Stemquill

Stemquill is a free, open-source desktop app that listens to an audio stem and writes out what it hears as a MIDI file, so you can play the part through your own instruments in any DAW.

Drop in a drum stem and you get kick, snare, closed and open hi-hat, toms, crash and ride on the right notes for your drum plugin, with maps for General MIDI (MT Power Drumkit, EZdrummer, Addictive Drums, Superior Drummer), pads in order (FL Studio FPC, Ableton Drum Rack, MPC) or your own custom notes. Bass and vocal stems come out as single-note melody lines; guitar, keys and synth stems come out as chords, with an optional "better chord detection" add-on for more accurate results.

Stemquill measures the song's real tempo from a stem so the MIDI lines up with your DAW grid, and can snap notes to 1/8, 1/16 or triplets or keep the original feel. Humanize adds small timing and velocity changes so parts feel played, not programmed. Each stem has its own sensitivity and settings, with Apply to all for the rest.

Press Play on any stem to hear the result with built-in sounds before saving, with the original stem mixed in to check the timing. Drop a whole folder of stems and convert them in one go; each row shows when its file is saved, and says "changed · convert again" if you tweak a setting afterwards, so you never drag an out-of-date file into your DAW.

Works with Waveform, FL Studio, Ableton Live, Reaper, Logic, Cubase and any other DAW that reads standard MIDI files. Reads WAV, MP3, FLAC, AIFF, OGG and M4A. There's also a command line for batch jobs.

Windows installer on itch.io (pay what you want, free is fine). macOS and Linux install it with Python. MIT licensed.