Implementation and performance analysis of a multimedia synchronizer.

Abstract

Synchronization is a crucial problem for distributed multimedia systems and has been the subject of a great many research investigations at all levels of a multimedia system, and on several of their components concerned with the issue of synchronization: the databases, the communication system, the operating system, the documents, applications themselves. Indeed, in the case of multimedia presentational applications, an efficient management of communication resources and the eventuality of having the data of different media types stored on distributed media-storing database servers requires the use of independent network connections for the transmission of each medium to a remote workstation. In this thesis, the implementation of a complete software synchronization control system for presentational application is described. In the target application--a News on Demand Application--a user wants to retrieve a multimedia document from a distributed database. Each medium present in the article is stored independently from the others and retrieved by its own media server. The synchronization among the media is achieved in two steps. Using a pre-defined scenario and QoS guarantees supported by ATM based virtual connections, a delivery schedule is derived and passed to each server, so that they can transmit the appropriate media subjects at the scheduled times, compensating for the delays and delay variations introduced by the network, and eventually the decoders. Additionally the Stream Synchronization Protocol (SSP) performs rescheduling operations at the client site to recover from jitters on the network and provide the user with a better and more acceptable service. The various components (database, client application, graphical interface) of this system, their software modules, and their interactions are described thoroughly. (Abstract shortened by UMI.)