• Success Criterion 1.2.4
  • Conformance level AA

Live Captions So Delayed They’re Useless During the Event

1.2.4 — Captions (Live)

Scenario

Setting

A car-rental site's checkout flow

What’s wrong

Live captions with latency so severe they can't be followed against visuals/slides.

Example

<div id="live-stream"><!-- live video, no caption feed --></div>

Why it matters

Deaf and hard-of-hearing participants in live streams, classes, and meetings.

How to test

Watch live captions against the speaker/slides: if the lag makes them unreadable relative to what's currently being shown, it fails.

How to fix

Readable, reasonably accurate real-time captions must run for the entire live event.

<div id="live-stream"><!-- live video --></div>
<div id="live-captions" aria-live="polite"></div>

Real-time captions, from a human captioner or a checked automated feed, must ship with the live audio, not after it.

Outcome

On a car-rental site's checkout flow, this barrier is gone for deaf and hard-of-hearing participants in live streams, classes — they get the same result as anyone else here.

Who is affected

Deaf and hard-of-hearing participants in live streams, classes, and meetings.

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