comirva.audio.util
Class FFT

java.lang.Object
  comirva.audio.util.FFT

public class FFT
extends java.lang.Object

Class for computing a windowed fast Fourier transform. Implements some of the window functions for the STFT from Harris (1978), Proc. IEEE, 66, 1, 51-83.

Field Summary

static int	FFT_FORWARD used in fft(double[], double[], int) to specify a forward Fourier transform
static int	FFT_INLINE_POWER_PHASE used to specify a inline power phase Fourier transform
static int	FFT_MAGNITUDE used to specify a magnitude Fourier transform
static int	FFT_MAGNITUDE_PHASE used to specify a magnitude phase Fourier transform
static int	FFT_NORMALIZED_POWER used to specify a normalized power Fourier transform
static int	FFT_POWER used to specify a power Fourier transform
static int	FFT_POWER_PHASE used to specify a power phase Fourier transform
static int	FFT_REVERSE used in fft(double[], double[], int) to specify an inverse Fourier transform
static int	WND_BH3 used in FFT#makeWindow(int,int,int) to specify a 61-dB 3-sample Blackman-Harris window function
static int	WND_BH3MIN used in FFT#makeWindow(int,int,int) to specify a minimum 3-sample Blackman-Harris window function
static int	WND_BH4 used in FFT#makeWindow(int,int,int) to specify a 74-dB 4-sample Blackman-Harris window function
static int	WND_BH4MIN used in FFT#makeWindow(int,int,int) to specify a minimum 4-sample Blackman-Harris window function
static int	WND_GAUSS used in FFT#makeWindow(int,int,int) to specify a Gaussian window function
static int	WND_HAMMING used in FFT#makeWindow(int,int,int) to specify a Hamming window function
static int	WND_HANNING used in FFT#makeWindow(int,int,int) to specify a Hanning window function
static int	WND_NONE used in FFT#makeWindow(int,int,int) to specify a rectangular window function
static int	WND_RECT used in FFT#makeWindow(int,int,int) to specify a rectangular window function
static int	WND_USER_DEFINED used in FFT#makeWindow(int,int,int) to specify a Hanning window function

Constructor Summary

FFT(int transformationType, int windowSize)

FFT(int transformationType, int windowSize, double[] windowFunction)

FFT(int transformationType, int windowSize, int windowFunctionType)

FFT(int transformationType, int windowSize, int windowFunctionType, int support)

Method Summary

int	getTransformationType()
int	getWindowFunctionType()
void	setWindowFunction(int windowFunctionType, int support) Returns an array of values of a normalised smooth window function, as used for performing a short time Fourier transform (STFT).
void	transform(double[] re, double[] im)

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

FFT_FORWARD

public static final int FFT_FORWARD

used in fft(double[], double[], int) to specify a forward Fourier transform

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Constant Field Values

FFT_REVERSE

public static final int FFT_REVERSE

used in fft(double[], double[], int) to specify an inverse Fourier transform

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Constant Field Values

FFT_MAGNITUDE

public static final int FFT_MAGNITUDE

used to specify a magnitude Fourier transform

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Constant Field Values

FFT_MAGNITUDE_PHASE

public static final int FFT_MAGNITUDE_PHASE

used to specify a magnitude phase Fourier transform

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Constant Field Values

FFT_NORMALIZED_POWER

public static final int FFT_NORMALIZED_POWER

used to specify a normalized power Fourier transform

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Constant Field Values

FFT_POWER

public static final int FFT_POWER

used to specify a power Fourier transform

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Constant Field Values

FFT_POWER_PHASE

public static final int FFT_POWER_PHASE

used to specify a power phase Fourier transform

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Constant Field Values

FFT_INLINE_POWER_PHASE

public static final int FFT_INLINE_POWER_PHASE

used to specify a inline power phase Fourier transform

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Constant Field Values

WND_NONE

public static final int WND_NONE

used in FFT#makeWindow(int,int,int) to specify a rectangular window function

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Constant Field Values

WND_RECT

public static final int WND_RECT

used in FFT#makeWindow(int,int,int) to specify a rectangular window function

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Constant Field Values

WND_HAMMING

public static final int WND_HAMMING

used in FFT#makeWindow(int,int,int) to specify a Hamming window function

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Constant Field Values

WND_BH3

public static final int WND_BH3

used in FFT#makeWindow(int,int,int) to specify a 61-dB 3-sample Blackman-Harris window function

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Constant Field Values

WND_BH4

public static final int WND_BH4

used in FFT#makeWindow(int,int,int) to specify a 74-dB 4-sample Blackman-Harris window function

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Constant Field Values

WND_BH3MIN

public static final int WND_BH3MIN

used in FFT#makeWindow(int,int,int) to specify a minimum 3-sample Blackman-Harris window function

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Constant Field Values

WND_BH4MIN

public static final int WND_BH4MIN

used in FFT#makeWindow(int,int,int) to specify a minimum 4-sample Blackman-Harris window function

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Constant Field Values

WND_GAUSS

public static final int WND_GAUSS

used in FFT#makeWindow(int,int,int) to specify a Gaussian window function

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Constant Field Values

WND_HANNING

public static final int WND_HANNING

used in FFT#makeWindow(int,int,int) to specify a Hanning window function

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Constant Field Values

WND_USER_DEFINED

public static final int WND_USER_DEFINED

used in FFT#makeWindow(int,int,int) to specify a Hanning window function

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Constant Field Values

Constructor Detail

FFT

public FFT(int transformationType,
           int windowSize)

FFT

public FFT(int transformationType,
           int windowSize,
           int windowFunctionType)

FFT

public FFT(int transformationType,
           int windowSize,
           int windowFunctionType,
           int support)

FFT

public FFT(int transformationType,
           int windowSize,
           double[] windowFunction)

Method Detail

transform

public void transform(double[] re,
                      double[] im)

setWindowFunction

public void setWindowFunction(int windowFunctionType,
                              int support)

Returns an array of values of a normalised smooth window function, as used for performing a short time Fourier transform (STFT). All functions are normalised by length and coherent gain. More information on characteristics of these functions can be found in F.J. Harris (1978), On the Use of Windows for Harmonic Analysis with the Discrete Fourier Transform, Proceedings of the IEEE, 66, 1, 51-83.

Parameters:

choice - the choice of window function, one of the constants defined above

support - the number of non-zero values in the array, if the array is larger than this, it is zero-padded symmetrically at both ends

getTransformationType

public int getTransformationType()

getWindowFunctionType

public int getWindowFunctionType()