public static Matrix ShortTimeFourierTransform(Complex[] sig, Set filter, double vol = 0.01, int dbMin = -20, int dbMax = +20)
{
Console.Write($"\r\nBuilding a new Mel model...\r\n");
double norm = 0.0,
cc = 0;
var Model = new Matrix((int)Math.Ceiling(sig.Length / (double)2048));
foreach (var STFT in Complex.ShortTimeFourierTransform(sig))
{
int i = Model.Count;
if (i >= Model.Capacity)
{
throw new OutOfMemoryException();
}
Vector it;
Debug.Assert(Model[i] == null);
Model[i] = it = MelFromFourier(STFT);
for (var j = 0; j < it.Axis.Length; j++)
{
norm += it.Axis[j].Re;
cc++;
}
}
if (cc > 0)
{
norm = norm /= cc;
if (norm > 0)
{
norm = 1d / norm;
}
}
for (int i = 0; i < Model.Count; i++)
{
var it = Model[i];
if (it != null)
{
for (var j = 0; j < it.Axis.Length; j++)
{
it.Axis[j].Re = Math.Round(norm
/* Note that this surface is really wierd... i.e. There are
* positive and negative decibeles */
* it.Axis[j].Re / (it.Axis.Length * 0.1), 3);
it.Axis[j].Re = it.Axis[j].Re;
if (it.Axis[j].Re > 0)
{
RunSpeachFrequencyFilters(it, j, vol, dbMin, dbMax);
}
if (it.Axis[j].Re > 0 && filter != null)
{
/* Filter out the specified pitches */
var n = Envelopes.MIDI2NOTE(Envelopes.FREQ2MIDI(it.Axis[j].Im));
if (string.IsNullOrWhiteSpace(n) || filter.Has(n))
{
it.Axis[j].Re = 0;
}
}
double finalMag = Math.Round(it.Axis[j].Re, 2);
it.Axis[j].Re
= finalMag;
}
double dot = 0.0;
for (var j = 0; j < it.Axis.Length; j++)
{
dot += it.Axis[j].Re * 1;
}
it.Score.Im = Math.Round(
Tanh.f(dot), 2);
}
}
return(Model);
}