针对H.264中模式选择计算复杂度高的问题，提出一种快速模式选择算法。根据帧间编码最佳模式的统计规律，找出宏块的时间空间特性与最佳模式的关系，在帧间模式选择的各个阶段，检测宏块的时间空间特性，一旦满足相应的残差一致性条件或空间一致性条件，则提前终止模式选择。实验结果表明，该方法在输出比特率平均升高2.11%的情况下，编码时间能平均减少23.11%，峰值信噪比平均提高0.058dB。

To simplify the computational complexity in mode selection process for H.264,a fast mode decision algorithm is proposed in this paper.According to the statistical rule of the best mode chosen by inter frame,the relationship of the temporal and spatial characteristics with the best mode is found. At each stage of inter mode selection,the temporal and spatial characteristics of macroblock(MB) are detected,once the residual homogeneous or spatial homogeneous conditions are satisfied,the mode selection process is terminated.Experimental results show that this method can make the encoding speed accelerate about 23.11% and peak signal to noise ratio(PSNR) improve about 0.058dB,with only 2.11% increase about bit rate.