1.2.7 Extended Audio Description (Prerecorded)

Level: AAA | Principle: Perceivable | Since: WCAG 2.0 | Automation: Manual

What This Means

When the natural pauses in a video's dialogue are not long enough to fit all necessary audio descriptions, the video must be paused to allow extended audio description. This is an enhancement over standard audio description (1.2.5), which only fits descriptions into existing gaps.

Some videos have dense dialogue or rapid scene changes, leaving no room for adequate audio description. Extended audio description solves this by freezing the video while the narrator describes what is happening visually, then resuming playback.

This criterion ensures that blind and low-vision users receive the same level of visual information as sighted viewers, even for fast-paced or dialogue-heavy content.

Who This Affects

  1. Blind users — rely entirely on audio description to understand visual content
  2. Users with low vision — may miss fast visual details that are not described
  3. Users with cognitive disabilities — pausing for description allows more processing time
  4. Users who cannot see the screen — such as those listening while multitasking

Common Pitfalls

1. Skipping visual details because there is no gap in dialogue

<!-- Bad: standard audio description only, skips important visual context -->
<video controls>
  <source src="lecture.mp4" type="video/mp4">
  <track kind="descriptions" src="standard-desc.vtt" srclang="en">
</video>

<!-- Good: extended audio description version that pauses for full descriptions -->
<video controls>
  <source src="lecture-extended-ad.mp4" type="video/mp4">
  <track kind="descriptions" src="extended-desc.vtt" srclang="en">
</video>

2. No way to toggle extended descriptions

<!-- Bad: only one version with no choice -->
<video src="movie.mp4" controls></video>

<!-- Good: let user choose their preferred version -->
<div role="group" aria-label="Video options">
  <button onclick="playStandard()">Standard version</button>
  <button onclick="playExtended()">Version with extended audio description</button>
</div>
<video id="player" controls></video>

How to Test

  1. Identify all prerecorded videos where visual information cannot fit into natural pauses in the dialogue.
  2. Watch the video with standard audio description enabled and note any visual details that are skipped because there is no gap in dialogue.
  3. Check whether an extended audio description version exists (one that pauses the video to allow full descriptions).
  4. If an extended version exists, play it and verify the video pauses appropriately and descriptions cover all significant visual information.
  5. Confirm the extended version is clearly linked and easy to discover from the video player.
  6. Pass: An extended audio description version exists for dialogue-heavy videos, pausing playback to describe all significant visual content.
  7. Fail: Important visual information is omitted because standard audio description has no room, and no extended version is provided.

How to Fix

  1. Review all prerecorded video content for scenes where standard audio description is insufficient
  2. Create an alternate version of the video that pauses at key moments for extended descriptions
  3. Write audio description scripts that cover all significant visual information
  4. Provide a clear mechanism (button, link, or player setting) to switch to the extended version
  5. Ensure the extended version still synchronizes correctly when playback resumes

Resources

  1. WCAG Understanding 1.2.7
  2. How to Meet 1.2.7