Creating Audio Descriptions for Rich Media

What are audio descriptions?

Audio descriptions are extra narration inserted into the natural pauses of the program audio which describe key visual elements in a program that a visually impaired viewer would ordinarily miss. Actions, scenery, expressions, and are some of the elements that engage the blind viewer with the story when described. Typically, audio descriptions are squeezed into pauses in dialog or sounds, and as a result often need to be very brief.

What are extended audio descriptions?

A feature available to creators of online multimedia is the ability to pause a video in order to include audio descriptions which provide more detail. These descriptions are said to be "extended" because they extend beyond the normal constraints. They also extend the overall length of the video, so discretion is important in determining how much information to provide. Extended audio descriptions are particularly useful in settings where there is an abundance of important information which is presented quickly, as in an online college physics lecture or in a technical advisory where techniques are shown, but not thoroughly described.

Extended audio descriptions are part of the pending SMIL 2.0 recommendation from the W3C. The recommendation will allow developers to create a multimedia presentation that includes extended and normal audio description, and will allow the user to determine whether they want to hear the descriptions or not.

Examples

If you are interested viewing examples of Rich Media with audio descriptions, please visit the Rich Media Showcase to search for examples with audio description.

How can I add audio descriptions to my content?

SMIL 1.0 is capable of synchronizing audio description sound files with a video, and this can also be accomplished with QuickTime, using the 'pro' version or using QuickTime SMIL. Creating extended audio descriptions is possible technically, but laborious in practice. The not-yet-released SMIL 2.0 recommendation provides additional functionalities, including a new tag which can be used to easily add extended audio descriptions.

Tutorials:

Adding audio descriptions in QuickTime
Adding audio descriptions in SMIL 1.0
Adding extended audio descriptions in QuickTime
Adding extended audio descriptions in SMIL 1.0