1.2.7 Extended Audio Description (Prerecorded)

WCAG 2.2 · 1.2.7 AAA Perceivable

What it requires

Where the standard pauses in a video's existing soundtrack are too short to insert enough audio description to convey the sense of the synchronised visual content, extended audio description must be provided for the prerecorded synchronised media. Extended audio description pauses (freezes) the video at intervals so a longer narration of what is happening on screen can play, then resumes playback. This goes beyond standard audio description (1.2.5) by removing the time limit imposed by the original pauses in dialogue.

People who are blind or have low vision and cannot perceive the visual track. When meaningful action, on-screen text, characters, or scene changes are conveyed only visually and the natural gaps in dialogue are too brief to describe them, these users miss essential information. Extended descriptions give them time to receive a full account without losing the original audio.

How to detect it

Concrete checks for Extended Audio Description
Check How Catches it?
Identify visual-only content Watch the video with sound off; note any action, text, or context not spoken in the soundtrack. Manual
Measure the pauses Confirm the existing dialogue gaps are too short to describe that content. Manual
Check for an extended track Look for a control or alternate version that pauses the video to play longer descriptions. Manual / keyboard
Verify the control is operable Reach and toggle the extended-description option by keyboard and screen reader. Keyboard / SR
Automated tools axe and similar scanners can flag a missing <track>, but cannot judge whether descriptions are adequate. No (human judgement required)

How to fix it

  1. Script descriptions for every essential visual element the soundtrack does not convey.
  2. Where a description will not fit in an existing pause, mark a point to freeze the video and play the extended narration.
  3. Produce the extended audio description track (or a separate described version of the media).
  4. Expose a clear, keyboard- and screen-reader-operable control to turn it on; announce its state.
  5. Test with assistive technology that the video pauses, the description plays, and playback resumes cleanly.
<video controls>
  <source src="lecture.mp4" type="video/mp4">
  <!-- Extended audio description as a selectable track -->
  <track kind="descriptions" src="lecture-ead.vtt"
         srclang="en" label="Extended audio description">
</video>

Copy-paste tests

Automated coverage

There is no fully automated axe-core rule for 1.2.7: a scanner cannot judge whether a video needs extended audio description or whether the descriptions are adequate. This criterion needs manual review using the console check and steps below.

Run this in the browser console

console — list-media.js 
// Read-only: surfaces <video> elements and their description tracks for manual review.
const vids = [...document.querySelectorAll('video')];
console.table(vids.map(v => ({
  src: v.currentSrc || v.querySelector('source')?.src || '(none)',
  hasDescriptions: [...v.querySelectorAll('track')].some(t => t.kind === 'descriptions'),
  trackLabels: [...v.querySelectorAll('track')].map(t => t.label || t.kind).join(', ') || '(none)'
})));
vids.forEach(v => v.style.outline = '3px solid orange'); // visual only

What to check manually: watch each highlighted video with sound off and confirm any visual-only action is described; then verify the existing dialogue pauses are long enough — if not, an extended (video-pausing) description track must be present and operable.