public static Complex[] get_pink_noise(int size)
{
Complex[] res = new Complex[size];
for (int i = 0; i < (size + 1) / 2; ++i)
{
double mag = Math.Pow((double)i, -0.5f);
double phase = (2 * GlobalMembersSpectrogram.random_double() - 1) * Math.PI; //+-pi random phase
Complex complex = new Complex(mag * Math.Cos(phase), mag * Math.Sin(phase));
res[i] = complex;
}
return(res);
}
public double[] synt_sine(Bitmap image, int samplerate)
{
int samples = image.Width * samplerate / pixpersec;
Complex[] spectrum = new Complex[samples / 2 + 1];
double filterscale = ((double)spectrum.Length * 2) / samplerate;
Filterbank filterbank = Filterbank.get_filterbank(frequency_axis, filterscale, basefreq, bandwidth, overlap);
for (int bandidx = 0; bandidx < image.Height; ++bandidx)
{
//if (cancelled())
// return List<int>();
band_progress(bandidx, image.Height - 1);
double[] envelope = envelope_from_spectrogram(image, bandidx);
// random phase between +-pi
double phase = (2 * GlobalMembersSpectrogram.random_double() - 1) * Math.PI;
double[] bandsignal = new double[envelope.Length * 2];
for (int j = 0; j < 4; ++j)
{
double sine = Math.Cos(j * Math.PI / 2 + phase);
for (int i = j; i < bandsignal.Length; i += 4)
{
bandsignal[i] = envelope[i / 2] * sine;
}
}
Complex[] filterband = GlobalMembersSpectrogram.padded_FFT(bandsignal);
for (int i = 0; i < filterband.Length; ++i)
{
double x = (double)i / filterband.Length;
// normalized blackman window antiderivative
filterband[i] *= x - ((0.5 / (2.0 * Math.PI)) * Math.Sin(2.0 * Math.PI * x) + (0.08 / (4.0 * Math.PI)) * Math.Sin(4.0 * Math.PI * x) / 0.42);
}
Console.Out.WriteLine("spectrum size: {0}", spectrum.Length);
//std::cout << bandidx << ". filterband size: " << filterband.Length << "; start: " << filterbank->get_band(bandidx).first <<"; end: " << filterbank->get_band(bandidx).second << "\n";
double center = filterbank.get_center(bandidx);
double offset = Math.Max((uint)0, center - filterband.Length / 2);
Console.Out.WriteLine("offset: {0} = {1} hz", offset, offset / filterscale);
for (uint i = 0; i < filterband.Length; ++i)
{
if (offset + i > 0 && offset + i < spectrum.Length)
{
spectrum[(int)(offset + i)] += filterband[i];
}
}
}
double[] @out = GlobalMembersSpectrogram.padded_IFFT(spectrum);
Console.Out.WriteLine("samples: {0} -> {1}", @out.Length, samples);
GlobalMembersSpectrogram.normalize_signal(ref @out);
return(@out);
}