Please follow these instructions to control Harmony Engine with a MIDI track in Pro Tools:
1. If you intend to use a MIDI keyboard, connect it to your computer, start Pro Tools, and make a new session.
2. Create an audio track and a MIDI track. Record or import an audio recording onto the audio track.
3. Load Harmony Engine as a plugin insert on the audio track.
4. In the Harmony Engine plug-in window, set the "Harmony Source” control to “MIDI omni.” (There are two other specialized MIDI modes as well. For a more detailed explanation about how each of these work, please see the Harmony Engine user guide).
5. Set the output of your MIDI track to Harmony Engine -> channel 1.
6. Record enable the MIDI track, start playback (or recording) and perform on your MIDI controller to harmonize your audio input. Alternatively, you can import a MIDI file onto your MIDI track and use this instead.