Checkpoint 1.2.1 Audio-only and Video-only (Prerecorded)

For prerecorded audio-only or video-only media, an alternative provides equivalent information. (Level A)

Rationale

This checkpoint requires that when information is presented in a playable medium, the user has an alternative way of consuming it.

For audio-only information, such as a recording of a speech, provide a transcript. A transcript is also the preferred alternative for video-only information, such as a soundless demonstration video. This is because a transcript – which in the case of a video describes all important visual information -- can be presented to the user in many different ways by assistive technology. The alternative for video-only material could also be provided as an audio track.

Note: Anything which has a play button is typically “time-based media,” which includes anything that has duration and plays to the user over time. Video, audio and animation are all time-based media.

Exception: This checkpoint does not apply when the audio-only or video-only content is actually the media alternative for Text content, and is labeled as such. This alternative equivalent should provide no more information than is available in the text content.

Refer to Understanding SC 1.2.1 for more information (external link to WCAG).

Development Techniques

Review the General techniques as well as other tabs applicable to your technology.  Prioritize the use of technology-specific techniques, and implement the General techniques as needed. You are always required to find, understand and implement accessible code techniques to meet the checkpoint. The documented techniques and supplements are not exhaustive; they illustrate acceptable ways to achieve the spirit of the checkpoint. If numbered, techniques are in order of preference, with recommended techniques listed first. Where used, IBM information that complements the WCAG techniques is indicated as supplemental.

General techniques

Instructions: Select the following situation that matches your content. Any item in the described situation represents a technique that is deemed sufficient for meeting this checkpoint. Where numbered, techniques are ordered from most to least preferred. Ensure you review WCAG Common Failures to avoid development mistakes.

Situation A: If the content is prerecorded audio-only

Situation B: If the content is prerecorded video-only

  1. G159: Providing an alternative for time-based media for video-only content
  2. G166: Providing audio that describes the important video content and describes the audio file as the video alternative

Web (HTML, ARIA, CSS) techniques

Instructions: In addition to the General techniques, any of these Web techniques are deemed sufficient in the following situations when used as instructed.

Situation B: If the content is prerecorded video-only

Where supported and appropriate, the HTML5 <track> element satisfies both General techniques for Situation B, since it provides a text alternative and an audio description.

Mobile (iOS) techniques

There are no specific Mobile Native iOS technniques for this checkpoint. However, in addition to the General and Web techniques, the techniques in this section provide additional information and context for hybrid applications.

Hybrid techniques

Situation B: If the content is prerecorded video-only

Where supported and appropriate, the HTML5 <track> element satisfies both General techniques for Situation B, since it provides a text alternative and an audio description.

Hybrid supplements

H96: Using the track element to provide audio descriptions

Apple recommends using the HTML5 <audio>, <video>, and <track> elements for audio and video content on mobile Safari. These elements support audio and video playback natively in the browser  using the browser's  built-in controls.  Developers can also create their own customized media controllers for rich interactivity using web-standard CSS and JavaScript.  Developers should references Apple's "About HTML5 Audio and Video", "iOS-Specific Considerations", and "Use audio descriptions to hear narration describing a video clip, show, or movie" for proper implementation.

Eclipse techniques

There are no specific Eclipse techniques for this checkpoint. Refer to the examples in the General techniques section.

Windows-based (MSAA+IA2) techniques

There are no specific Windows-based (MSAA+IA2) techniques for this checkpoint. Refer to the General techniques section.


Most links in this checklist reside outside ibm.com at the Web Content Accessibility Guidelines (WCAG) 2.0. W3C Recommendation 11 December 2008: http://www.w3.org/TR/WCAG20/

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