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Proposed Video element auditory content has correct captions

Description

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

Applicability

This rule applies to captions provided for a non-streaming video element that is visible where the video contains audio.

Expectation

For each test target, speech and non-speech audio information that is not conveyed visually in the video is available in the captions.

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

Background

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 accessibility support issues known.

Bibliography

Accessibility Requirements Mapping

Input Aspects

The following aspects are required in using this rule.

Test Cases

Passed

Passed Example 1

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The open captions contain all of the audio content.

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

Passed Example 2

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The closed captions contain all of the audio content.

<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

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A video element with an associated track element that contains incorrect captions. Specifically, the captions flip the role of the mouse and computer by saying, “Not being able to use your mouse because your computer doesn’t work is frustrating.”

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

Inapplicable

Inapplicable Example 1

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A video element without audio.

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

Inapplicable Example 2

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A video element that is not visible.

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

Inapplicable Example 3

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A video element without any form of captions.

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

Inapplicable Example 4

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A video element with text on the same page that describes 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>

Inapplicable Example 5

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A video element with an explicitly associated text on the same page that describes 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>

Glossary

Audio output

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

Non-streaming media element

A non-streaming media element is an HTML Media Element for which the duration property is not 0.

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 five following types:

Note: A rule has one passed or failed outcome for every test target. When a tester evaluates a test target it can also be reported as cantTell if the rule cannot be tested in its entirety. For example, when applicability was automated, but the expectations have to be evaluated manually.

When there are no test targets the rule has one inapplicable outcome. If the tester is unable to determine whether there are test targets there will be one cantTell outcome. And when no evaluation has occurred the test target has one untested outcome. This means that each test subject always has one or more outcomes.

Outcomes used in ACT Rules can be expressed using the outcome property of the [EARL10-Schema][].

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.

Rule Versions

This is the first version of this ACT rule.

Implementations

There are currently no known implementations for this rule. If you would like to contribute an implementation, please read the ACT Implementations page for details.

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This is an unpublished draft preview that might include content that is not yet approved. The published website is at w3.org/WAI/.