Content-based transcoding for dynamic video transmission

Video transcoding is one of the key technologies in implementing dynamic bit rate adaptation of a pre-encoded video stream to the available bandwidth over various networks. Though there have been many different transcoding schemes, since they do not concern the contents of video, the quality of transmitted video becomes proportionally worse as the rate of reduction increases. In this paper, we propose a content-based MPEG transcoding method using a discontinuity feature in the Discrete Cosine Transform (DCT) domain. The discontinuity heights in DCT blocks are evaluated by a method of model-based DCT alignment, and a DCT block is transcoded differently depending on the height of a block. In the experiment, we show the result that the video quality of content-based transcoding is better than that of a constant cut-off method and the processing time of the adaptive method is much faster compared with the pixel domain methods in the same bandwidth.