Video has captions


Description

This rule checks that captions are available for audio information in non-streaming video elements.

Applicability

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

Expectation

For each test target, audio information that is not conveyed visually in the video, is available through captions.

Note: Captions can be either embedded in the video file itself or can be made available trough a separate track.

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 that has captions for all the audio baked into it.

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

Passed Example 2

A video element with an associated track element that contain 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>

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 with an associated track element that contain incorrect captions.

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

Failed Example 3

A video element with a text on the same page that described the audio in the video.

<p>
	The video below shows a man working on a keyboard. A voiceover is heard saying the following text: Web accessibility
	perspectives. Keyboard compatibility. 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.
</p>
<video src="../test-assets/perspective-video/perspective-video.mp4" controls></video>

Failed Example 4

A video element with an explicitly associated text on the same page that described the audio in the video.

<p id="text">
	The video below shows a man working on a keyboard. A voiceover is heard saying the following text: Web accessibility
	perspectives. Keyboard compatibility. 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.
</p>
<video src="../test-assets/perspective-video/perspective-video.mp4" controls ariadescribedby="text"></video>

Inapplicable

Inapplicable Example 1

A video element without audio.

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

Inapplicable Example 2

A video element that is not visible on the page.

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

Glossary

Audio output

key: audio-output

This test aspect includes all auditory data output from the web page into an audio channel.

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, 2019run prettier formmating (#811)
Aug 21, 2019fix: update links to WCAG21 resources (#776)
Aug 21, 2019Editorial changes (#725)
Aug 13, 2019fix: update test assets being referred for media rules (f51b46,… (#731)
Jul 30, 2019Remove unintended 1.2.2 from Video has captions (#705)
Jul 26, 2019Editorial changes (#702)
Jul 19, 2019chore: run prettier (#688)
Jul 17, 2019Typos (#683)
Jul 17, 2019fix: test if definition for all referenced glossary terms exist (#634)
Jul 4, 2019chore: fix typo in example description of rule video has captions (#650)
Jul 2, 2019chore: Correct various typos (#640)
May 9, 2019Chore: Adapt site to ACT Rules CR format (#547)
May 7, 2019Template update - video has captions (#535)
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)
Oct 9, 2018Fix: testcase generation (#296)
Oct 8, 2018fix: front matter for rule (#286)
Oct 2, 2018SC1.2.2-video-captions (#158)

Useful Links



Acknowledgements