H-SMIL-Net: A Hierarchical Petri Net Model for SMIL Documents

We propose in this paper a hierarchical and temporal extension of Petri Nets for the incremental authoring of SMIL multimedia documents. The complexity of these documents can lead authors, in some cases, to specify synchronization relations which could not be satisfied during the presentation of the document, what characterizes the occurrence of inconsistencies; a consistency checking mechanism is then necessary. This new model, named H-SMIL-Net (Hierarchical SMIL-Petri Net) proposes a technique for the incremental verification of temporal consistency. The originality of the solution resides in the modular aspect of the modelling, and the local approach of verification, what optimizes the verification time after each editing operation. This formal approach has been integrated in an incremental authoring tool for SMIL presentations.