概要 | パッケージ | クラス | 階層ツリー | 非推奨 API | 索引 | ヘルプ
前のクラス 次のクラス | フレームあり フレームなし
概要: 入れ子 | フィールド | コンストラクタ | メソッド | 詳細: フィールド | コンストラクタ | メソッド

## jAudioFeatureExtractor.jAudioTools
クラス FFT

    java.lang.Object
      jAudioFeatureExtractor.jAudioTools.FFT

    public class FFT

extends java.lang.Object

This class performs a complex to complex Fast Fourier Transform. Forward and inverse transforms may both be performed. The transforms may be performed with or without the application of a Hanning window.

The FFT is performed by this class' constructor. The real and imaginary results are both stored, and the magnitude spectrum, power spectrum and phase angles may also be accessed (along with appropriate frequency bin labels for the magnitude and power spectra).

作成者:
  Cory McKay

コンストラクタの概要
`FFT(double[] real_input, double[] imaginary_input, boolean inverse_transform, boolean use_hanning_window)` Performs the Fourier transform and stores the real and imaginary results.

メソッドの概要
`double[]` | `getBinLabels(double sampling_rate)` Returns the frequency bin labels for each bin referred to by the real values, imaginary values, magnitudes and phase angles as determined by the given sampling rate.
`double[]` | `getImaginaryValues()` Returns the real values as calculated by the FFT.
`double[]` | `getMagnitudeSpectrum()` Returns the magnitudes spectrum.
`double[]` | `getPhaseAngles()` Returns the phase angle for each frequency bin.
`double[]` | `getPowerSpectrum()` Returns the power spectrum.
`double[]` | `getRealValues()` Returns the real values as calculated by the FFT.

クラス java.lang.Object から継承されたメソッド
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

コンストラクタの詳細

### FFT

    public FFT(double[] real_input,
               double[] imaginary_input,
               boolean inverse_transform,
               boolean use_hanning_window)
        throws java.lang.Exception

  Performs the Fourier transform and stores the real and imaginary results. Input signals are zero-padded if they do not have a length equal to a power of 2.

  パラメータ:
    `real_input` - The real part of the signal to be transformed.
    `imaginary_input` - The imaginary part of the signal to be. transformed. This may be null if the signal is entirely real.
    `inverse_transform` - A value of false implies that a forward transform is to be applied, and a value of true means that an inverse transform is tob be applied.
    `use_hanning_window` - A value of true means that a Hanning window will be applied to the real_input. A value of valse will result in the application of a Hanning window.
  例外:
    `java.lang.Exception` - Throws an exception if the real and imaginary inputs are of different sizes or if less than three input samples are provided.

メソッドの詳細

### getMagnitudeSpectrum

    public double[] getMagnitudeSpectrum()

  Returns the magnitudes spectrum. It only makes sense to call this method if this object was instantiated as a forward Fourier transform.

  Only the left side of the spectrum is returned, as the folded portion of the spectrum is redundant for the purpose of the magnitude spectrum. This means that the bins only go up to half of the sampling rate.

  戻り値:
    The magnitude of each frequency bin.

### getPowerSpectrum

    public double[] getPowerSpectrum()

  Returns the power spectrum. It only makes sense to call this method if this object was instantiated as a forward Fourier transform.

  Only the left side of the spectrum is returned, as the folded portion of the spectrum is redundant for the purpose of the power spectrum. This means that the bins only go up to half of the sampling rate.

  戻り値:
    The magnitude of each frequency bin.

### getPhaseAngles

    public double[] getPhaseAngles()

  Returns the phase angle for each frequency bin. It only makes sense to call this method if this object was instantiated as a forward Fourier transform.

  Only the left side of the spectrum is returned, as the folded portion of the spectrum is redundant for the purpose of the phase angles. This means that the bins only go up to half of the sampling rate.

  戻り値:
    The phase angle for each frequency bin in degrees.

### getBinLabels

    public double[] getBinLabels(double sampling_rate)

  Returns the frequency bin labels for each bin referred to by the real values, imaginary values, magnitudes and phase angles as determined by the given sampling rate.

  パラメータ:
    `sampling_rate` - The sampling rate that was used to perform the FFT.
  戻り値:
    The bin labels.

### getRealValues

    public double[] getRealValues()

  Returns the real values as calculated by the FFT.

  戻り値:
    The real values.

### getImaginaryValues

    public double[] getImaginaryValues()

  Returns the real values as calculated by the FFT.

  戻り値:
    The real values.

概要 | パッケージ | クラス | 階層ツリー | 非推奨 API | 索引 | ヘルプ
前のクラス 次のクラス | フレームあり フレームなし
概要: 入れ子 | フィールド | コンストラクタ | メソッド | 詳細: フィールド | コンストラクタ | メソッド