ACM Transactions on Computer Systems (TOCS)
The evolution of DVI system software
Communications of the ACM
Time, clocks, and the ordering of events in a distributed system
Communications of the ACM
Digital Video in the PC Environment
Digital Video in the PC Environment
Synchronization properties in multimedia systems
IEEE Journal on Selected Areas in Communications
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The integration of continuous presentation media like audio and video into current workstation and networking environments imposes tight timing constraints on A/V data transfer. These constraints are summarized under the term Quality of Service (QoS), which comprise a number of parameters. Among those, delay and delay jitter are the most important. In the study presented in this paper, measurement and modelling methods have been applied to analyse the delay and delay jitter incurred by audio/video streams. An experimental audio/video distribution system called HeiDi (Heidelberg A/V Distribution System) intended for the fully digital distribution of compressed, packetized audio and video over a token ring local area network served as testbed for the analysis. Measurements were conducted with the ZM4 (abbreviation for the German name Zahlmonitor 4) monitoring system developed at the University of Erlangen-Nurnberg especially for performance analysis of distributed systems. For modelling, Monitoring Petri Nets are used, a class of Petri nets which lends itself well for the integration of measurement and modelling. Results indicate that the audio/ video subsystem and the communication subsystem must be closely integrated to yield a sufficient performance.