Navigating Multimedia
Recent developments in the design of digital talking books for the print disabled has resulted in the creation of a model of document navigation that offers enhanced usability for a broad base of web-based content. The navigation model allows the semantic structure of a document, document set, or presentation to be represented separately from the content, and utilized by a navigation-aware software, such as media players or browsers. Using the navigation structure, software can immediately expose the overall structure of the content to the user, thereby providing an understandable roadmap to what might otherwise be a complex multimedia presentation. This approach can provide efficient navigation, exploration, and review for users of all levels of ability.
Digital Talking Books have been developed as a modern hybrid of the traditional audio book integrated with the full textual version of the corresponding publication, allowing the listener a rich reading experience that allows rapid navigation and exploration of both modalities of presentation. The concept of structured audio navigation was pioneered by the Daisy Consortium (http://www.daisy.org) , and has led to the creation of the Daisy 3.0/NISO Digital Talking Book Standard (http://www.niso.org). A key goal in the Daisy standards effort is the adoption and promotion of open standards that are implementable across multiple platforms and support internationalization, with specific attention paid to the information needs of developing countries.
One advantage of the navigation model is that it can supply structure where it was not originally authored. Flat or otherwise non-structured documents (or presentations) that did not include explicit structur, can have the navigationally significant points identified and annotated. SMIL presentations, for example, allow definition of complex sequences of multimedia content, but the language itself contains no mechanism for adding navigational semantics. In addition to adding navigation structure, application specific navigation orders can be authored to supplement or re-purpose an existing set of documents or presentations. The implication is that a content producer (for example, an editor, anthologist, or educator) can customize the navigational significance of the source material, allowing for the easy creation of alternate views or entirely new, composite works, without touching or modifying the source content.
Through the work to address the specific needs of the visually impaired, a navigation model was created to enhance usability of digital talking books. This model has been extended to apply to a broad range of content and interface styles and can serve to make multimedia information more accessible to persons with and without disabilities. Based upon open standards, and being implemented in open source software projects, perhaps someday soon, we will all be able to make better sense of the multimedia content we encounter on our computers and digital televisions, and be able to thank the digital talking book community for this advancement.
M. T. Hakkinen and G. Kerscher. Applying a Navigation Layer to Digital Talking Books: SMIL, XML and NCX . The Web and Multimedia Workshop - WWW9 Amsterdam, May 2000.
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Hakkinen, M. DeMeglio and H. Kawamura. gNCX: Structure-based Navigation to Enhance Usability of Multimedia Content. Poster Presentation at WWW2002, Honolulu, May 2002.