video element visual content has transcript


Description

This rule checks that non-streaming video elements have all audio and visual information available in a transcript.

Applicability

The rule applies to every non-streaming video element that is visible where the video contains audio.

Expectation

A text transcript containing all the visual and auditory information of the test target is available, either on the page or available through a link.

Note: A "text transcript" in the context of this rule is defined in WCAG 2 as an alternative for time based media.

Assumptions

  • This rule assumes that a mechanism is available to start the video and that the video element is not simply used to display the poster.
  • This rule assumes that the language of each test target can be correctly determined (either programmatically or by analyzing the content), and sufficiently understood.

Accessibility Support

There are no major accessibility support issues known for this rule.

Background

Test Cases

Passed

Passed Example 1

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A video element with a text transcript on the same page.

<html lang="en">`
<video controls>
  <source src="/test-assets/rabbit-video/video.mp4" type="video/mp4"></source>
  <source src="/test-assets/rabbit-video/video.webm" type="video/webm"></source>
</video>
<p>The above video shows a giant fat rabbit climbing out of a hole in the ground.
He stretches, yaws, and then starts walking.
Then he stops to scratch his bottom.</p>
</html>

Passed Example 2

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A video element with a link to a text transcript on a different page.

<html lang="en">`
<video controls>
  <source src="/test-assets/rabbit-video/video.mp4" type="video/mp4"></source>
  <source src="/test-assets/rabbit-video/video.webm" type="video/webm"></source>
</video>
<a href="/test-assets/rabbit-video/transcript.html">Transcript</a>
</html>

Failed

Failed Example 1

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A video element with an incorrect text transcript on the same page.

<html lang="en">`
<video controls>
  <source src="/test-assets/rabbit-video/video.mp4" type="video/mp4"></source>
  <source src="/test-assets/rabbit-video/video.webm" type="video/webm"></source>
</video>
<p>The above video shows a giant fat dog climbing out of a hole in the ground.
He stretches, yaws, and then starts walking.
Then he stops to scratch his bottom.</p>
</html>

Failed Example 2

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A video element with a link to an incorrect text transcript on a different page.

<html lang="en">`
<video controls>
  <source src="/test-assets/rabbit-video/video.mp4" type="video/mp4"></source>
  <source src="/test-assets/rabbit-video/video.webm" type="video/webm"></source>
</video>
<a href="/test-assets/rabbit-video/incorrect-transcript.html">Transcript</a>
</html>

Inapplicable

Inapplicable Example 1

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A video element that is not visible.

<html lang="en">`
<video controls style="display: none;">
  <source src="/test-assets/rabbit-video/video.mp4" type="video/mp4"></source>
  <source src="/test-assets/rabbit-video/video.webm" type="video/webm"></source>
</video>
<a href="/test-assets/rabbit-video/transcript.html">Transcript</a>
</html>

Inapplicable Example 2

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A video element without audio.

<html lang="en">`
<video controls>
  <source src="/test-assets/rabbit-video/silent.mp4" type="video/mp4"></source>
  <source src="/test-assets/rabbit-video/silent.webm" type="video/webm"></source>
</video>
<a href="/test-assets/rabbit-video/transcript.html">Transcript</a>
</html>

Glossary

Outcome

An outcome is a conclusion that comes from evaluating an ACT Rule on a test subject or one of its constituent test target. An outcome can be one of the three following types:

  • Inapplicable: No part of the test subject matches the applicability
  • Passed: A test target meets all expectations
  • Failed: A test target does not meet all expectations

Note: A rule has one passed or failed outcome for every test target. When there are no test targets the rule has one inapplicable outcome. This means that each test subject will have one or more outcomes.

Note: Implementations using the EARL10-Schema can express the outcome with the outcome property. In addition to passed, failed and inapplicable, EARL 1.0 also defined an incomplete outcome. While this cannot be the outcome of an ACT Rule when applied in its entirety, it often happens that rules are only partially evaluated. For example, when applicability was automated, but the expectations have to be evaluated manually. Such "interim" results can be expressed with the incomplete outcome.

Visible

Content perceivable through sight.

Content is considered visible if making it fully transparent would result in a difference in the pixels rendered for any part of the document that is currently within the viewport or can be brought into the viewport via scrolling.

Content is defined in WCAG.

For more details, see examples of visible.


Useful Links


Implementations

This section is not part of the official rule. It is populated dynamically and not accounted for in the change history or the last modified date. This section will not be included in the rule when it is published on the W3C website.

No Implementations

Implementation reports are not provided for this rule.

Acknowledgments

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