A Time Efficient Architecture for Multimedia Applications

This paper presents an architecture that enforces time requirements and gives minimal end-toend delays for multimedia applications. The layers and mechanisms allowing the system to fulfil the selected synchronisation, i.e. the logical relationships and timed interval semantics, are presented. The proposed approach relies on the use of a formal model based on extended time Petri nets, i.e. the Time Stream Petri Net model (TStreamPN), that allows the user to completely specify the time requirements of a given application. The architecture implements, in the application layer and on top of asynchronous environments, the requested quality of service (perceived by the user) with respect to time. At the transport layer, the use of a partial order transport service improves the reactive response of the communication transfers. Its principles are presented together with a pre-synchronisation sub-layer, that makes the partial order transport service match the applicative synchronisation requirements. Moreover, measurements on the implementation of a videoconference system show that the requirements of the quality of service are fulfilled. Keywords Multimedia communication architecture, multimedia synchronisation, real-time presentation, partial order transport, videoconference