The model for Enhanced Multimedia Meta Objects (EMMOs) was developed from the intuition that in a knowledge and content sharing economy, different applications would need to adhere to open standards with respect to the containers that knowledge and media objects are delivered in. The idea was to standardise a number of interfaces that such container objects would require. Examples are interfaces for querying the ontology, for accessing digital rights information, and for adding further knowledge to an existing EMMO, using different authoring tools.
The project developed a formal model of EMMOs whose most important characteristic is the ability to combine three views on the semantics of content:
- Media related semantics (as covered by the MPEG standards),
- Domain specific semantics (as expressed in a domain specific ontology),
- Functional semantics (i.e. the formal operations available to access or manipulate the EMMO).
The EMMO model can be regarded as an enrichment layer on top of standard database technology.
The fundamental idea underlying the concept of Emmos is that an Emmo is an object unifying three different aspects of multimedia content, namely the media aspect, the semantic aspect, and the functional aspect. In the following, the Emmo idea is compared with other approaches to the representation of multimedia content and show that the idea of unifying these three aspects is unique.
Inter-relating basic media objects like single images and videos to form multimedia content is the task of multimedia document models. Recently, several standards for multimedia document models have emerged [3], such as HTML [24], XHTML+SMIL [21], HyTime [14], MHEG-5 [10], MPEG-4 BIFS and XMT [23], SMIL [1], and SVG [8]. Multimedia document models can be regarded as composite media formats that model the presentation of multimedia content by arranging basic media objects according to temporal, spatial, and interaction relationships. They thus mainly address the media aspect of multimedia content. Compared to Emmos, however, multimedia document models neither interrelate multimedia content according to semantic aspects nor do they allow providing functionality on the content. They rely on external applications like presentation engines for reasonable content processing.
In parallel to research concerning the Semantic Web, a variety of standards have appeared that can be used to model multimedia content by describing the information it conveys on a semantic level, such as RDF [18, 4], Topic Maps [15], MPEG-7 (especially MPEG-7 s graph tools for the description of content semantics [12]), and Conceptual Graphs [16]. These standards clearly cover the semantic aspect of multimedia content.
In summary, these standards - since they also offer means of addressing media objects within a description - undoubtedly refer to the media aspect of multimedia content as well. Compared to Emmos, however, these approaches do not provide specific functionality on multimedia content. They rely on external software like database and knowledge base technology, search engines, user agents, etc. for the processing of content descriptions. Furthermore, media descriptions and the media objects described are separate entities potentially scattered around different places on the Internet created and maintained by different and unrelated authorities not necessarily aware of each other and not necessarily synchronized whereas Emmos combine media objects and their semantic relationships into a single unit.