WCAG 1.2.4 Captions (Live)

Success criterion 1.2.4 extends captions to live events: webinars, live shopping, product launches and streamed talks. Without captions, people who are deaf or hard of hearing cannot follow them in real time. It is level AA and part of EN 301 549 (clause 9.1.2.4).

What the criterion requires

Captions must be provided for all live audio content in synchronized media, that is, live video with sound.

Live means information captured from a real-world event and sent to the viewer with no more than a broadcast delay. A short delay for cueing or censoring still counts as live; content that is completely computer-generated does not.

Like prerecorded captions, live captions should convey the speech, identify speakers and note important sounds.

The W3C Understanding document notes that 1.2.4 is not intended to require captions for two-way multimedia calls between individuals.

Typical failures on an online shop

• a live shopping event or product launch on your site with no captions at all;
• a webinar embedded from a platform where captions are available but switched off;
• automatic live captions so inaccurate that product names and prices are unreadable;
• the recording published afterwards without corrected captions.

How to check it

Automated: no automated rule in our checker maps to this criterion. A scan only sees a page at one moment and cannot tell if a stream is live or captioned. This needs a manual check.

By hand: during a live event, open it as a viewer and turn captions on. Check that captions appear for the whole stream, keep up with the speakers, and are accurate enough to follow. Check that the captions control is visible in your embedded player.

How to fix it

• Choose a streaming or webinar platform that supports live captions and turn them on by default.
• For important events, book a human real-time captioner (CART or respeaking).
• Give captioners a list of product names and terms in advance.
• After the event, correct the captions before publishing the recording.

Related criteria

• 1.2.2 Captions (Prerecorded) — captions for recorded video.
• 1.2.5 Audio Description (Prerecorded) — the other level AA media criterion.
• WCAG 2.2 checklist — all A and AA criteria on one page.

Frequently asked questions

Do live shopping streams need captions?

Yes, if they are part of your website or app and have audio. 1.2.4 asks for captions for all live audio content in synchronized media.

Are video calls with one customer covered?

The W3C Understanding document says 1.2.4 is not intended to require captions for two-way calls between individuals in a web app; responsibility then lies with the participants or the host.

Who can produce live captions?

A real-time captioning service (CART, stenography or respeaking), or automatic speech recognition. Automatic captions should be accurate enough to follow; a human captioner is more reliable for names and numbers.

What happens to the recording after the stream?

Once a live stream is published as a recording, it is prerecorded media and falls under 1.2.2 Captions (Prerecorded), so the captions should be checked and corrected.