Video transcoder architectures for bit rate scaling of H.263 bit streams

Video transcoding is one of the key technologies in implementing dynamic adaptation of the bit rate of a pre-encoded video stream to the available bandwidth over various networks. Many different transcoder architectures have been proposed to achieve fast processing. However, they suffer from quality degradation due to the drift error. In this paper, we investigate the drift caused by the fast transcoder architectures for transcoding H.263 bitstreams. We also discuss the limitations of the existing fast transcoder architectures and the flexibility that can be offered by a cascaded pixel-domain transcoder. In favor of drift-free performance and transcoding flexibility, we propose methods to reduce the computational complexity of the cascaded pixel-domain transcoder.