public void PlotFFTFull(PlotView view, WindowType windowType)
{
var fft = new FFTWrapper(waveList);
var result = fft.CalculateMagnitude(windowType);
FillFFTView(view, result);
}
public void PlotBandEnergy(PlotView view, WindowType windowType, int frameLength, double overlap, double minFrequency, double maxFrequency)
{
FillDefaultPlotView(view, "", new double[0]);
var binWidth = sampleRate / frameLength;
var data = ForEachFrame(windowType, frameLength, overlap, (double[] sample, int idx) => {
sample = sample.Take(frameLength / 2).ToArray();
double limiter = 0;
for (int i = 0; i < sample.Length; i++)
{
var w = i * binWidth;
if (w >= minFrequency && w <= maxFrequency)
{
limiter += sample[i] * sample[i];
}
}
var window = FFTWrapper.GetWindow(windowType, frameLength);
var denominator = window.Sum();
return(limiter / denominator);
});
FillDefaultPlotView(view, "Band Energy", data);
}
public void PlotFundamentalFrequency(PlotView view, WindowType windowType, int frameLength, double overlap)
{
var span = (int)Math.Round(frameLength * (1.0 - overlap));
var columns = waveList.Count / span;
var data = new double[columns];
var begin = 2 * 50 * frameLength / sampleRate;
var end = 2 * 400 * frameLength / sampleRate;
if (begin == end)
{
FillDefaultPlotView(view, "Frequency (Hz)", data);
return;
}
for (int i = 0, beginPoint = 0; i < columns; i++, beginPoint += span)
{
var sample = GetSample(frameLength, beginPoint);
var fft = new FFTWrapper(sample);
var forward = fft.CalculateMagnitude(windowType);
var inverse = new FFTWrapper(forward.Select(d => new Complex(Math.Log10(d), 0)).ToArray());
var result = inverse.Calculate(windowType, false).Select(d => d.Real);
var resultSnip = result.Skip(begin).Take(end - begin).ToList();
var max = resultSnip.IndexOf(resultSnip.Max());
var realIdx = max + begin;
data[i] = realIdx * sampleRate / (2 * frameLength);
}
FillDefaultPlotView(view, "Frequency (Hz)", data);
}
public void PlotFFTFrame(PlotView view, WindowType type, int frameLength, double beginTime)
{
var result = GetSample(frameLength, beginTime).ToList();
var fft = new FFTWrapper(result);
var calculated = fft.CalculateMagnitude(type);
FillFFTView(view, calculated);
}
private double[] ForEachFrame(WindowType windowType, int frameLength, double overlap, Func <double[], int, double> calculationFunc)
{
var span = (int)Math.Round(frameLength * (1.0 - overlap));
int columns = waveList.Count / span;
var data = new double[columns];
for (int i = 0, beginPoint = 0; i < columns; i++, beginPoint += span)
{
var sample = GetSample(frameLength, beginPoint);
var fft = new FFTWrapper(sample);
var result = fft.CalculateMagnitude(windowType);
data[i] = calculationFunc(result, i);
}
return(data);
}
public void PlotSpectogram(PlotView view, WindowType windowType, int frameLength, double overlap)
{
var span = (int)Math.Round(frameLength * (1.0 - overlap));
int columns = waveList.Count / span;
var data = new double[columns, frameLength / 2];
for (int i = 0, beginPoint = 0; i < columns; i++, beginPoint += span)
{
var sample = GetSample(frameLength, beginPoint);
var fft = new FFTWrapper(sample);
var result = fft.CalculateMagnitude(windowType);
for (int y = 0; y < frameLength / 2; y++)
{
data[i, y] = 20 * Math.Log10(result[y]);
}
}
FillSpectogram(view, data);
}
