Architecture of HeiPhone: A Testbed for Audio/Video Teleconferencing

Due to recent advances in computer technology the integration of multimedia data with computing is becoming feasible. Such integration will allow for scenarios in which computer systems support collab-orative conferencing. We have developed a testbed for multimedia teleconferencing that is used to study experimental protocols that can manage and organize multiparty conferences and transmit digital video and audio data. We distinguish between real-time communication, which is needed to support the transfer of continuous-media data, and non-real-time communication, which is used to exchange control messages such as invitations to a conference. These communication types are supported by different communication stacks within our testbed: Digital video and audio are transmitted via ST-II and HeiTP with media-specific protocols on top of them and control information for conference management is transmitted via remote procedure calls (RPC). An overview of the working system, its current communication mechanisms, and the services provided is the subject matter of this paper.