p.s. about "how lighting is mapped to midi" IMHO most of the code in the DJ / Lighting industry is heavily proprietary and non-OSS. There's no silver bullet in the hack-a-day scene, but plenty of one-off projects and code snippets because as you say midi is well known / supported.
??? MIDI is an open protocol. ArtNet is open. sACN 1.31 is open. DMX512 is open. OSC is open. rtp-Midi (Apple MIDI) is open and free to use. IDN (laser projector stuff) is open but not popular, people use the EtherDream protocol which is open for unprotected content. Some of these are commercially developed but no real restrictions? The protocols from sender boards to LED video walls are proprietary, but some reverse engineering has been done on the lower end stuff. But most people don't care about those. There are some open source apps for this stuff, but they aren't very usable when compared to commercial competitors. But this is the case with a lot of software? Qlight+ and all that. - Ethan