public float[] ProcessFrame(float[] frame)
{
DSPTools.PreEmphasise(frame, this.PreEmphasiseFactor);
DSPTools.ApplyWindow(frame, this.FilterWindow);
int valid_nfft = this.MBI.nfft / 2 + 1;
Complex[] Outputs = DSPTools.FFT(frame.Select(D => new Complex(D, 0.0f)).ToArray(), valid_nfft);
float[] Internals = Outputs.Select(O => (float)O.Magnitude).ToArray();
float[] Results = new float[this.dct.dctlen];
for (int i = 0; i < this.dct.dctlen; i++)
{
double t = 0.0f;
for (int j = 0; j < this.MBI.nfilters; j++)
{
//DCT变换，解卷积
t += this.dct.coeff[i, j] * Math.Log(
DSPTools.Product(Internals, this.MBI.filter, j, valid_nfft) +
DSPTools.EPS,
DSPTools.NewBase);
}
Results[i] = (float)(t * this.LifterWindow[i]);//倒谱提升
}
return(Internals);
}
public MFCC(int sample_rate = 8000, int frame_length = 512, int nfft = 512, int low = 0, int high = 4000, int nfilters = 24, int ndcts = 12)
{
this.MBI.nfft = nfft;
this.MBI.low = low;
this.MBI.high = high;
this.MBI.nfilters = nfilters;
this.dct.dctlen = ndcts;
int valid_nfft = nfft / 2 + 1;
DSPTools.DctCoeff(ndcts, nfilters, this.dct.coeff = new float[ndcts, nfilters]);
DSPTools.MelBank(sample_rate, nfft, low, high, nfilters, this.MBI.filter = new float[nfilters, valid_nfft]); //Mel滤波器系数
DSPTools.CreateHammingWindow(this.FilterWindow = new float[frame_length]); //加窗
DSPTools.CreateLiftWindow(this.LifterWindow = new float[this.dct.dctlen]);
}
