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帧内预测是H.264编码中用来提升帧内编码压缩效率的编码工具,它通过计算和比较多种帧内预测模式下的宏块率失真代价,并选择最优的帧内预测模式来充分消除图像信号的空间冗余,提升视频信号帧内编码的压缩效率,但多种帧内预测模式下的宏块率失真代价计算使帧内编码运算量成倍增长,阻碍了其实际应用。为此,提出一种帧内预测模式判定快速算法,以提升H.264帧内编码的计算效率。该算法包括3个部分:1)加快4 4帧内预测模式判定的两级预测模式判定快速算法;2)加快宏块帧内预测模式判定的亮度分量帧内预测分区类型提前判定算法;3)融合上述2种算法的宏块帧内预测模式快速判定流程。测试结果显示,与H.264标准参考编解码器JM10.1相比,所提算法编码时间节省52%左右,峰值信噪比仅下降0.03 dB,码率增长约为2.5%。由此证明,所提算法能在保持视频压缩效率基本不变的前提下,有效提升视频编码的运算效率。
Intra prediction is a coding tool used to improve the intra-frame coding compression efficiency in H.264 coding. By calculating and comparing the macroblock rate-distortion costs in various intra-frame prediction modes and selecting the optimal intra-frame prediction mode The spatial redundancy of the image signal is fully eliminated, and the compression efficiency of the intra-frame coding of the video signal is improved. However, the calculation of the macroblock rate distortion cost in multiple intra-frame prediction modes double the intra-frame coding computational complexity, which hinders its practical application. Therefore, a fast intra-prediction mode decision algorithm is proposed to improve the computational efficiency of H.264 intra-frame coding. The algorithm consists of three parts: 1) fast two-stage predictive mode decision algorithm to speed up 4 4 intra-prediction mode decision; 2) fast intra-prediction partition type advance decision algorithm to determine the intra- Combining the above two algorithms, the macro block intra prediction mode fast decision process. The test results show that compared with H.264 reference codec JM10.1, the proposed algorithm saves about 52% coding time, the peak SNR decreases only 0.03 dB, and the code rate increases about 2.5%. It proves that the proposed algorithm can effectively improve the efficiency of video coding while maintaining the same video compression efficiency.