Add xtract_midicent() convenience function to convert from frequency to MIDI cent

2 files changed, 17 insertions, 2 deletions

diff --git a/xtract/libxtract.h b/xtract/libxtract.h
index ce12e14..1f4a787 100644
--- a/xtract/libxtract.h
+++ b/xtract/libxtract.h
@@ -71,7 +71,7 @@ extern "C" {
   * @{
   */
 
-#define XTRACT_FEATURES 60
+#define XTRACT_FEATURES 61
     
 /** \brief Enumeration of features, elements are used as indixes to an array of pointers to feature extracton functions */
 enum xtract_features_ {
@@ -117,6 +117,7 @@ enum xtract_features_ {
     XTRACT_F0,
     XTRACT_FAILSAFE_F0,
     XTRACT_WAVELET_F0,
+    XTRACT_MIDICENT,
     XTRACT_LNORM,
     XTRACT_FLUX,
     XTRACT_ATTACK_TIME,
@@ -208,7 +209,8 @@ typedef enum unit_ {
     XTRACT_DBFS_HERTZ,
     XTRACT_PERCENT,
     XTRACT_BINS,
-    XTRACT_SONE
+    XTRACT_SONE,
+    XTRACT_MIDI_CENT
 } xtract_unit_t;
 
 /** \brief Boolean */
diff --git a/xtract/xtract_scalar.h b/xtract/xtract_scalar.h
index e18aea6..4e39fd9 100644
--- a/xtract/xtract_scalar.h
+++ b/xtract/xtract_scalar.h
@@ -434,6 +434,19 @@ int xtract_failsafe_f0(const double *data, const int N, const void *argv, double
  */
 int xtract_wavelet_f0(const double *data, const int N, const void *argv, double *result);
 
+    
+/** \brief Convenience function to convert a frequency in Hertz to a "pitch" value in MIDI cents
+ *
+ * \param *data: not used
+ * \param N: not used
+ * \param *argv: a pointer to a double-precision floating point value representing a frequency in Hertz
+ * \param *result: a pointer to a double-precision floating point value representing a "pitch" in MIDI cents
+ * \return if *argv value causes a *result within the range 0..127, XTRACT_SUCCESS will be returned, otherwise XTRACT_ARGUMENT_ERROR
+ *
+ */
+int xtract_midicent(const double *data, const int N, const void *argv, double *result);
+
+    
 /** \brief Extract the number of non-zero elements in an input vector
  * 
  * \param *data: a pointer to the first element in an array of doubles