Multimedia Synchronization Protocols for Broadband Integrated Services

Synchronization of multiple data streams in time has been recognized as a significant requirement of future multimedia applications utilizing broadband communication technology. Although this requirement has been approached for such single channel media as packetized audio and video, a general solution has not been identified for the provision of synchronization of real-time stream traffic as well as pre-orchestrated stored data to support multimedia applications. In this paper we propose protocols to provide synchronization of data elements with arbitrary temporal relationships of both stream and non-stream broadband traffic types. We indicate how the synchronization functionality can be carried out within a packet-switched network and, accordingly, present a two-level communication architecture. The lower level, called the network synchronization protocol (NSP), provides functionality to establish and maintain individual connections with some specified synchronization characteristics. The upper level, the application synchronization protocol (ASP), supports an integrated synchronization service for multimedia applications. The ASP uses temporal relationships of an application’s data objects and manages the synchronization of arriving data for playout. The proposed NSP and ASP are mapped to the session and application layers of the OSI reference model, respectively.