This paper proposes a lossless re-encoding scheme for video data which are already encoded by the MPEG-1 video coding standard. In order to avoid any additional loss of quality, quantized DCT coefficients and motion vectors extracted from the original MPEG-1 bitstream are losslessly re-encoded using an adaptive arithmetic coder. Probability models used in the arithmetic coder are iteratively optimized so that the number of coding bits required for the whole group of pictures (GOP) can be a minimum. Furthermore, H.264-like block-adaptive intra prediction is introduced into not only I pictures but also P and B pictures to exploit inter-block correlations of the DCT coefficients. Simulation results indicate that the proposed scheme can reduce the coding rate of monochrome MPEG-1 video by 12–22 %.
['Ichiro Matsuda', 'Kei Wakabayashi', 'Yu Ikeda', 'Susumu Itoh']
A lossless re-encoding scheme for MPEG-1 video