A novel fast intra-prediction algorithm for high-efficiency video coding based on structural similarity

High-efficiency video coding (HEVC) adopts the quadtree structure to partition coding units, and each coding unit has 35 intra-prediction modes candidates. The intra-mode decision process in HEVC is performed traversing all the quadtree partition depths and prediction modes to find the one with the minimum rate distortion cost. This leads to high coding efficiency and high computation complexity at the same time. In this paper, a fast intra-prediction algorithm is proposed by adopting the structure similarity between adjacent coding units. The prediction mode and partition structure for the current coding unit will inherit its optimal prediction coding unit (OPCU) directly if existing. Otherwise, an accelerated mode decision process based on HM encoder according to the statistical properties of the reference samples is further designed. Experimental results show that the proposed algorithm can save encoding time by 24.12 and 10.17% on average in the low bitrate and high bitrate range, respectively. The compression efficiency keeps almost the same in the low bitrate range, and it has a little improvement in the high bitrate range compared with HM13.0.