Continuous Real-Time Determination of Key And Chords in Live Music Using Minimum Description Length

Abstract

We describe a real-time method for continuously determining the key of live music and detecting chords using a minimum description length (MDL) criterion. MDL is based on the idea that the model that provides the simplest explanation of the data is the “best” model. Pitch detection is performed in the time domain using a bank of gamma-tone filters tuned to the musical range of interest. Outputs across octave are collapsed into a chromagram that is matched against interval and scale models to detect chords and determine the musical key. We analyze several Bach inventions, a Beethoven piano sonata, and a portion of a jazz piece.

Keywords: Pitch detection, gamma-tone filter, musical key, chord detection, minimum description length