We propose in this paper a formal methodology that improves the temporal consistency verification of multimedia presentations. It extends the standard approaches to check over inconsistencies due to output resource conflicts. This goal is achieved thanks to the definition of a new model that extends time Petri net to preemptor hyperarcs. This specification framework called preemptive resource time Petri nets (PRTPN) makes it possible to model correctly and accurately output resource requirements. A special attention is given to the modelling of user interactions when resource constrained. In order to be able to derive the reachability graph of this specification, the syntax and the formal semantics of the model are provided. The obtained graph is used in the verification of inconsistencies due inter alia to resource conflicts; hence a new paradigm called 'qualitative consistency' is defined.