A Fast Macroblock Inter Mode Decision Algorithm for H.264

This paper proposed a fast mode decision algorithm for H.264. It performs SKIP mode test firstly. If the SKIP mode is not suitable for the current MB, it performs 16times 16 mode test secondly. If the 16 times 16 mode is not suitable for the current MB, candidate modes for current MB are inferred from given coded correlated MBs by adopting the information of defined mode subsets. Then bottom-up merging and top-down splitting methods are developed based on spatial correlation of MBs. A partial RDO approach which involved these methods is applied to the candidate modes to make target mode selection. Simulation results demonstrate that the proposed algorithm can achieve up speed up 56.56% ~ 81.54% ratio with a little PSNR loss. Increment in bit requirement is also not much noticeable.