view util/pitch_bihist.py @ 1:c4ef4a02fc19

core functions

# -*- coding: utf-8 -*-
"""
Created on Tue Feb  2 22:26:10 2016

@author: mariapanteli
"""
"""Pitch bihistogram descriptor from chroma representation"""

import numpy
import scipy.signal

import smoothiecore as s

class PitchBihist:
    def __init__(self):
        self.y = None
        self.sr = None
        self.chroma = None
        self.chromasr = None
        self.bihist = None

    def bihist_from_chroma(self, filename='test.wav'):
        self.chroma, self.chromasr = s.get_chroma(filename=filename)
        
        # second frame decomposition
        win2 = int(round(8 * self.chromasr))  # default win2 size 8 sec.
        hop2 = int(round(0.5 * self.chromasr))  # default hop2 size 0.5 sec.
        n_bins, n_chroma_frames = self.chroma.shape
        n_frames = max(1, int(1 + numpy.floor((n_chroma_frames-win2) / float(hop2))))
        bihistframes = numpy.empty((n_bins * n_bins, n_frames))
        
        # loop over all 8-sec frames
        for i in range(n_frames):
            frame = self.chroma[:, (i*  hop2):min((i * hop2 + win2), n_chroma_frames)]
            bihist = self.bihistogram(frame)
            bihist = numpy.reshape(bihist, -1)
            bihistframes[:, i] = bihist
        self.bihist = bihistframes

    def bihistogram(self, spec, winsec=0.5, align=True):
        win = int(round(winsec * self.chromasr))
        ker = numpy.concatenate([numpy.zeros((win, 1)), numpy.ones((win+1, 1))], axis=0)
        spec = spec.T  # transpose to have frames as rows in convolution

        # energy threshold
        thr = 0.3 * numpy.max(spec)
        spec[spec < max(thr, 0)] = 0

        # transitions via convolution
        tra = scipy.signal.convolve2d(spec, ker, mode='same')
        tra[spec > 0] = 0

        # multiply with original
        B = numpy.dot(tra.T, spec)

        # normalize
        mxB = numpy.max(B)
        mnB = numpy.min(B)
        if mxB != mnB:  # avoid division by 0
            B = (B - mnB) / float(mxB-mnB)

        # circularly shift to highest magnitude
        if align:
            ref = numpy.argmax(numpy.sum(spec, axis=0))
            B = numpy.roll(B, -ref, axis=0)
            B = numpy.roll(B, -ref, axis=1)
        return B

    def get_pitchbihist(self, filename='test.wav'):
        self.bihist_from_chroma(filename=filename)
        return self.bihist


if __name__ == '__main__':
    pb = PitchBihist()
    pb.get_pitchbihist()