The document summarizes a system called CA3M (Context-Aware Mobile Multimedia Service) that provides multimedia content with semantic metadata and handles context and uncertainty. It converts MPEG-7/MPEG-21 multimedia files to RDF/OWL format using an MPEG-7 ontology. A context reasoner uses SPARQL queries to search multimedia based on semantic context types while managing uncertainty through clustering and user feedback. The system was evaluated within a cluster of excellence for applications in cultural heritage, mobile guides and games.