Add a captions Browser Source in Moblin
Use a Moblin Browser widget when you want to choose the translated subtitles shown in your video. This is optional: the Twitch Extension instead lets each viewer choose a language. A Browser Source displays captions; your RTMP destination supplies the audio.
Open ControlChoose your IRL setupWhat you need
- A working Moblin RTMP caption destination in IRL Mode.
- Your Browser Source URL from StreamTranslate Control, not your RTMP URL.
- Access to the scene that Moblin uses for your live broadcast.
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
- Choose Browser Source output
In Control, select IRL Mode and Browser Source: you choose the language. Copy your Browser Source URL.
- Create a Browser widget
In Moblin, open Settings, Scenes, Widgets, Create and Browser. Paste the Browser Source URL.
- Add it to your active scene
Enable the widget in the scene used for your broadcast. Turn Local only off so viewers can see it, rather than only your local phone preview.
- Match the video canvas
Use dimensions matching your stream, such as 1920 × 1080 landscape or 1080 × 1920 portrait. Leave browser rendering mode at its default. Position the caption layer above the camera.
- Set the subtitle appearance
In Control, select Translate To and adjust font size, text colors, box style and spoken-caption visibility. Pro can display a second translated language.
Choose one caption experience
Browser Source captions are composited into the broadcast, so everyone sees the language and appearance you choose. Twitch Extension translations remain personalized for viewers.
Avoid displaying the same spoken captions twice through both routes. Check the stream as a viewer, not only inside the phone preview, and make sure the captions do not cover chat or important camera details.
The Extension caption-delay slider applies to Extension viewers. It does not add delay to the Browser widget, and copying a new RTMP URL into the widget will not display captions.
Frequently asked questions
Do I need the Moblin OBS remote-control settings?
No. The Browser widget works in the phone scene. OBS remote-control WebSocket settings are a different feature.
Can I change colors while live?
Yes. Browser Source language and appearance settings come from Control, so you can adjust them during your stream.
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.