VAMP: a service for validating MPEG-7 descriptions w.r.t. to formal profile definitions

MPEG-7 can be used to create complex and comprehensive metadata descriptions of multimedia content. Since MPEG-7 is defined in terms of an XML schema, the semantics of its elements has no formal grounding. In addition, certain features can be described in multiple ways. MPEG-7 profiles are subsets of the standard that apply to specific application areas and that aim to reduce this syntactic variability, but they still lack formal semantics. We propose an approach for expressing the semantics explicitly by formalizing the constraints of various profiles using ontologies, logical rules and ad-hoc programming, thus enabling interoperability and automatic use for MPEG-7 based applications. We have implemented VAMP, a full semantic validation service that detects any inconsistencies of the semantic constraints formalized. Another contribution of this paper is an analysis of how MPEG-7 is practically used. We report on experiments about the semantic validity of MPEG-7 descriptions produced by numerous tools and projects and we categorize the most common errors found.