public double[] Extract(float[] frame, out bool isEmpty)
{
HammingWindowDef.HammingWindow hammingWindow;
if (!_hammingWindows.TryGetValue(frame.Length, out hammingWindow))
{
hammingWindow = new HammingWindowDef.HammingWindow(new HammingWindowDef(), frame.Length);
_hammingWindows.Add(frame.Length, hammingWindow);
}
var windowedSample = hammingWindow.Apply(frame);
FourierTransform ft = new FourierTransform();
var nummberOfCoeff = ft.ComputeFft(windowedSample, _numberOfFftCoeff);
double frameEnergy;
var result = ft.GetMagnitudeSquared(nummberOfCoeff, out frameEnergy);
if (_filterBankCoefficients == null)
{
_filterBankCoefficients = ComputeMelFilterBank(result.Length, _lowerfrequency, _higherfrequency,
_samplingRate, _numberOfFilterBanks + 2);
}
var cepstra = ApplyFilterbankFilter(result, _filterBankCoefficients);
var ret = _dct.Apply(cepstra);
ret[0] = Utils.Log(frameEnergy);
isEmpty = false;
return ret;
}
