A model for editing operations on active, Temporal multimedia documents

Inclusion of content with temporal behavior in a structured document leads to such a document gaining temporal semantics. If we then allow changes to the document during its presentation, this brings with it a number of fundamental issues that are related to those temporal semantics. In this paper we study modifications of active multimedia documents and the implications of those modifications for temporal consistency. Such modifications are becoming increasingly important as multimedia documents move from being primarily a standalone presentation format to being a building block in a larger application. We present a categorization of modification operations, where each category has distinct consistency and implementation implications for the temporal semantics. We validate the model by applying it to the SMIL language, categorizing all possible editing operations. Finally, we apply the model to the design of a teleconferencing application, where multimedia composition is only a small component of the whole application, and needs to be reactive to the rest of the system. The primary contribution of this paper is the development of a temporal editing model and a general analysis which we feel can help application designers to structure their applications such that the temporal impact of document modification can be minimized.