annotate dsp/transforms/kissfft/kiss_fftr.h @ 73:dcb555b90924

* Key detector: when returning key strengths, use the peak value of the
  three underlying chromagram correlations (from 36-bin chromagram)
  corresponding to each key, instead of the mean.
  Rationale: This is the same method as used when returning the key value,
  and it's nice to have the same results in both returned value and plot.
  The peak performed better than the sum with a simple test set of triads,
  so it seems reasonable to change the plot to match the key output rather
  than the other way around.

* FFT: kiss_fftr returns only the non-conjugate bins, synthesise the rest
  rather than leaving them (perhaps dangerously) undefined.  Fixes an
  uninitialised data error in chromagram that could cause garbage results
  from key detector.

* Constant Q: remove precalculated values again, I reckon they're not
  proving such a good tradeoff.

#ifndef KISS_FTR_H
#define KISS_FTR_H

#include "kiss_fft.h"
#ifdef __cplusplus
extern "C" {
#endif

    
/* 
 
 Real optimized version can save about 45% cpu time vs. complex fft of a real seq.

 
 
 */

typedef struct kiss_fftr_state *kiss_fftr_cfg;


kiss_fftr_cfg kiss_fftr_alloc(int nfft,int inverse_fft,void * mem, size_t * lenmem);
/*
 nfft must be even

 If you don't care to allocate space, use mem = lenmem = NULL 
*/


void kiss_fftr(kiss_fftr_cfg cfg,const kiss_fft_scalar *timedata,kiss_fft_cpx *freqdata);
/*
 input timedata has nfft scalar points
 output freqdata has nfft/2+1 complex points
*/

void kiss_fftri(kiss_fftr_cfg cfg,const kiss_fft_cpx *freqdata,kiss_fft_scalar *timedata);
/*
 input freqdata has  nfft/2+1 complex points
 output timedata has nfft scalar points
*/

#define kiss_fftr_free free

#ifdef __cplusplus
}
#endif
#endif