aubio · cemkod · Mar 17, 2026
diff --git a/src/onset/onset.c b/src/onset/onset.c
@@ -50,13 +50,17 @@ struct _aubio_onset_t {
   smpl_t lambda_compression;
   uint_t apply_awhitening;      /**< apply adaptive spectral whitening */
   aubio_spectral_whitening_t *spectral_whitening;
+  uint_t skip_phas;             /**< skip phase computation for norm-only ODFs */
 };
 
 /* execute onset detection function on iput buffer */
 void aubio_onset_do (aubio_onset_t *o, const fvec_t * input, fvec_t * onset)
 {
   smpl_t isonset = 0;
-  aubio_pvoc_do (o->pv,input, o->fftgrain);
+  if (o->skip_phas)
+    aubio_pvoc_do_norm(o->pv, input, o->fftgrain);
+  else
+    aubio_pvoc_do(o->pv, input, o->fftgrain);
   /*
   if (apply_filtering) {
   }
@@ -295,9 +299,11 @@ uint_t aubio_onset_set_default_parameters (aubio_onset_t * o, const char_t * ons
 
   /* method specific optimisations */
   if (strcmp (onset_mode, "energy") == 0) {
+    o->skip_phas = 1;
   } else if (strcmp (onset_mode, "hfc") == 0 || strcmp (onset_mode, "default") == 0) {
     aubio_onset_set_threshold (o, 0.058);
     aubio_onset_set_compression (o, 1.);
+    o->skip_phas = 1;
   } else if (strcmp (onset_mode, "complexdomain") == 0
              || strcmp (onset_mode, "complex") == 0) {
     aubio_onset_set_delay (o, 4.6 * o->hop_size);
@@ -313,17 +319,21 @@ uint_t aubio_onset_set_default_parameters (aubio_onset_t * o, const char_t * ons
     aubio_onset_set_threshold (o, 0.05);
     aubio_onset_set_awhitening(o, 1);
     aubio_onset_set_compression (o, 0.02);
+    o->skip_phas = 1;
   } else if (strcmp (onset_mode, "kl") == 0) {
     aubio_onset_set_threshold (o, 0.35);
     aubio_onset_set_awhitening(o, 1);
     aubio_onset_set_compression (o, 0.02);
+    o->skip_phas = 1;
   } else if (strcmp (onset_mode, "specflux") == 0) {
     aubio_onset_set_threshold (o, 0.18);
     aubio_onset_set_awhitening(o, 1);
     aubio_spectral_whitening_set_relax_time(o->spectral_whitening, 100);
     aubio_spectral_whitening_set_floor(o->spectral_whitening, 1.);
     aubio_onset_set_compression (o, 10.);
+    o->skip_phas = 1;
   } else if (strcmp (onset_mode, "specdiff") == 0) {
+    o->skip_phas = 1;
   } else if (strcmp (onset_mode, "old_default") == 0) {
     // used to reproduce results obtained with the previous version
     aubio_onset_set_threshold (o, 0.3);

diff --git a/src/spectral/fft.c b/src/spectral/fft.c
@@ -336,6 +336,11 @@ void aubio_fft_do(aubio_fft_t * s, const fvec_t * input, cvec_t * spectrum) {
   aubio_fft_get_spectrum(s->compspec, spectrum);
 }
 
+void aubio_fft_do_norm_only(aubio_fft_t * s, const fvec_t * input, cvec_t * spectrum) {
+  aubio_fft_do_complex(s, input, s->compspec);
+  aubio_fft_get_norm(s->compspec, spectrum);
+}
+
 void aubio_fft_rdo(aubio_fft_t * s, const cvec_t * spectrum, fvec_t * output) {
   aubio_fft_get_realimag(spectrum, s->compspec);
   aubio_fft_rdo_complex(s, s->compspec, output);

diff --git a/src/spectral/fft.h b/src/spectral/fft.h
@@ -66,6 +66,14 @@ void del_aubio_fft(aubio_fft_t * s);
 
 */
 void aubio_fft_do (aubio_fft_t *s, const fvec_t * input, cvec_t * spectrum);
+/** compute forward FFT, filling only the norm (magnitude) component
+
+  \param s fft object as returned by new_aubio_fft
+  \param input input signal
+  \param spectrum output spectrum (phas is left uninitialised)
+
+*/
+void aubio_fft_do_norm_only (aubio_fft_t *s, const fvec_t * input, cvec_t * spectrum);
 /** compute backward (inverse) FFT
 
   \param s fft object as returned by new_aubio_fft

diff --git a/src/spectral/phasevoc.c b/src/spectral/phasevoc.c
@@ -60,6 +60,13 @@ void aubio_pvoc_do(aubio_pvoc_t *pv, const fvec_t * datanew, cvec_t *fftgrain) {
   aubio_fft_do (pv->fft,pv->data,fftgrain);
 }
 
+void aubio_pvoc_do_norm(aubio_pvoc_t *pv, const fvec_t * datanew, cvec_t *fftgrain) {
+  aubio_pvoc_swapbuffers(pv, datanew);
+  fvec_weight(pv->data, pv->w);
+  fvec_shift(pv->data);
+  aubio_fft_do_norm_only(pv->fft, pv->data, fftgrain);
+}
+
 void aubio_pvoc_rdo(aubio_pvoc_t *pv,cvec_t * fftgrain, fvec_t * synthnew) {
   /* calculate rfft */
   aubio_fft_rdo(pv->fft,fftgrain,pv->synth);

diff --git a/src/spectral/phasevoc.h b/src/spectral/phasevoc.h
@@ -68,6 +68,17 @@ void del_aubio_pvoc(aubio_pvoc_t *pv);
 
 */
 void aubio_pvoc_do(aubio_pvoc_t *pv, const fvec_t *in, cvec_t * fftgrain);
+/** compute spectral frame, filling only the norm (magnitude) component
+
+  Like aubio_pvoc_do() but skips phase computation (atan2), saving work for
+  onset detection functions that never read the phase array.
+
+  \param pv phase vocoder object as returned by new_aubio_pvoc
+  \param in new input signal (hop_s long)
+  \param fftgrain output spectral frame (phas is left uninitialised)
+
+*/
+void aubio_pvoc_do_norm(aubio_pvoc_t *pv, const fvec_t *in, cvec_t * fftgrain);
 /** compute signal from spectral frame
 
   This function takes an input spectral frame fftgrain of size

diff --git a/tests/src/spectral/bench-pvoc-norm.c b/tests/src/spectral/bench-pvoc-norm.c
@@ -0,0 +1,41 @@
+#include <aubio.h>
+#include "utils_tests.h"
+#include <time.h>
+
+#define N_FRAMES 100000
+#define WIN_S    1024
+#define HOP_S    256
+
+int main (void)
+{
+  uint_t i;
+  fvec_t *in       = new_fvec(HOP_S);
+  cvec_t *fftgrain = new_cvec(WIN_S);
+  aubio_pvoc_t *pv = new_aubio_pvoc(WIN_S, HOP_S);
+  if (!in || !fftgrain || !pv) return 1;
+
+  /* fill with arbitrary non-zero data */
+  for (i = 0; i < HOP_S; i++) in->data[i] = (smpl_t)i / HOP_S;
+
+  clock_t t0 = clock();
+  for (i = 0; i < N_FRAMES; i++)
+    aubio_pvoc_do(pv, in, fftgrain);
+  double ms_full = (double)(clock() - t0) / CLOCKS_PER_SEC * 1000.0;
+
+  t0 = clock();
+  for (i = 0; i < N_FRAMES; i++)
+    aubio_pvoc_do_norm(pv, in, fftgrain);
+  double ms_norm = (double)(clock() - t0) / CLOCKS_PER_SEC * 1000.0;
+
+  PRINT_MSG("pvoc_do      (full):      %.1f ms for %d frames (%.2f us/frame)\n",
+      ms_full, N_FRAMES, ms_full * 1000.0 / N_FRAMES);
+  PRINT_MSG("pvoc_do_norm (no phase):  %.1f ms for %d frames (%.2f us/frame)\n",
+      ms_norm, N_FRAMES, ms_norm * 1000.0 / N_FRAMES);
+  PRINT_MSG("speedup: %.2fx\n", ms_full / ms_norm);
+
+  del_aubio_pvoc(pv);
+  del_fvec(in);
+  del_cvec(fftgrain);
+  aubio_cleanup();
+  return 0;
+}