Interweaved Prediction for Affine Motion Compensation

Abstract

With affine motion compensation (AMC) in the emerging next generation video coding standard Versatile Video Coding (VVC), a coding-block is divided into sub-blocks, and each sub-block is assigned with an individual motion vector derived by the affine model. The sub-block-based design for AMC faces a dilemma. With smaller sub-blocks, AMC can achieve a better coding performance but suffers a higher complexity burden. In this contribution, an interweaved prediction approach is proposed for AMC to address the dilemma. With the interweaved prediction, a coding block is divided into sub-blocks with two different dividing patterns. Then two auxiliary predictions are generated by AMC with the two dividing patterns respectively. The final prediction is calculated as a weighted-sum of the two auxiliary predictions. The interweaved prediction is only applied on the luma-component for affine-coded blocks with uni-prediction. Simulation results show 0.53% Bjontegaard-Delta rate savings in average can be achieved compared to VTM-3.0 under random access configurations. The coding gain on sequences with affine motions is up to 3.3%.