[0] RTMP is common; `nginx-rtmp` is not common in industry to my knowledge. RTMP ingest is a pretty different task from HTTP reverse proxying. Wowza used to be the common software that was used. Twitch moved off of Wowza and wrote their own ingest stack when I worked there.
RTMP is still the best protocol for publishing live streams IMO, and in my experience http-flv blows HLS out of the water for < 1 sec latency. The protocol is old but at least you aren't 15 seconds behind the action.
FB live says there that they use a modified version of nginx-rtmp for delivery. I don’t know about ingest.
I still think RTMP is a tough choice for delivery. I winder if they are still doing that, 5 years later? I would be surprised, but maybe.
There are lots of ways to make HLS run at much less than 15 seconds. With some clever tricks, a cooperative player, and good network conditions, it can be under 0.5s. Hitting 2-4s latency is relatively straightforward. The strategies here are sometimes bundled under the term “LHLS,” and Apple’s LLHLS incorporates some (not all, grrr) of them.
I admit I do the same thing when looking at projects. When was the last commit? Is that the best measure though? For something like this maybe there doesn’t need to be any more activity?