基于SATD准则的HEVC快速帧内预测算法

Fast intra prediction algorithm based on SATD criterion for HEVC

相比于H.264/AVC视频编码标准,高效视频编码（HEVC）具有更大的压缩率和计算复杂度。HEVC更多的帧内预测模式显著地提升了编码器的率失真性能,但更高的算法复杂度使得编码时间大大增加。通过对典型序列编码的统计分析,提出一种基于变换残差绝对值和（SATD）的帧内预测模式快速选择算法,以降低HEVC帧内预测过程的计算复杂度。所提算法通过比较SATD来加速帧内预测模式的判决,避免了耗时的率失真代价（RD-Cost）计算,并且选择性地降低候选预测模式的数量,以减少总体编码时间。通过与现有其他HEVC快速算法进行比较测试,结果表明,所提算法平均减少了12.90%~19.89%的编码时间（编码器不进行任何优化）,而BD-Rate码率指标仅增加了0.5%~0.96%,几种算法的率失真性能基本一致。

As compared with H.264/AVC, the High Efficiency Video Coding（HEVC）has greater compression ratio and computation complexity. The increase of HEVC intra prediction modes can improve its Rate-Distortion（RD） performance at the cost of greater encoding complexity, which leads to the significant increase of encoding time. According to the statistical analysis, this paper proposes a fast intra prediction algorithm based on the SATD（Sum of Absolute Transformed Differences）criterion for HEVC, which can selectively reduce the number of candidate modes and accelerate the mode decision by comparing the SATD to avoid unnecessary RD-Cost calculation. In contrast with other fast intra-mode decision algorithms in HEVC, the proposed algorithm averagely provides about 12.90% ~19.89% speedup（without any platform or source code level optimization）with just the 0.5%~0.96% BD-rate（Bjontegaard Delta rate）increase according to the HEVC common test conditions, and significantly reduces the encoding time while maintaining a similar RD performance.