New architecture for enforcing multimedia synchronization in videoconferencing applications

This paper presents a formally defined architecture allowing the design and the corresponding implementation of a set of modules that fulfill the quality of service requirements of PNSVS (Petri Net Synchronised Videoconference System), an application designed to run on top of an asynchronous environment. It describes the mechanisms and architecture allowing the system to enforce the temporal synchronisation between the audio and video streams, the presentation quality, and the end to end delay. This synchronisation method relies on a formal model extending time Petri nets : the Time Stream Petri Net model (TSPN), that will be used to completely specify the time constraints of the application streams. From this, the communication architecture is improved by introducing a new partial order transport service that maximizes the PNSVS quality of service. The partial order transport principle is presented together with the pre-synchronisation sub-layer, which makes the partial order transport service match the applicative synchronisation requirements. Moreover, it will be shown that each layer of this synchronisation architecture can be formally modeled by a welle defined set of TSPN models.