A Fast Intra-prediction Mode Selection Algorithm of H.264/AVC Based on Adaptive Thresholds

In H.264/AVC, intra-prediction is used to improve the coding efficiency of I- frames. The size for the chroma block is 8×8, and the sizes for the luma block are 4×4 and 16×16. Each kind of block provides many prediction modes, so that this multi-mode selection increases the coding complexity greatly while improving coding efficiency. In this paper, a fast intra-prediction mode selection algorithm with adaptive thresholds and 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 the proposed algorithm can averagely speed up 6 times for I frame coding or provide 25% time savings for P frames in comparison with JM7.2 while maintaining similar PSNR and bit rate.