A cooperative playback system for on-demand multimedia sessions over Internet

IP multicast has fueled an assortment of large-scale applications over the Internet ranging from interactive video conferencing to whiteboards to video recording on-demand systems. Such applications are mainly based on the lightweight session model and on Internet standard protocols. In particular, video recording on-demand systems allow a remote client to request recording of an advertised multimedia session and playback of sessions previously archived. They are primarily designed for serving the needs of a single user who wishes, for instance, to watch a movie or to attend a recorded seminar. No groupware support is normally offered. We introduce the cooperative playback systems, which enable explicitly grouped users to jointly work and cooperatively control playbacks of on-demand multimedia sessions. We also present a multicast control streaming protocol based on an extension of RTSP adapted on top of LRMP, and illustrate our Java-enabled cooperative playback system, ViCRO/sup c/.