Design of Perspective Affine Motion Compensation for Versatile Video Coding (VVC)

The fundamental motion model of the conventional block-based motion compensation in High Efficiency Video Coding (HEVC) is a translational motion model. However, in the real world, the motion of an object exists in the form of combining many kinds of motions. In Versatile Video Coding (VVC), a block-based 4-parameter and 6-parameter affine motion compensation (AMC) is being applied. The AMC still has a limit to accurate complex motions in the natural video. In this paper, we design a perspective affine motion compensation (PAMC) method which can improve the coding efficiency and maintain low-computational complexity compared with existing AMC. Because the block with the perspective motion model is a rectangle without specific feature, the proposed PAMC shows effective encoding performance for the test sequence containing irregular object distortions or dynamic rapid motions in particular. Our proposed algorithm is implemented on VTM 2.0. The experimental results show that the BD-rate reduction of the proposed technique can be achieved up to 0.30%, 0.76%, and 0.04% for random access (RA) configuration and 0.45%, 1.39%, and 1.87% for low delay P (LDP) configuration on Y, U, and V components, respectively. Meanwhile, the increase of encoding complexity is within an acceptable range.