1.2.3 Audio Description or Media Alternative
Level: A | Principle: Perceivable | Since: WCAG 2.0 | Automation: Manual
What This Means
Pre-recorded video with audio must provide either an audio description track or a full text alternative (such as a screenplay-style transcript) that describes all visual information not already conveyed by the existing audio track. This includes on-screen actions, scene changes, on-screen text, and visual cues that are essential to understanding the content.
Blind and low-vision users cannot see what is happening on screen. If a presenter says "as you can see here" while pointing at a chart, that information is lost without an audio description or text alternative.
Who This Affects
- Blind users — they rely entirely on audio and need descriptions of visual content
- Low-vision users — they may miss visual details that are not described in dialogue
- Deafblind users — a full text alternative can be rendered in braille
Common Pitfalls
1. Video relies on visuals with no description
<!-- Bad: cooking video where ingredients and steps are shown but not spoken -->
<video controls src="pasta-recipe.mp4">
<track kind="captions" src="pasta-captions.vtt" srclang="en" label="English">
</video>
<!-- Chef says "add this much" while holding up a measuring cup — amount never spoken -->
2. Presentation video where slides are not described
<!-- Bad: speaker references slides that are never read aloud -->
<video controls src="quarterly-review.mp4"></video>
<!-- Speaker: "As this graph clearly shows..." but the data is never stated -->
3. Providing a summary instead of a full alternative
<!-- Bad: a brief overview is not a sufficient media alternative -->
<video controls src="safety-training.mp4"></video>
<p>This video covers workplace safety procedures.</p>
How to Fix
Option A: Audio description track
<!-- Good: separate audio description track describes visual content -->
<video controls src="quarterly-review.mp4">
<track kind="captions" src="captions.vtt" srclang="en" label="English" default>
<track kind="descriptions" src="descriptions.vtt" srclang="en" label="Audio descriptions">
</video>
Audio description example (VTT format)
WEBVTT
00:00:15.000 --> 00:00:19.000
A bar chart shows Q3 revenue at 4.2 million, up 18% from Q2.
00:01:02.000 --> 00:01:06.000
The presenter clicks to a slide titled "2026 Roadmap" showing three phases.
00:02:30.000 --> 00:02:34.000
A pie chart breaks down expenses: 45% engineering, 30% marketing, 25% operations.
Option B: Full text alternative
<!-- Good: complete text transcript that includes visual descriptions -->
<video controls src="quarterly-review.mp4"></video>
<details>
<summary>Full text alternative (with visual descriptions)</summary>
<p>[Slide: Q3 Revenue — bar chart showing $4.2M, up 18% from Q2]</p>
<p>PRESENTER: As this graph clearly shows, we had a strong quarter
with revenue reaching 4.2 million dollars...</p>
<p>[Slide transitions to "2026 Roadmap" with three phases listed]</p>
<p>PRESENTER: Looking ahead, our roadmap has three phases...</p>
</details>
How to Test
- Identify all prerecorded videos with audio on the page.
- Watch each video with your eyes closed (or screen off) and listen for visual information that is never described in the audio track (e.g., on-screen text, charts, actions, scene changes).
- Check if an audio description track or a full text alternative is provided near the video player.
- If an audio description exists, enable it and verify it covers all significant visual information missed by the dialogue.
- If a text alternative is provided, verify it includes both the spoken dialogue and descriptions of all visual content.
- Pass: Every video has an audio description track or a complete text alternative that fills in visual information not conveyed by dialogue.
- Fail: Any video relies on visuals that are never described in audio or text form.
axe-core Rules
No automated axe-core rules. This criterion requires manual testing.