Ask HN: Open-Source Alternatives to Restream?

Trying to figure out how I might run a self-hosted solution that accomplishes the main feature of Restream, that is, multiplexing a single RTMP stream to various platforms at the same time. (Youtube, Facebook, Twitch, etc.) I get the sense that Nginx could be configured to do what I want to do, but does anyone know of an open-source solution that comes ready to do it out of the box?