//##################################################################################################################################
/// <summary>
/// NOTE!!!! The decibel array has been normalised in 0 - 1.
/// </summary>
protected static Tuple <double[, ], double[]> MakeCepstrogram(SonogramConfig config, double[,] matrix, double[] decibels, int sampleRate)
{
double[,] m = matrix;
int nyquist = sampleRate / 2;
double epsilon = config.epsilon;
bool includeDelta = config.mfccConfig.IncludeDelta;
bool includeDoubleDelta = config.mfccConfig.IncludeDoubleDelta;
//Log.WriteIfVerbose(" MakeCepstrogram(matrix, decibels, includeDelta=" + includeDelta + ", includeDoubleDelta=" + includeDoubleDelta + ")");
//(i) APPLY FILTER BANK
int bandCount = config.mfccConfig.FilterbankCount;
bool doMelScale = config.mfccConfig.DoMelScale;
int ccCount = config.mfccConfig.CcCount;
int fftBinCount = config.FreqBinCount; //number of Hz bands = 2^N +1. Subtract DC bin
int minHz = config.MinFreqBand ?? 0;
int maxHz = config.MaxFreqBand ?? nyquist;
Log.WriteIfVerbose("ApplyFilterBank(): Dim prior to filter bank =" + matrix.GetLength(1));
//error check that filterBankCount < FFTbins
if (bandCount > fftBinCount)
{
throw new Exception(
"## FATAL ERROR in BaseSonogram.MakeCepstrogram():- Can't calculate cepstral coeff. FilterbankCount > FFTbins. (" +
bandCount + " > " + fftBinCount + ")\n\n");
}
//this is the filter count for full bandwidth 0-Nyquist. This number is trimmed proportionately to fit the required bandwidth.
if (doMelScale)
{
m = MFCCStuff.MelFilterBank(m, bandCount, nyquist, minHz, maxHz); // using the Greg integral
}
else
{
m = MFCCStuff.LinearFilterBank(m, bandCount, nyquist, minHz, maxHz);
}
Log.WriteIfVerbose("\tDim after filter bank=" + m.GetLength(1) + " (Max filter bank=" + bandCount + ")");
//(ii) CONVERT AMPLITUDES TO DECIBELS
m = MFCCStuff.DecibelSpectra(m, config.WindowPower, sampleRate, epsilon); //from spectrogram
//(iii) NOISE REDUCTION
var tuple1 = SNR.NoiseReduce(m, config.NoiseReductionType, config.NoiseReductionParameter);
m = tuple1.Item1;
//(iv) calculate cepstral coefficients
m = MFCCStuff.Cepstra(m, ccCount);
//(v) NormaliseMatrixValues
m = DataTools.normalise(m);
//(vi) Calculate the full range of MFCC coefficients ie including decibel and deltas, etc
m = MFCCStuff.AcousticVectors(m, decibels, includeDelta, includeDoubleDelta);
var tuple2 = Tuple.Create(m, tuple1.Item2);
return(tuple2); // return matrix and full bandwidth modal noise profile
}
