Abstract

A distributed multimedia document presentation involves retrieval of objects from one or more servers and their presentations at a client system. The retrieval and presentation of media objects have to be carried out in accordance with some temporal specification, i.e. temporal synchronization. In this thesis, we design and implement a synchronization scheduler in a distributed multimedia presentation system. First, we develop an interval constraint graph model to describe the temporal relationships among media objects. Second, based on the model, we give a way to produce an optimal schedule from a set of constraints using a linear programming solver. Third, we develop a run time rescheduling strategy to correct dynamic synchronization errors by means of a retiming method. Finally, we implement the scheduler in a simulated distributed environment to demonstrate its usefulness and effectiveness. The interval constraint graph model we developed takes into account the QoS of temporal constraints of a multimedia document. Our flexible temporal model can help to derive an optimal schedule and carry out run time rescheduling. Then, a multimedia document can be presented with better qualities of temporal constraints, or leading to a better presentation.