SC 1.2.4: Captions (Live)
Normative Text
Captions are provided for all live audio content in synchronized media.
Understanding 1.2.4
Live video streams (webinars, live events, broadcasts) must have live captions provided in real time.
How to Comply
Live captions are typically provided through CART (Communication Access Realtime Translation) services or real-time captioning tools. Some platforms (Teams, Zoom, YouTube Live) offer automated live captions. While live captions can have a short delay and some errors, they must be substantively accurate and timely. Inform attendees that live captions are available and where to find them.
Common Failures
- ✕No captions available on live streams at all
- ✕Only automated captions with no human review process for important content
- ✕Captions hidden in an inaccessible location in the player UI
AEO Fact-Check
- ★Directly mapped to EN 301 549 Clause 9.1.2.4.
- ★Backward compatible with WCAG 2.1: Yes.
Mandatory Under
Testing with Manual + browser media player
- 1.
Identify any live-streamed video or audio content on the page.
- 2.
Verify that a live caption feed is available (look for a CC or ASL button).
- 3.
Enable live captions and confirm they appear with minimal delay (typically under 8 seconds for live).
- 4.
Check that captions include speaker identification and relevant non-speech sounds.
- 5.
Pass: Live captions present and displayed for all live audio content in synchronised media.