A Very Low Latency Pitch Tracker for Audio to MIDI Conversion

Olivier Derrien
DAFx-2014 - Erlangen
An algorithm for estimating the fundamental frequency of a singlepitch audio signal is described, for application to audio-to-MIDI conversion. In order to minimize latency, this method is based on the ESPRIT algorithm, together with a statistical model for partials frequencies. It is tested on real guitar recordings and compared to the YIN estimator. We show that, in this particular context, both methods exhibit a similar accuracy but the periodicity measure, used for note segmentation, is much more stable with the ESPRITbased algorithm. This allows to significantly reduce ghost notes. This method is also able to get very close to the theoretical minimum latency, i.e. the fundamental period of the lowest observable pitch. Furthermore, it appears that fast implementations can reach a reasonable complexity and could be compatible with real-time, although this is not tested is this study.