MediaMTX live captions and OBS workflows
MediaMTX is a media server and proxy, not a scene editor. Use it to receive your IRL feed, then capture received audio through OBS or a dedicated FFmpeg audio output for StreamTranslate captions. Your own pipeline remains responsible for the video broadcast.
Open ControlChoose your IRL setupWhat you need
- MediaMTX on a computer or server you control.
- An incoming phone or encoder stream with audio.
- OBS with the StreamTranslate plugin, or an FFmpeg output configured for our RTMP caption endpoint.
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
- Receive the ordinary stream
Configure a private test path in your MediaMTX receiver. Publish the phone feed using a protocol and codec the receiver accepts, then verify its audio locally.
- Choose the OBS route
Read the MediaMTX feed in OBS as a Media Source. Attach the StreamTranslate audio filter and supply the key after /live/ from your account’s IRL Mode URL.
- Or configure an audio-only output
Use MediaMTX’s lifecycle hooks or your own supervised FFmpeg process to read the feed, discard video, encode compatible AAC audio and publish RTMP to your StreamTranslate URL. Test this configuration before making it automatic.
- Leave video destinations independent
Continue forwarding or broadcasting video through your own MediaMTX, OBS or cloud provider. Do not route Twitch video through StreamTranslate’s captions-only endpoint.
- Test disconnect and cleanup
Stop the publisher, confirm the audio process exits and usage stops, then reconnect. Check that only one caption session starts and no old process keeps sending silence.
A useful free test receiver
MediaMTX can help reproduce the receive-and-forward part of a Cloud OBS setup on your own machine. Add OBS if you also need scenes, Browser Sources and the audio plugin. MediaMTX alone is not the complete IRL Toolkit product.
Do not expose unauthenticated playback, admin ports or your private stream key publicly. Keep local test receivers private and use the server’s supported authentication features when deploying them.
Receiving SRT in your own MediaMTX does not enable SRT on our public service. Convert or capture audio at your receiver, then use the supported StreamTranslate connection.
Frequently asked questions
Does MediaMTX automatically make the caption upload audio-only?
No. Configure an audio-only output explicitly. A normal forwarded feed can still contain video and use extra bandwidth.
Do we host the main broadcast in this setup?
No. Your receiver or streaming provider handles the video and platform destination. StreamTranslate processes the caption audio.
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.