ACT-Rules Community

Video element visual-only content is media alternative for text

Description

This rule checks non-streaming silent video is a media alternative for text on the page.

Applicability

This rule applies to any non-streaming video element that is visible where the video does not contain audio.

Expectation 1

All the information contained in each target element is available as text (directly or via text alternatives) that is visible and included in the accessibility tree.

Expectation 2

Each target element is labeled as a video alternative for text on the page by content that is visible and included in the accessibility tree.

Assumptions

  • A mechanism is available to start the video and that the video element is not simply used to display the poster.
  • 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 major accessibility support issues known for this rule.

Background

The term label used in expectations 2 and 3 does not refer to the label element.

Bibliography

Test Cases

Passed

Passed Example 1

Open in a new tab

This video element, which has no audio, is a media alternative for the text in the page and it is labeled as such.

<html lang="en">
	<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-with-captions-silent.mp4" controls></video>
</html>

Failed

Failed Example 1

Open in a new tab

This video element, which has no audio, has more information than the text on the page.

<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-with-captions-silent.mp4" controls></video>
</html>

Failed Example 2

Open in a new tab

This video element, which has no audio, is a media alternative for the text in the page and labeled as such, but the text is not visible.

<html lang="en">
	<p style="display: none;">
		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-with-captions-silent.mp4" controls></video>
</html>

Failed Example 3

Open in a new tab

This video element, which has no audio, is a media alternative for the text in the page but not labeled as such.

<html lang="en">
	<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.
	</p>
	<video src="/test-assets/perspective-video/perspective-video-with-captions-silent.mp4" controls></video>
</html>

Failed Example 4

Open in a new tab

This video element, which has no audio, is a media alternative for the text in the page and labeled as such, but the label is not visible.

<html lang="en">
	<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.
	</p>
	<p style="display: none;">
		See the video below to watch the same information again in video form.
	</p>
	<video src="/test-assets/perspective-video/perspective-video-with-captions-silent.mp4" controls></video>
</html>

Inapplicable

Inapplicable Example 1

Open in a new tab

This video element has audio.

<html lang="en">
	<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>
</html>

Inapplicable Example 2

Open in a new tab

This video element is not visible.

<html lang="en">
	<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-with-captions-silent.mp4"
		controls
		style="display: none;"
	></video>
</html>

Glossary

Focusable

An element is focusable if one or both of the following are true:

Exception: Elements that lose focus during a period of up to 1 second after gaining focus, without the user interacting with the page the element is on, are not considered focusable.

Notes:

  • The 1 second time span is an arbitrary limit which is not included in WCAG. Given that scripts can manage the focus state of elements, testing the focusability of an element consistently would be impractical without a time limit.
  • The tabindex value of an element is the value of the tabindex attribute parsed using the rules for parsing integers. For the tabindex value to be different from null, it needs to be parsed without errors.

Included in the accessibility tree

Elements included in the accessibility tree of platform specific accessibility APIs are exposed to assistive technologies. This allows users of assistive technology to access the elements in a way that meets the requirements of the individual user.

The general rules for when elements are included in the accessibility tree are defined in the core accessibility API mappings. For native markup languages, such as HTML and SVG, additional rules for when elements are included in the accessibility tree can be found in the HTML accessibility API mappings (working draft) and the SVG accessibility API mappings (working draft).

For more details, see examples of included in the accessibility tree.

Programmatically hidden elements are removed from the accessibility tree. However, some browsers will leave focusable elements with an aria-hidden attribute set to true in the accessibility tree. Because they are hidden, these elements are considered not included in the accessibility tree. This may cause confusion for users of assistive technologies because they may still be able to interact with these focusable elements using sequential keyboard navigation, even though the element should not be included in the accessibility tree.

Outcome

An outcome is 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: Implementations 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.

Programmatically Hidden

An HTML element is programmatically hidden if either it has a computed CSS property visibility whose value is not visible; or at least one of the following is true for any of its inclusive ancestors in the flat tree:

  • has a computed CSS property display of none; or
  • has an aria-hidden attribute set to true

Note: Contrary to the other conditions, the visibility CSS property may be reverted by descendants.

Note: The HTML standard suggests setting the CSS display property to none for elements with the hidden attribute. While not required by HTML, all modern browsers follow this suggestion. Because of this the hidden attribute is not used in this definition. In browsers that use this suggestion, overriding the CSS display property can reveal elements with the hidden attribute.

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.

Useful Links

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. This section will not be included in the rule when it is published on the W3C website.

ToolConsistencyCompleteReport
QualWebconsistentYesView Report

Acknowledgments

Authors

Funding

  • WAI-Tools

Assets

  • Web Accessibility Perspective videos by W3C WAI.
Table of Contents