The Effects of High-Performance Processors, Real-Time Priorities and High-Speed Networks on Jitter i

Multimedia applications have the potential to enhance work for teams of users collaborating across distances. Jitter hampers the e ectiveness of these multimedia applications. Jitter is the variation in the end-to-end delay of data sent from one user to another. Jitter can cause silent gaps in the playout of an audio stream such as in an audioconference, or a choppy appearance to a video stream for a videoconference. We experimentally measure the e ects of three jitter reduction techniques: high-performance processors, real-time priorities and high-speed networks. We incorporate our jitter measurements into a general model for multimedia application quality. Our model allows us to explore how advances in networks and processors will improve application quality compared with real-time priorities. As an example, we apply our model to a videoconference. We nd high-performance processors, real-time priorities and high-speed networks all signi cantly reduce jitter under conditions of heavy processor and network load. For the next ve years, processor and network improvements alone will not reduce jitter enough to eliminate the need for application bu ering techniques. However, for multimedia on a LAN, real-time priorities can reduce jitter enough to eliminate the need for application bu ering today. On a WAN, especially the Internet, real-time priorities may not be available on all routers, reducing the e ectiveness of real-time priorities in reducing jitter. In this case, bu ering techniques may still be needed.