Use Reatune to write audio to midi

From CockosWiki

1. -Add ReaTune to the FX of the audio track you want "convert" to midi.
2. -Inside Reatune check "Send MIDI events when pitch changes"
3. -Go to the "I/O Routing" of the Audio track. Route it to the track where you have your midi synth, under "SENDS": Route ONLY the MIDI data "All channels to All channels". In the Audio combo box route "None to Channel 1/2"
4. -Go to the "I/O Routing" of the MIDI Track. Select the Audio track in your "RECEIVES" (if you did the previous step well, it is done automatically)
5. -You are done.

• Tip 1: If you want, you can select an specific midi channel instead of all them.

• Tip 2: You can put GSNAP or any other AUTOTUNE in the fx sidechain before REATUNE, to make more easy for REATUNE to recognize the pitch of your audio.