Intent
The intent of this Success Criterion is to enable people who are deaf or hard of hearing to watch synchronized media presentations. Captions provide the part of the content available via the audio track. Captions not only include dialogue, but identify who is speaking and include non-speech information conveyed through sound, including meaningful sound effects.
It is acknowledged that at the present time there may be difficulty in creating captions for time-sensitive material and this may result in the author being faced with the choice of delaying the information until captions are available, or publishing time-sensitive content that is inaccessible to the deaf, at least for the interval until captions are available. Over time, the tools for captioning as well as building the captioning into the delivery process can shorten or eliminate such delays.
Captions are not needed when the synchronized media is, itself, an alternate presentation of information that is also presented via text on the Web page. For example, if information on a page is accompanied by a synchronized media presentation that presents no more information than is already presented in text, but is easier for people with cognitive, language, or learning disabilities to understand, then it would not need to be captioned since the information is already presented on the page in text or in text alternatives (e.g., for images).
See also 1.2.1: Captions (Live).
Benefits
- People who are deaf or have a hearing loss can access the auditory information in the synchronized media content through captions.
Examples
-
A captioned tutorial
A video clip shows how to tie a knot. The captions read,
"(music)
Using rope to tie knots was an important skill
for the likes of sailors, soldiers and woodsmen.."
From Sample Transcript Formatting by Whit Anderson.
- A complex legal document contains synchronized media clips for different paragraphs that show a person speaking the contents of the paragraph. Each clip is associated with its corresponding paragraph. No captions are provided for the synchronized media.
- An instruction manual containing a description of a part and its necessary orientation is accompanied by a synchronized media clip showing the part in its correct orientation. No captions are provided for the synchronized media clip.
-
An orchestra provides captions for videos of performances. In addition to capturing dialog and lyrics verbatim, captions identify non-vocal music by title, movement, composer, and any information that will help the user comprehend the nature of the audio. For instance captions read,
"[Orchestral Suite No. 3.2 in D major, BWV 1068, Air]
[Johann Sebastian Bach, Composer]
♪ Calm melody with a slow tempo ♪"
Style guides for captions may differ among different languages.
Related Resources
Resources are for information purposes only, no endorsement implied.
Guides to Captioning
SMIL Resources
Other Captioning Resources
Captioning Tools
Techniques
Each numbered item in this section represents a technique or combination of techniques that the WCAG Working Group deems sufficient for meeting this Success Criterion. However, it is not necessary to use these particular techniques. For information on using other techniques, see Understanding Techniques for WCAG Success Criteria, particularly the "Other Techniques" section.
Sufficient Techniques
- Providing open (always visible) captions
- Providing closed captions using any readily available media format that has a video player that supports closed captioning
-
Providing closed captions using any of the technology-specific techniques below
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.
- Providing a note saying "No sound is used in this clip" for video-only clips (future link)
- Using SMIL 1.0 to provide captions for all languages for which there are audio tracks (future link)
- Using SMIL 2.0 to provide captions for all languages for which there are audio tracks (future link)
Failures
The following are common mistakes that are considered failures of this Success Criterion by the WCAG Working Group.
- Failure due to captions omitting some dialogue or important sound effects
- Failure of Success Criterion 1.2.1 by providing synchronized media without captions when the synchronized media presents more information than is presented in its associated text.
- Failure of 1.2.1 due to not labeling a synchronized media alternative to text as an alternative
Key Terms
the technology of sound reproduction
Audio can be created synthetically (including speech synthesis), recorded from real world sounds, or both.
media that presents no more information than is already presented in text (directly or via text alternatives)
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.
information that is not live
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