• Success Criterion 1.2.2
  • Conformance level A

Captions That Drift Out of Sync With the Audio

1.2.2 — Captions (Prerecorded)

Scenario

Setting

An email client's compose window

What’s wrong

Captions not synchronized (drift, appear seconds late/early).

Example 

00:00:05.000 --> 00:00:08.000
Click the paperclip icon to attach a file.

00:00:20.000 --> 00:00:23.000
Then choose "Insert signature" from the toolbar.

REM Actual audio speaks these lines at 0:02 and 0:14; captions lag
REM 5-6 seconds behind, well after the video has moved on.

Why it matters

A deaf user following the captioned tutorial clicks the wrong toolbar icon, because the caption for "attach a file" appears well after the video has already moved to a different step.

How to test

Play the video and read along with the captions: if captions appear noticeably before or after the matching audio, it fails.

How to fix

Caption timing has to match the actual audio within a fraction of a second, not just appear somewhere in the general vicinity.

00:00:02.000 --> 00:00:04.500
Click the paperclip icon to attach a file.

00:00:14.000 --> 00:00:16.500
Then choose "Insert signature" from the toolbar.

Outcome

A deaf user clicks the correct icon on the first try because the caption appears exactly when it's spoken.

Who is affected

Deaf and hard-of-hearing users trying to follow along step by step lose track of which instruction matches which part of the video.

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