Fast coding unit mode decision for hevc intra coding based on breadth-first search

Abstract

This research proposed a fast CU mode decision algorithm for intra coding in HEVC. The main idea is simple, but effective early termination on quadtree decision process inspired by the breadth-first search algorithm. RDO process is entailed to ensure the visual quality of encoded video sequences. However, the number of calculation of the RD cost is significantly increased in HEVC standard due to quadtree structure, increase in intra modes, and variable size of CTUs. This phenomena lead to increase in computational complexity in HEVC intra coding. In order to reduce this complexity, we proposed an algorithm for fast CU mode decision for HEVC intra coding based on breadth-first search. By observing the RD cost improvement of the coding tree structure, a new algorithm is proposed and tested. The proposed technique reduced the encoding time alone at the cost of slight increase in bit rate and negligible PSNR loss. There is a complexity reduction about 66.93% at very less loss in performance with high complexity reduction. The average loss in PSNR is only 0.42dB in comparison with HEVC standard.