The protocol is one thing, the other nearly more important one is the bandwidth/encoding for each platform. On YouTube you may want to put out a high-res/high bitrate version and let YouTube handle the churning down to lower resolutions. On Twitch, unless you're a partner, you want to pick a low enough bitrate, otherwise your viewers will be hit with a high bitrate and some end up unable to watch the stream.

So lots of reencoding happening on the fly, which is why I know of some streamers using dedicated streaming computers, that take the OBS stream as input, but I don't know what software they use to distribute it.

[0]There are services that do this. Of course, this goes against TOS for affiliate and partnered streamers on twitch. As of my last check, it's not an issue for other platforms yet.

Being able to do this is actually the number one reason why I strongly believe nobody should ever become a Twitch affiliate.

[0]https://restream.io/

I've been looking into building a containerized FFMPEG stream routing solution but haven't been able to think of a good use-case. What is your alternative destination after Facebook RTMPS?

We’re just trying to stream to YouTube and Facebook at the same time.

Actually, ffmpeg is the other solution I was looking at playing with on the weekend.

FFMPEG is a great tool for any IP video streaming workflow. You can easily define multiple outputs. Check out the live streaming guide: https://trac.ffmpeg.org/wiki/StreamingGuide

I just haven't yet found a good way to export active stream status from the CLI out to other interfaces for the tool I'm working on.