Specifying Multimedia QoS Parameters and Synchronization using

A distributed multimedia system (DMS) involves the transmissions of different types of data over the same or different communication channels. Data include noncontinuous ones, like text and image, and continuous ones, like video and audio, which are characterized by time. A specification language to specify multimedia Quality of Service (QoS) parameters synchronisation mechanisms, it must be able to support the timing relationship between different types of data. Estelle, an internationally standardized Formal Description Technique (FDT) for specifying communication protocols and distributed systems, does not have enough expressing power to specify the timedependent behaviours of a module of a distributed system. To address this limitation, we have developed an extended Estelle, called Time-Estelle [1] which is capable of describing QoS parameters and synchronization requirements of a DMS. In this paper, we first present a review of QoS formal specification, then Time-Estelle, and finally describe the application of TimeEstelle to specify some QoS parameters and synchronization mechanisms for a DMS.