Transmitting additional data of MPEG-2 compressed video to support interactive operations

We address the problem of supporting interactive playout, both forward and backward, of MPEG-2 encoded video stream. Typically, the forward and backward operations are used mainly in the form of fast forward (FF) and fast backward or fast rewind (FR). The proposed approach is based on transmitting additional data of the same movie from the server to the digital storage device (DSD) in a client station. The server responses to FF/FR request by switching via the digital device from normal version to appropriate FF/FR version. The special additional data consists solely of I frames by removing the P and B frames and showing only the I frames. The alternative "interactive" data is generated from the storage at the server every n-th frame from the original MPEG-2 compressed video. Interactive operations are supported using extra network bandwidth than that is already allocated for normal playback. Specifically the server can decide the bit rate of the additional data, required for transmission to the digital device by varying the frame rate (number of I frames/sec), depending on the availability of the network bandwidth.