Fast H.264/AVC to HEVC Transcoding Based on Compressed Domain Information

One of the most important issue in applying High Efficiency Video Coding (HEVC) is how to fast transcode data from H.264/AVC to HEVC, because there are a large amount of H.264/AVC devices and videos. In this paper, unlike the traditional transcoding algorithms and other existing methods, we present a novel fast transcoding approach by exploiting the temporal and spatial information in the compressed domain which comes from both the input H.264/AVC and the previously-encoded HEVC bitstream. To solve the key issue of enhancing the relevance between compressed domain and the decisions making process in HEVC, the basic features, such as motion vectors, dividing depths and bit allocations, are further processed and composed into complex features. In the re-encoding process, an approach based on Bayesian rule is utilized to help fast decide the coding unit size and partition mode with above features. Experimental results show that this proposed transcoding approach can significantly reduce the computational complexity while retaining high coding efficiency.