Fast mode decision algorithm using efficient block skip techniques for H.264 P slices

Abstract

In this paper, we propose a fast algorithm that can reduce the complexity for inter mode decision of the H.264 encoder by minimizing a large number of calculations of inter mode decision process adaptively. The main idea is to use the technique skipping unnecessary macroblock modes. We focus on two block size modes, which is 16x16 and 8x8 block size modes, in proposed algorithm. The percentage of 16x16 block size modes is the largest in most of the sequences. This means that many redundant mode calculations can be removed. The percentage of 8x8 block size mode is small. But time consumption caused in the mode decision of encoder is very considerable. Therefore if we can extract the unnecessary 8x8 block size mode calculation well, a large amount of time can be saved in total encoding process. The experimental results show that the proposed algorithm can achieve up to 43% speed up ratio with a little PSNR loss. Increase of total bits encoded is also not much noticeable.