TEMPORAL SYNCHRONIZATION SUPPORT FOR DISTRIBUTED MULTIMEDIA INFORMATION-SYSTEMS

In distributed interactive multimedia information systems (DMIS), info rmation of multiple media types is involved in an application. Informa tion in these different media types is related and has to be presented in a specified order. To achieve this, a synchronization scheme is re quired to orchestrate the presentation of these media. There are four media synchronization requirements in DMIS: (1) to provide a means for users to specify media relationships expressively; (2) to ensure a sm ooth playback of the continuous media; (3) to ensure intermedia synchr onization by overcoming the stochastic network access delay and host p rocessing delay through proper transmission scheduling and buffer mana gement; and (4) to support user interactions and to provide anomaly sy nchronization. This paper presents a synchronization scheme that can m eet these requirements. In the scheme, media relationships are specifi ed using an expressive script language that is being developed. A pres entation schedule can then be generated from the script specifications . The presentation schedule is maintained by controlling the request t imes of data transfer for different media streams and by providing sui table buffers at the receiver. The main feature of the proposed scheme is that it can be used in general DMISs where the inter-media relatio nships are complex and the media data is stored in more than one serve r in the network. The scheme has been tested on an Ethernet-Unix platf orm and has proved to be reliable.