ref: f15b8cf940ae0a55176fa9a7d071a99af0fcb1a9
dir: /src/spectral/filterbank_mel.c/
/* Copyright (C) 2007-2009 Paul Brossier <piem@aubio.org> and Amaury Hazan <ahazan@iua.upf.edu> This file is part of aubio. aubio 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 3 of the License, or (at your option) any later version. aubio 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 aubio. If not, see <http://www.gnu.org/licenses/>. */ #include "aubio_priv.h" #include "fmat.h" #include "fvec.h" #include "cvec.h" #include "spectral/filterbank.h" #include "spectral/filterbank_mel.h" #include "mathutils.h" uint_t aubio_filterbank_set_triangle_bands (aubio_filterbank_t * fb, const fvec_t * freqs, smpl_t samplerate) { fmat_t *filters = aubio_filterbank_get_coeffs (fb); uint_t n_filters = filters->height, win_s = filters->length; fvec_t *lower_freqs, *upper_freqs, *center_freqs; fvec_t *triangle_heights, *fft_freqs; uint_t fn; /* filter counter */ uint_t bin; /* bin counter */ smpl_t riseInc, downInc; /* freqs define the bands of triangular overlapping windows. throw a warning if filterbank object fb is too short. */ if (freqs->length - 2 > n_filters) { AUBIO_WRN ("not enough filters, %d allocated but %d requested\n", n_filters, freqs->length - 2); } if (freqs->length - 2 < n_filters) { AUBIO_WRN ("too many filters, %d allocated but %d requested\n", n_filters, freqs->length - 2); } if (freqs->data[freqs->length - 1] > samplerate / 2) { AUBIO_WRN ("Nyquist frequency is %fHz, but highest frequency band ends at \ %fHz\n", samplerate / 2, freqs->data[freqs->length - 1]); } /* convenience reference to lower/center/upper frequency for each triangle */ lower_freqs = new_fvec (n_filters); upper_freqs = new_fvec (n_filters); center_freqs = new_fvec (n_filters); /* height of each triangle */ triangle_heights = new_fvec (n_filters); /* lookup table of each bin frequency in hz */ fft_freqs = new_fvec (win_s); /* fill up the lower/center/upper */ for (fn = 0; fn < n_filters; fn++) { lower_freqs->data[fn] = freqs->data[fn]; center_freqs->data[fn] = freqs->data[fn + 1]; upper_freqs->data[fn] = freqs->data[fn + 2]; } /* compute triangle heights so that each triangle has unit area */ for (fn = 0; fn < n_filters; fn++) { triangle_heights->data[fn] = 2. / (upper_freqs->data[fn] - lower_freqs->data[fn]); } /* fill fft_freqs lookup table, which assigns the frequency in hz to each bin */ for (bin = 0; bin < win_s; bin++) { fft_freqs->data[bin] = aubio_bintofreq (bin, samplerate, (win_s - 1) * 2); } /* zeroing of all filters */ fmat_zeros (filters); if (fft_freqs->data[1] >= lower_freqs->data[0]) { /* - 1 to make sure we don't miss the smallest power of two */ uint_t min_win_s = (uint_t) FLOOR (samplerate / lower_freqs->data[0]) - 1; AUBIO_WRN ("Lowest frequency bin (%.2fHz) is higher than lowest frequency \ band (%.2f-%.2fHz). Consider increasing the window size from %d to %d.\n", fft_freqs->data[1], lower_freqs->data[0], upper_freqs->data[0], (win_s - 1) * 2, aubio_next_power_of_two (min_win_s)); } /* building each filter table */ for (fn = 0; fn < n_filters; fn++) { /* skip first elements */ for (bin = 0; bin < win_s - 1; bin++) { if (fft_freqs->data[bin] <= lower_freqs->data[fn] && fft_freqs->data[bin + 1] > lower_freqs->data[fn]) { bin++; break; } } /* compute positive slope step size */ riseInc = triangle_heights->data[fn] / (center_freqs->data[fn] - lower_freqs->data[fn]); /* compute coefficients in positive slope */ for (; bin < win_s - 1; bin++) { filters->data[fn][bin] = (fft_freqs->data[bin] - lower_freqs->data[fn]) * riseInc; if (fft_freqs->data[bin + 1] >= center_freqs->data[fn]) { bin++; break; } } /* compute negative slope step size */ downInc = triangle_heights->data[fn] / (upper_freqs->data[fn] - center_freqs->data[fn]); /* compute coefficents in negative slope */ for (; bin < win_s - 1; bin++) { filters->data[fn][bin] += (upper_freqs->data[fn] - fft_freqs->data[bin]) * downInc; if (filters->data[fn][bin] < 0.) { filters->data[fn][bin] = 0.; } if (fft_freqs->data[bin + 1] >= upper_freqs->data[fn]) break; } /* nothing else to do */ } /* destroy temporarly allocated vectors */ del_fvec (lower_freqs); del_fvec (upper_freqs); del_fvec (center_freqs); del_fvec (triangle_heights); del_fvec (fft_freqs); return 0; } uint_t aubio_filterbank_set_mel_coeffs_slaney (aubio_filterbank_t * fb, smpl_t samplerate) { uint_t retval; /* Malcolm Slaney parameters */ smpl_t lowestFrequency = 133.3333; smpl_t linearSpacing = 66.66666666; smpl_t logSpacing = 1.0711703; uint_t linearFilters = 13; uint_t logFilters = 27; uint_t n_filters = linearFilters + logFilters; uint_t fn; /* filter counter */ smpl_t lastlinearCF; /* buffers to compute filter frequencies */ fvec_t *freqs = new_fvec (n_filters + 2); /* first step: fill all the linear filter frequencies */ for (fn = 0; fn < linearFilters; fn++) { freqs->data[fn] = lowestFrequency + fn * linearSpacing; } lastlinearCF = freqs->data[fn - 1]; /* second step: fill all the log filter frequencies */ for (fn = 0; fn < logFilters + 2; fn++) { freqs->data[fn + linearFilters] = lastlinearCF * (POW (logSpacing, fn + 1)); } /* now compute the actual coefficients */ retval = aubio_filterbank_set_triangle_bands (fb, freqs, samplerate); /* destroy vector used to store frequency limits */ del_fvec (freqs); return retval; }