WCAG 1.2.7 — Extended Audio Description (Prerecorded)

What this requires

For prerecorded synchronised media at Level AAA, extended audio description must be provided when the gaps between dialogue are too short to narrate the visual information. The player pauses the video, the description plays in full, and the video resumes. The result is a longer total runtime but a complete equivalent for blind users — no crucial visual is lost because there was no time to describe it.

How AI coding tools fail this

This is a production-and-tooling concern more than a code-generation concern. AI tools fail it by treating audio description as a single binary box: either there's a description track or there isn't. The nuance — "is the description complete, or did the producer cut content to fit it into existing pauses?" — never enters the conversation.

The code-level failure: custom video players that don't support pausing the main track to let a description segment play. Native <track kind="descriptions"> in browsers that support it can handle this; custom players written from scratch generally don't.

Failing examples

A dialogue-heavy video with a standard description track that's been trimmed to fit the pauses, missing visual content:

<video controls>
  <source src="/feature-demo.mp4" type="video/mp4" />
  <track kind="descriptions" src="/feature-demo.desc.en.vtt" srcLang="en" />
</video>

(Failure is in the content, not the markup: the description omits visual information because there was no time to say it.)

Passing examples

A separately produced extended-description version of the video, offered as an alternate source:

<>
  <div role="group" aria-labelledby="version-label">
    <span id="version-label">Choose version:</span>
    <button onClick={() => setVersion("default")} aria-pressed={version === "default"}>
      Standard
    </button>
    <button onClick={() => setVersion("extended")} aria-pressed={version === "extended"}>
      With extended audio description
    </button>
  </div>
  <video controls key={version}>
    <source
      src={version === "extended" ? "/feature-demo.extended-ad.mp4" : "/feature-demo.mp4"}
      type="video/mp4"
    />
    <track kind="captions" src="/feature-demo.en.vtt" srcLang="en" default />
  </video>
</>

Edge cases

Production overhead. Extended description usually means re-editing the source video, which is expensive. Plan for it on flagship content, not on every clip.
Alternative: a full text transcript covering all visual information satisfies 1.2.8 at AAA and is sometimes easier to produce than a separate extended-description video.
The default video is still the default. The extended version is in addition to, not in place of, the standard one.
Browser implementation of kind="descriptions" has historically been weak. A separately produced video file is the most reliable delivery method.

How Jeikin handles this

This is a manual review item. The scanner records each <video> and asks the reviewer whether the standard audio description is complete or whether extended description (or a full transcript covering visuals) is needed. The dashboard keeps the answer as evidence.