Accessible Multimedia Objects

When thinking about interactive multimedia objects for the web, web developers should not hesitate because of accessibility. It is not correct that accessible resources need to be bland and boring. In fact, for many with disabilities, multimedia products are most helpful. What is required is that there are deprecated and alternative versions of the objects available.

Let's start with a typical video with full sound:

• not useful to a blind person who wants to ignore the images and get access to both the audio stream and an audio description of what is happening in the video
• not useful to a person with visibility problems who wants to enlarge still images from the video and hear the audio stream
• not useful to a blind person who needs to use a Braille device so needs the video to go more slowly
• not useful to a person with hearing difficulties unless the voices can be made to stand-out from the background sounds
• not useful to a deaf person who wants everything rendered in text as sub-titles or closed captions
• not useful to a deaf person who needs to see the dialogue presented in sign language
• and so on ...

The available combinations of assets need to be:

• the original video
• the audio stream synchronised with audio captioning
• the audio stream synchronised with a series of still images
• synchronised text captioning and original audio track with timing control
• dialogue tracks separated from background sounds, all synchronised with video images
• closed text captions and text track for dialogue
• sign language version of the dialogue tracks

All of these can be created at the time of making the video and they can be compiled within a single object for presentation on a web page. Even if they are not presented as a single object, they should be synchronised (using SMIL).

So the complete range of assets will be:

• original video with timing control
• a series of still images
• audio dialogue track
• text dialogue track
• background sound track
• audio captioning
• text captioning
• sign language video of dialogue

Once all these are ready, they should be combined with SMIL so they can be used, as required, and the synchronisation will work.

NCAM offers tutorials on - creating captions, adding a caption track in QuickTime, creating audio descriptions for rich media and creating cross-platform displays. All of this can be found in learning area on NCAM's accessibility pages at http://www.ncam.org/.

From Macromedia:

"After completing an interactive, Macromedia Flash-based tutorial on the human knee, Swarm Interactive realized the animation needed to be revised to make it accessible to all users. By adding text-equivalent keystroke events and narration, Swarm significantly improved the accessibility of the Flash content.

Highlights of Case Study

• Use the d-link option to make the text accessible for an existing Flash file
• Use keyboard controls to convert previously inaccessible animation.
• There are certain technical requirements in order for this solution to succeed."

To read the full case study, click the link below:

http://dynamic.macromedia.com/bin/MM/showcase/scripts/showcase_cs_body.jsp?Showcase_OID=316821

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Last updated: 8 March 2002