Prerecorded video should provide an audio description

Rule media-audio-description · Document, language & navigation · impact moderate · Static + live

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Why it matters#

Prerecorded video needs an audio description of important visual information (actions, scene changes, on-screen text) so people who are blind or have low vision can follow it. A <video> with no <track kind="descriptions"> almost certainly ships no timed description — but the description may also live in an alternate audio track or a separately linked audio-described version that markup cannot reveal, so this is a warning for author review. Same scope as media-captions: hidden players and silent-signature videos (muted with no native controls) present no content to describe here and are exempt.

How to fix#

Add a <track kind="descriptions" srclang="…" src="…"> with timed descriptions of the visual information, or publish/link an audio-described version of the video. If the video’s soundtrack already narrates everything visible (or the video is decorative), this can be dismissed.

Example#

<video src="talk.mp4" controls><track kind="captions" srclang="en" src="talk.vtt"></video>

<video src="talk.mp4" controls><track kind="captions" srclang="en" src="talk.vtt"><track kind="descriptions" srclang="en" src="talk-ad.vtt"></video>

Captions (1.2.2) serve people who can’t hear; audio descriptions (1.2.5) serve people who can’t see — one track does not satisfy the other.

Example#

<video src="promo.mp4" controls></video>

<video src="hero.mp4" muted loop></video>

A muted video without native controls has the silent-background signature — no audible presentation exists, so it is out of scope.

WCAG success criteria#

1.2.5 Audio Description (Prerecorded) — Level AA#

Prerecorded video needs an audio description of important visual information (actions, characters, scene changes, on-screen text) so people who are blind or have low vision can follow it — at AA a transcript alone no longer suffices.

Understanding 1.2.5

Standards#

This rule contributes to the following standards:

WCAG AA EN 301 549 Section 508

References#

• WCAG — Audio Description (Prerecorded)