Requirements for practical multimedia annotation

Applications that use annotated multimedia assets need to be able to process all the annotations about a specific media asset. At first sight, this seems almost trivial, but annotations are needed for different levels of description, these need to be related to each other in the appropriate way and, in particular on the Semantic Web, annotations may not all be stored in the same place. We distinguish between technical descriptions of a media asset from content-level descriptions. At both levels, the annotations needed in a single application may come from different vocabularies. In addition, the instantiated values for a term used from an ontology also need to be specified. We present a number of existing vocabularies related to multimedia, discuss the above problems then discuss requirements for and the desirability of a lightweight multimedia ontology.