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In Brief
- Goal
- Videos can be played with audio descriptions.
- What to do
- Provide a synchronized spoken description of the visual content in videos.
- Why it's important
- People who cannot see or understand the visual content can hear about it while playing videos.
Success Criterion (SC)
Audio description is provided for all prerecorded video content in synchronized media.
Intent
The intent of this success criterion is to provide people who are blind or visually impaired access to the visual information in a synchronized media presentation in the same human language as the video or page on which it appears. 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.
Note
For 1.2.3, 1.2.5, and 1.2.7, if all of the important information in the video track is already conveyed in the audio track, no additional audio description is necessary.
1.2.3, 1.2.5, and 1.2.8 overlap somewhat with each other. This is to give the author some choice at the minimum conformance level, and to provide additional requirements at higher levels. At Level A in Success Criterion 1.2.3, authors do have the choice of providing either an audio description or a full text alternative. If they wish to conform at Level AA, under Success Criterion 1.2.5 authors must provide an audio description - a requirement already met if they chose that alternative for 1.2.3, otherwise an additional requirement. At Level AAA under Success Criterion 1.2.8 they must provide an extended text description. This is an additional requirement if both 1.2.3 and 1.2.5 were met by providing an audio description only. If 1.2.3 was met, however, by providing a text description, and the 1.2.5 requirement for an audio description was met, then 1.2.8 does not add new requirements.
Benefits
- People who are blind or have low vision as well as those with cognitive limitations who have difficulty interpreting visually what is happening benefit from audio description of visual information.
Examples
- A movie with audio description
-
Describer: A title, "Teaching Evolution Case Studies. Bonnie Chen." A teacher shows photographs of birds with long, thin beaks.
Bonnie Chen: "These photos were all taken at the Everglades."
Describer: The teacher hands each student two flat, thin wooden sticks.
Bonnie Chen: "Today you will pretend to be a species of wading bird that has a beak like this."
Describer: The teacher holds two of the sticks to her mouth making the shape of a beak.
Transcript of audio based on the first few minutes of "Teaching Evolution Case Studies, Bonnie Chen" (copyright WGBH and Clear Blue Sky Productions, Inc.)
Related Resources
Resources are for information purposes only, no endorsement implied.
- Description of Visual Information, in Making Audio and Video Media Accessible, W3C Web Accessibility Initiative (WAI)
- NCAM Rich Media Accessibility, Accessible SMIL Templates
- Standard Techniques in Audio Description
- Synchronized Multimedia Integration Language (SMIL) 1.0
- Synchronized Multimedia Integration Language (SMIL 2.0)
- Accessibility Features of SMIL
Techniques
Each numbered item in this section represents a technique or combination of techniques that the Accessibility Guidelines Working Group deems sufficient for meeting this Success Criterion. A technique may go beyond the minimum requirement of the criterion. There may be other ways of meeting the criterion not covered by these techniques. For information on using other techniques, see Understanding Techniques for WCAG Success Criteria, particularly the "Other Techniques" section.
Sufficient Techniques
- G78: Providing a second, user-selectable, audio track that includes audio descriptions
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G173: Providing a version of a movie with audio descriptions using one of the following:
- SM6: Providing audio description in SMIL 1.0
- SM7: Providing audio description in SMIL 2.0
- G226: Providing audio descriptions by incorporating narration in the soundtrack
- Using any player that supports audio and video
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G8: Providing a movie with extended audio descriptions using one of the following:
- SM1: Adding extended audio description in SMIL 1.0
- SM2: Adding extended audio description in SMIL 2.0
- Using any player that supports audio and video
- G203: Using a static text alternative to describe a talking head video
Advisory Techniques
Although not required for conformance, the following additional techniques should be considered in order to make content more accessible. Not all techniques can be used or would be effective in all situations.
Failures
The following are common mistakes that are considered failures of this Success Criterion by the Accessibility Guidelines Working Group.
Key Terms
- audio
the technology of sound reproduction
Note
Audio can be created synthetically (including speech synthesis), recorded from real world sounds, or both.
- audio description
narration added to the soundtrack to describe important visual details that cannot be understood from the main soundtrack alone
Note 1
Audio description of video provides information about actions, characters, scene changes, on-screen text, and other visual content.
Note 2
In standard audio description, narration is added during existing pauses in dialogue. (See also extended audio description.)
Note 3
Where all of the video information is already provided in existing audio, no additional audio description is necessary.
Note 4
Also called "video description" and "descriptive narration."
- extended audio description
audio description that is added to an audiovisual presentation by pausing the video so that there is time to add additional description
Note
This technique is only used when the sense of the video would be lost without the additional audio description and the pauses between dialogue/narration are too short.
- human language
language that is spoken, written or signed (through visual or tactile means) to communicate with humans
Note
See also sign language.
- live
information captured from a real-world event and transmitted to the receiver with no more than a broadcast delay
Note 1
A broadcast delay is a short (usually automated) delay, for example used in order to give the broadcaster time to cue or censor the audio (or video) feed, but not sufficient to allow significant editing.
Note 2
If information is completely computer generated, it is not live.
- media alternative for text
media that presents no more information than is already presented in text (directly or via text alternatives)
Note
A media alternative for text is provided for those who benefit from alternate representations of text. Media alternatives for text may be audio-only, video-only (including sign-language video), or audio-video.
- prerecorded
information that is not live
- sign language
a language using combinations of movements of the hands and arms, facial expressions, or body positions to convey meaning
- synchronized media
audio or video synchronized with another format for presenting information and/or with time-based interactive components, unless the media is a media alternative for text that is clearly labeled as such
- video
the technology of moving or sequenced pictures or images
Note
Video can be made up of animated or photographic images, or both.
Test Rules
The following are Test Rules for certain aspects of this Success Criterion. It is not necessary to use these particular Test Rules to check for conformance with WCAG, but they are defined and approved test methods. For information on using Test Rules, see Understanding Test Rules for WCAG Success Criteria.