Problem with Midi Learn

In both AU and VST it is 100% clear that the plugin is required to report such changes to the host if the controlled parameter is exposed as an automatable and/or host visible parameter.

So why would a internally midi controlled parameter be any different for a plugin? It is effectively being modified internally in the same way.


Because that’s precisely the difference between the parameters a plugin exposes to the host and those it keeps internal. By exposing them as automatable to the host, the plugin enters into a contract with the host, part of which reads “i will not modify the value of these parameters without telling you”. Parameters the plugin keeps internal to itself are of no significance to the host.