midiFILTr-VF is an Audio Unit v3 MIDI Effect and CoreMIDI capable app that improves the MIDI capabilities of a hardware Volca FM synthesizer. The Volca FM is notorious for having a unique MIDI spec that does not listen to the velocity of incoming MIDI notes. midiFILTr-VF allows you to play notes with velocity as you would expect to by adding a MIDI CC message along with each note that controls the note's velocity. The Audio Unit also allows you to control the MIDI CC parameters of the Volca FM using AU parameters.

This app requires:
A hardware Volca FM synthesizer
A hardware MIDI interface connected to the Volca FM

An Audio Unit host that supports AUv3 MIDI Effects such as AudioBus or AUM is recommended for ease of use, though the app can also be configured with regular CoreMIDI.