I was playing with this exact idea today!
Control-wise, rtmp was better, (using the Larix Broadcaster app on the phones/tablets with nginx-rtmp running on my desktop).
You can skip running a server by using the RTSP Camera Server app for android. It will print out a local network url that you can add as a media source in OBS. Takes a few tries to get it working, and it has similar delays to using an rtmp server, but it was the least hassle to set up.
If you need lower latency, webrtc is the way to go (or maybe NDI, but I haven't tried that, myself).
If you do this using webrtc, you need to be okay giving up manual control of your phone cameras (focus, ISO, etc).
With webrtc, you also give up a bit of quality as you add connected devices. Your bottleneck is normally bandwidth. For me, the tradeoff is mostly worth it, since I normally just use autofocus on my phone, anyway.
My webrtc setup today was:
- Samsung Galaxy S7
- Samsung Galaxy S5
- Samsung Galaxy Tablet (old)
- Kindle Fire 8 (2017)
- PC running 4 separate Node servers that handle the webrtc connection (It was hacky, and hopefully I'll get it down to 1 server when I get a little more time).
Window capture sources for fullscreen Firefox (browser source doesn't support webrtc, AFAIK). Requires an internet connection to do the initial handshake, but runs on the local network after that. It doesn't work cross-network.
Here is a screenshot from my webrtc setup, once it was running. I had to blur them out, but you can see the four spaces for each server.
I'd like to get this down to an easy-to-use version with some default configurations, but it's hard to know if it's worth it to take the time.
