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WCAG-Compliant Live Streaming — How to Add Captions

WCAG 2.1 AA requires live captions for synchronized media. StreamTranslate satisfies Success Criterion 1.2.4 with our industry-leading speech AI accuracy via OBS browser source — here's what you need to know.

Add WCAG-Compliant Captions

WCAG 2.1 Requirements for Live Video

The Web Content Accessibility Guidelines (WCAG) 2.1 include specific requirements for live audio and video content. For live streaming, the key criterion is Success Criterion 1.2.4 — Captions (Live) at Level AA.

SC 1.2.4 states: "Captions are provided for all live audio content in synchronized media." In plain terms: if you're streaming live video with audio — a live event, webinar, conference, or broadcast — and you're required to meet WCAG 2.1 AA, you need real-time captions.

WCAG 2.1 AA is the standard referenced by most accessibility laws globally: the European Accessibility Act, the UK Equality Act, Section 508 in the United States, and AODA in Canada all reference WCAG 2.1 AA as the technical standard. Meeting WCAG 2.1 AA for live streaming means implementing compliant real-time captions.

SC 1.2.4 — Captions Live

WCAG 2.1 Level AA requires captions for all live synchronized media — the standard referenced by most global accessibility laws.

Synchronized Captions

StreamTranslate delivers real-time captions synchronized to your audio stream — meeting the "synchronized media" requirement of SC 1.2.4.

our industry-leading speech AI Accuracy

Accurate captions that faithfully represent spoken content — a core requirement for WCAG compliance that generic tools often fail to meet on complex audio.

How StreamTranslate Satisfies SC 1.2.4

To satisfy WCAG 2.1 SC 1.2.4, a live captioning solution must provide real-time captions that accurately represent the audio content, appear synchronously with the speech, and are visible to viewers of the live stream.

StreamTranslate meets all three requirements. Captions are generated by our industry-leading speech AI in real time — typically within 1-2 seconds of speech — and delivered as a browser source overlay in OBS. When the stream goes live, viewers see captions directly embedded in the video, synchronized to the speaker's words.

For organizations that need WCAG compliance documentation, StreamTranslate's architecture is straightforward to document: it is a real-time speech-to-text captioning layer delivered as an OBS browser source, powered by our industry-leading speech AI, supporting 125+ languages. The captions are baked into the stream output, not a separate opt-in feature.

Organizations in government, education, healthcare, and financial services that operate live streaming services should evaluate StreamTranslate as their WCAG compliance captioning layer. See the setup guide or contact us about volume pricing for enterprise or institutional use.

Frequently Asked Questions

What WCAG requirement covers live stream captions?

WCAG 2.1 Success Criterion 1.2.4 (Captions — Live) at Level AA requires that live audio-only content or synchronized media include captions.

Does StreamTranslate meet WCAG 2.1 AA for live captions?

Yes. StreamTranslate delivers synchronized, real-time captions via OBS browser source using our industry-leading speech AI, satisfying WCAG 2.1 SC 1.2.4 requirements for live captioning.

Who needs WCAG-compliant live streaming?

Government websites, educational institutions, healthcare organizations, financial services, and any organization subject to accessibility regulations must meet WCAG 2.1 AA for online video.

What is the difference between WCAG 2.1 AA and AAA for live captions?

WCAG 2.1 AA (SC 1.2.4) requires captions for live video. AAA adds extended audio descriptions and sign language interpretation. Most legal requirements only mandate AA.

How accurate do WCAG captions need to be?

WCAG itself doesn't specify a numeric accuracy rate, but captions must accurately convey the content. our industry-leading speech AI via StreamTranslate delivers accuracy that consistently satisfies this requirement for live content.