private void UpdateAutoCorrelation()
{
var pos = _hopSize * _specNo;
var pitch = //Pitch.FromHss(_signal, pos, pos + _fftSize);
Pitch.FromAutoCorrelation(_signal, pos, pos + _fftSize, 80, 1000);
//Pitch.FromZeroCrossingsSchmitt(_signal, pos, pos + _fftSize);
//Pitch.FromYin(_signal, pos, pos + _fftSize);
spectrumPanel.Mark = (int)(_fftSize * pitch / _signal.SamplingRate); // pitch index
spectrumPanel.Legend = string.Format("{0:F2} Hz", pitch);
var block = _signal[pos, pos + _fftSize];
var autoCorrelation = Operation.CrossCorrelate(block, block).Last(_fftSize);
autoCorrPanel.Line = autoCorrelation.Samples;
autoCorrPanel.Mark = pitch == 0 ? 0 : (int)(_signal.SamplingRate / pitch); // pitch index
}