Synchronization mechanisms for distributed multimedia presentation systems

We present some mechanisms to ensure synchronization in distributed multimedia presentations, in the presence of multiple remote sources, limited network bandwidth, statistical network delays, and asynchronous user interaction. The various network problems are modelled as bounded probabilistic delays. Using an interval based presentation schedule, the mechanisms predict the optimal time to initiate the request for the multimedia objects. From the presentation schedule, we construct a presentation graph using a timed Petri net structure with additional time parameters. The new time parameters provide a greater modelling power to the Petri net representation and thus provide ways to capture special user interaction. In particular, using the concepts of hypermedia links and parallel temporal relations we extend the hierarchical modelling capability of the Petri net representation to form a global presentation graph, with which the mechanisms support asynchronous user modification of the presentation sequence.