Reverse playback of MPEG video from a random access source takes advantage of the symmetry of B frames within an IB data stream. The IB data stream is processed by a parsing algorithm to identify within the B frames during playback those bits associated with motion vector identification and values...http://www.google.com.tw/patents/US5739862?utm_source=gb-gplus-share專利 US5739862 - Reverse playback of MPEG video
