Joint source and channel rate allocation for video transmission over erasure channels

This paper presents a joint source and channel rate allocation algorithm for video transmission over erasure channels. The approach relies on unequal error protection (UEP) of the video stream, in order to minimize the received signal distortion. It takes into account both the frames and the channel characteristics. The loss behavior is approximated by a two states Markov model. The algorithm is incorporated in a H.263 version 2 compliant encoder. The encoder supports in addition a TCP-compatible (TCPC) congestion control mechanism and adapts the coding mode of each macro-block (MB) to the network loss behavior. Rate-distortion models are introduced in order to reduce the computational cost. A new payload format is also described for the transport of the streams over RTP. The overall approach, compared against equal error protection and against FEC-forward error correction- adapted to the channel only, leads to improved PSNR performance, with a more stable video quality.