From: Paul Brossier <piem@piem.org>
Date: Tue, 17 Apr 2007 19:59:15 +0000 (+0200)
Subject: mathutils.c: add aubio_zero_crossing_rate at Amaury's request
X-Git-Tag: bzr2git~525
X-Git-Url: http://git.tremily.us/?a=commitdiff_plain;h=fff2bee8ed03bff37c5f9c2189639a30a1ea6054;p=aubio.git

mathutils.c: add aubio_zero_crossing_rate at Amaury's request
---

diff --git a/src/mathutils.c b/src/mathutils.c
index dfb40195..e91f3e9f 100644
--- a/src/mathutils.c
+++ b/src/mathutils.c
@@ -440,6 +440,23 @@ smpl_t aubio_level_detection(fvec_t * ibuf, smpl_t threshold) {
       return loudness;
 }
 
+smpl_t aubio_zero_crossing_rate(fvec_t * input) {
+  uint_t i=0,j;
+  uint_t zcr = 0;
+  for ( j = 1; j < input->length; j++ ) {
+    // previous was negative
+    if( input->data[i][j-1] <= 0. ) {
+      if ( input->data[i][j] > 0. ) {
+        zcr += 1;
+      }
+    //previous was positive
+    } else if ( input->data[i][j] <= 0. ){
+      zcr += 1;
+    }
+  }
+  return zcr/(smpl_t)input->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 dc130de3..9bf0f583 100644
--- a/src/mathutils.h
+++ b/src/mathutils.h
@@ -203,6 +203,10 @@ smpl_t aubio_level_detection(fvec_t * ibuf, smpl_t threshold);
  * calculate normalised autocorrelation function
  */
 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);
 /**
  * clean up cached memory at the end of program
  *