current block.

Provided is a video decoding method including: generating a merge candidate list including neighboring blocks referred to predict a motion vector of a current block in a skip mode or a merge mode; when a merge motion vector difference is used according to merge difference mode information indicating whether the merge motion vector difference and a motion vector determined from the merge candidate list are used, determining a base motion vector from a candidate determined among the merge candidate list based on merge candidate information; determining the motion vector of the current block by using the base motion vector and a merge motion vector difference of the current block, the merge motion vector difference being determined by using a distance index and direction index of the merge motion vector difference of the current block; and reconstructing the current block by using the motion vector of the current block.

A video decoding method performed by a video decoding apparatus, according to the present document, comprises the steps of: parsing a flag for weighted prediction from a bitstream; parsing a prediction weighted table syntax from the bitstream on the basis of the flag; generating prediction samples by performing weighted prediction on a current block within a current picture on the basis of the prediction weighted table syntax; and generating reconstructed samples for the current block on the basis of the prediction samples, wherein the prediction weighted table syntax may be parsed from a picture header or slice header of the bitstream on the basis of a value of the flag.

A video decoding method performed by a video decoding apparatus, according to the present document, comprises the steps of: parsing a flag for weighted prediction from a bitstream; parsing a prediction weighted table syntax from the bitstream on the basis of the flag; generating prediction samples by performing weighted prediction on a current block within a current picture on the basis of the prediction weighted table syntax; and generating reconstructed samples for the current block on the basis of the prediction samples, wherein the prediction weighted table syntax may be parsed from a picture header or slice header of the bitstream on the basis of a value of the flag.

Provided are inter prediction methods and a decoder. In the method, a bitstream is parsed to determine a prediction mode parameter of a current block; a Geometrical Partition Mode (GPM) parameter of the current block and a merge candidate list of the current block and attribute information of motion information in the merge candidate list are determined when the prediction mode parameter indicates to determine an inter prediction value of the current block by using GPM; a first motion information mapping table of a first partition and a second motion information mapping table of a second partition are determined according to the GPM parameter, merge candidate list and attribute information; and the inter prediction value of the current block is determined based on the first and second motion information mapping tables and merge candidate list.

Provided are inter prediction methods and a decoder. In the method, a bitstream is parsed to determine a prediction mode parameter of a current block; a Geometrical Partition Mode (GPM) parameter of the current block and a merge candidate list of the current block and attribute information of motion information in the merge candidate list are determined when the prediction mode parameter indicates to determine an inter prediction value of the current block by using GPM; a first motion information mapping table of a first partition and a second motion information mapping table of a second partition are determined according to the GPM parameter, merge candidate list and attribute information; and the inter prediction value of the current block is determined based on the first and second motion information mapping tables and merge candidate list.

A visual media processing method includes performing a conversion between a current video block of a visual media data and a bitstream representation of the current video block. The bitstream representation is configured according to a format rule that specifies that a syntax element is selectively included or excluded in the bitstream representation indicative of a maximum number of merge candidates for a coding tool, thereby indicating whether the coding tool is enabled or disabled for the conversion. The maximum number of merge candidates for the coding tool is zero or a positive number.

An inter-prediction method according to the present invention comprises the steps of: deriving motion information of a current block; and generating a prediction block for the current block on the basis of the derived motion information. According to the present invention, computational complexity can be reduced and encoding efficiency can be improved.

An inter-prediction method according to the present invention comprises the steps of: deriving motion information of a current block; and generating a prediction block for the current block on the basis of the derived motion information. According to the present invention, computational complexity can be reduced and encoding efficiency can be improved.

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.