中文摘要：

针对H.264编码算法中,预测帧（P帧）编码模式的选择过程异常复杂,开销大的问题,提出了一种新的快速模式选择算法,该算法利用直流系数能预先判定P帧编码模式的有效范围,缩小备选编码模式的可选范围,从而使模式选择的复杂度大为降低。实验结果表明,该算法可以使编码时间降低54%～74%,峰值信噪比提高0.05 dB～0.17 dB,同时码率变化范围为-3.14%～3.97%。应用结果表明,该算法在基于TI＇s TMS320DM642视频压缩系统中1路D1视频的压缩速度为25帧/s。

英文摘要：

The procedure of mode checking is very complex.It costs much time for predictive-frame（P-Frame） in the encoding algorithm of H.264.In this paper,a fast mode checking algorithm is presented to reduce the complexity of mode checking procedure based on direct current（DC） coefficient by reducing the number of modes required to be checked.Experimental results show that the proposed algorithm can reduce the encoding time by 54%～74% and increase the peak signal-to-noise ratio（PSNR） by 0.05 dB～0.17 dB while incurring up to 3.14% reduction or up to 3.97% increment on the total bit rate.Application shows that its encoding speed is 25 frames per second in a video encoder with TI’s TMS320DM642 for D1 video signal.