"Resource Scheduling for Composite Multimedia Objects"

by Minos N. Garofalakis, Yannis E. Ioannidis, and Banu Özden.
Proceedings of VLDB'98, New York City, USA, August 1998, pp. 74-85.


Scheduling algorithms for composite multimedia presentations need to ensure that the user-defined synchronization constraints for the various presentation components are met. This requirement gives rise to task models that are significantly more complex than the models employed in scheduling theory and practice. In this paper, we formulate the resource scheduling problems for composite multimedia objects and develop novel efficient scheduling algorithms drawing on a number of techniques from pattern matching and multiprocessor scheduling. Our formulation is based on a novel sequence packing problem, where the goal is to superimpose numeric sequences (representing the objects' resource needs as a function of time) within a fixed capacity bin (representing the server's resource capacity). Given the intractability of the problem, we propose heuristic solutions using a two-step approach. First, we present a "basic step" method for packing two composite object sequences into a single, combined sequence. Second, we show how this basic step can be employed within different scheduling algorithms to obtain a playout schedule for multiple objects. More specifically, we present an algorithm based on Graham's list-scheduling method that is provably near-optimal for monotonic object sequences. We also suggest a number of optimizations on the base list-scheduling scheme. Preliminary experimental results confirm the effectiveness of our approach.

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