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.