H.264帧内4×4块预测模式选择快速算法研究

On Fast Intra Prediction Mode Decision Algorithm for 4×4 Blocks in H.264

在H.264视频编码过程中,编码时间受诸多因素的影响,如帧间/帧内模式选择、运动估计(ME)、率失真优化(RDO)等。为了以较快速度和较好质量进行编码,针对H.264帧内模式选择,提出了一种适用于H.264帧内4×4块预测的模式选择快速算法。该算法利用帧内4×4块最优预测模式与和它相邻的预测模式之间率失真代价(RD Cost)的高相关性,以及绝对变换误差和(SATD)与率失真(RD)性能之间的强相关性,有效地跳过一些不太可能的预测模式,从而使帧内4×4块模式选择过程只需进行4次率失真代价计算即可。实验结果显示,该算法在编码性能和编码速度之间取得了很好的折衷。

In the video-encoding process, the encoding time is greatly influenced by many factors, such as inter/intra mode decision, motion estimation（ ME）, etc. In order to encode the video with faster speed and beteer quality, this paper only focuses on the intra mode decision in H. 264 and presents a fast intra prediction mode decision algorithm for 4 × 4 blocks in H. 264. The proposed algorithm uses： （i） high correlation of RD cost between best prediction mode and its neighborhood prediction mode, （ ii ） strong correlation between sums of absolute transform differences （ SATD ） and ratedistortion（RD） performance, efficiently skipping some unlikely prediction modes. Thus, it can complete 4 × 4 intra prediction by only computing RD cost for four times. The simulation result shows that the proposed algorithm is a good compromise between the coding performance and the encoding speed.