Most individuals who are blind can access the audio content of a video or multimedia presentation. However, if any portion of the video content is presented only visually and cannot be inferred from the audio, the inaccessible visual content should be described by a narrator. This process is known as audio description.
In audio description, narrators typically describe actions, gestures, scene changes, and other visual information that is important for understanding the content of the product. They also describe titles, speaker names, and other text that may appear on the screen.
An educational entity purchasing a video should check with the publisher or distributor as to whether an audio described version is available. If the product is not available in an audio-described form, a person who has sight can describe the visual content to the student who is blind. In some cases, a transcript may be used, but this accommodation is less desirable, because the content is not synchronized with the production.
For video produced in-house, audio description can be added post-production. Tools, techniques, and other issues related to audio description are described in the following AccessIT Knowledge Base articles:
- What is audio description? 
- How do I make multimedia accessible? 
- Are there standards or guidelines for providing audio description? 
- How do I turn on captions or descriptive audio in my media player? 
-  What is audio description?
-  How do I make multimedia accessible?
-  Are there standards or guidelines for providing audio description?
-  How do I turn on captions or descriptive audio in my media player?