Video has audio alternative


Description

This rule checks that video elements have an alternative for information conveyed through audio.

Applicability

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

Expectation

For each test target, the outcome of at least one of the following rules is passed:

Assumptions

This rule assumes that the video element is used to play a video (for example, not only used to display an image), and that there is a mechanism to start the video.

Accessibility Support

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

Background

Test Cases

Passed

Passed Example 1

A video element with an associated track element that contains captions for all the audio.

<video src="../test-assets/perspective-video/perspective-video.mp4" controls>
	<track src="/test-assets/perspective-video/perspective-caption.vtt" kind="captions" />
</video>

Passed Example 2

A video element that describes some of the text on the same page. The text on the page labels the video as an alternative.

<p>
	Not being able to use your computer because your mouse doesn't work, is frustrating. Many people use only the keyboard
	to navigate websites. Either through preference or circumstance. This is solved by keyboard compatibility. Keyboard
	compatibility is described in WCAG. See the video below to watch the same information again in video form.
</p>
<video src="../test-assets/perspective-video/perspective-video.mp4" controls></video>

Failed

Failed Example 1

A video element without any form of captions.

<video src="../test-assets/perspective-video/perspective-video.mp4" controls></video>

Failed Example 2

A video element that describes some of the text on the same page. The video contains more information than the text does.

<p>
	Not being able to use your computer because your mouse doesn't work, is frustrating. Either through preference or
	circumstance. This is solved by keyboard compatibility. Keyboard compatibility is described in WCAG. See the video
	below to watch the same information again in video form.
</p>
<video src="../test-assets/perspective-video/perspective-video.mp4" controls></video>

Inapplicable

Inapplicable Example 1

A video element without that is not visible on the page.

<video src="../test-assets/perspective-video/perspective-video.mp4" controls style="display: none;"></video>

Inapplicable Example 2

A video element without audio.

<video src="../test-assets/perspective-video/perspective-video-silent.mp4" controls></video>

Glossary

Outcome

key: outcome

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: 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: 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.


Changelog

Aug 21, 2019fix: update links to WCAG21 resources (#776)
Aug 21, 2019Editorial changes (#725)
Jul 26, 2019Editorial changes (#702)
Jul 19, 2019chore: run prettier (#688)
Jul 17, 2019Typos (#683)
Jul 2, 2019Composite rules: Fix broken links in expectations (#627)
May 9, 2019Chore: Adapt site to ACT Rules CR format (#547)
May 7, 2019Template update - Video has audio alternative (#534)
Apr 29, 2019chore: rename files and update associations (#489)
Apr 16, 2019chore: add unique id to all rules (#478)
Apr 15, 2019chore: WCAG ACT RULES CG Website Update (#437)
Jan 22, 2019rule: SC 1.2.3 & 1.2.5 Video alternatives (#204)
Jan 14, 2019fix: composite rules have a listing of atomic rules
Jan 10, 2019fix: media rules update (issue #298) (#381)
Oct 9, 2018Fix: testcase generation (#296)
Oct 2, 2018SC1.2.2-video-captions (#158)

Useful Links


Implementations

Tool NameCreated ByReport
Axe-coreDeque SystemsView Report

Acknowledgements