Non-streaming media element
key: non-streaming-media-elementAn HTML Media Element for which the duration property is not 0.
Video element 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 a 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.
Accessibility Support
There are no major accessibility support issues known for this rule.
Background
- Understanding Success Criterion 1.2.3: Audio Description or Media Alternative (Prerecorded)
- Understanding Success Criterion 1.2.8: Media Alternative (Prerecorded)
- G78: Providing a second, user-selectable, audio track that includes audio descriptions
- G173: Providing a version of a movie with audio descriptions
- G203: Using a static text alternative to describe a talking head video
Test Cases
Passed
Passed Example 1
A video element with a text transcript on the same page.
<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>Passed Example 2
A video element with a link to a text transcript on a different page.
<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</p>Failed
Failed Example 1
A video element with an incorrect text transcript on the same page.
<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>Failed Example 2
A video element with a link to an incorrect text transcript on a different page.
<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</p>Inapplicable
Inapplicable Example 1
A video element that is not visible on the page.
<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</p>Inapplicable Example 2
A video element without audio.
<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</p>Glossary
Outcome
key: outcomeA 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: Implementers 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
key: visibleContent 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.
Changelog
Useful Links
- Github issues related to this rule
- Test case file for use in the WCAG-EM Report Tool
- Propose a change to the rule