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Description

Non-streaming video elements without audio must have an audio alternative

Test Procedure

Applicability

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

Expectation

The visual information of each test target is available through an audio track.

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 video element without audio has a separate audio track that describes the visual information.

Code Snippet:
 <video controls>
  <source src="../test-assets/rabbit-video/silent.mp4" type="video/mp4" />
  <source src="../test-assets/rabbit-video/silent.webm" type="video/webm" />
</video>

<audio controls>
  <source src="../test-assets/rabbit-video/audio-description.mp3" type="audio/mpeg">
</audio>
 
Example Output: Open in a new tab/ window

Failed

Fail example 1

A video element without an audio track.

Code Snippet:
 <video controls>
  <source src="../test-assets/rabbit-video/silent.mp4" type="video/mp4" />
  <source src="../test-assets/rabbit-video/silent.webm" type="video/webm" />
</video>
 
Example Output: Open in a new tab/ window

Fail example 2

A video element without audio has a separate audio track that incorrectly describes the visual information.

Code Snippet:
 <video controls>
  <source src="../test-assets/rabbit-video/silent.mp4" type="video/mp4" />
  <source src="../test-assets/rabbit-video/silent.webm" type="video/webm" />
</video>

<audio controls>
  <source src="../test-assets/rabbit-video/incorrect-audio-description.mp3" type="audio/mpeg">
</audio>
 
Example Output: Open in a new tab/ window

Inapplicable

Inapplicable example 1

A video element with audio.

Code Snippet:
 <video controls>
  <source src="../test-assets/rabbit-video/video.mp4" type="video/mp4" />
  <source src="../test-assets/rabbit-video/video.webm" type="video/webm" />
</video>
 
Example Output: Open in a new tab/ window

Inapplicable example 2

A video element without sound that is not visible on the page.

Code Snippet:
 <video controls style="display: none;">
  <source src="../test-assets/rabbit-video/silent.mp4" type="video/mp4" />
  <source src="../test-assets/rabbit-video/silent.webm" type="video/webm" />
</video>
 
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.

Test Aspects

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

  • CSS Styling

  • Audio output

  • Visual output

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