A unified transcoding approach to fast forward and reverse playback of compressed video

We propose a unified approach for realizing fast-forward and fast-reverse playback of a pre-coded video by generating a new and lower-bit rate video through video transcoding. To reduce the computational complexity, we develop fast algorithms to estimate the motion vectors required for transcoding the video. To accommodate changes due to frameskipping and to sustain satisfactory coding efficiency, we adaptively alter the group-of-pictures structure of the transcoded video to suit for different playback speeds. Subjective tests are conducted to assess the perceived quality of video played back at various fast speeds. Experimental results and complexity analysis are presented in this paper to show the efficacy of the proposed approach.