PostScript (112 KB)Algorithms and Performance Evaluation of the
Xphone Multimedia Communication System
Proceedings, ACM Multimedia '93 Conference, Anaheim, California, August 1993, pp. 311-320
Abstract
We describe and evaluate the performance of the algorithms used in Columbia University's "Xphone" multimedia communication system. The system assumes a "best-effort" operating system and network, and provides synchronized video/audio acquisition/playback (locally or across a network) with minimized and bounded end-to-end delay. Synchronization is achieved using an algorithm based on time-stamps and device state information. The effects of jitter (delay variation) are mitigated using silence detection; the end-to-end delay is kept bounded using a restart mechanism. Finally, for live video sources, we describe a source bit-rate adaptation algorithm that maximizes the video image quality to the available network bandwidth and video display window size.