From 0dbdb401e562c7e0359415653ec1d5276daa7787 Mon Sep 17 00:00:00 2001
From: Paul Brossier <piem@piem.org>
Date: Wed, 18 Apr 2007 01:07:48 +0200
Subject: [PATCH] mathutils.c: add aubio_spectral_centroid

---
 src/mathutils.c | 13 +++++++++++++
 src/mathutils.h |  4 ++++
 2 files changed, 17 insertions(+)

diff --git a/src/mathutils.c b/src/mathutils.c
index e91f3e9f..d561fced 100644
--- a/src/mathutils.c
+++ b/src/mathutils.c
@@ -457,6 +457,19 @@ smpl_t aubio_zero_crossing_rate(fvec_t * input) {
   return zcr/(smpl_t)input->length;
 }
 
+smpl_t aubio_spectral_centroid(cvec_t * spectrum, smpl_t samplerate) {
+  uint_t i=0, j;
+  smpl_t sum = 0., sc = 0.;
+  for ( j = 0; j < spectrum->length; j++ ) {
+    sum += spectrum->norm[i][j];
+  }
+  if (sum == 0.) return 0.;
+  for ( j = 0; j < spectrum->length; j++ ) {
+    sc += (smpl_t)j * spectrum->norm[i][j];
+  }
+  return sc / sum * samplerate / (smpl_t)(spectrum->length);
+}
+
 void aubio_autocorr(fvec_t * input, fvec_t * output){
         uint_t i = 0, j = 0, length = input->length;
         smpl_t * data = input->data[0];
diff --git a/src/mathutils.h b/src/mathutils.h
index 9bf0f583..75fc5d7e 100644
--- a/src/mathutils.h
+++ b/src/mathutils.h
@@ -207,6 +207,10 @@ void aubio_autocorr(fvec_t * input, fvec_t * output);
  * zero-crossing rate (number of zero cross per sample)
  */
 smpl_t aubio_zero_crossing_rate(fvec_t * input);
+/**
+ * spectrum centroid computed on a cvec
+ */
+smpl_t aubio_spectral_centroid(cvec_t * input, smpl_t samplerate);
 /**
  * clean up cached memory at the end of program
  *
-- 
2.26.2