ref: fa713bddc04f8732b89abba20b48b8699dafca07
parent: 2886984b75b4a146642769acb43335362a06e0c1
author: Paul Brossier <piem@piem.org>
date: Fri Nov 16 22:15:07 EST 2018
[filterbank] add set_mel_coeffs
--- a/src/spectral/filterbank_mel.c
+++ b/src/spectral/filterbank_mel.c
@@ -206,3 +206,91 @@
return retval;
}
+
+uint_t
+aubio_filterbank_set_mel_coeffs (aubio_filterbank_t * fb, smpl_t samplerate,
+ smpl_t freq_min, smpl_t freq_max)
+{+ uint_t m, retval;
+ smpl_t start, end, step;
+ fvec_t *freqs;
+ fmat_t *coeffs = aubio_filterbank_get_coeffs(fb);
+ uint_t n_bands = coeffs->height;
+
+ if (freq_max < 0) {+ AUBIO_ERR("filterbank: set_mel_coeffs freq_max should be > 0\n");+ return AUBIO_FAIL;
+ } else if (freq_max == 0) {+ end = aubio_hztomel(samplerate / 2.);
+ } else {+ end = aubio_hztomel(freq_max);
+ }
+ if (freq_min < 0) {+ AUBIO_ERR("filterbank: set_mel_coeffs freq_min should be > 0\n");+ return AUBIO_FAIL;
+ } else {+ start = aubio_hztomel(freq_min);
+ }
+ if (n_bands <= 0) {+ AUBIO_ERR("filterbank: set_mel_coeffs n_bands should be > 0\n");+ return AUBIO_FAIL;
+ }
+
+ freqs = new_fvec(n_bands + 2);
+ step = (end - start) / (n_bands + 1);
+
+ for (m = 0; m < n_bands + 2; m++)
+ {+ freqs->data[m] = MIN(aubio_meltohz(start + step * m), samplerate/2.);
+ }
+
+ retval = aubio_filterbank_set_triangle_bands (fb, freqs, samplerate);
+
+ /* destroy vector used to store frequency limits */
+ del_fvec (freqs);
+ return retval;
+}
+
+uint_t
+aubio_filterbank_set_mel_coeffs_htk (aubio_filterbank_t * fb, smpl_t samplerate,
+ smpl_t freq_min, smpl_t freq_max)
+{+ uint_t m, retval;
+ smpl_t start, end, step;
+ fvec_t *freqs;
+ fmat_t *coeffs = aubio_filterbank_get_coeffs(fb);
+ uint_t n_bands = coeffs->height;
+
+ if (freq_max < 0) {+ AUBIO_ERR("filterbank: set_mel_coeffs freq_max should be > 0\n");+ return AUBIO_FAIL;
+ } else if (freq_max == 0) {+ end = aubio_hztomel_htk(samplerate / 2.);
+ } else {+ end = aubio_hztomel_htk(freq_max);
+ }
+ if (freq_min < 0) {+ AUBIO_ERR("filterbank: set_mel_coeffs freq_min should be > 0\n");+ return AUBIO_FAIL;
+ } else {+ start = aubio_hztomel_htk(freq_min);
+ }
+ if (n_bands <= 0) {+ AUBIO_ERR("filterbank: set_mel_coeffs n_bands should be > 0\n");+ return AUBIO_FAIL;
+ }
+
+ freqs = new_fvec (n_bands + 2);
+ step = (end - start) / (n_bands + 1);
+
+ for (m = 0; m < n_bands + 2; m++)
+ {+ freqs->data[m] = MIN(aubio_meltohz_htk(step * m), samplerate/2.);
+ }
+
+ retval = aubio_filterbank_set_triangle_bands (fb, freqs, samplerate);
+
+ /* destroy vector used to store frequency limits */
+ del_fvec (freqs);
+ return retval;
+}
--- a/src/spectral/filterbank_mel.h
+++ b/src/spectral/filterbank_mel.h
@@ -57,14 +57,60 @@
\param fb filterbank object
\param samplerate audio sampling rate
- The filter coefficients are built according to Malcolm Slaney's Auditory
- Toolbox, available online at the following address (see file mfcc.m):
+ The filter coefficients are built to match exactly Malcolm Slaney's Auditory
+ Toolbox implementation (see file mfcc.m). The number of filters should be 40.
+ References
+ ----------
+
+ Malcolm Slaney, *Auditory Toolbox Version 2, Technical Report #1998-010*
https://engineering.purdue.edu/~malcolm/interval/1998-010/
*/
uint_t aubio_filterbank_set_mel_coeffs_slaney (aubio_filterbank_t * fb,
smpl_t samplerate);
+
+/** Mel filterbank initialization
+
+ \param fb filterbank object
+ \param samplerate audio sampling rate
+ \param fmin start frequency, in Hz
+ \param fmax end frequency, in Hz
+
+ The filterbank will be initialized with bands linearly spaced in the mel
+ scale, from `fmin` to `fmax`.
+
+ References
+ ----------
+
+ Malcolm Slaney, *Auditory Toolbox Version 2, Technical Report #1998-010*
+ https://engineering.purdue.edu/~malcolm/interval/1998-010/
+
+*/
+uint_t aubio_filterbank_set_mel_coeffs(aubio_filterbank_t * fb,
+ smpl_t samplerate, smpl_t freq_min, smpl_t freq_max);
+
+/** Mel filterbank initialization
+
+ \param fb filterbank object
+ \param samplerate audio sampling rate
+ \param fmin start frequency, in Hz
+ \param fmax end frequency, in Hz
+
+ The bank of filters will be initalized to to cover linearly spaced bands in
+ the Htk mel scale, from `fmin` to `fmax`.
+
+ References
+ ----------
+
+ Douglas O'Shaughnessy (1987). *Speech communication: human and machine*.
+ Addison-Wesley. p. 150. ISBN 978-0-201-16520-3.
+
+ HTK Speech Recognition Toolkit: http://htk.eng.cam.ac.uk/
+
+*/
+uint_t aubio_filterbank_set_mel_coeffs_htk(aubio_filterbank_t * fb,
+ smpl_t samplerate, smpl_t freq_min, smpl_t freq_max);
#ifdef __cplusplus
}