//Complex->Real
public static fftw_plan dft_c2r_1d(int n, fftw_complexarray input, fftw_complexarray output, fftw_direction direction, fftw_flags flags)
{
fftw_plan p = new fftw_plan();
p.handle = fftw.dft_c2r_1d(n, input.Handle, output.Handle, (uint)flags);
return(p);
}
//Real<->Real
public static fftw_plan r2r_1d(int n, fftw_complexarray input, fftw_complexarray output, fftw_kind kind, fftw_flags flags)
{
fftw_plan p = new fftw_plan();
p.handle = fftw.r2r_1d(n, input.Handle, output.Handle, (int)kind, (uint)flags);
return(p);
}
public static fftw_plan dft_r2c(int rank, int[] n, fftw_complexarray input, fftw_complexarray output, fftw_flags flags)
{
fftw_plan p = new fftw_plan();
p.handle = fftw.dft_r2c(rank, n, input.Handle, output.Handle, (uint)flags);
return(p);
}
public static fftw_plan dft_r2c_2d(int nx, int ny, fftw_complexarray input, fftw_complexarray output, fftw_flags flags)
{
var p = new fftw_plan();
p.handle = fftw.dft_r2c_2d(nx, ny, input.Handle, output.Handle, flags);
return(p);
}
//Real->Complex transforms
public static fftw_plan dft_r2c_1d(int n, fftw_complexarray input, fftw_complexarray output, fftw_flags flags)
{
fftw_plan p = new fftw_plan();
p.handle = fftw.dft_r2c_1d(n, input.Handle, output.Handle, flags);
return(p);
}
public static fftw_plan dft_c2r_3d(int nx, int ny, int nz, fftw_complexarray input, fftw_complexarray output, fftw_direction direction, fftw_flags flags)
{
var p = new fftw_plan();
p.handle = fftw.dft_c2r_3d(nx, ny, nz, input.Handle, output.Handle, flags);
return(p);
}
public static fftw_plan dft_r2c_3d(int nx, int ny, int nz, fftw_complexarray input, fftw_complexarray output, fftw_flags flags)
{
fftw_plan p = new fftw_plan();
p.handle = fftw.dft_r2c_3d(nx, ny, nz, input.Handle, output.Handle, (uint)flags);
return(p);
}
public static fftw_plan dft_c2r(int rank, int[] n, fftw_complexarray input, fftw_complexarray output, fftw_direction direction, fftw_flags flags)
{
var p = new fftw_plan();
p.handle = fftw.dft_c2r(rank, n, input.Handle, output.Handle, flags);
return(p);
}
public static fftw_plan r2r_2d(int nx, int ny, fftw_complexarray input, fftw_complexarray output, fftw_kind kindx, fftw_kind kindy, fftw_flags flags)
{
var p = new fftw_plan();
p.handle = fftw.r2r_2d(nx, ny, input.Handle, output.Handle, kindx, kindy, flags);
return(p);
}
public static fftw_plan r2r_3d(int nx, int ny, int nz, fftw_complexarray input, fftw_complexarray output,
fftw_kind kindx, fftw_kind kindy, fftw_kind kindz, fftw_flags flags)
{
fftw_plan p = new fftw_plan();
p.handle = fftw.r2r_3d(nx, ny, nz, input.Handle, output.Handle,
(int)kindx, (int)kindy, (int)kindz, (uint)flags);
return(p);
}
public static fftw_plan r2r(int rank, int[] n, fftw_complexarray input, fftw_complexarray output,
fftw_kind[] kind, fftw_flags flags)
{
var p = new fftw_plan();
p.handle = fftw.r2r(rank, n, input.Handle, output.Handle,
kind, flags);
return(p);
}
/// <summary>
/// Perform the Fast Fourier Transform utilisizing the FFTW library
/// </summary>
/// <param name="in">Input Signal</param>
/// <param name="out">Output Signal</param>
/// <param name="N">N</param>
/// <param name="method">FFT Method (DFT, IDFT, DHT)</param>
public static void FFT(ref double[] @in, ref double[] @out, int N, FFTMethod method)
{
var complexInput = new fftw_complexarray(@in);
var complexOutput = new fftw_complexarray(@out);
switch(method) {
case FFTMethod.DFT:
// fftw_kind.R2HC: input is expected to be real while output is returned in the halfcomplex format
fftw_plan fft = fftw_plan.r2r_1d(N, complexInput, complexOutput, fftw_kind.R2HC, fftw_flags.Estimate);
fft.Execute();
@out = complexOutput.Values;
// free up memory
fft = null;
break;
case FFTMethod.IDFT:
// fftw_kind.HC2R: input is expected to be halfcomplex format while output is returned as real
fftw_plan ifft = fftw_plan.r2r_1d(N, complexInput, complexOutput, fftw_kind.HC2R, fftw_flags.Estimate);
ifft.Execute();
//@out = complexOutput.ValuesDividedByN; // dividing by N gives the correct scale
@out = complexOutput.Values;
// free up memory
ifft = null;
break;
case FFTMethod.DHT:
fftw_plan dht = fftw_plan.r2r_1d(N, complexInput, complexOutput, fftw_kind.DHT, fftw_flags.Estimate);
dht.Execute();
@out = complexOutput.Values;
// free up memory
dht = null;
break;
}
// free up memory
complexInput = null;
complexOutput = null;
GC.Collect();
}
public static fftw_plan r2r_3d(int nx, int ny, int nz, fftw_complexarray input, fftw_complexarray output,
fftw_kind kindx, fftw_kind kindy, fftw_kind kindz, fftw_flags flags)
{
fftw_plan p = new fftw_plan();
p.handle = fftw.r2r_3d(nx, ny, nz, input.Handle, output.Handle,
kindx, kindy, kindz, flags);
return p;
}
//Real<->Real
public static fftw_plan r2r_1d(int n, fftw_complexarray input, fftw_complexarray output, fftw_kind kind, fftw_flags flags)
{
fftw_plan p = new fftw_plan();
p.handle = fftw.r2r_1d(n, input.Handle, output.Handle, kind, flags);
return p;
}
public static fftw_plan r2r(int rank, int[] n, fftw_complexarray input, fftw_complexarray output,
fftw_kind[] kind, fftw_flags flags)
{
fftw_plan p = new fftw_plan();
p.handle = fftw.r2r(rank, n, input.Handle, output.Handle,
kind, flags);
return p;
}
public static fftw_plan dft_r2c_3d(int nx, int ny, int nz, fftw_complexarray input, fftw_complexarray output, fftw_flags flags)
{
fftw_plan p = new fftw_plan();
p.handle = fftw.dft_r2c_3d(nx, ny, nz, input.Handle, output.Handle, flags);
return p;
}
public static fftw_plan dft_r2c(int rank, int[] n, fftw_complexarray input, fftw_complexarray output, fftw_flags flags)
{
fftw_plan p = new fftw_plan();
p.handle = fftw.dft_r2c(rank, n, input.Handle, output.Handle, flags);
return p;
}
public static fftw_plan dft_c2r_2d(int nx, int ny, fftw_complexarray input, fftw_complexarray output, fftw_direction direction, fftw_flags flags)
{
fftw_plan p = new fftw_plan();
p.handle = fftw.dft_c2r_2d(nx, ny, input.Handle, output.Handle, flags);
return p;
}
/// <summary>
/// Perform the Fast Fourier Transform utilisizing the FFTW library
/// </summary>
/// <param name="in">Input Signal</param>
/// <param name="out">Output Signal</param>
/// <param name="N">N</param>
/// <param name="method">FFT Method (DFT, IDFT, DHT)</param>
public static void FFT(ref double[] @in, ref double[] @out, int N, FFTMethod method)
{
fftw_complexarray complexInput = new fftw_complexarray(@in);
fftw_complexarray complexOutput = new fftw_complexarray(@out);
switch(method) {
case FFTMethod.DFT:
fftw_plan fft = fftw_plan.r2r_1d(N, complexInput, complexOutput, fftw_kind.R2HC, fftw_flags.Estimate);
fft.Execute();
@out = complexOutput.Values;
// free up memory
fft = null;
break;
case FFTMethod.IDFT:
fftw_plan ifft = fftw_plan.r2r_1d(N, complexInput, complexOutput, fftw_kind.HC2R, fftw_flags.Estimate);
ifft.Execute();
@out = complexOutput.ValuesDividedByN;
// free up memory
ifft = null;
break;
case FFTMethod.DHT:
fftw_plan dht = fftw_plan.r2r_1d(N, complexInput, complexOutput, fftw_kind.DHT, fftw_flags.Estimate);
dht.Execute();
@out = complexOutput.Values;
// free up memory
dht = null;
break;
}
// free up memory
complexInput = null;
complexOutput = null;
GC.Collect();
}
/// <summary>
/// Generate a spectrogram array spaced linearily
/// </summary>
/// <param name="samples">audio data</param>
/// <param name="fftWindowsSize">fft window size</param>
/// <param name="fftOverlap">overlap in number of samples (normaly half of the fft window size) [low number = high overlap]</param>
/// <returns>spectrogram jagged array</returns>
public static float[][] CreateSpectrogramFFTWLIB(float[] samples, int fftWindowsSize, int fftOverlap)
{
int numberOfSamples = samples.Length;
// overlap must be an integer smaller than the window size
// half the windows size is quite normal
double[] windowArray = FFTWindowFunctions.GetWindowFunction(FFTWindowFunctions.HANNING, fftWindowsSize);
// width of the segment - e.g. split the file into 78 time slots (numberOfSegments) and do analysis on each slot
int numberOfSegments = (numberOfSamples - fftWindowsSize)/fftOverlap;
float[][] frames = new float[numberOfSegments][];
// even - Re, odd - Img
double[] complexSignal = new double[2*fftWindowsSize];
for (int i = 0; i < numberOfSegments; i++)
{
// apply Hanning Window
for (int j = 0; j < fftWindowsSize; j++)
{
// Weight by Hann Window
complexSignal[2*j] = (double) (windowArray[j] * samples[i * fftOverlap + j]);
// need to clear out as fft modifies buffer (phase)
complexSignal[2*j + 1] = 0;
}
// prepare the input arrays
fftw_complexarray complexInput = new fftw_complexarray(complexSignal);
fftw_complexarray complexOutput = new fftw_complexarray(complexSignal.Length/2);
fftw_plan fft = fftw_plan.dft_1d(complexSignal.Length/2, complexInput, complexOutput, fftw_direction.Forward, fftw_flags.Estimate);
// perform the FFT
fft.Execute();
// get the result
float[] band = MathUtils.DoubleToFloat(complexOutput.Abs);
frames[i] = band;
// free up memory
complexInput = null;
complexOutput = null;
//GC.Collect();
}
return frames;
}
public static void FFTWTestUsingDoubleFFTWLIB(string CSVFilePath=null, double[] audio_data=null, int testLoopCount=1)
{
if (audio_data == null) {
audio_data = GetSignalTestData();
}
// prepare the input arrays
double[] complexSignal = FFTUtils.DoubleToComplexDouble(audio_data);
fftw_complexarray complexInput = new fftw_complexarray(complexSignal);
fftw_complexarray complexOutput = new fftw_complexarray(audio_data.Length);
fftw_plan fft = fftw_plan.dft_1d(audio_data.Length, complexInput, complexOutput, fftw_direction.Forward, fftw_flags.Estimate);
// loop if neccesary - e.g. for performance test purposes
for (int i = 0; i < testLoopCount; i++) {
// perform the FFT
fft.Execute();
}
// get the result
double[] spectrum_fft_real = complexOutput.Real;
double[] spectrum_fft_imag = complexOutput.Imag;
double[] spectrum_fft_abs = complexOutput.Abs;
// perform the inverse FFT (IFFT)
fftw_complexarray complexOutput2 = new fftw_complexarray(audio_data.Length);
fftw_plan ifft = fftw_plan.dft_1d(audio_data.Length, complexOutput, complexOutput2, fftw_direction.Backward, fftw_flags.Estimate);
// perform the IFFT
ifft.Execute();
// get the result
double[] spectrum_inverse_real = complexOutput2.RealDividedByN;
double[] spectrum_inverse_imag = complexOutput2.ImagDividedByN;
double[] spectrum_inverse_abs = complexOutput2.AbsDividedByN;
if (CSVFilePath!=null) {
CommonUtils.Export.exportCSV(CSVFilePath, audio_data, spectrum_fft_real, spectrum_fft_imag, spectrum_fft_abs, spectrum_inverse_real, spectrum_inverse_imag, spectrum_inverse_abs);
}
}
public static fftw_plan dft_c2r(int rank, int[] n, fftw_complexarray input, fftw_complexarray output, fftw_direction direction, fftw_flags flags)
{
fftw_plan p = new fftw_plan();
p.handle = fftw.dft_c2r(rank, n, input.Handle, output.Handle, (uint)flags);
return p;
}
//Real->Complex transforms
public static fftw_plan dft_r2c_1d(int n, fftw_complexarray input, fftw_complexarray output, fftw_flags flags)
{
fftw_plan p = new fftw_plan();
p.handle = fftw.dft_r2c_1d(n, input.Handle, output.Handle, (uint)flags);
return p;
}