src/spectral/filterbank_mel.{c,h}: rename _set_mel_coeffs to _set_triangle_bands...

diff --git a/src/spectral/filterbank_mel.c b/src/spectral/filterbank_mel.c
index 0bd68874f70fcbd8b1b2f587a93cbdee33c976ec..3d0a9531a75c7d082f2f480d39bd3b3ab74940e3 100644 (file)
--- a/src/spectral/filterbank_mel.c
+++ b/src/spectral/filterbank_mel.c
@@ -25,9 +25,9 @@
 #include "spectral/filterbank.h"
 #include "mathutils.h"
 
-void
-aubio_filterbank_set_mel_coeffs (aubio_filterbank_t * fb, fvec_t * freqs,
-    smpl_t samplerate)
+uint_t
+aubio_filterbank_set_triangle_bands (aubio_filterbank_t * fb,
+    smpl_t samplerate, fvec_t * freqs)
 {
 
   fvec_t *filters = aubio_filterbank_get_coeffs (fb);
@@ -43,6 +43,16 @@ aubio_filterbank_set_mel_coeffs (aubio_filterbank_t * fb, fvec_t * freqs,
         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[0][freqs->length - 1] > samplerate / 2) {
+    AUBIO_WRN ("Nyquist frequency is %fHz, but highest frequency band ends at \
+%fHz\n", samplerate / 2, freqs->data[0][freqs->length - 1]);
+  }
+
   /* convenience reference to lower/center/upper frequency for each triangle */
   fvec_t *lower_freqs = new_fvec (n_filters, 1);
   fvec_t *upper_freqs = new_fvec (n_filters, 1);
@@ -69,12 +79,24 @@ aubio_filterbank_set_mel_coeffs (aubio_filterbank_t * fb, fvec_t * freqs,
 
   /* fill fft_freqs lookup table, which assigns the frequency in hz to each bin */
   for (bin = 0; bin < win_s; bin++) {
-    fft_freqs->data[0][bin] = aubio_bintofreq (bin, samplerate, (win_s - 1) * 2);
+    fft_freqs->data[0][bin] =
+        aubio_bintofreq (bin, samplerate, (win_s - 1) * 2);
   }
 
   /* zeroing of all filters */
   fvec_zeros (filters);
 
+  if (fft_freqs->data[0][1] >= lower_freqs->data[0][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][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[0][1], lower_freqs->data[0][0],
+        upper_freqs->data[0][0], (win_s - 1) * 2,
+        aubio_next_power_of_two (min_win_s));
+  }
+
   /* building each filter table */
   for (fn = 0; fn < n_filters; fn++) {
 
@@ -82,10 +104,10 @@ aubio_filterbank_set_mel_coeffs (aubio_filterbank_t * fb, fvec_t * freqs,
     for (bin = 0; bin < win_s - 1; bin++) {
       if (fft_freqs->data[0][bin] <= lower_freqs->data[0][fn] &&
           fft_freqs->data[0][bin + 1] > lower_freqs->data[0][fn]) {
+        bin++;
         break;
       }
     }
-    bin++;
 
     /* compute positive slope step size */
     smpl_t riseInc =
@@ -97,10 +119,11 @@ aubio_filterbank_set_mel_coeffs (aubio_filterbank_t * fb, fvec_t * freqs,
       filters->data[fn][bin] =
           (fft_freqs->data[0][bin] - lower_freqs->data[0][fn]) * riseInc;
 
-      if (fft_freqs->data[0][bin + 1] > center_freqs->data[0][fn])
+      if (fft_freqs->data[0][bin + 1] >= center_freqs->data[0][fn]) {
+        bin++;
         break;
+      }
     }
-    bin++;
 
     /* compute negative slope step size */
     smpl_t downInc =
@@ -112,7 +135,11 @@ aubio_filterbank_set_mel_coeffs (aubio_filterbank_t * fb, fvec_t * freqs,
       filters->data[fn][bin] +=
           (upper_freqs->data[0][fn] - fft_freqs->data[0][bin]) * downInc;
 
-      if (fft_freqs->data[0][bin + 1] > upper_freqs->data[0][fn])
+      if (filters->data[fn][bin] < 0.) {
+        filters->data[fn][bin] = 0.;
+      }
+
+      if (fft_freqs->data[0][bin + 1] >= upper_freqs->data[0][fn])
         break;
     }
     /* nothing else to do */
@@ -127,12 +154,15 @@ aubio_filterbank_set_mel_coeffs (aubio_filterbank_t * fb, fvec_t * freqs,
   del_fvec (triangle_heights);
   del_fvec (fft_freqs);
 
+  return 0;
 }
 
-void
+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;
@@ -160,9 +190,10 @@ aubio_filterbank_set_mel_coeffs_slaney (aubio_filterbank_t * fb,
   }
 
   /* now compute the actual coefficients */
-  aubio_filterbank_set_mel_coeffs (fb, freqs, samplerate);
+  retval = aubio_filterbank_set_triangle_bands (fb, samplerate, freqs);
 
   /* destroy vector used to store frequency limits */
   del_fvec (freqs);
 
+  return retval;
 }

diff --git a/src/spectral/filterbank_mel.h b/src/spectral/filterbank_mel.h
index 9b5d21f600b6ee64072a99d2022233c1d4602b57..cb269fb5b095bd907f916f458a2bf3cd330ccb40 100644 (file)
--- a/src/spectral/filterbank_mel.h
+++ b/src/spectral/filterbank_mel.h
@@ -39,18 +39,18 @@ extern "C"
 {
 #endif
 
-/** filterbank initialization for mel filters
+/** filterbank initialization with triangular and overlapping bands
 
   \param fb filterbank object
   \param freqs arbitrary array of boundary frequencies
   \param samplerate audio sampling rate
 
   This function computes the coefficients of the filterbank based on the
-  boundaries found in freqs, in Hz, and using triangular overlapping windows.
+  boundaries found in freqs, in Hz, and using triangular overlapping bands.
 
 */
-void aubio_filterbank_set_mel_coeffs (aubio_filterbank_t * fb,
-    fvec_t * freqs, smpl_t samplerate);
+uint_t aubio_filterbank_set_triangle_bands (aubio_filterbank_t * fb,
+    smpl_t samplerate, fvec_t * freqs);
 
 /** filterbank initialization for Mel filters using Slaney's coefficients
 
@@ -60,7 +60,7 @@ void aubio_filterbank_set_mel_coeffs (aubio_filterbank_t * fb,
   This function fills the filterbank coefficients according to Malcolm Slaney.
 
 */
-void aubio_filterbank_set_mel_coeffs_slaney (aubio_filterbank_t * fb,
+uint_t aubio_filterbank_set_mel_coeffs_slaney (aubio_filterbank_t * fb,
     smpl_t samplerate);
 
 #ifdef __cplusplus