---
name: Audio description
slug: audio-description
category: accessibility
status: published
created: 2026-08-21T00:00:00.000Z
modified: 2026-08-21T00:00:00.000Z
definition: A narration track describing visual information the soundtrack
  leaves out, fitted into the gaps between dialogue.
aliases:
  - name: described video
    source: community
  - name: AD track
    source: community
  - name: extended audio description
    source: wcag
tags:
  - media
  - sound
  - wcag
relations:
  contrastWith:
    - captions
    - transcript
  variantOf: []
  partOf: []
  seeAlso:
    - video-player
implementations: []
sources:
  - title: "WCAG 2.2: Audio Description (Prerecorded)"
    url: https://www.w3.org/TR/WCAG22/#audio-description-prerecorded
demo: inline
exhibit: false
useWhen: the picture carries information the audio does not
---

Some of what a video says is only ever shown. A character reads a letter without saying
a word about it, a diagram fills the frame while the presenter says "as you can see
here", a number appears on screen and is never spoken. Audio description is the second
narration track that says those things out loud, written to fit the silences the
dialogue leaves and voiced between the lines rather than over them. The constraint is
the whole craft: a describer has a few seconds of room at a time, has to spend them on
what actually carries the story, and has to get out of the way before the next line
lands.

When the gaps are not long enough, the standard track has to drop information, which is
what extended audio description exists for. There the playback pauses so the
description can finish, then resumes, and the running time of the video grows. WCAG asks
for description of prerecorded video at level A, where a full text alternative is
allowed as a substitute, and again at level AA, where description is required outright.
Extended description sits at AAA, and pausing playback is only workable where the viewer
controls the player rather than sitting in a cinema.

The three text and audio alternatives are often confused, and they answer different
questions. [Captions](/captions) turn the soundtrack into synchronised text, for a
viewer who cannot hear it. Audio description turns the picture into sound, for a viewer
who cannot see it. A [transcript](/transcript) is the whole programme as text, dialogue
and description alike, readable without playing anything, which is the only route that
works through a braille display. A described video with no captions and a captioned
video with no description each leave out a different audience.

Writing them is a specialist job, closer to editing than to copywriting. Describers work
in the present tense, name what is on screen without interpreting it, keep character
names consistent with the dialogue, and resist filling every silence, since a pause can
be the point. Delivery is a recorded human voice or synthesized speech from a timed text
file, and the web mechanism is a second audio track the player mixes in. Cheaper than
all of it: shoot and script so the audio carries the meaning already, say the number
rather than only showing it, and the description track has less to rescue.