A video decoding method includes: obtaining two or more base motion vectors from an adjacent block of a current block; obtaining correction information for correcting the two or more base motion vectors; determining two or more affine motion vectors by correcting the two or more base motion vectors according to the correction information; obtaining a plurality of affine parameters of the current block according to the two or more affine motion vectors; and predicting the current block according to the plurality of affine parameters.

A method for inter-coding video is provided in which transmission bandwidth requirements associated with second motion vectors for bi-directional temporal prediction is reduced. In the method motion vector information for only one of the two motion vectors for bi-directional temporal prediction can be transmitted together with information on how to derive or construct the second motion vector. Thus, rather than sending express information regarding two motion vectors, express information related to only one motion vector along with information related to reconstruction/derivation of the second motion vector is transmitted, thus reducing bandwidth requirements and increasing coding efficiency.

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.

Systems, methods, and instrumentalities are disclosed for motion vector clipping when affine motion mode is enabled for a video block. A video coding device may determine that an affine mode for a video block is enabled. The video coding device may determine a plurality of control point affine motion vectors associated with the video block. The video coding device may store the plurality of clipped control point affine motion vectors for motion vector prediction of a neighboring control point affine motion vector. The video coding device may derive a sub-block motion vector associated with a sub-block of the video block, clip the derived sub-block motion vector, and store it for spatial motion vector prediction or temporal motion vector prediction. For example, the video coding device may clip the derived sub-block motion vector based on a motion field range that may be based on a bit depth value.

Systems, methods, and instrumentalities are disclosed for motion vector clipping when affine motion mode is enabled for a video block. A video coding device may determine that an affine mode for a video block is enabled. The video coding device may determine a plurality of control point affine motion vectors associated with the video block. The video coding device may store the plurality of clipped control point affine motion vectors for motion vector prediction of a neighboring control point affine motion vector. The video coding device may derive a sub-block motion vector associated with a sub-block of the video block, clip the derived sub-block motion vector, and store it for spatial motion vector prediction or temporal motion vector prediction. For example, the video coding device may clip the derived sub-block motion vector based on a motion field range that may be based on a bit depth value.

A method of motion compensation for geometry representation of 3D data is described herein. The method performs motion compensation by first identifying correspondent 3D surfaces in time domain, then followed by a 3D to 2D projection of motion compensated 3D surface patches, and then finally performing 2D motion compensation on the projected 3D surface patches.

A method of motion compensation for geometry representation of 3D data is described herein. The method performs motion compensation by first identifying correspondent 3D surfaces in time domain, then followed by a 3D to 2D projection of motion compensated 3D surface patches, and then finally performing 2D motion compensation on the projected 3D surface patches.

Technology for improving coding efficiency by performing a block split suitable for picture coding and decoding is provided. A moving-picture coding device for performing an affine transform in units of coding blocks includes an affine inheritance merging candidate derivation unit configured to derive an affine inheritance merging candidate for inheriting an affine model of blocks neighboring a coding target block in a space domain, an affine construction merging candidate derivation unit configured to derive an affine construction merging candidate from a plurality of motion information elements of blocks neighboring the coding target block in a space or time domain, and an affine fixation merging candidate derivation unit configured to derive an affine fixation merging candidate in which motion information of an affine control point is fixed. A motion vector of each affine control point is fixed to (0, 0) in the affine fixation merging candidate.

A video decoding apparatus is provided for decoding pictures using inter-prediction. The video decoding apparatus includes a predictor that generates affine prediction samples for respective subblocks in a target block in a current picture to be decoded by performing affine motion prediction on a subblock-by-subblock basis using control point motion vectors which respectively correspond to corners of the target block. The predictor also modifies sample values of the affine prediction samples by executing a first coding tool, the first coding tool compensating for motion according to sample positions in each of the subblocks using the control point motion vectors.

A method and apparatus use a geometric modified image for video encoding/decoding. The encoding method may include: generating a geometric modified reference picture by geometrically modifying a reference picture; generating a prediction block of a current block within an encoding target picture by performing inter prediction by referencing the reference picture or the geometrically modified reference picture; and encoding inter-prediction information of the current block.