MPEG-4 to H.264 transcoding

In this paper, a temporal resolution reduction transcoding method that transforms an MPEG-4 video bitstream into an H.264 video bitstream is proposed. The block modes and motion vectors in the MPEG-4 bitstream are utilized in the H.264 encoder for block mode conversion and motion vector interpolation methods. The proposed four types of motion vector interpolation methods are developed not to perform brute-force motion estimation again in the H.264. In the experimental results, the proposed methods achieve 3-4 times improvement in computational complexity compared to the cascade pixel-domain transcoding, while the PSNR (peak signal to noise ratio) is degraded with 0.2-0.9dB depending on the bitrates.