The Chromeleiter

Electronic Musician playing live in a Jazz band:

"Hey that sounds cool, what are you playing?"

The Guitar player answers

"Thats A# Minor"

Electronic Musician

???

The Chromeleiter helps you to not embarrass yourself anymore. It shows you the pitches/notes of what the others are currently playing, and enables you to play along with them without knowing what the are actually playing. Essentially it is a realtime visualisation of harmonic pitch class profiles or chroma vector mapped to the chromatic keyboard mode of a Novation Launchpad / Ableton Push device. It lights up the pads of the corresponding notes that are currently used by other players as well as an chord estimate. It is a provided as a C++ command line application that listens to the Audio input and connects to the Launchpad via MIDI.

Usage

./Chromeleiter 0

runs the chromeleiter application and listens to audio on the first audio input device.

How does it work

• Audio signal is captured from microphone
• Chromagram is computed via method described in [1]
• Resulting pitch class vector is scaled, thresholded and mapped to MIDI sysex output.
• ChordDetection is used to detect the quality of the chords (Major and Minor for now) and change the colors of the pads accordingly.

Used tools

• Realtime Chromagram
• Portaudio
• RTMidi

Compile on OS X

1. Install dependencies with homebrew

• portaudio

2. Run make

References

[1] Real-Time Chord Recognition For Live Performance", A. M. Stark and M. D. Plumbley. In Proceedings of the 2009 International Computer Music Conference (ICMC 2009), Montreal, Canada, 16-21 August 2009

License

GPL