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Set up live captions with RTMP audio
Send a separate caption feed from Moblin, Larix or another supported encoder while keeping your usual video destination enabled.
Follow the steps
Choose your app before going live
Open Control or Twitch Setup → IRL Mode. Select your streaming app and the language you speak.
Copy the right connection fields
Generate your RTMP URL if prompted. For a single address field, use Copy full RTMP URL. For separate fields, copy Stream URL and Stream key. Keep them private; the Browser Source URL is for displaying captions.
Connect Moblin
Before broadcasting, enable Show all settings. Open Settings → Streams → your Twitch stream → Multi streaming → Create. Paste the full RTMP URL and enable that destination. Keep Twitch as your main destination. The extra feed uses data and battery.
Or connect Larix
Add a connection named StreamTranslate. Paste the full RTMP URL and choose Audio only for that connection. Keep Twitch on Video plus audio, enable both connections, and leave global audio-only capture off.
Connect another encoder
Use an additional RTMP output with the Stream URL and Stream key from Control. Keep your normal video destination enabled. StreamTranslate extracts audio for captions; it does not forward the feed to Twitch.
Set up caption delivery
Activate the Twitch Extension for viewer-selected languages, or use your separate Browser Source URL in a supported overlay widget for captions inside the video.
Verify and stop from your sender
Go live from the streaming app, with the website microphone off. Check incoming audio and captions from a second device. Adjust extension caption delay to match the video. When finished, stop or disable the StreamTranslate destination in the app; closing Control does not stop the sender.
Quick troubleshooting
Will StreamTranslate forward my video to Twitch?
No. Keep your usual Twitch video destination enabled. The extra connection supplies audio for captions.
Do I paste the Browser Source URL into RTMP?
No. Use the full RTMP URL, or the separate Stream URL and Stream key shown for your app.
Does this replace my main streaming connection?
No. Keep the normal video destination enabled alongside the caption connection.
Read the video transcript
Let’s set up Stream Translate with RTMP. Your streaming app sends a second connection for captions, while your usual Twitch destination keeps sending the video. Before you broadcast, open Control or Twitch Setup, choose IRL Mode and select your streaming app. Set the language you speak. Generate your RTMP URL if prompted, then copy it. Keep the URL and key private. If your app asks for one address, use Copy full RTMP URL. If it asks for two fields, copy Stream URL and Stream key separately. The Browser Source URL is for showing captions, not sending audio. For Moblin, make these changes before going live. Enable Show all settings. Open Settings, Streams, your Twitch stream, then Multi streaming. Choose Create, paste the full URL, and enable the new destination. Keep Twitch as your main destination. The additional Moblin feed uses extra data and battery. Stream Translate extracts audio for captions; it does not forward that feed to Twitch. If you use Larix instead, add a connection named Stream Translate. Paste the full RTMP URL and choose Audio only. Keep Twitch on Video plus audio, enable both connections, and leave global audio-only capture off. For the Twitch Extension, link your channel and activate the extension. Viewers choose their own language. For captions inside the video, use your separate Browser Source URL in a supported overlay widget. When ready, go live from Moblin or Larix, not the website microphone. Confirm that audio is arriving and check captions from a second device. Adjust extension caption delay to match your video. When you finish, stop or disable the Stream Translate destination in your streaming app. Closing Control or hiding an overlay does not stop an RTMP sender. That’s the RTMP setup.