In: Multimedia Systems, Vol. 10, No. 3, pages 199-219. 2005.
Abstract: Slow access to disk-based multimedia data is a major limiting factor in the performance of modern multimedia Web servers connected over broadband networks. The I/O bottleneck becomes even more pronounced for currently evolving systems handling multimedia data, such as audio and video. Retrieval of complex multimedia documents needs to be handled at two levels: I/O bandwidth management for multiple multimedia streams, and interstream and intrastream synchronization for multimedia objects constituting these documents. In this paper, based on the diverse characteristics of multimedia data, we propose efficient techniques for synchronous retrieval and delivery of such data from the storage system to the main memory of the server. We propose methods to quantify user perceived quality via quality-of-presentation (QoP) parameters. We combine QoP and Object Composition Petri Net (OCPN) multimedia data modeling to develop techniques for efficient synchronous retrieval of multimedia data. Since I/O bandwidth is a precious resource, the proposed techniques have low overhead, which is O(n log n + mn) , where m is the number of logical I/O channels and n is the total number of frames of multimedia data in a scheduling period. We simulate the relative performance of these techniques under diverse I/O conditions and determine the tradeoffs between the system resources, such as memory, bandwidth, and the improvement in QoP for multimedia applications.