Modeling, Analysis and Implementation of Actor-based Multimedia Systems

This paper presents an approach centered on a time-sensitive Actor framework suited to the modeling, analysis and implementation of multimedia systems. A distributed multimedia system consists of a collection of autonomous media actors interacting to one another to fulfil a common goal, e.g., interactive videoconference, video recording on-demand, etc. Timing synchronization activities rest on reflective Actors (QoSsynchronizers) which filter inter-communication messages and constrain them according to application-dependent QoS parameters. The synchronizers have a link with a constraint-directed scheduling structure that can be customized through programming. In order to support timing QoS constraints validation and to analyze the time-dependent dynamic behavior of a multimedia system and its associated parameters, the modeled media actors are prototyped under simulation, by exploiting a flexibility of the adopted actor framework to be transparently operated under real or virtual time. The approach smoothes the transition of media actors from the prototyping to the real operating environment, by changing the time notion in the scheduler. The transition from the modeling, to analysis, down through to the implementation stages is seamless. The proposed methodology is applied to the development and analysis of an application-level inter-media stream synchronization filter of multimedia sessions both live and on-demand.