TEMPORAL SYNCHRONIZATION SUPPORT FOR DISTRIBUTED MULTIMEDIA INFORMATION-SYSTEMS

In distributed interactive multimedia information systems (DMIS), information of multiple media types is involved in an application. Information in these different media types is related and has to be presented in a specified order. To achieve this, a synchronization scheme is required 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 smooth playback of the continuous media; (3) to ensure intermedia synchronization by overcoming the stochastic network access delay and host processing delay through proper transmission scheduling and buffer management; and (4) to support user interactions and to provide anomaly synchronization. This paper presents a synchronization scheme that can meet these requirements. In the scheme, media relationships are specified using an expressive script language that is being developed. A presentation schedule can then be generated from the script specifications. The presentation schedule is maintained by controlling the request times of data transfer for different media streams and by providing suitable buffers at the receiver. The main feature of the proposed scheme is that it can be used in general DMISs where the inter-media relationships are complex and the media data is stored in more than one server in the network. The scheme has been tested on an Ethernet-Unix platform and has proved to be reliable.