# Streaming and broadcast

Every streaming platform has its own rules for captions. Line 21 handles them from one place: send your stream in, and get it back with captions wherever your audience watches.

Encode captions for social platforms, post them to YouTube through its caption API, or publish your own player with a caption track for every language.

Covers: YouTube Live, Twitch, Vimeo, LinkedIn Live, Facebook Live, Your own player.

## What makes it hard

**One caption track**: Most social platforms accept a single caption track in the stream, so one language at a time.

**Platform by platform**: YouTube, Twitch, Facebook and Vimeo each set up captions differently.

**Delay and sync**: Encoding adds delay, and captions have to stay in step with the picture.

## How Line 21 handles it

### Encoded and simulcast

CEA-608 captions encoded into your RTMP or SRT feed and sent to YouTube, Twitch, Facebook, X, Vimeo or any custom RTMP endpoint.

[Caption encoding](https://line-21.com/features/caption-encoding)

### Your own player, every language

An embeddable HLS player with a caption track per language, delivered through a CDN to any number of viewers.

[HLS streaming](https://line-21.com/features/hls-streaming)

### YouTube without re-encoding

Send timestamped captions to YouTube Live through its caption ingestion URL.

[Text destinations](https://line-21.com/docs/destinations/text-destinations)

### Eyes on every output

Watch the captioned video and every destination from one screen while you are live.

[Monitor](https://line-21.com/features/monitor)

## Further reading

- [5 tools for live captioning on YouTube Live](https://line-21.com/blog/2026-07-06-5-tools-for-live-captioning-on-youtube-live)
- [5 tools for closed captioning across multiple streaming destinations](https://line-21.com/blog/2026-07-29-5-tools-for-closed-captioning-across-multiple-streaming-destinations)
- [Live captioning for HLS video players: comparing 5 platforms](https://line-21.com/blog/2026-08-03-live-captioning-for-hls-video-players-comparing-5-platforms)
- [5 tools for live captioning on Twitch](https://line-21.com/blog/2026-07-10-5-tools-for-live-captioning-on-twitch)

Talk to us: [contact page](https://line-21.com/contact) or hello@line-21.com.