UNIVERSAL USABILITY IN PRACTICE

Textual equivalents for audio/video representations of content can be either in the form of summary or the full content. For summaries, it could be a short description using attribute ALT=ˇ¨textˇ¨ for the audio/video content. For full content, we could use closed captions. Closed captioning was initially developed by WGBH [5], the public TV station in Boston, for the estimated 20 million Americans who are deaf or hard of hearing. The goal for closed captioning is to provide an alternative representation (usually text) for all information in a media piece whether it is audio, video or animation. In addition, closed captioning implies that the captions are synchronized with audio content. Microsoft Synchronized Accessible Media Interchange (SAMI) [8] expands the ability to provide closed captioning to a wide range of multimedia products. It simplifies captioning for web developers and the file format specification is available to the public as an ˇ§openˇ¨(no license fee) standard.

SAMI is simply a format optimized for authoring captions (CC) and audio descriptions (AD) in a single document. SAMI is based on HTML to provide a familiar, user readable format. The full implementation of SAMI is designed to 
support the various CC and AD specifications in a single authoring format. This will allow for cross-use and re-use of CC and AD content. For example, a SAMI document authored for encoding a program for broadcast could also be used to deliver captions to the Web. With above methods, users can get alternative text information conveyed with the audio/video content with equally opportunity compared to normal users.

There are two categories divided according to the usages for the audio/video content. 

• For general purpose (ex. News)
  • The textual equivalents for audio/video representations of content would be better a summary.
• For specific purpose (ex. Video viewing, Audio listening)
  • The textual equivalents for audio/video representations of content would be better a text transcript of the dialogue appear in the audio/video. If possible, provide both summary and full text transcript options for users.

For example, CNN.com [6], it is a web site for world news.. Users may be only interested in a title-like succinct summary for an audio/video. Thus, the alternative text representations for audio/video can be reduced to a summary level. Another example, Hollywood.com [7], it is a web site for movies, CDs, and all kinds of media. Users can preview a short commercial-purposed audio/video on the web site. They may want to have a whole content for the audio/video instead of just summaries. Thus, the alternative text representations for audio/video cannot be reduced. The alternative text must have all the information conveyed with the audio/video, which can be reached by SAMI.