Perceivable Guideline 1.2 Time-based Media

1.2.5 Audio Description (Prerecorded)

Recorded video needs audio description of what is shown

Level AA Needs a person to check

What it asks for, in plain English

Where a recorded video shows things that matter and the soundtrack does not say them, there has to be a version with audio description: a voice that fills the gaps in the dialogue by describing the on-screen action, text or data.

At this level a text transcript is no longer an acceptable substitute (that was the Level A option in 1.2.3). The description has to be audio, either mixed into an alternative version of the video or available as a track the viewer can switch on.

If everything important is already spoken, for example an interview or a presenter who reads out what is on each slide, there is nothing to describe and the video passes as it is.

This is an independent explanation. The binding wording is the W3C Recommendation, and the W3C's own Understanding 1.2.5 page has the full intent, techniques and definitions.

Who it affects

Someone who is blind watching a recipe video hears the music and 'now add this', and never learns what 'this' was.

A learner with low vision taking a video course misses the code shown on screen unless the narrator reads it out.

Anyone listening to a video while driving benefits from the same described track.

How to check it

  1. Watch each video without looking at the screen and write down every moment where the audio alone leaves you guessing.
  2. Look for an audio described version or a description track in the player, and play it.
  3. Check each of your noted moments is now narrated, in the pause nearest to when it appears.
  4. Confirm the described version is as easy to find as the original.

What Websight checks for 1.2.5

Websight has no automated check for this criterion. It lists it in the manual checklist that comes with every report, so it is not forgotten.

Only a person can check this. A scanner cannot know what a video shows, let alone whether the soundtrack explains it.

Practical tips

  • Write the script so the presenter describes what is on screen as they go. It is the cheapest form of audio description and often the best.
  • If the video has long stretches without speech, a separate description track is easier to fit than editing the original.
  • Produce the description at the same time as the captions; the same person already knows the content.

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