public float[] BuildFilterReal()
{
float[] taps = new float[TapCount];
float[] window = WindowUtil.MakeWindow(Window, TapCount);
int M = (TapCount - 1) / 2;
float fwT0 = 2 * MathF.PI * LowCutoffFreq / SampleRate;
float fwT1 = 2 * MathF.PI * HighCutoffFreq / SampleRate;
for (int n = -M; n <= M; n++)
{
if (n == 0)
{
taps[n + M] = (fwT1 - fwT0) / MathF.PI * window[n + M];
}
else
{
taps[n + M] = (MathF.Sin(n * fwT1) - MathF.Sin(n * fwT0)) / (n * MathF.PI) * window[n + M];
}
}
float fmax = taps[0 + M];
for (int n = 1; n <= M; n++)
{
fmax += 2 * taps[n + M] * MathF.Cos(n * (fwT0 + fwT1) * 0.5f);
}
float gain = 1f / fmax;
for (int i = 0; i < TapCount; i++)
{
taps[i] *= gain;
}
return(taps);
}
public FFTWindow(int fftBins, WindowType type = WindowType.HannPoisson)
{
this.fftBins = fftBins;
window = WindowUtil.MakeWindow(type, fftBins);
}