How it works
Sourcesphone, action cam, drone
SRT / RTMP
Feedserver in Norway
SRT
OBSone Media Source
RTMP
Twitchas usual
A feed is one Media Source in OBS. Its sources are the cameras that can feed it - each sends to its own address. The feed shows one source at a time: the first live one in your order, or one you pick. If it drops, the next live one takes over; when a higher one comes back, the feed switches back to it. Each switch makes OBS reconnect, which takes about a second.
Cameras you want as separate OBS sources - say a drone next to your main camera - get feeds of their own.
SRT resends lost packets within the delay you set, so a shaky mobile connection shows up as a short wait instead of broken pictures. The server sits in Norway, a couple of milliseconds from Oslo, so resends come back fast and you can run a shorter delay than with a relay further south.
Apps and devices
- Moblin (iPhone) and Larix Broadcaster (iPhone, Android): open the source's Set up, pick the app and use Open in … on the phone, or scan the QR code from your computer - it sets up the address, the delay and the camera settings in one go.
- IRL Pro (Android): paste the source's address as the SRT URL (or scan it as a QR code), and set the latency there to the source's value.
- OBS on another PC: a source of kind PC - Settings → Stream → Service Custom…, Server = its address, Stream key empty.
- DJI drones, Osmo and GoPro: they only send RTMP. Make the source kind Drone and use its RTMP server and stream key (or the full RTMP address).
- Hardware encoders and SRT cameras: mode Caller, and enter server, port, stream id and latency (and passphrase) in their own fields.
Where the delay comes from
From moving the phone to seeing it in OBS, the time adds up like this:
- The camera app captures and encodes: about 0.1-0.3 s (B-frames off keeps it low).
- Camera → server: the SRT delay. SRT uses the larger of what the app and the server ask for, so the app's own setting decides. Moblin starts at 3000 ms - on its own that's 3 seconds. The one-tap setup sets it to the source's value.
- The server passes packets straight on - it adds next to nothing.
- Server → OBS: SRT's standard 120 ms.
- OBS decodes and shows it: about 0.1-0.3 s with the Media Source settings on the feed's OBS tab.
So a phone set to 800 ms lands in OBS about 1.2-1.5 s later; at Moblin's 3000 ms it's about 3.5 s. While a source is live, the feed shows the delay the camera really uses - and warns when it's longer than the source is set to. Each source keeps a summary of its last streams.
Viewers see it later still: Twitch adds its own few seconds on top of OBS. A server in Norway shortens the round trip for resends (about 2 ms to Oslo, against 20-30 ms to relays in Amsterdam or Frankfurt), which is what lets the camera delay go down without the picture breaking up.
Picking the delay
- Phone on 4G/5G: start at 1000 ms. If the picture never stutters, try 800 or 500.
- Phone or camera on good Wi-Fi or cable: 300-500 ms.
- Moving through tunnels and bad coverage: 1500-2000 ms.
The delay is set per source, in the camera app - the setup links put it there for you.
Best picture and sound
- Video: H.265 (HEVC) if the phone can - same quality at a lower bitrate. 1080p at 6-12 Mbps, more on good 5G.
- Keyframe every 1 s, so OBS shows the picture quickly after a reconnect or a switch between sources.
- Sound: AAC at 48 kHz, 160-256 kbps.
- OBS turns this into your Twitch stream, so a high-quality feed in means less loss when OBS encodes again.
Automatic scene switching (NOALBS)
NOALBS runs next to OBS and switches scenes by itself: to BRB when the feed's camera drops (and no other source takes over), to a "low" scene when the connection gets weak, and back to live when it recovers. Each feed's NOALBS tab has the stats address and a block to paste into NOALBS's config.json.
Getting help: editors
Streaming from a phone, with nobody at a computer? Let someone else run the feed for you - a moderator, or whoever runs your OBS. In the feed's Settings, Invite an editor makes a link: send it to them, and when they open it and sign in with Twitch, they can change everything in the feed and see its addresses.
- They can add and set up sources, switch cameras, change the delay, encryption and keys, and disconnect a camera.
- Only you can delete the feed and decide who edits it. Remove an editor at any time; they can also stop by themselves.
- An invite link works once, for 48 hours. They don't need access of their own to help.
- Changes show up for everyone at once - the page says who changed what.
When it doesn't connect
- The feed says why the server turned a camera or OBS away (a wrong key, a passphrase that doesn't match, a source that's switched off …).
- Encryption on? Every camera in the feed and OBS need the passphrase - it's already in the addresses and setup links.
- Some venue Wi-Fi and company networks block UDP, which SRT needs. Use mobile data, or RTMP as a fallback.
- Made a new key? The old address stops working at once - put the new one into the camera (or OBS).
