在H.264/AVC中,帧内编码是采用帧内预测来提高编码效率,其色度块尺寸为8×8,亮度块包括4×4和16×16两种尺寸。由于每种块可提供多种预测模式,因此这种多模式选择大大增加了编码的复杂性。针对这种多模式选择,为了加快编码速度,利用色度块和亮度块以及亮度4×4和16×16块模式选择之间的关系,提出一种基于RDO(rate d istortion optim ization)的不同判决依据的快速帧内预测模式选择算法。实验证明,在信噪比和码率变化不大的同时,该算法可使编码速度平均提高6倍。

In H.264/AVC, intraprediction is used to improve the coding efficiency of I frame. There are one size of 8×8 for the chroma block and two sizes including 4×4 and 16×16 for the luma block. Each kind of block provides many prediction modes, so that this multimode selection increases the coding complexity greatly while improving coding efficiency. In this paper, a fast intraprediction mode selection algorithm with different criterion based on RDO(Rate distortion optimization) is proposed using the mode selection relation of chroma block and luma block and the relation of luma 4×4 block and luma 16×16 block. Experiment results show that our proposed algorithm can averagely speed up to times while maintaining similar PSNR and bit rate.