A video encoding method includes a first mode selection step of selecting at least one mode as a first candidate mode from a predetermined first mode group for encoding a video, a second mode selection step of selecting one mode as an encoding mode from a predetermined second mode group, based on the selected first candidate mode, and an encoding step of encoding the video in the selected encoding mode.

A video encoding method includes a first mode selection step of selecting at least one mode as a first candidate mode from a predetermined first mode group for encoding a video, a second mode selection step of selecting one mode as an encoding mode from a predetermined second mode group, based on the selected first candidate mode, and an encoding step of encoding the video in the selected encoding mode.

An image decoding method according to the present document comprises the steps of: acquiring inter prediction mode information from encoded information; constructing a motion vector predictor candidate list of a current block on the basis of the inter prediction mode information; deriving a motion vector of the current block on the basis of the motion vector predictor candidate list; and generating prediction samples of the current block on the basis of the motion vector.

A method of performing bi-directional optical flow, BDOF, processing for a video sequence of images, with each image including a plurality of blocks with bidirectional-predicted inter coding blocks, BPICBs. The method includes obtaining a shifted pair of refinement parameters per a subblock of a bidirectional-predicted inter coding block, wherein the shifted pair of refinement parameters includes a shifted first refinement parameter and a shifted second refinement parameter. The method includes determining a BDOF offset without performing any right shifting using at least the shifted pair of refinement parameters by, for each sample in each subblock within each bidirectional-predicted inter coding block, determining the BDOF offset using the shifted first refinement parameter, the shifted second refinement parameter, a first horizontal gradient block and a first vertical gradient block for a first prediction block, and a second horizontal gradient block and a second vertical gradient block for a second prediction block.

A method of performing bi-directional optical flow, BDOF, processing for a video sequence of images, with each image including a plurality of blocks with bidirectional-predicted inter coding blocks, BPICBs. The method includes obtaining a shifted pair of refinement parameters per a subblock of a bidirectional-predicted inter coding block, wherein the shifted pair of refinement parameters includes a shifted first refinement parameter and a shifted second refinement parameter. The method includes determining a BDOF offset without performing any right shifting using at least the shifted pair of refinement parameters by, for each sample in each subblock within each bidirectional-predicted inter coding block, determining the BDOF offset using the shifted first refinement parameter, the shifted second refinement parameter, a first horizontal gradient block and a first vertical gradient block for a first prediction block, and a second horizontal gradient block and a second vertical gradient block for a second prediction block.

Disclosed is a method for decoding a current block in a current picture included in a high-level layer performed based on a reference picture included in a low-level layer and having a different resolution. A prediction mode for the current block, a decoded residual signal, and decoding information for the current block, are obtained. When the prediction mode is the inter-prediction, a prediction signal for the current block is generated based on the decoding information. A reconstructed block is then generated by adding the prediction signal to the residual signal. Filtering is then performed for correcting the different resolution that is applied to a reference block included in the reference picture such that the different resolution matches a resolution of the current block.

Systems, methods and apparatus for video processing are described. The video processing may include video encoding, video decoding, or video transcoding. One example method of video processing includes performing a conversion between a video including one or more video regions and a bitstream of the video according to a format rule. The format rule specifies that a variable X indicates whether B slice is allowed or used in a video region. The format rule further specifies that the variable X is based on values of a reference picture list information present flag and/or a field indicating a number of entries in a reference picture list syntax structure.

Techniques for implementing video processing techniques are described. In one example implementation, a method of video processing includes determining, for a conversion between a current block of a video and a bitstream representation of the video, a manner in which coding information of the current block is represented in the bitstream representation in part based on whether a condition associated with a size of the current block is satisfied. The method also includes performing the conversion based on the determining.

A method for derivation of a temporal motion data (TMD) candidate for a prediction unit (PU) in video encoding or video decoding is provided. The derived TMD candidate is for inclusion in an inter-prediction candidate list for the PU. The method includes determining a primary TMD position relative to a co-located PU in a co-located largest coding unit (LCU), wherein the co-located PU is a block in a reference picture having a same size, shape, and coordinates as the PU, and selecting at least some motion data of a secondary TMD position as the TMD candidate when the primary TMD position is in a bottom neighboring LCU or in a bottom right neighboring LCU of the co-located LCU, wherein the secondary TMD position is determined relative to the co-located PU.

A method for derivation of a temporal motion data (TMD) candidate for a prediction unit (PU) in video encoding or video decoding is provided. The derived TMD candidate is for inclusion in an inter-prediction candidate list for the PU. The method includes determining a primary TMD position relative to a co-located PU in a co-located largest coding unit (LCU), wherein the co-located PU is a block in a reference picture having a same size, shape, and coordinates as the PU, and selecting at least some motion data of a secondary TMD position as the TMD candidate when the primary TMD position is in a bottom neighboring LCU or in a bottom right neighboring LCU of the co-located LCU, wherein the secondary TMD position is determined relative to the co-located PU.