Web Content Accessibility Guidelines 2.0
WCAG 2.0 Guidelines for Audio and Video
If you use audio files on your web page, a text transcript or other text-based material should be provided.
WCAG 2.0 Guideline 1.2.1
"An alternative for time-based media is provided that presents equivalent information for prerecorded audio-only content."
If video files are used, captions or a synchronized text transcript should
NOTE: Captions also benefit non-native speakers, users with audio disabled or viewers watching a video with poor quality audio.
WCAG 2.0 Guideline 1.2.2
"Captions are provided for all prerecorded audio content in synchronized media, except when the media is a media alternative for text and is clearly labeled as such."
Video files should be embedded or displayed in a player that can be accessed by a screen reader via keyboard commands.
Accessible players include QuickTime, RealPlayer, iTunes, Vimeo, Panopto, JW Player and YouTube.
WCAG 2.0 Guideline 2.1
"Make all functionality available from a keyboard."
Videos that include visual information critical to comprehension should include a description of events or images for visually impaired audiences. For example, a screencast of a software product should name the buttons and commands being used,
not just say "click here".
WCAG 2.0 Guideline 1.2.3
An alternative for time-based media or audio description of the prerecorded video content is provided for synchronized media, except when the media is a media alternative for text and is clearly labeled as such.
A lengthy piece of audio or video should not be played by default when entering a page. Instead, the user should be able to click the play button to start the file.
This provision prevents audio from interfering with the screen reading technology.