I have to write an application (like a step sequencer or arpeggiator) that sends MIDI note to a generic DAW , so I think that only way to implement such thing is to create a virtual MIDI device that should be recognised as a MIDI input/output interface by the OS.
I was wondering if this could be developed using Portmidi or if I need something more complicated.
OS X support is a must, Linux and Windows support is a nice to have.