private double[] MagnitudeSpectrum(float[] frame)
{
// prepare the input arrays
FFTW.DoubleArray fftwInput = new FFTW.DoubleArray(MathUtils.FloatToDouble(frame));
int complexSize = (frame.Length >> 1) + 1;
FFTW.ComplexArray fftwOutput = new FFTW.ComplexArray(complexSize);
FFTW.ForwardTransform(fftwInput, fftwOutput);
double[] magSpectrum = fftwOutput.Abs;
/*
double[] magSpectrum = new double[frame.Length];
// calculate FFT for current frame
fft.ComputeFFT(frame);
// System.err.println("FFT SUCCEED");
// calculate magnitude spectrum
for (int k = 0; k < frame.Length; k++)
{
magSpectrum[k] = Math.Sqrt(fft.real[k] * fft.real[k] + fft.imag[k] * fft.imag[k]);
}
*/
return magSpectrum;
}
public static void ForwardTransform(FFTW.DoubleArray input, FFTW.ComplexArray output)
{
IntPtr plan = FFTW.dft_r2c_1d(input.Length, input.Handle, output.Handle, Flags.Estimate);
//FFTW.print_plan(plan);
FFTW.execute(plan);
FFTW.destroy_plan(plan);
}
public static void BackwardTransform(FFTW.ComplexArray input, FFTW.DoubleArray output)
{
// TODO: make sure to use input.Length and not the output.Length ?!
IntPtr plan = FFTW.dft_c2r_1d(input.Length, input.Handle, output.Handle, Flags.Estimate);
//FFTW.print_plan(plan);
FFTW.execute(plan);
FFTW.destroy_plan(plan);
}
private static double GetComponentWeightCenter(List<double[]> a, int size, int component)
{
double[] windowedValues = a.GetWindowedDimension(component, size, HannWindow);
FFTW.DoubleArray fftwInput = new FFTW.DoubleArray(windowedValues);
FFTW.ComplexArray fftwOutput = new FFTW.ComplexArray((size >> 1) + 1);
FFTW.ForwardTransform(fftwInput, fftwOutput);
return fftwOutput.Values.GetWeightCenter();
}
private static double GetComponentWeightCenter(List <double[]> a, int size, int component)
{
double[] windowedValues = a.GetWindowedDimension(component, size, HannWindow);
FFTW.DoubleArray fftwInput = new FFTW.DoubleArray(windowedValues);
FFTW.ComplexArray fftwOutput = new FFTW.ComplexArray((size >> 1) + 1);
FFTW.ForwardTransform(fftwInput, fftwOutput);
return(fftwOutput.Values.GetWeightCenter());
}
public static void FFTWTestUsingDouble(string CSVFilePath=null, double[] audio_data=null, int testLoopCount=1)
{
if (audio_data == null) {
audio_data = GetSignalTestData();
}
// prepare the input arrays
FFTW.DoubleArray fftwInput = new FFTW.DoubleArray(audio_data);
int complexSize = (audio_data.Length >> 1) + 1;
FFTW.ComplexArray fftwOutput = new FFTW.ComplexArray(complexSize);
// loop if neccesary - e.g. for performance test purposes
for (int i = 0; i < testLoopCount; i++) {
// perform the FFT
FFTW.ForwardTransform(fftwInput, fftwOutput);
}
// get the result
double[] spectrum_fft_real = fftwOutput.Real;
double[] spectrum_fft_imag = fftwOutput.Imag;
double[] spectrum_fft_abs = fftwOutput.Abs;
// prepare the input arrays
FFTW.ComplexArray fftwBackwardInput = new FFTW.ComplexArray(spectrum_fft_real, spectrum_fft_imag);
FFTW.DoubleArray fftwBackwardOutput = new FFTW.DoubleArray(audio_data.Length);
// perform the inverse FFT (IFFT)
FFTW.BackwardTransform(fftwBackwardInput, fftwBackwardOutput);
// get the result
double[] spectrum_inverse_real = fftwBackwardOutput.ValuesDivedByN;
// pad for output
if (spectrum_fft_real.Length != audio_data.Length) Array.Resize(ref spectrum_fft_real, audio_data.Length);
if (spectrum_fft_imag.Length != audio_data.Length) Array.Resize(ref spectrum_fft_imag, audio_data.Length);
if (spectrum_fft_abs.Length != audio_data.Length) Array.Resize(ref spectrum_fft_abs, audio_data.Length);
if (CSVFilePath!=null) {
CommonUtils.Export.exportCSV(CSVFilePath, audio_data, spectrum_fft_real, spectrum_fft_imag, spectrum_fft_abs, spectrum_inverse_real);
}
}