Line 21 Live Captions is a live captioning platform where AI and human specialists work together to deliver accurate, readable captions for streams and recordings.
Live captions and speech recognition
The service combines manual captioning with automatic speech recognition (ASR) to produce real-time captions. It supports RTMP and HLS streaming and provides caption encoding that follows CEA-608/708 standards.
AI-assisted caption quality
Line 21 includes AI tools designed to improve accuracy and context across different languages and audiences:
- AI translation
- AI proofreader
- AI Context Builder
Integrations and ways to use it
Line 21 offers multiple options for embedding and connecting captions into your workflow:
- Embeddable player and a dedicated caption viewing page
- Overlays and playlists
- API for integrating with your services and apps
- Meeting bot to add captions to online meetings and webinars
It’s suited for media teams, education, and business use cases that need reliable captions in live and recorded formats.
