Video Conferencing over Packet-Based Networks

The Internet explosion is driving the need for new collaboration tools which will enable two or more users to share data, audio and video. The real-time packet-based solutions which are emerging differ considerably from the circuit switch solutions which have existed for some time now. In this paper we present one such packet-based approach, the Multimedia Multiparty Teleconferencing (MMT ) system, which was fully implemented as a research prototype. Using MMT as an example, we address some of the fundamental issues related to videoconferencing systems in a packet-based environment and discuss the differences with the traditional circuit switch approaches, namely the ITU H.320 standard. In particular, MMT is a distributed solution while H.320 is centralized. The use of multicast and a novel video mixing technique to facilitate the distributed solution are presented. Furthermore, MMT audio and video streams are susceptible to congestion and packet loss in the shared media packet-based environment while H.320 streams use dedicated connections. As such, synchronization and rate control schemes for the packet-based system are presented.

By: Marc H. Willebeek-LeMair and Zon-Yin Shae

Published in: RC20480 in 1996


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