Describing and processing multimedia objects by Petri Nets

In this paper we show how we can synthesize multimedia structures by executing formal models. The kind of model used here is an `ad hoc' arrangement of Petri Nets and a multimedia algebra; multimedia objects are associated to places; music transformations are described by algorithms associated to transitions and coded by expressions based on the set of operators and on syntactic rules defined for this project. This approach allows the description of multimedia objects, as well as their transformation, at various levels of representation, with an interactive graphic user interface. We discuss how Petri Nets (PNs) can be used for describing and structuring MultiMedia Processes (MMPs). We define the notion of MultiMedia Petri Net Model (MMPNM), to describe a multimedia `score' that integrates different media such as video sequences, digital audio and MIDI sequences. We refer to MediaSynth, a software system we have developed as experimental tool. MediaSynth is an integrated environment for the construction of MMPNMs.