Multi-pitch estimation of audio recordings using a codebook-based approach

In this paper, a method for multi-pitch estimation of single-channel mixtures of harmonic signals is presented. Using the method, it is possible to resolve amplitudes of overlapping harmonics, which is otherwise an ill-posed problem. The method is based on the extended invariance principle (EXIP), and a codebook consisting of realistic amplitude vectors. A nonlinear least squares (NLS) cost function is formed based on the observed signal and a parametric model of the signal, for a set of fundamental frequency candidates. For each of these, amplitude estimates are computed. The magnitudes of these estimates are quantized according to a codebook, and an updated cost function is used to estimate the fundamental frequencies of the sources. The performance of the proposed estimator is evaluated using synthetic and real mixtures, and the results show that the proposed method is able to estimate multiple pitches in a mixture of sources with overlapping harmonics.