US 2022/0191536 A1 · METHOD AND APPARATUS FOR INTER PREDICTION IN VIDEO CODING SYSTEM

Abstract

A video decoding method performed by a decoding apparatus comprises deriving control points (CPs) for the current block; obtaining motion vectors for the CPs; deriving a motion vector of a sub-block or a sample unit in the current block on the basis of the obtained motion vectors; deriving a prediction sample for the current block on the basis of the derived motion vector; and generating a reconstruction sample on the basis of the prediction sample. The method enables effective performance of inter prediction through the motion vectors (transformation prediction), not only when an image in the current block is moved in a plane, but also when the image in the current block is rotated, zoomed in, zoomed out, or transformed into a parallelogram. Accordingly, the amount of data for the residual signal for the current block can be eliminated or reduced, and the overall coding efficiency can be improved.

Claims14

Dependent claims

A video decoding method performed by a decoding apparatus, the method comprising:

deriving control points (CPs) for a current block;
acquiring motion vectors for the CPs;
deriving motion vectors of sub-blocks in the current block based on the acquired motion vectors;
deriving a prediction sample for the current block based on the derived motion vectors;
and
generating a reconstructed sample based on the prediction sample,
wherein, based on the number of CPs being 3, the coordinates of CP0 are (0, 0), the coordinates of CP1 are (S, 0), and the coordinates of CP2 are (0, S) when the coordinates of a top-left sample position of the current block are (0, 0) and the height and the width of the current block are S,
wherein the motion vectors for the CPs are derived by deriving motion vector predictors (MVPs) of the CPs based on motion vectors of neighboring blocks and adding motion vector differences to the MVPs, and
wherein reference picture indices for the neighboring blocks for the CPs are the same as to reference picture index of the current block.

6 more elements

A video encoding method performed by an encoding apparatus, comprising:

deriving control points (CPs) for a current block;
acquiring motion vectors for the CPs;
deriving motion vectors in units of sub-blocks in the current block based on the acquired motion vectors;
generating a prediction sample for the current block based on the derived motion vectors;
and
encoding prediction mode information about the current block and information about the derived motion vector and outputting the encoded information,
wherein, based on the number of CPs being 3, the coordinates of CP0 are (0, 0), the coordinates of CP1 are (S, 0), and the coordinates of CP2 are (0, S) when the coordinates of a top-left sample position of the current block are (0, 0) and the height and the width of the current block are S,
wherein the motion vectors for the CPs are derived by deriving motion vector predictors (MVPs) of the CPs based on motion vectors of neighboring blocks and adding motion vector differences to the MVPs, and
wherein reference picture indices for the neighboring blocks for the CPs are the same as to reference picture index of the current block.

6 more elements

Dependencies are inferred from the claim text.

Method and apparatus for inter prediction in video coding system

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Method and apparatus for inter prediction in video coding system

Life of this patent

Abstract

Claims14