Last updated:

Created by:

Description

Non-streaming video elements without audio must have all visual information available in a transcript.

Test Procedure

Applicability

The rule applies to any non-streaming video element visible where the video doesn’t contain audio.

Expectation

The visual information of each test target is available through a text transcript that is available either on the page or through a link. The text transcript needs to be visibile and included-in-the-accessibility-tree.

Note: A “text transcript” in the context of this rule is defined in WCAG 2 as an alternative for time based media.

Assumptions

This rule assumes that a mechanism is available to start the video and that the video element is not simply used to display the poster.

Accessibility support

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

Background

Test Cases

Passed

Pass example 1

A silent video element with a text transcript on the same page.

Code Snippet:
 <video controls data-rule-target>
  <source src="../test-assets/rabbit-video/silent.mp4" type="video/mp4"></source>
  <source src="../test-assets/rabbit-video/silent.webm" type="video/webm"></source>
</video>
<p>The above video shows a giant fat rabbit climbing out of a hole in the ground. 
He stretches, yaws, and then starts walking. 
Then he stops to scratch his bottom.</p>
 
Example Output: Open in a new tab/ window

Pass example 2

A silent video element with a link to a text transcript on a different page.

Code Snippet:
 <video controls data-rule-target>
  <source src="../test-assets/rabbit-video/silent.mp4" type="video/mp4"></source>
  <source src="../test-assets/rabbit-video/silent.webm" type="video/webm"></source>
</video>
<a href="/test-assets/rabbit-video-transcript.html">Transcript</p>
 
Example Output: Open in a new tab/ window

Failed

Fail example 1

A silent video element with an incorrect text transcript on the same page.

Code Snippet:
 <video controls data-rule-target>
  <source src="../test-assets/rabbit-video/silent.mp4" type="video/mp4"></source>
  <source src="../test-assets/rabbit-video/silent.webm" type="video/webm"></source>
</video>
<p>The above video shows a giant fat dog climbing out of a hole in the ground. 
He stretches, yaws, and then starts walking. 
Then he stops to scratch his bottom.</p>
 
Example Output: Open in a new tab/ window

Fail example 2

A silent video element with a link to an incorrect text transcript on a different page.

Code Snippet:
 <video controls data-rule-target>
  <source src="../test-assets/rabbit-video/silent.mp4" type="video/mp4"></source>
  <source src="../test-assets/rabbit-video/silent.webm" type="video/webm"></source>
</video>
<a href="/test-assets/rabbit-video-incorrect-transcript.html">Transcript</p>
 
Example Output: Open in a new tab/ window

Failed example 3

A silent video element with an invisible text transcript on the same page.

Code Snippet:
 <video controls data-rule-target>
  <source src="../test-assets/rabbit-video/silent.mp4" type="video/mp4"></source>
  <source src="../test-assets/rabbit-video/silent.webm" type="video/webm"></source>
</video>
<p style="text-indent: -9999px;">The above video shows a giant fat rabbit climbing out of a hole in the ground. 
He stretches, yaws, and then starts walking. 
Then he stops to scratch his bottom.</p>
 
Example Output: Open in a new tab/ window

Failed example 4

A silent video element with a text transcript on the same page that is not included in the accessibility tree.

Code Snippet:
 <video controls data-rule-target>
  <source src="../test-assets/rabbit-video/silent.mp4" type="video/mp4"></source>
  <source src="../test-assets/rabbit-video/silent.webm" type="video/webm"></source>
</video>
<p aria-hidden="true">The above video shows a giant fat rabbit climbing out of a hole in the ground. 
He stretches, yaws, and then starts walking. 
Then he stops to scratch his bottom.</p>
 
Example Output: Open in a new tab/ window

Inapplicable

Inapplicable example 1

A silent video element that is not visible on the page.

Code Snippet:
 <video controls style="display: none;" data-rule-target>
  <source src="../test-assets/rabbit-video/silent.mp4" type="video/mp4"></source>
  <source src="../test-assets/rabbit-video/silent.webm" type="video/webm"></source>
</video>
<a href="/test-assets/rabbit-video-transcript.html">Transcript</p>
 
Example Output: Open in a new tab/ window

Inapplicable example 2

A video element with audio.

Code Snippet:
 <video controls data-rule-target>
  <source src="../test-assets/rabbit-video/video.mp4" type="video/mp4"></source>
  <source src="../test-assets/rabbit-video/video.webm" type="video/webm"></source>
</video>
<a href="/test-assets/rabbit-video-transcript.html">Transcript</p>
 
Example Output: Open in a new tab/ window

Glossary

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.

Included in the accessibility tree

Elements included in the accessibility tree of platform specific accessibility APIs. Elements in the accessibility tree are exposed to assistive technologies, allowing users to interact with the elements in a way that meet 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 and the SVG accessibility API mappings.

Note: Users of assistive technologies might still be able to interact with elements that are not included in the accessibility tree. An example of this is a focusable element with an aria-hidden attribute with a value of true. Such an element could still be interacted with using sequential keyboard navigation regardless of the assistive technologies used, even though the element would not be included in the accessibility tree.

Test Aspects

Test aspects are defined as part of the ACT Rules format 1.0.
  • DOM Tree

  • CSS Styling

  • Audio output

  • Visual output

Contribute






GitHub

Contributing is open to anyone. We welcome any new issues or pull requests for changes. Auto WCAG Rules has conference calls every 4 weeks. If you are interested in becoming an active contributor or reviewer, we ask that you join the Auto WCAG Rules community group through the W3C Website. This requires setting up a W3C account, may require approval by the organization you work for if they are a W3C member.

Learn more about contributing to Auto WCAG Rules Join the Auto WCAG Rules community group now!