Complexity Reduction Algorithms for MPEG-2 to H.264 Video Transcoding

The main design criterion of efficient transcoding system is to utilize the information embedded in coded bitstream to reduce the computational complexity of the transcoding. H.264 encoder spends significant time and computations to determine the best encoding mode for a Macroblock (MB) encoding mode. We propose to use MB encoding mode and residue statistics of MPEG-2 coded bitstream to decide on the best MB partition mode for H.264 encoding. Performance evaluations have shown that for similar objective and subjective quality, our proposed scheme can reduce the computational complexity to half as compared to the full decode-encode system, while transcoding at half the bitrate as compared to the MPEG-2 bitrate.