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//-*- C++ -*-
/*
* YIN pitch estimator
* Copyright (C) 2008 Piotr Pawlow <pp@siedziba.pl>
*
* This file is part of lingot.
*
* lingot is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* lingot is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with lingot; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/* Implementation of YIN algorithm, published in:
*
* A. de Cheveigne and H. Kawahara: YIN, an F0 estimator
* J. Acoust. Soc. Am., Vol. 111, No. 4, April 2002
* http://www.ircam.fr/pcm/cheveign/pss/2002_JASA_YIN.pdf
*/
#include "lingot-yin.h"
inline FLT yin_sqr(FLT x)
{
return x*x;
}
inline FLT yin_interpolate_tau(FLT y1, FLT y2, FLT y3)
{
return ((y1 - y3)/(2.0*(y3 + y1 - (2.0*y2))));
}
FLT yin(LingotCore* core) {
FLT dt_tau;
FLT dt_tau_sum = 0;
FLT dpt_right = 1.0/0.0, dpt_center, dpt_left;
FLT thr = core->conf->yin_threshold;
FLT dpt_min = 1.0/0.0;
FLT dpt_min_left, dpt_min_right;
int j, tau, tau_min;
int len = core->conf->temporal_buffer_size / 2;
for (tau = 1; (tau < len) && ((dpt_center > thr) || (dpt_right < dpt_center) || (tau <= 2)); tau++)
{
dt_tau = 0;
for (j = 0; j < len ; j++)
{
dt_tau += yin_sqr(core->temporal_buffer[j] - core->temporal_buffer[j+tau]);
}
dt_tau_sum += dt_tau;
dpt_left = dpt_center;
dpt_center = dpt_right;
dpt_right = dt_tau / ( 1.0 / tau * dt_tau_sum );
if (dpt_center < dpt_min)
{
dpt_min_left = dpt_left;
dpt_min = dpt_center;
dpt_min_right = dpt_right;
tau_min = tau - 1;
}
}
return (FLT)tau_min + yin_interpolate_tau(dpt_min_left, dpt_min, dpt_min_right);
}