Line 21 vs CaptionHub
CaptionHub is built around enterprise subtitling, translation and voiceover for recorded video, with CaptionHub Live adding AI subtitles to live streams. Line 21 is built for live events first: human and AI captioning, live translation and dubbing, and delivery into the stream itself.
At a glance
| Feature | Line 21 | CaptionHub |
|---|---|---|
| Live AI captions | Yes, in 100+ languages | Yes: CaptionHub Live |
| Human (CART) captioners | Yes: accredited stenographers and respeakers, or your own captioners, free | Not stated publicly for live events |
| Speech recognition engines | Choose per language: Speechmatics, Deepgram, Gladia, AWS Transcribe, Microsoft | Not stated publicly |
| Correcting AI captions | AI Proofreader checks every line against your event's names and terms | Termbases, dictionaries and approval workflows |
| Live translation | Yes, 90+ languages with DeepL, Google, Azure and OpenAI | Yes, into 90+ languages |
| Live AI dubbing | Yes (beta): 75 languages with Gemini Live Translate | Voiceover for recorded video |
| Captions encoded into streams | Yes: CEA-608 into RTMP and SRT, in the cloud | No: subtitles are delivered alongside the stream |
| Multi-language HLS player | Yes: a caption and dubbed audio track per language | Through supported players, such as Brightcove |
| Zoom and Teams | Yes: caption token for Zoom and Teams, plus a Zoom app | Not stated publicly |
| Pricing | Free pay as you go; plans from $199 a month | Not published |
Key differences
Live first or recorded first
CaptionHub's strength is subtitling and voiceover workflows for recorded content. Line 21 is designed for live events, from the speaker's microphone to every screen.
Captions in the stream
Line 21 encodes captions into RTMP and SRT streams for YouTube, Twitch and other platforms, as well as publishing them alongside.
Human captioners
Line 21 supplies accredited human captioners for live events and connects their CART software directly.
Live dubbing
Line 21 dubs speech into other languages live, in sync with the video, rather than after the event.
Choose Line 21 if
- Your priority is live events and live streams
- You need human captioners or captions encoded into the stream
- You want live AI dubbing during the event
Choose CaptionHub if
- Most of your work is subtitling and voiceover for recorded video
- You need approval workflows across large localisation teams
About CaptionHub
CaptionHub is an AI platform for multilingual subtitling and voiceover, with approval workflows, roles and ISO 27001 certification. CaptionHub Live adds AI captions and translations to live streams without sitting in the stream path, delivering subtitles through a CDN. CaptionHub Voiceover turns captions into synthetic dubbed audio.
Sources
Based on CaptionHub's public information, reviewed October 2026. Spotted something out of date? Tell us.
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