Donald Bren School of Information and Computer Sciences

Layered encoding is often recommended as a solution to the problem of varying bandwidth constraints in video multicast applications. However, multi-layered encoding of video is not sufficient to provide ideal video quality and bandwidth utilization, because network bandwidth constraints change over time. Adaptive techniques are required. In this paper we consider a rate-based Source-Adaptive Multi-layered Multicast (SAMM) algorithm that operates on an end-to-end basis. Video senders adapt the rates of their video layers in response to congestion feedback from receivers. To prevent feedback implosion, the use of computationally simple feedback merging servers is proposed. Network switches and routers are not required to implement complex flow or congestion control algorithms. The performance of the end-to-end SAMM algorithm is evaluated through simulations and compared with that of a non-source-adaptive mechanism.