The Advanced Scene Switcher plugin is already working on that, or at least something similar:
This plugin will allow you to automate various tasks using "Macros". Macros consist of a list of conditions under which a list of actions will be performed. Examples and guides can be found in the wiki. Feel free to contribute! If you run...
obsproject.com
It's not in the official release yet, only a handful of incremental test builds so that the person who requested some functionality could test it. But as far as I've seen in those test builds, it does handle MIDI Note commands at least, to and from a physical device.
OSC over UDP is also in the works, to control DAW's and physical consoles. Probably Generic UDP first, then add another option later for OSC on top of it.
Something I did a long time ago, when Windows XP was still current, was to create some pre-fab MIDI files that could be played as "soundtracks" from the projection app (our automation was all in there, as it was literally laid out as a script), and then use WinXP's audio controls to route the MIDI data to my "automation hub" instead of the cheesy built-in synth. Maybe that could still be an option as well, albeit modified for modern tools?
