Methods for matching compressed video to ATM networks

Over the last few years three technologies have reached the stage of maturation where then can become synergistic. These are wideband, high speed networking, high quality video compression (MPEG-I and II), and high capacity affordable digital storage media. This paper addresses the interaction of these three technologies. In particular, it examines the problem of taking a compressed video data stream that is stored on a server, and transmitting it over an ATM channel which has a capacity smaller than that required by the data stream. The conventional approach to this problem would be to transcode by decoding the video data, and then re-encoding so as to meet the channel constraints. Currently this is not a cost effective solution since, while MPEG decoders are relatively inexpensive, encoders are not. Our approach to this problem is to partially decompress the video bitstream. Then, perform the transcoding in the quantized data domain. Finally, a valid bitstream is reassembled and transmitted. This approach has the advantage of providing nearly identical quality as the traditional transcoding approach, at a fraction of the hardware cost.