KissFFT output returns nan value? - c++

Question

currently i m working on the Tizen IDE.
I had read the input data from the MicroPhone and Try to apply FFT on it...
but everytime I gets the nan output from the FFT.
Here is my code..
ShortBuffer *pBuffer1 = pData->AsShortBufferN();
fft = new KissFFT(BUFFER_SIZE);
std::vector<short> input(pBuffer1->GetPointer(),
pBuffer1->GetPointer() + BUFFER_SIZE); // this contains audio data
std::vector<float> specturm(BUFFER_SIZE);
fft->spectrum(input, specturm);
applying FFT
void KissFFT::spectrum(KissFFTO* fft, std::vector<short>& samples2,
std::vector<float>& spectrum) {
int len = fft->numSamples / 2 + 1;
kiss_fft_scalar* samples = (kiss_fft_scalar*) &samples2[0];
kiss_fftr(fft->config, samples, fft->spectrum);
for (int i = 0; i < len; i++) {
float re = scale(fft->spectrum[i].r) * fft->numSamples;
float im = scale(fft->spectrum[i].i) * fft->numSamples;
if (i > 0)
spectrum[i] = sqrtf(re * re + im * im) / (fft->numSamples / 2);
else
spectrum[i] = sqrtf(re * re + im * im) / (fft->numSamples);
AppLog("specturm %d",spectrum[i]); // everytime returns returns nan output
}
}
KissFFTO* KissFFT::create(int numSamples) {
KissFFTO* fft = new KissFFTO();
fft->config = kiss_fftr_alloc(numSamples/2, 0, NULL, NULL);
fft->spectrum = new kiss_fft_cpx[numSamples / 2 + 1];
fft->numSamples = numSamples;
return fft;
}
scaling
static inline float scale(kiss_fft_scalar val) {
if (val < 0)
return val * (1 / 32768.0f);
else
return val * (1 / 32767.0f);
}

Answer 1

AppLog("specturm %d",spectrum[i]); // everytime returns returns nan output
Try using %f rather than %d.