N-Way Conferencing with Packet Video.

摘要

Packet switching technology promises to allow improvement of video quality by efficiently supporting variable-rate video coding. Its inherent multiplexing of multiple streams also allows more efficient multi-destination delivery for N-way conferencing. However, most commercial video codecs are designed to work with circuits, not packets, in part because these benefits are accompanied by some problems. This paper describes a packet video system implementation in which commercial codecs were adapted to exploit the benefits of packet switching while addressing the problems as follows: 1) clock synchronization was obviated by asynchronous operation; 2) delay was reduced by bandwidth reservation and fast packet forwarding; and 3) packet loss was reduced by bandwidth reservation and forward error correction. An overview of the system is followed by sections addressing each of the problems and benefits, plus future directions for expansion of the system. (rh)