Make audio and video related content fully accessible to vision and hearing impaired users.
Video Content with Audio (prerecorded)
Users who are deaf, hard of hearing, or having trouble understanding the audio information must be provided with a text based alternative.
Captioning should be provided for the audio portion of a video.
The captioning must be synchronized with the audio so that someone reading the captions could also watch the speaker and associate relevant body language with the speech.
Example:
https://www.w3.org/WAI/media/av/captions/
Provide a text based transcript for any prerecorded video content with audio.
Audio-Only Content with No Video
Audio files with no video are not considered multimedia. However, since audio is a non-text element one of the following text-equivalents must be provided for deaf or hearing impaired users.
HTML based transcript
Text transcript
A text or HTML summary
https://www.w3.org/WAI/media/av/captions/
Provide a Description of the Visual Content in Videos (prerecorded)
Provide vision impaired users access to the visual information in a synchronized media presentation.
Alternative One
One approach is to provide audio description of the video content. The audio description augments the audio portion of the presentation with the information needed when the video portion is not available. During existing pauses in dialogue, audio description provides information about actions, characters, scene changes, and on-screen text that are important and are not described or spoken in the main sound track.
Alternative Two
The second approach involves providing all of the information in the synchronized media (both visual and auditory) in text form. An alternative for time-based media provides a running description of all that is going on in the synchronized media content.
Live Audio and Real Time Presentations
Provide hearing impaired users with synchronized captions for any live audio and real time presentations.