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Audio-only and Video-only (Prerecorded):
Understanding SC 1.2.1

1.2.1 Audio-only and Video-only (Prerecorded): For prerecorded audio-only and prerecorded video-only media, the following are true, except when the audio or video is a media alternative for text and is clearly labeled as such: (Level A)
Prerecorded Audio-only: A text alternative is provided that presents equivalent information for prerecorded audio-only content.
Prerecorded Video-only: Either a text alternative or an audio track is provided that presents equivalent information for prerecorded video-only content.

Intent of this Success Criterion

The intent of this Success Criterion is to make information conveyed by prerecorded audio-only and prerecorded video-only content available to all users. Text alternatives used to make information accessible because they can be rendered through any sensory modality (for example, visual, auditory or tactile) to match the needs of the user.

For prerecorded video content, authors have the option to provide an audio track. This makes it possible for users with and without vision impairment to review content simultaneously. The approach can also make it easier for those with cognitive, language and learning disabilities to understand the content because it would provide parallel presentation.

Specific Benefits of Success Criterion 1.2.1:

This Success Criterion helps people who have difficulty perceiving visual content. Assistive technology can read text alternatives aloud, present them visually, or convert them to braille.
Text alternatives may help some people who have difficulty understanding the meaning of prerecorded video content.
People who are deaf, are hard of hearing, or who are having trouble understanding audio information for any reason can read the text presentation. Research is ongoing regarding automatic translation of text into sign language.
People who are deaf-blind can read the text in braille.
Additionally, text alternatives support the ability to search for non-text content and to repurpose content in a variety of ways.

Examples of Success Criterion 1.2.1

An audio recording of a speech
The link to an audio clip says, "Chairman's speech to the assembly." A link to a text transcript is provided immediately after the link to the audio clip.
An audio recording of a press conference
A Web page includes a link to an audio recording of a press conference that identifies the audio recording. The page also links to a text transcript of the press conference. The transcript includes a verbatim record of everything the speakers say. It identifies who is speaking as well as noting other significant sounds that are part of the recording, such as applause, laughter, questions from the audience, and so on.
An animation that illustrates how a car engine works
An animation shows how a car engine works. There is no audio and the animation is part of a tutorial that describes how an engine works. Since the text of the tutorial already provides a full explanation, the media is an alternative for text and the text alternative includes only a brief description of the animation and refers to the tutorial text for more information.
A video-only file with an audio track
A silent movie includes an audio track which includes a description of the action in the video.

Related Resources

Resources are for information purposes only, no endorsement implied.

(none currently documented)

Techniques and Failures for Success Criterion 1.2.1 - Audio-only and Video-only (Prerecorded)

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. The techniques listed only satisfy the Success Criterion if all of the WCAG 2.0 conformance requirements have been met.

Sufficient Techniques

Instructions: Select the situation below that matches your content. Each situation includes techniques or combinations of techniques that are known and documented to be sufficient for that situation.

Situation A: If the content is prerecorded audio-only:

G158: Providing a full text transcript for the audio

Situation B: If the content is prerecorded video-only:

G159: Providing a full text transcript of the video content
Adding an audio track that describes the important video content and describing it as such (future link)

Additional Techniques (Advisory) for 1.2.1

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 transcript of a live audio only presentation after the fact (future link)
Linking to textual information that provides comparable information (e.g. for a traffic Webcam, a municipality could provide a link to the text traffic report.) (future link)

Common Failures for SC 1.2.1

The following are common mistakes that are considered failures of Success Criterion 1.2.1 by the WCAG Working Group.

Key Terms

audio-only: a time-based presentation that contains only audio (no video and no interaction)
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
text alternative: programmatically determined text that is used in place of non-text content, or text that is used in addition to non-text content and referred to from the programmatically determined text
Example: An image of a chart is described in text in the paragraph after the chart. The short text alternative for the chart indicates that a description follows.
video-only: a time-based presentation that contains only video (no audio and no interaction)

Audio-only and Video-only (Prerecorded):Understanding SC 1.2.1