That Obscure Object of Desire: Multimedia Metadata on the Web (Part II)

This article discusses the state of the art in metadata for audio-visual media in large semantic networks, such as the Semantic Web. Our discussion is predominantly motivated by the two most widely known approaches towards machine-processable and semantic-based content description, namely the Semantic Web activity of the W3C and ISO's efforts in the direction of complex media content modeling, in particular the Multimedia Content Description Interface (MPEG-7). We explain that the conceptual ideas and technologies discussed in both approaches are essential for the next step in multimedia development. Unfortunately, there are still many practical obstacles that block their widespread use for providing multimedia metadata on the Web. Based on a scenario to explain our vision of a media-aware Semantic Web, we derive in Part I a number of problems regarding the semantic content description of media units. We then discuss the multimedia production chain, in particular emphasizing the role of progressive metadata production. As a result we distill a set of media-based metadata production requirements and show how current media production environments fail to address these. We then introduce those parts of the W3C and ISO standardization works that are relevant to our discussion. In Part II of this article, we analyze their abilities to define structures for describing media semantics, discuss syntactic and semantic problems, ontological problems for media semantics, and the problems of applying the theoretical concepts to real world problems. Part II concludes with implications of the findings for future action with respect to the actions the community should take.