This document provides information about the related Acquia Optimize check:
Videos that contain important visual information must provide an audio description. This ensures that users who are blind or have low vision can understand key visual elements that are not conveyed through dialog alone.
An audio description is a spoken narration added to a video that describes:
This differs from captions, which transcribe spoken words but do not describe visual content.
This check applies to pre-recorded videos that include important visual elements that users need in order to understand the content.
Videos often rely on visual elements to convey important information. Without an audio description, users who cannot see the screen miss critical details.
For example, in a video tutorial that demonstrates how to adjust settings on an app:
A video with an audio description track
Include a separate narration to describe important visual elements.
<video controls>
<source src="video-with-audio-description.mp4" type="video/mp4">
<track kind="descriptions" src="audio-description.vtt" srclang="en" label="Audio Description">
</video>
A separate version of the video with audio descriptions is available
If it is not possible to add an audio description track, provide an alternate version.
<p>Watch the <a href="video-with-audio-description.mp4">accessible version with audio descriptions</a>.</p>
Visual information is already included in the narration
If all important actions and visuals are naturally described in the dialogue, an additional audio description may not be necessary.
No audio description for important visuals
A silent instructional video that relies on on-screen text and actions without a voiceover.
Only captions provided, no audio description
Captions transcribe speech but do not describe visual actions, which can still leave blind users without key information.
This check primarily benefits:
This section provides instructions about how to review a video for an audio description.
When this check flags a video, follow these steps:
This section provides a few suggestions about how you can correct the issue.
Add an audio description track
Include an audio description track in your <video>
element:
<video controls>
<source src="video.mp4" type="video/mp4">
<track kind="descriptions" src="audio-description.vtt" srclang="en" label="Audio Description">
</video>
Provide an alternative version
If it is not possible to add an audio track, provide a separate version with audio descriptions:
<p>Watch the <a href="video-with-audio-description.mp4">accessible version with audio descriptions</a>.</p>
WCAG success criteria
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Thu Mar 13 2025 09:34:13 GMT+0000 (Coordinated Universal Time)