Global MIDI transformation #1124
Description
ReaLearn already supports global MIDI filtering: It can globally filter out particular MIDI messages from particular devices, so that they will never arrive at tracks. By default, it filters out any message that is used to control something. So as soon as you map a key, button, fader, etc. within ReaLearn, it will not trigger MIDI notes in VST instruments anymore ... which is great!
We could actually take this one step further and allow arbitrary transformation of incoming messages.
Example use case: Add a mod wheel to controller that don't have one
I really like the APC Key 25 mk2 keyboard. The only thing I frequently miss is a mod wheel. I could transform the first knob into a mod-wheel control on a case-by-case basis, by using a single ReaLearn instance or JSFX on top of the VSTi in question. But that's too much effort in my cases, so I end up not doing it in most cases.
Using global MIDI transformation, I would set this up once on the monitoring FX chain and be done with it!
Implementation idea
All the ingredients are there already! Visually, it would just need a checkbox "Transform globally" in the "MIDI: Send message" target. Or better: A new entry "Replace globally" in the output dropdown.