public override PcmFormat Setup(PcmFormat inputFormat)
{
SampleRate = inputFormat.SampleRate;
mFilterFreq = ButterworthFilter.Design(SampleRate, CutoffFrequency, FFT_LEN, FilterSlopeDbOct);
mIfftAddBuffer = null;
mFirstFilterDo = true;
return(new PcmFormat(inputFormat));
}
private void DesignFreqFilter()
{
var filter = ButterworthFilter.Design(mInputPcmFormat.SampleRate, mInputPcmFormat.SampleRate * 0.465, FftLength, 600);
mFreqFilter = new double[UpsampleFftLength];
mFreqFilter[0] = filter[0].Magnitude();
for (int i = 1; i < mFreqFilter.Length; ++i)
{
if (i <= FftLength / 2)
{
mFreqFilter[i] = filter[i].Magnitude();
mFreqFilter[UpsampleFftLength - i] = mFreqFilter[i];
}
}
}