LOW-COMPLEXITY VIDEO CODING FOR RECEIVER-DRIVEN LAYERED MULTICAST

In recent years, the ''Internet Multicast Backbone,'' or MBone, has ri sen from a small, research curiosity to a large-scale and widely used communications infrastructure. A driving force behind this growth was the development of multipoint audio, video, and shared whiteboard conf erencing applications. Because these real-time media are transmitted a t a uniform rate to all of the receivers in the network, a source must either run at the bottleneck rate or overload portions of its multica st distribution tree. We overcome this limitation by moving the burden of rate adaptation from the source to the receivers with a scheme we call receiver-driven layered multicast, or RLM. In RLM, a source distr ibutes a hierarchical signal by striping the different layers across m ultiple multicast groups, and receivers adjust their reception rate by simply joining and leaving multicast groups. In this paper, we descri be a layered video compression algorithm which, when combined with RLM , provides a comprehensive solution for scalable multicast video trans mission in heterogeneous networks. In addition to a layered representa tion, our coder has low complexity (admitting an efficient software im plementation) and high loss resilience (admitting robust operation in loosely controlled environments like the Internet). Even with these co nstraints, our hybrid DCT/wavelet-based coder exhibits good compressio n performance. It outperforms all publicly available Internet video co decs while maintaining comparable run-time performance. We have implem ented our coder in a ''real'' application-the UCB/LBL videoconferencin g tool vie. Unlike previous work on layered video compression and tran smission, we have built a fully operational system that is currently b eing deployed on a very large scale over the MBone.