- Added extra argument to xtract_spectrum to give the option of normalising the magnitude/power coeffificients

- Removed duplicate code block (argc assignment) from descriptors.c
- Added some extra documentation to libxtract.h

1 files changed, 6 insertions, 3 deletions

diff --git a/xtract/xtract_vector.h b/xtract/xtract_vector.h
index 7effac0..e758f10 100644
--- a/xtract/xtract_vector.h
+++ b/xtract/xtract_vector.h
@@ -34,12 +34,15 @@ extern "C" {
   * @{
   */
 
-/** \brief Extract normalized (0-1) frequency domain spectrum from time domain signal 
+/** \brief Extract frequency domain spectrum from time domain signal
  * 
  * \param *data: a pointer to the first element in an array of floats representing an audio vector
  * \param N: the number of array elements to be considered
- * \param *argv: a pointer to an array of floats, the first representing (samplerate / N), the second will be cast to an integer and determines the spectrum type (e.g. XTRACT_MAGNITUDE_SPECTRUM, XTRACT_LOG_POWER_SPECTRUM). The third argument determines whether or not the DC component is included in the output. If argv[2] == 1, then the DC component is included in which case the size of the array pointed to by *result must be N+2. For any further use of the array pointed to by *result, the value of N must reflect the (larger) array size.
- * \param *result: a pointer to an array of size N containing N/2 magnitude/power/log magnitude/log power coefficients and N/2 bin frequencies.
+ * \param *argv: a pointer to an array of floats, the first representing (samplerate / N), the second will be cast to an integer and determines the spectrum type (e.g. XTRACT_MAGNITUDE_SPECTRUM, XTRACT_LOG_POWER_SPECTRUM). The third argument determines whether or not the DC component is included in the output. If argv[2] == 1, then the DC component is included in which case the size of the array pointed to by *result must be N+2. For any further use of the array pointed to by *result, the value of N must reflect the (larger) array size. The fourth argument determines whether the magnitude/power coefficients are to be normalised. If argv[3] == 1, then the coefficients are normalised.
+ * \param *result: a pointer to an array of size N containing N/2 magnitude/power/log magnitude/log power coefficients and N/2 bin frequencies. 
+ *
+ * The magnitude/power coefficients are scaled to the range 0-1 so that for a given coefficient x, 0 <= x <= 1
+ *
  */
 int xtract_spectrum(const float *data, const int N, const void *argv, float *result);