The present disclosure relates to an apparatus and a method for providing a plurality of motion vectors related to an image coded in a bitstream, comprising obtaining a set of sample positions within the image, obtaining respective motion vectors associated with the set of sample positions, deriving an additional motion vector based on information coded in the bitstream, determining an additional sample position located within a triangle, which is formed by three sample positions of the set of sample positions, based on the respective motion vectors associated with the three sample positions, the triangle not including any other sample position of the set, adding the additional sample position to the set of sample positions, and associating the derived additional motion vector with the additional sample position. Such method and apparatus provide for an efficient motion flow compression and reconstruction enabling to recover some sample positions without signaling them in the bitstream.

Systems and methods are described for video coding using affine motion models with adaptive precision. In an example, a block of video is encoded in a bitstream using an affine motion model, where the affine motion model is characterized by at least two motion vectors. A precision is selected for each of the motion vectors, and the selected precisions are signaled in the bitstream. In some embodiments, the precisions are signaled by including in the bitstream information that identifies one of a plurality of elements in a selected predetermined precision set. The identified element indicates the precision of each of the motion vectors that characterize the affine motion model. In some embodiments, the precision set to be used is signaled expressly in the bitstream; in other embodiments, the precision set may be inferred, e.g., from the block size, block shape or temporal layer.

The present disclosure provides video decoding method. An exemplary method includes: decoding a first parameter for a coding unit from a bitstream, and determining a candidate for the coding unit based on the first parameter; determining a value of a second parameter associated with the coding unit based on a value of a second parameter associated with the candidate, wherein the second parameter indicates whether a bi-directional prediction correction is enabled; and in response to the value of the second parameter associated with the coding unit indicating the bi-directional prediction correction being enabled, performing the bi-directional prediction correction on the coding unit.

In a method and a device for encoding or decoding an image according to the present invention, motion information for bidirectional prediction of a current block may be derived on the basis of an inter mode previously defined in the device for encoding or decoding an image, and inter prediction may be performed on the current block on the basis of the motion information, wherein the motion information for bidirectional prediction is adjusted to be motion information for unidirectional prediction according to the predefined inter mode.

A video processing method includes performing a conversion between a video block of a video and a bitstream of the video according to a rule. The rule specifies whether or how usage of a secondary transform within a video unit is indicated in the bitstream. The secondary transform is applied before quantization or after de-quantization.

An electronic apparatus performs a method of coding video data. The method includes receiving, from a bitstream of the video data, a first syntax that indicates an affine motion model enabled for a current coding block, estimating parameters of the affine motion model using gradients of motion vectors of multiple spatial neighboring blocks of the current coding block, and constructing motion vectors of the affine motion model for the current coding block by using the estimated parameters. In some embodiments, constructing motion vectors further includes converting the estimated parameters into control point motion vectors (CPMVs), and adding the CPMVs into a current affine merge candidate list. In some embodiments, constructing motion vectors further includes deriving a motion vector predictor for an affine mode.

Disclosed are a method for processing video signals and an apparatus therefor. Specifically, the method for processing video signals on the basis of inter prediction comprises the steps of: inducing a motion vector predictor using motion data of a neighboring block of the current block; parsing layer data indicating the current layer to which a motion vector difference used in inter prediction of the current block belongs, in a previously defined layer structure in which the combination of one or more horizontal and vertical components of motion vector differences are divided into multiple layers; parsing index data indicating a particular combination within the current layer; inducing a motion vector difference of the current block using the layer data and index data; and inducing the motion vector for the current block by adding the motion vector difference to the motion vector predictor.

A method for video encoding includes setting a motion vector precision associated with a current block to be encoded in a current picture, and determining a motion vector for encoding the current block based on the motion vector precision. The method also includes determining a motion vector difference for the current block based on (i) the determined motion vector for encoding the current block, (ii) a predicted motion vector of the current block in inter prediction mode, and (iii) the motion vector precision. The method further includes encoding the current block according to the determined motion vector, and generating a coded video bitstream including the encoded current block and including prediction information indicating that the current block is coded in inter prediction mode and indicating the determined motion vector difference for the current block.

A video processing method includes determining, for a conversion between a current video block of a video including multiple video blocks and a coded representation of the video, and from types of reference pictures used for the conversion, applicability of a coding tool to the current video block and performing the conversion based on the determining. The method may be performed by a video decoder or a video encoder or a video transcoder.

A video encoder or decoder processes portions of video using virtual temporal affine motion candidates. Under the general aspects, virtual temporal affine candidates are created using only the classical temporal motion buffer information, avoiding the storage of additional affine parameters in a temporal motion buffer. A motion field for encoding or decoding a video block is generated based on the virtual temporal affine candidates. In one embodiment, collocated motion candidates are rescaled by adjusting the picture order count of the determined motion field. In another embodiment, resolution adaptation is performed to enable a current motion buffer to correspond to a reference motion buffer.