How-Tos and Demos
Accessible Multimedia
Example: Captioned video of a performance with audio description
Captioned video of a described dance performance 
In this example, a still image combined with text acts as a link that launches
a video clip in a new window. (you will need to download the RealOne media player if it is not already installed on your computer). The video is very dark
and very small. It shows a short segment from a dance called "Sextet," choreographed by Allison Orr to music by the minimalist composer Terence
Reilly. The dance features two men who are blind, their guide dogs, and
two women dancers. The original performance included spoken, real-time
description of what the performers were doing. The video includes the audio
description plus synchronized captions that present the descriptions in
text form.
How to do it
Code example for video with captions and audio descriptions
Rationale
Audio description provides essential information about events on screen for the benefit
of people who can't see the screen. This includes people who are blind
and people who must keep their eyes focused on a complex task. It may also
be useful when poor contrast makes it difficult to see clearly. The audio
description in our example was scripted as part of the actual performance,
but audio description is more often done after the fact and inserted into
naturally occurring pauses in the soundtrack using a tool such as MAGpie from the National Center for Accessible Media
Captions provide a text transcript of speech and other sounds. The transcript should be word-for-word, or as close as possible, and must be synchronized with the video. In our example, the captions provide a synchronized transcript of the audio description. Captioning supports people who can't hear the soundtrack or have trouble understanding spoken language. This includes people who are Deaf and hard of hearing as well as people who are not native speakers of the language used in the soundtrack. People who are learning to read and people with learning disabilities have also been shown to benefit from captions. Captions may be open (visible to everyone) or closed (viewers must turn them on to see them). The captions for "Sextet" are closed-- if you don't see them when you launch the video, open the View menu in RealOne, choose Tools, then Preferences. In the Preferences dialog, choose Content from the list; then select the checkboxes for playing captions and audio descriptions if available. Press OK, then restart the "Sextet" video.
The link that launches the video clip actually points to a SMIL (Syncrhonized Multimedia Integration Language; pronounced "smile") file. The SMIL file was generated automatically by the MAGpie software mentioned above. It synchronizes the video with the text file that contains the captions. (If the audio description had been recorded separately, the SMIL file would also take care of synchronizing that separate audio stream.)
How it sounds with the JAWS screen reader
[Screen readers do not read captions. After the video player opens, users who are blind will hear the music and the audio description of the performance.]
JAWS transcript
[Screen readers do not read captions. After the video player opens, users who are blind will hear the music and the audio description of the performance.]