Efficient 16×16 block size mode detection in H.264

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 amount of calculation of inter mode decision process adaptively. We focus mainly on extracting the large block size mode, which is 16x16 mode, efficiently. From examination of various sequences, we know that the percentage of large block size mode which selected in best mode is highest of all possible modes. Therefore the efficient filter to extract large block size mode early is proposed in this paper. When the proposed algorithm is adopted in H.264, encoder is shown to have good performance in terms of time saving. The experimental results show that the proposed algorithm can achieve up to 39% speed up ratio with a little PSNR loss. Increase of total bits encoded is also not much noticeable.