allanger/paulxstretch
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fixed scaling issue with VDSP fft impl

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This commit is contained in:
essej 2022-04-18 11:46:04 -04:00
parent 97b982aa85
commit c37aab3dcc
1 changed files with 7 additions and 3 deletions
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10
Source/PS_Source/Stretch.cpp
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@ -121,6 +121,11 @@ void FFT::smp2freq()
//DebugLogC("post fft: %g %g\n", A.realp[fftFrameSize/4], A.imagp[fftFrameSize/4 + 1]); //DebugLogC("post fft: %g %g\n", A.realp[fftFrameSize/4], A.imagp[fftFrameSize/4 + 1]);
// forward scale
const float scale = 0.5f;
vDSP_vsmul(A.realp, 1, &scale, A.realp, 1, halfsamples);
vDSP_vsmul(A.imagp, 1, &scale, A.imagp, 1, halfsamples);
// Absolute square (equivalent to mag^2) // Absolute square (equivalent to mag^2)
vDSP_zvmags(&A, 1, freq.data(), 1, halfsamples); vDSP_zvmags(&A, 1, freq.data(), 1, halfsamples);
@ -183,8 +188,7 @@ void FFT::freq2smp()
vDSP_ztoc(&A, 1, (COMPLEX*)data.data(), 2, halfsamples); vDSP_ztoc(&A, 1, (COMPLEX*)data.data(), 2, halfsamples);
// scale // scale
//float scale = 1.f/data[0]; // 1.0f / nsamples ?? float scale = 1.f / nsamples;
float scale = 1.f / nsamples; // 1.0f / nsamples ??
vDSP_vsmul(data.data(), 1, &scale, smp.data(), 1, nsamples); vDSP_vsmul(data.data(), 1, &scale, smp.data(), 1, nsamples);
@ -426,7 +430,7 @@ REALTYPE Stretch::process(REALTYPE *smps,int nsmps)
REALTYPE hinv_sqrt2=0.853553390593f;//(1.0+1.0/sqrt(2))*0.5; REALTYPE hinv_sqrt2=0.853553390593f;//(1.0+1.0/sqrt(2))*0.5;
REALTYPE ampfactor=2.0f; REALTYPE ampfactor=2.0f;
//remove the resulted unwanted amplitude modulation (caused by the interference of N and N+1 windowed buffer and compute the output buffer //remove the resulted unwanted amplitude modulation (caused by the interference of N and N+1 windowed buffer and compute the output buffer
for (int i=0;i<bufsize;i++) { for (int i=0;i<bufsize;i++) {
REALTYPE a=(float)((0.5+0.5*cos(i*tmp))); REALTYPE a=(float)((0.5+0.5*cos(i*tmp)));