Level AA · WCAG 2.0
1.2.4 Captions (Live)
Live video with sound — a webinar, a keynote, a broadcast — needs captions while it is live, not only in the recording published afterwards.
Manual only No automated check says anything useful.
How it fails in practice
A product launch streamed to thousands with captions promised “in the replay next week”. An automatic live caption track that drops names, numbers and every other sentence, and nobody watching it.
How to fix it
Book a live captioner (CART) for anything that matters, or run automatic captions with a person correcting them as they go. Carry the captions in the stream itself, so every player that shows the video can show them.
At a glance
- Level
- Level AA — the level EN 301 549 requires, and therefore the level the BFSG and the EAA are measured against.
- Principle
- Perceivable
- Guideline
- 1.2 Time-based Media
- Added in
- WCAG 2.0
- EN 301 549
- 9.1.2.4
- Automated check
- Manual only
How to test it by hand
- Join a live stream — or the next scheduled one — and look for a captions control on the live player, not on the recording.
- Watch five minutes with the sound off. The captions keep pace with the speech, name who is speaking when that changes, and include the sounds that matter.
- Check the hard words: product names, people’s names and numbers. They are what automatic captions get wrong and what carries the meaning.
- Ask how captions are produced for the next event. “The platform does it” with nobody checking is the answer that fails.
In code
#EXTM3U
#EXT-X-STREAM-INF:BANDWIDTH=2500000,RESOLUTION=1280x720
keynote-720p.m3u8#EXTM3U
#EXT-X-MEDIA:TYPE=SUBTITLES,GROUP-ID="subs",LANGUAGE="en",NAME="English (live captions)",DEFAULT=YES,AUTOSELECT=YES,URI="captions-en.m3u8"
#EXT-X-STREAM-INF:BANDWIDTH=2500000,RESOLUTION=1280x720,SUBTITLES="subs"
keynote-720p.m3u8Manual only
How far an automated check gets
Nothing automatic decides this. A scanner that reports it as passing is reporting that it did not look. It stays untested until a person tests it and records what they did — which is exactly how we treat it: as untested, not as passed.
Related criteria
Other criteria under the same guideline.
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