Light-weight stream synchronization framework for multimedia collaborative applications

Today's Internet best-effort services introduce unavoidable uncertainties in the data transfer delay and create the need for synchronization mechanisms that preserve the temporal relationship among streams of distributed multimedia applications. We present algorithms for stream synchronization that are immune to moderate clock skew between sender and receivers and take into account the different time constraints of each media. In our time model, we introduce the idea of virtual observer, which perceives the session as being in the same room with a sender. We propose policies for delay management and special consideration is given to the time the algorithms take to reach steady state. We avoid the need for globally synchronized clocks for media synchronization by introducing the concept of user's multimedia presence, which defines a new manner for combining streams coming from multiple sites. Finally, we evaluate this framework with traces collected from the Internet.