Synchronization representation and traffic source modeling in orchestrated presentation

Multimedia applications comprise several media streams, which are semantically synchronized at different time instants. The application behavior is stored along with the multimedia database using representation mechanisms such as OCPN (object composition Petri nets) or dynamic timed Petri nets (DTPN). It is imperative that one translates the application behavior to the corresponding schedulable entities, such as packets, so that the performance engineering of any system can be done, using the traffic model arising out of the (media related) application behavior as opposed to individual media level behavior. This requires that a function be defined, which takes the stored temporal representation as input and produces packets as output, preserving the semantic relationships among the streams. The authors propose a methodology based on probabilistic, attributed context free grammar (PACFG) to address this issue. They demonstrate the appropriateness of this methodology by applying it to the OCPN/DTPN representation of a typical multimedia application vis-a-vis orchestrated presentation.