A client/server application as an example for MPEG-4 systems

One of the most important standardization efforts in the broad field of audio-visual coding is MPEG-4 which introduces objects as smallest accessible units inside frames. This conceptual step forward led to completely new possibilities for applications using content-based scalability or content-based interactivity. When MPEG-4 started in 1994 it was no more than an ambitious vision. Then, in March 1998, it received the status of the final committee draft of an international standard and it is certainly a milestone in realizing second-generation audio-visual communication systems. In this paper, we give a brief introduction to MPEG-4 systems terminology and discuss the set-up procedure of an application using MPEG-4 systems. We present a prototype implementation of a video-on-demand application that enables distributed event handling of object-related events created by a user. Our system consists of a client/server architecture, where the client side handles events like zooming or moving single video objects at presentation time, while the server side manages user control concerning the quality of a lossy encoding of the single video objects. The system is introduced by means of OMT diagrams, status diagrams and block diagrams.