An EFSM-based multimedia synchronization model and the authoring system

Multimedia synchronization is one of the key issues to be resolved in order to have smooth multimedia presentations. The demand of bringing multimedia information systems into distributed environments makes multimedia synchronization more difficult. In this paper, we apply extended finite state machines (EFSM) to formally specify multimedia synchronization among multiple media streams. Using the EFSM model, the intra-medium synchronization is handled by an actor, which is formally represented as an EFSM, The inter-media synchronization is handled by a synchronizer, which is also represented as an EFSM, Both centralized and distributed synchronization cases can be specified. Synchronizer and Actors achieve the corresponding multimedia presentations cooperatively. We also propose some policies to rectify the random delays caused by networks in the distributed presentation case. These policies, which can be formally specified in the corresponding EFSMs, are classified as intra-stream and inter-stream synchronization policies. Using the EFSM-based model, an authoring system and an associated experimental execution environment has been developed on SUN SPARC workstations.