zynaddsubfx

commit c99be90be0a3f855366f4a5b132e3b239e4ae992
parent 7729d999239766f058c730418f4517db724a0cef
Author: fundamental <mark.d.mccurry@gmail.com>
Date:   Mon, 22 Aug 2011 11:09:52 -0400

Synth: fixing fft related bugs

- convert2sine's angles were off by 90 degrees,
  fixed by determining angles based upon cosine reference
- ifft produced ringing at nyquist, fixed by nulling that channel

Diffstat:
M
src/DSP/FFTwrapper.cpp
 | 
6
+++++-
M
src/Synth/OscilGen.cpp
 | 
5
+++--

2 files changed, 8 insertions(+), 3 deletions(-)
diff --git a/src/DSP/FFTwrapper.cpp b/src/DSP/FFTwrapper.cpp
@@ -29,7 +29,7 @@ FFTwrapper::FFTwrapper(int fftsize_)
 {
     fftsize  = fftsize_;
     time     = new fftw_real[fftsize];
-    fft      = new fftw_complex[fftsize];
+    fft      = new fftw_complex[fftsize + 1];
     planfftw = fftw_plan_dft_r2c_1d(fftsize,
                                     time,
                                     fft,
@@ -67,6 +67,10 @@ void FFTwrapper::freqs2smps(const fft_t *freqs, float *smps)
     //Load data
     memcpy( (void*)fft, (const void*)freqs, fftsize*sizeof(double));
 
+    //clear unused freq channel
+    fft[fftsize/2][0] = 0.0;
+    fft[fftsize/2][1] = 0.0;
+
     //IDFT
     fftw_execute(planfftw_inv);
 
diff --git a/src/Synth/OscilGen.cpp b/src/Synth/OscilGen.cpp
@@ -52,10 +52,11 @@ inline float abs(const fft_t *freqs, off_t x)
     return abs(freqs[x]);
 }
 
-//return angle aka phase
+//return angle aka phase from a sine (not cosine wave)
 inline float arg(const fft_t *freqs, off_t x)
 {
-    return arg(freqs[x]);
+    const fft_t tmp(freqs[x].imag(), freqs[x].real());
+    return arg(tmp);
 }
 
 /**