For the past couple of months I have made few Arduino projects for the purpose of integration various systems with Resolume Arena.
Custom VJ controller's, custom RGB and 12V LED Lights, custom video wall with WS2812 stripe and tested them live on stage few times.
In theory, MIDI and OSC protocols seem to be a good choice for communication, but in practice that has been shown differently...
Arduino projects where hardware mostly need to receive signal or information from the software, the DMX protocol was best choice.
Main goal in such projects is fast communication.
Projects where software receives commands from hardware needs much less communication but goal here is highest possible reliability.
I have managed to get most reliable results sending signals to opensource software MCE Controller which act as tiny server who then
send's keystrokes and other commands to running Arena instance.
Using this method i have minimalise every possible interference with other devices that may be used live on stage which have MIDI as only option for communication.