public List <Sound> Calculate(WavData wavData)
{
var frequencies = new List <Sound>();
for (int i = 0; i < wavData.ChunkedSamples.Length; i++)
{
var samples = wavData.ChunkedSamples[i];
var reducedSamples = FourierHelper.ReduceToPow2(samples);
reducedSamples = FourierHelper.PreEmphasis(reducedSamples);
reducedSamples = _fourierWindow.Windowing(reducedSamples);
var complexSamples = FourierTransform.FFT(reducedSamples);
complexSamples = complexSamples.Take(complexSamples.Length / 2).ToArray();
var threshold = complexSamples.Max(c => c.Magnitude) / 10;
var localMax = 0;
for (int j = 1; j < complexSamples.Length; j++)
{
if (complexSamples[j].Magnitude > threshold && complexSamples[j].Magnitude > complexSamples[j - 1].Magnitude && complexSamples[j].Magnitude > complexSamples[j + 1].Magnitude)
{
localMax = j;
break;
}
}
var frequency = (wavData.FormatChunk.SampleRate / (complexSamples.Length * 2)) * localMax;
if (frequencies.Any() && frequencies.Last().Frequency == frequency)
{
frequencies.Last().EndTime += 50;
}
else
{
frequencies.Add(new Sound
{
StartTime = i * 50,
EndTime = i * 50 + 50,
Frequency = frequency,
Result = complexSamples.Select(c => c.Magnitude).ToArray()
});
}
}
return(frequencies);
}
public double[] FilterData(WavData wavData)
{
var result = new double[wavData.Samples.Length + _filterLength - 1];
var filterFactors = BasicFilter.LowPassFilterFactors(_cutFreq, wavData.FormatChunk.SampleRate, _filterLength);
var filtered = _window.Windowing(filterFactors);
var data = wavData.Samples.ToList();
var zeros = new double[_filterLength - 1];
data.InsertRange(0, zeros);
data.AddRange(zeros);
for (int i = _filterLength - 1; i < data.Count; i++)
{
for (int j = 0; j < filtered.Length; j++)
{
result[i - _filterLength + 1] += data[i - j] * filtered[j];
}
}
return(result);
}