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Perceivable WCAG 1.2.3

1.2.3 Audio Description or Media Alternative (Prerecorded)

An alternative for time-based media or audio description of the video content must be provided for prerecorded synchronized media, unless the media is a media alternative for text.

Level A Serious WCAG 2.0 (new) WCAG 2.1 WCAG 2.2

What this rule means

WCAG 1.2.3 requires that prerecorded synchronized media (video with audio) provides either an audio description track or a full text alternative that describes both the visual and auditory content. An audio description narrates important visual information — such as actions, scene changes, on-screen text, and facial expressions — during natural pauses in dialogue.

A media alternative is a text document that presents all visual and auditory information in reading order. This can be a screenplay-style transcript or a structured document that describes what happens both visually and aurally throughout the video.

Why it matters

Blind and low-vision users rely on audio descriptions to understand visual content that is not conveyed through the existing audio track. Without this alternative, they miss critical context — a presenter pointing at a chart, on-screen demonstrations, or visual humor.

A full media alternative benefits users who cannot play media, those with both visual and auditory disabilities, and users of assistive technologies that render text. It also serves as a fallback when audio description tracks are not supported by the media player.

Related axe-core rules

There are no axe-core rules that directly test for audio descriptions or media alternatives. This criterion requires manual testing because automated tools cannot evaluate whether visual information has been adequately described.

How to test

  1. Identify all prerecorded videos with audio tracks on the page.
  2. Check whether an audio description track is available in the media player controls.
  3. If no audio description is provided, verify that a complete text alternative (media alternative) is available.
  4. Play the video with audio description enabled and verify that key visual elements are described during pauses in dialogue.
  5. If a text alternative is provided, compare it against the video to ensure all visual and auditory information is represented.

How to fix

Option 1: Add an audio description track using the <track> element:

<video controls>
  <source src="/training-video.mp4" type="video/mp4" />
  <track
    kind="captions"
    src="/training-captions.vtt"
    srclang="en"
    label="English Captions"
    default
  />
  <track
    kind="descriptions"
    src="/training-descriptions.vtt"
    srclang="en"
    label="Audio Descriptions"
  />
</video>

The audio description WebVTT file describes visual content:

WEBVTT

1
00:00:03.000 --> 00:00:06.000
A bar chart shows quarterly revenue
increasing from Q1 to Q4.

2
00:00:15.000 --> 00:00:18.000
The presenter clicks on the Q3 bar,
revealing a detailed breakdown by region.

3
00:00:30.000 --> 00:00:33.000
A world map highlights active markets
in blue across Europe and Asia.

Option 2: Provide a full media alternative as a linked transcript:

<video controls>
  <source src="/training-video.mp4" type="video/mp4" />
</video>
<a href="/training-full-transcript.html">
  Full media alternative: Complete text description
  of the training video including visual content
</a>

Common mistakes

  • Providing captions but no audio description — captions alone do not satisfy this criterion.
  • Describing only what is spoken, omitting visual-only information such as on-screen text, charts, or actions.
  • Adding audio descriptions that overlap with dialogue, making both difficult to understand.
  • Providing a transcript that covers only spoken content without describing visual elements.
  • Assuming that an audio description is unnecessary because the presenter verbally describes everything — this is often not the case.

Resources