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Perceivable · Level A · 1.2.3

Audio Description or Media Alternative (Prerecorded)

When a prerecorded video shows important things that the dialogue never mentions — a silent gesture, an on-screen caption, a scene change — there needs to be either audio description narrating those visual details, or a full text alternative describing everything happening in the video, so someone who can't see it still gets that information.

  • Blind
  • Low vision

How to recognize it

Watch a video with your eyes closed and see how much you'd miss: if characters react silently, if plot-relevant on-screen text appears without being read aloud, if a scene change matters and nothing in the audio signals it, that visual information is invisible to a blind viewer unless something else carries it. Not every video fails this — if the existing dialogue already narrates everything important happening on screen, there's nothing extra to add and the criterion is already satisfied. The failure case is specifically silent-but-important visual content with no audio description track and no text alternative covering it either.

How to fix it

Two acceptable options, pick either: add an audio description track that narrates the missing visual information during natural pauses in the existing dialogue, or provide a full text alternative — a document describing everything happening in the video, visually and audibly, in order — as an alternative way to get the same information. Audio description is usually the better experience for someone who wants to watch the video itself rather than read about it; a full text alternative is a reasonable fallback where adding a narration track isn't feasible.

Example

Avoid

<video src="tutorial.mp4" controls></video>
<!-- character silently points at a chart the dialogue never mentions; nothing describes it -->

Prefer

<video src="tutorial.mp4" controls>
  <track kind="descriptions" src="tutorial-ad.vtt" srclang="en" label="Audio description">
</video>
<video src="tutorial.mp4" controls></video>
<p><a href="/tutorial-full-description">Full text description of this video</a></p>

Resources