Package com.badlogic.gdx.audio.analysis

Class FFT

java.lang.Object
com.badlogic.gdx.audio.analysis.FourierTransform
com.badlogic.gdx.audio.analysis.FFT
public class FFT extends FourierTransform
FFT stands for Fast Fourier Transform. It is an efficient way to calculate the Complex Discrete Fourier Transform. There is not much to say about this class other than the fact that when you want to analyze the spectrum of an audio buffer you will almost always use this class. One restriction of this class is that the audio buffers you want to analyze must have a length that is a power of two. If you try to construct an FFT with a timeSize that is not a power of two, an IllegalArgumentException will be thrown.
See Also:

  • Constructor Details

    • FFT

      public FFT(int timeSize, float sampleRate)
      Constructs an FFT that will accept sample buffers that are timeSize long and have been recorded with a sample rate of sampleRate. timeSize must be a power of two. This will throw an exception if it is not.
      Parameters:
      timeSize - the length of the sample buffers you will be analyzing
      sampleRate - the sample rate of the audio you will be analyzing

  • Method Details

    • allocateArrays

      protected void allocateArrays()
      Specified by:
      allocateArrays in class FourierTransform

    • scaleBand

      public void scaleBand(int i, float s)
      Description copied from class: FourierTransform
      Scales the amplitude of the ith frequency band by s. You can use this to shape the spectrum before using inverse().
      Specified by:
      scaleBand in class FourierTransform
      Parameters:
      i - the frequency band to modify
      s - the scaling factor

    • setBand

      public void setBand(int i, float a)
      Description copied from class: FourierTransform
      Sets the amplitude of the ith frequency band to a. You can use this to shape the spectrum before using inverse().
      Specified by:
      setBand in class FourierTransform
      Parameters:
      i - the frequency band to modify
      a - the new amplitude

    • forward

      public void forward(float[] buffer)
      Description copied from class: FourierTransform
      Performs a forward transform on buffer.
      Specified by:
      forward in class FourierTransform
      Parameters:
      buffer - the buffer to analyze

    • forward

      public void forward(float[] buffReal, float[] buffImag)
      Performs a forward transform on the passed buffers.
      Parameters:
      buffReal - the real part of the time domain signal to transform
      buffImag - the imaginary part of the time domain signal to transform

    • inverse

      public void inverse(float[] buffer)
      Description copied from class: FourierTransform
      Performs an inverse transform of the frequency spectrum and places the result in buffer.
      Specified by:
      inverse in class FourierTransform
      Parameters:
      buffer - the buffer to place the result of the inverse transform in