Larix Broadcaster RTMP setup for iPhone and Android
Larix Broadcaster streams your phone's camera over RTMP. Point it at Upstream and Upstream copies the stream to up to 10 platforms, so your phone uploads one stream on mobile data instead of several.
The one tricky part: Larix wants the server address and the stream key together in a single URL, while Upstream shows them as two values. The steps below show how to join them. Use H.264 video and keep it at 1080p and 30 frames per second, or 60 on a paid plan.
- iPhone or Android
- Free app
Before you start
- An Upstream account (the free plan is enough to test)
- Larix Broadcaster on an iPhone (iOS 16 or later) or Android phone (Android 7 or later)
- A good mobile or Wi-Fi connection
Step 1
Get your server URL and stream key from Upstream
In Upstream, press Create stream, choose Multistream from OBS (it works for any RTMP app or device) and add your platforms, up to 10. The stream opens in Live Studio with the RTMP input on. For a stream you already have, open Live Studio, Source and set Live Source to RTMP.
- RTMP Server URL
rtmp://ingest.upstream.so:1935/live- Stream Key
- Unique to each stream. Copy it from Upstream and keep it private.
Step 2
Add Upstream as a connection
Join the two values from Upstream with a slash:
rtmp://ingest.upstream.so:1935/live/ followed by your Stream Key.
In Larix, open Settings, Connections and tap New connection. Give it a name, paste the full address into URL and save. Turn this connection on and the others off, then tap the red button to go live.
Video settings. Choose H.264 rather than HEVC, 1080p or lower, and 30 fps (60 if your Upstream stream is set to 60 fps). On Android you can type a bitrate. On iPhone you pick from presets: with "Bitrate matches resolution", 1080p uses 3,000 kbps.
Step 3
Start the stream, then go live
Start the stream in Upstream first, then start streaming from Larix. Live Studio switches from Not connected to Excellent, Good or Poor connection when the feed arrives, and Upstream sends it to every platform on the stream.
Troubleshooting
Larix can't connect
Check that the URL holds the server address and the key together:
rtmp://ingest.upstream.so:1935/live/, then the key, with the slash in between. Stopping
at /live leaves the key out.
Upstream gets no picture from Larix
Larix may be set to HEVC. Switch the video codec to H.264, which is what Upstream takes in.
I can't type a bitrate on iPhone
Larix on iPhone uses bitrate presets instead of a number field. Pick a preset that suits your connection.
For connection problems that aren't specific to Larix, such as Not connected, a poor connection or a leaked key, see the full RTMP troubleshooting list.
FAQ
Is Larix Broadcaster free?
Yes. Larix is free. Sending to three or more connections at once is a paid feature, but you only need one connection to Upstream.
Does Larix work on iPhone and Android?
Yes, on iOS 16 or later and Android 7 or later. Both use the same combined URL. Only the bitrate setting works differently.
Checked against Larix Broadcaster docs and the Upstream app, October 2026.
Set it up now
The free plan includes 24 hours of streaming a month and up to 10 of 30+ supported platforms.