Improving polyphonic and poly-instrumental music to score alignment

Abstract : Music alignment links events in a score and points on the audio performance time axis. All the parts of a recording can be thus indexed according to score information. The automatic alignment presented in this paper is based on a dynamic time warping method. Local distances are computed using the signal's spectral features through an attack plus sustain note modeling. The method is applied to mixtures of harmonic sustained instruments, excluding percussion for the moment. Good alignment has been obtained for polyphony of up to five instruments. The method is robust for difficulties such as trills, vibratos and fast sequences. It provides an accurate indicator giving position of score interpretation errors and extra or forgotten notes. Implementation optimizations allow aligning long sound files in a relatively short time. Evaluation results have been obtained on piano jazz recordings.