Moblin Setup: Stream From iPhone to OBS via SRT/RTMP

Moblin is a free, open-source IRL streaming app for iOS — “IRL” just means streaming live from out in the real world instead of from a desk. This guide shows you how to set it up so your iPhone’s camera sends video to a StreamRelay endpoint (your personal drop-off address on our servers) over SRT or RTMP — two ways of sending live video across the internet. From there it lands in OBS, the free studio software on your PC.

Before you start

• Moblin installed from the App Store.
• A StreamRelay endpoint — the dashboard gives you a ready-made publish URL (the web address Moblin sends video to, with your secret publish key already baked in). From €9.99/month.
• OBS on your PC, ready to pull the feed — meaning OBS reaches out and grabs the video from the relay.

Step 1: Add a stream destination in Moblin

Open Moblin → Settings → Streams → Add stream. Give it a name like “StreamRelay” so you recognise it later.

Step 2: Enter the StreamRelay URL

Pick which protocol you want (think of it as which “shipping method” your video travels by), then paste in the matching address:

• SRT (recommended for cellular):

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

• RTMP (simplest):

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

Use the publish URL from your dashboard (it carries the secret publish key — keep it private). Moblin works out which protocol to use from the start of the URL (the srt:// or rtmp:// part), so you don’t have to set it anywhere else.

Step 3: Set resolution and bitrate

Pick 1080p30 or 720p60 to start. Bitrate is how much data your video uses each second — higher looks sharper but needs a stronger connection. Set it to what your weakest signal can comfortably handle: 4,000–6,000 kbps on solid 5G/Wi-Fi, 2,500–3,500 kbps on a shaky connection. StreamRelay carries one single connection, so leaving some breathing room means a hiccup in your signal won’t drop the stream.

Step 4: Go live

Tap Go Live. Moblin sends one stream up to StreamRelay. Now tell OBS where to find it by adding the endpoint as a Media Source (a video feed OBS pulls in) — see the OBS setup guide.

SRT or RTMP in Moblin?

Use SRT when your signal comes and goes — it quietly re-sends any bits of video that got lost along the way, so the picture stays smooth on a single link. Use RTMP when you just want the simplest, rock-steady setup. Full comparison: SRT vs RTMP.

Frequently asked questions

Does Moblin support SRT? Yes — paste an srt:// URL as the stream destination. Moblin also supports RTMP.

Why won’t Moblin connect to my endpoint? Check the URL scheme, port, and stream-id/key are exact, and that your StreamRelay endpoint is active.

Keep reading

New to this? Read the phone-to-OBS guide.