为了进一步提高编码效率，提出了一种新的H．264中Pslices帧间快速自适应模式判决算法。在该算法中，SKIP模式无需经过拉格朗日率失真优化就可以判定为最佳模式；P8×8模式也可以在拉格朗日率失真优化之前从候选模式中排除。通过对以上两种特殊模式的判决，可以大大减少整个编码时间。仿真结果表明，和H．264参考软件JM10．2相比，该算法在整个编码时间上节省60％～80％的时间，而在PSNR和码率上的变化则可以忽略不计。

A new fast and adaptive intermode decision algorithm for Pslices in H.264 is proposed in this paper. In the algorithm, SKIP mode is decided to be the best mode without Lagrange rate-distortion optimization(RDO), P8×8 mode is decided to be removed from the candidate modes before Lagrange RDO. With the above decision of the two special modes, the entire encoding time is greatly reduced. Simulation results show that the proposed algorithm can save 60%~80% entire encoding time with negligible variance in PSNR and bit rate compared to the H.264 reference software JM 10.2.