Retrieval in Multimedia Presentations

In this paper we discuss issues concerning the consistent retrieval of 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 capable of reconstructing 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 that formally describes the presentation states entered by the events that 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.