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 qual ity of service requirements of PNSVS (Petri Net Synchronized Videoconferenc e System), an application designed to run on top of an asynchronous environ ment. It describes the mechanisms and architecture allowing the system to e nforce the temporal synchronization between the audio and video streams, th e presentation quality, and the end to end delay. This synchronization meth od relies on a formal model extending time Petri nets: the Time Stream Petr i Net (TSPN) model, that will be used to completely specify the time constr aints of the application streams. From this, the communication architecture is improved by introducing a new partial order transport service that maxi mizes the PNSVS quality of service. The partial order transport principle i s presented together with the pre-synchronization sub-layer, which makes th e partial order transport service match the applicative synchronization req uirements. Moreover, it will be shown that each layer of this synchronizati on architecture can be formally modeled by a well defined set of TSPN model s.