Live translated subtitles for Moblin
StreamTranslate adds live translated subtitles to your Moblin broadcast using a separate RTMP caption destination. Keep Twitch as your normal video destination. Viewers can choose their language in the Twitch Extension, or you can add a Browser Source to your phone scene.
Open ControlChoose your IRL setupWhat you need
- Moblin on your iPhone and an active StreamTranslate account with streaming hours.
- A normal Twitch destination in Moblin, plus access to its Multi streaming settings.
- Your full RTMP URL from Control or Twitch Setup. Keep this private.
Use the account and URLs for the same environment. A staging caption feed does not appear in the released Twitch Extension unless the test channel is deliberately connected to staging.
Choose your caption output
Twitch Extension: each viewer chooses their language and appearance. Keep your Twitch account linked and the Extension active on your channel.
Browser Source: you choose the language, colors and appearance in Control. The captions are included in your video for everyone.
Do not activate two audio capture routes for the same voice. The Browser Source URL is for display; the RTMP URL or OBS plugin supplies audio.
Setup steps
- Copy your full RTMP URL
Open Control or Twitch Setup, select IRL Mode, then press Copy full RTMP URL. Generate the URL first if prompted.
- Add a separate Moblin destination
Stop broadcasting before editing destinations. Enable Show all settings. In Settings, open Streams, your Twitch stream, Multi streaming, then Create and URL. Paste the full URL and enable it. Keep Twitch as the main destination.
- Choose what you speak
Select your spoken language in Control or Twitch Setup. Choose Extension captions for viewer-selected translations, or add the optional Browser widget for captions you control.
- Go live from Moblin
Start your normal Moblin broadcast. Check for Live from RTMP in StreamTranslate and captions on the linked Twitch channel. The browser microphone stays off.
- Check timing and recovery
Speak a complete sentence, change viewer language, then test Stop Captions and Resume. End and restart the phone stream to check that the caption connection returns.
Mobile data and your broadcast
The extra Moblin destination sends an additional audio/video feed. StreamTranslate extracts its audio for captions; it does not forward that video to Twitch. The extra upload uses mobile data and requires an internet connection.
Your normal Twitch destination is still responsible for putting you live on Twitch. Signing into Twitch inside the app is not a replacement for enabling that destination.
For a lower-bandwidth alternative with an OBS receiver, use the OBS audio plugin on the received feed. The plugin sends audio rather than an additional video stream from that receiver.
Frequently asked questions
Why do captions work in Control while Twitch is offline?
Your caption destination can connect independently of Twitch. Enable and verify Moblin’s normal Twitch destination as well.
Can I use Moblin without OBS?
Yes. The separate RTMP caption destination and Moblin Browser widget route do not require OBS.
Do I need to leave the Control microphone running?
No. In IRL Mode, audio comes from your RTMP destination or the OBS audio plugin. Use Control to change settings; do not start a second browser microphone session.
Who chooses the subtitle language?
With the Twitch Extension, each viewer chooses their own language and appearance. With a Browser Source, you choose the language and appearance in Control and viewers see those captions in your video.
How should I adjust caption timing?
For Twitch Extension viewers, internal testing found 3–5 seconds is the sweet spot. Adjust to your actual video delay. This setting does not delay a Browser Source composited into your broadcast.
More IRL setup guides
OBS Studio, Streamlabs, Meld and other supported desktop software remain available through the desktop setup guide. For captions on the move, choose your phone or cloud workflow in the IRL Hub.