A Bottom-up Fast CU Partition Scoring Mechanism for AVS3

The third generation of Audio Video Coding Standard (AVS3) achieves 22% coding performance improvement compared with High Efficiency Video Coding (HEVC). However, the improvement of encoding efficiency comes from a more flexible block partition scheme is at the cost of much higher encoding complexity. This paper proposes a bottom-up fast algorithm to prune the time-consuming search process of the CU partition tree. To be specific, we design a scoring mechanism based on the splitting patterns traced back from the bottom to predict the possibility of a partition type to be selected as optimal. The score threshold to skip the exhaustive Rate-Distortion Optimization (RDO) procedure of the partition type is determined by statistical analysis. The experimental results show that the proposed methods can achieve 24.56% time-saving with 0.37% BDBR loss under Random Access configuration and 12.50% complexity reduction with 0.08% BDBR loss under All Intra configuration. The effectiveness leads to the adoption by the open-source platform of AVS3 after evaluated by the AVS working group.