H.264帧内预测算法的研究与优化

Research and Optimization for the Intraframe Prediction in H.264

H.264作为最新的视频编码标准,为了获得最佳的帧内和帧间预测,H.264采用了率失真优化(RDO)技术,提高了编码质量,降低了比特率。RDO技术对所有的帧内/帧间预测模式采用全搜索算法,导致了很高的计算复杂度。本文中,引入了一种新颖的快速帧内预测算法,改变模式选择的顺序,利用临块之间预测模式的相关性,通过阈值比较及绝对差值和排序的方式,对H.264帧内预测算法进行了优化。实验结果表明:与全搜索算法相比,快速算法降低了30%左右的编码时间,而信噪比、码流几乎不变。

This paper focuses on the intraframe mode decision in H.264 and presents a fast intraframe prediction mode decision algorithm.In the paper,16 × 16 encoding mode is preferentially considered than 4 × 4 encoding mode.Based on a threshold,the algorithom determines whether to use 16 × 16 encoding mode .To 4 × 4 encoding mode,firstly compare RD cost using its neighborhood＇s prediction mode with a threshold.If it is less than the threshold,choose its neighborhood＇s prediction mode as its prediction mode,otherwise,compute and sort SADs of an intra 4 × 4 block with 9 prediction modes,then choose 3 modes with less SADs to compute RD cost.The simulation result shows that the proposed algorithm can achieve a great reduction of computation while maintaining similar PSNR and bit rate.