Understanding WCAG 2.0

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Captions (Prerecorded):
Understanding SC 1.2.1

1.2.1 Captions (Prerecorded): Captions are provided for prerecorded synchronized media, except if the synchronized media is an alternative to text and is clearly labeled as such . (Level A)

Intent of this Success Criterion

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).

Specific Benefits of Success Criterion 1.2.1:

  • People who are deaf or have a hearing loss can access the auditory information in the synchronized media content through captions.

Examples of Success Criterion 1.2.1

Related Resources

Resources are for information purposes only, no endorsement implied.

Guides to Captioning

SMIL Resources

Other Captioning Resources

Techniques and Failures for Success Criterion 1.2.1 - Captions (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

  1. G93: Providing open (always visible) captions

  2. G87: Providing closed captions using any readily available media format that has a video player that supports closed captioning

  3. G87: Providing closed captions using any of the technology-specific techniques below

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.

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


text presented and synchronized with synchronized media to provide not only the speech, but also non-speech information conveyed through sound, including meaningful sound effects and identification of speakers

Note 1: In some countries, the term "subtitle" is used to refer to dialogue only and "captions" is used as the term for dialogue plus sounds and speaker identification. In other countries, subtitle (or its translation) is used to refer to both.

Note 2: Audio descriptions can be, but do not need to be, captioned since they are descriptions of information that is already presented visually.

media alternative to text

media that presents no more information than is already presented in text (directly or via text alternatives)

Note: A media alternative to text is provided for those who benefit from alternate representations of text. Media alternatives to text may be audio-only, video-only (including sign-language video), or audio-video.

synchronized media

audio or video synchronized with another format for presenting information and/or with time-based interactive components