Larix Broadcaster Setup: SRT & RTMP to OBS

Larix Broadcaster is a free phone app (works on iPhone and Android) that turns your phone into a live camera. It speaks both SRT and RTMP — these are just the two common “languages” used to send live video over the internet. This guide sets Larix up to send your camera to a StreamRelay endpoint (your personal drop-off point on our servers), so the video shows up inside OBS on your PC.

Before you start

• Larix Broadcaster installed (iOS or Android).
• A StreamRelay endpoint — the dashboard gives you a ready-made publish URL (the web address your phone sends video to, with your secret publish key baked in). From €9.99/month.
• OBS on your PC, ready to pull the feed — OBS is the free broadcasting software that grabs your video and sends it on to Twitch, YouTube, etc.

Step 1: Create a new connection

Open Larix → Settings (gear) → Connections → New connection. A “connection” here just means one saved set of where-to-send-the-video details.

Step 2: Enter the StreamRelay URL

This URL is the address your phone delivers the video to. Pick one:

• SRT (recommended for cellular):

  srt://<id>.ingest.stream-relay.eu:4000?streamid=publish:live/<slug>:_:<publishKey>

• RTMP:

  rtmp://<id>.ingest.stream-relay.eu:1935/live/<slug>?pass=<publishKey>

  (Use the publish URL from your dashboard — it carries your secret publish key in the ?pass= part. Some apps split RTMP into a server box and a stream-key box; if so, put everything up to the slug — rtmp://<id>.ingest.stream-relay.eu:1935/live/<slug> — in the server box and pass=<publishKey> as the stream key, or just paste the whole URL into the server box and leave the key box empty.)

Larix figures out whether you mean SRT or RTMP from the start of the URL (the srt:// or rtmp:// part), so you don’t have to pick a protocol separately. Save the connection and make sure it’s switched on (ticked).

Step 3: Set video and bitrate

In Settings → Video, choose 1080p30 or 720p60 (resolution and frames per second — how sharp and how smooth the picture is). Then set the bitrate — that’s how much data per second your video uses; higher looks better but needs a stronger connection. Pick a number your weakest signal can hold steadily. StreamRelay carries one single connection, so leave some breathing room rather than maxing it out.

Step 4: Go live and add it in OBS

Tap the record/broadcast button to start sending. Now tell OBS where to pick the video up: add your endpoint as a Media Source (OBS’s term for an incoming feed) — see the OBS setup guide.

SRT or RTMP in Larix?

Larix handles both well. On a mobile (cellular) connection, use SRT — it recovers better when the signal wobbles and feels snappier (lower latency, meaning less delay). Use RTMP when you just want the simplest, most-compatible option. See SRT vs RTMP.

Frequently asked questions

Does Larix Broadcaster support SRT? Yes — create a connection with an srt:// URL. Larix also supports RTMP.

Why won’t Larix connect? Verify the URL scheme, port, and stream-id/key, confirm the connection is enabled, and that your StreamRelay endpoint is active.

Keep reading

New to this? Start with the phone-to-OBS guide.