/// <summary>
/// Evaluate harmonic and percussive mag-phase spectrograms from given signal.
/// Both spectrogram objects share the same phase array.
/// </summary>
/// <param name="signal"></param>
/// <returns></returns>
public (MagnitudePhaseList, MagnitudePhaseList) EvaluateSpectrograms(DiscreteSignal signal)
{
// spectrogram memory will be reused for harmonic magnitudes
var harmonicSpectrogram = _stft.MagnitudePhaseSpectrogram(signal);
var harmonicMagnitudes = harmonicSpectrogram.Magnitudes;
// median filtering along frequency axis:
var percussiveMagnitudes = new List <float[]>(harmonicMagnitudes.Count);
for (var i = 0; i < harmonicMagnitudes.Count; i++)
{
var mag = new DiscreteSignal(1, harmonicMagnitudes[i]);
percussiveMagnitudes.Add(_medianPercussive.ApplyTo(mag).Samples);
_medianPercussive.Reset();
}
// median filtering along time axis:
for (var j = 0; j <= _stft.Size / 2; j++)
{
int i = 0, k = 0;
for (; k < _medianHarmonic.Size / 2; k++) // feed first Size/2 samples
{
_medianHarmonic.Process(harmonicMagnitudes[k][j]);
}
for (; i < harmonicMagnitudes.Count - _medianHarmonic.Size / 2; i++, k++)
{
var h = _medianHarmonic.Process(harmonicMagnitudes[k][j]);
harmonicMagnitudes[i][j] *= _mask(h, percussiveMagnitudes[k][j]);
percussiveMagnitudes[i][j] *= _mask(percussiveMagnitudes[k][j], h);
}
for (k = 0; k < _medianHarmonic.Size / 2; i++, k++) // don't forget last samples
{
var h = _medianHarmonic.Process(0);
harmonicMagnitudes[i][j] *= _mask(h, percussiveMagnitudes[i][j]);
percussiveMagnitudes[i][j] *= _mask(percussiveMagnitudes[i][j], h);
}
_medianHarmonic.Reset();
}
var percussiveSpectrogram = new MagnitudePhaseList
{
Magnitudes = percussiveMagnitudes,
Phases = harmonicSpectrogram.Phases
};
return(harmonicSpectrogram, percussiveSpectrogram);
}