Retrieval in Multimedia Presentations

In this paper we discuss issues about consistently retrieving parts of multimedia presentations from multimedia repositories. We introduce a class of multimedia presentations made of independent and synchronized media, and discuss retrieval requirements of presentation fragments. Then we discuss a retrieval model able to reconstruct the fragments of a presentation from the atomic components returned by the execution of queries to multimedia presentation repositories. The retrieval model is based on an automaton which formally describes the presentation states entered by the events which trigger media playback. Retrieving a consistent fragment corresponds to building a new presentation with all the media related to the retrieved ones, with their original structural and synchronization relationships.