Proposed Video element auditory content has accessible alternative
Description
This rule checks that video elements have an alternative for information conveyed through audio.
Applicability
This 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:
Background
Assumptions
- This rule assumes that the video element is used to play synchronized media (video with audio), and that there is a mechanism to start the media.
- 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 accessibility support issues known.
Bibliography
- Understanding Success Criterion 1.2.2: Captions (Prerecorded)
- G93: Providing open (always visible) captions
- G87: Providing closed captions
- H95: Using the track element to provide captions
Accessibility Requirements Mapping
1.2.2 Captions (Prerecorded) (Level A)
- Learn more about 1.2.2 Captions (Prerecorded)
- Required for conformance to WCAG 2.0 and later on level A and higher.
- Outcome mapping:
- Any
failedoutcomes: success criterion is not satisfied - All
passedoutcomes: success criterion needs further testing - An
inapplicableoutcome: success criterion needs further testing
- Any
G87: Providing closed captions
- Learn more about technique G87
- Not required for conformance to any W3C accessibility recommendation.
- Outcome mapping:
- Any
failedoutcomes: technique is not satisfied - All
passedoutcomes: technique needs further testing - An
inapplicableoutcome: technique needs further testing
- Any
G93: Providing open (always visible) captions
- Learn more about technique G93
- Not required for conformance to any W3C accessibility recommendation.
- Outcome mapping:
- Any
failedoutcomes: technique is not satisfied - All
passedoutcomes: technique needs further testing - An
inapplicableoutcome: technique needs further testing
- Any
H95: Using the track element to provide captions
- Learn more about technique H95
- Not required for conformance to any W3C accessibility recommendation.
- Outcome mapping:
- Any
failedoutcomes: technique is not satisfied - All
passedoutcomes: technique needs further testing - An
inapplicableoutcome: technique needs further testing
- Any
Input Rules
Outcomes of the following rules are required as input for this rule.
Test Cases
Passed
Passed Example 1
A video element with an associated track element that contains captions for all the audio.
<html lang="en">
<video src="/test-assets/perspective-video/perspective-video.mp4" controls>
<track src="/test-assets/perspective-video/perspective-caption.vtt" kind="captions" />
</video>
</html>
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.
<html lang="en">
<p>
Web Accessibility Perspectives: Keyboard Accessibility. 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>
</html>
Failed
Failed Example 1
A video element without any form of captions.
<html lang="en">
<video src="/test-assets/perspective-video/perspective-video.mp4" controls></video>
</html>
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.
<html lang="en">
<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>
</html>
Inapplicable
Inapplicable Example 1
A video element that is not visible.
<html lang="en">
<video src="/test-assets/perspective-video/perspective-video.mp4" controls style="display: none;"></video>
</html>
Inapplicable Example 2
A video element without audio.
<html lang="en">
<video src="/test-assets/perspective-video/perspective-video-silent.mp4" controls></video>
</html>
Glossary
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:
- 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
- cantTell: Whether the rule is applicable, or not all expectations were met could not be fully determined by the tester.
- Untested: The tester has not attempted to evaluate the test subject.
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.
For more details, see examples of visible.
Rule Versions
This is the first version of this ACT rule.
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.
| Implementation | Type | Consistency | Report |
|---|---|---|---|
| Alfa (semi-automated) 0.80.0 | Semi-automated tool | Consistent |  |