public static double FrequencyDistribution(byte[] x, byte[] y)
{
if (x.Length != y.Length)
{
throw new ArgumentException("interval lengths do not match");
}
int samples = x.Length / 4;
float[] xF = new float[samples];
float[] yF = new float[samples];
Buffer.BlockCopy(x, 0, xF, 0, x.Length);
Buffer.BlockCopy(y, 0, yF, 0, y.Length);
int fftSize = 2048; // max FFT size
// if there are less samples to analyze, find a fitting FFT size
while (fftSize > samples)
{
fftSize /= 2;
}
int hopSize = fftSize / 8;
if (fftSize < 64)
{
throw new Exception("FFT might be too small to get a meaningful result");
}
double[] xSum = new double[fftSize / 2];
double[] ySum = new double[fftSize / 2];
float[] buffer = new float[fftSize];
if (windowFunction == null || windowFunction.Size != fftSize)
{
windowFunction = WindowUtil.GetFunction(WindowType.Hann, fftSize);
}
var fft = FFTFactory.CreateInstance(fftSize);
int blocks = (samples - fftSize) / hopSize;
for (int block = 0; block < blocks; block++)
{
Array.Copy(xF, block * hopSize, buffer, 0, buffer.Length);
FrequencyDistributionBlockProcess(buffer, xSum, fft);
Array.Copy(yF, block * hopSize, buffer, 0, buffer.Length);
FrequencyDistributionBlockProcess(buffer, ySum, fft);
}
fft.Dispose();
// remove DC offset
xSum[0] = 0;
ySum[0] = 0;
double xScalarSum = xSum.Sum();
double yScalarSum = ySum.Sum();
double result = 0;
for (int i = 0; i < fftSize / 2; i++)
{
result += Math.Abs(xSum[i] / xScalarSum - ySum[i] / yScalarSum);
}
return(1 - result);
}
