void onAudio(AudioIOData& io){
float pshift = 1.7831; //pshift = 1./pshift;
while(io()){
float s = play(); play.loop();
if(stft(s)){
enum{
PREV_MAG=0,
TEMP_MAG,
TEMP_FRQ
};
// Compute spectral flux (L^1 norm on positive changes)
float flux = 0;
for(unsigned k=0; k<stft.numBins(); ++k){
float mcurr = stft.bin(k)[0];
float mprev = stft.aux(PREV_MAG)[k];
if(mcurr > mprev){
flux += mcurr - mprev;
}
}
//printf("%g\n", flux);
//gam::printPlot(flux); printf("\n");
// Store magnitudes for next frame
stft.copyBinsToAux(0, PREV_MAG);
// Given an onset, we would like the phases of the output frame
// to match the input frame in order to preserve transients.
if(flux > 0.2){
stft.resetPhases();
}
// Initialize buffers to store pitch-shifted spectrum
for(unsigned k=0; k<stft.numBins(); ++k){
stft.aux(TEMP_MAG)[k] = 0.;
stft.aux(TEMP_FRQ)[k] = k*stft.binFreq();
}
// Perform the pitch shift:
// Here we contract or expand the bins. For overlapping bins,
// we simply add the magnitudes and replace the frequency.
// Reference:
// http://oldsite.dspdimension.com/dspdimension.com/src/smbPitchShift.cpp
if(pshift > 0){
unsigned kmax = stft.numBins() / pshift;
if(kmax >= stft.numBins()) kmax = stft.numBins()-1;
for(unsigned k=1; k<kmax; ++k){
unsigned j = k*pshift;
stft.aux(TEMP_MAG)[j] += stft.bin(k)[0];
stft.aux(TEMP_FRQ)[j] = stft.bin(k)[1]*pshift;
}
}
// Copy pitch-shifted spectrum over to bins
stft.copyAuxToBins(TEMP_MAG, 0);
stft.copyAuxToBins(TEMP_FRQ, 1);
}
s = stft();
io.out(0) = io.out(1) = s;
}
}
