cAcf

Description

This component computes the autocorrelation function (ACF) by squaring a magnitude spectrum and applying an inverse Fast Fourier Transform. This component must read from a level containing *only* FFT magnitudes in a single field. Use the 'cTransformFFT' and 'cFFTmagphase' components to compute the magnitude spectrum from PCM frames. Computation of the Cepstrum is also supported (this applies a log() function to the magnitude spectra).

Type hierarchy

cDataProcessor → cVectorProcessor → cAcf

Fields

  • nameAppend (string) [default: acf]

    A string suffix to append to the input field names (default: empty)

  • usePower (numeric) [default: 1.0]

    1 = square input values; you must leave this at default 1, when using fft magnitude as input for ACF. For cepstrum this will be set to 0 by default, unless you explicitly give the value 1.

  • cepstrum (numeric) [default: 0.0]

    1 = compute the real valued cepstrum instead of the standard ACF. This applies a log() to the magnitudes bevore transforming from the spectral domain back to the time domain. You might want to set 'nameAppend=cepstrum' when using this option. See the cCepstrum component for complex valued cepstrum and more options (only in commercial version).

  • inverse (numeric) [default: 0.0]

    1 = do the inverse transform of cepstrum or ACF. The output is an FFT magnitude spectrum.

  • cosLifterCepstrum (numeric) [default: 0.0]

    1 = apply cosine lifter function to the cepstrum, effectively applying a Hanning window function to the cepstrum.

  • expBeforeAbs (numeric) [default: 1.0]

    1 = perform exp operation before computing magnitude spectrum (for inverse cepstrum only).

  • symmetricData (numeric) [default: 1.0]

    1 = treat data in acf/cepstral domain as symmetric data, i.e. output only half of the buffer or symmetrically duplicate the input before applying fft.

  • acfCepsNormOutput (numeric) [default: 1.0]

    1 = Divide the output values by the framesize (this is the default since version 2.0, however for older versions, such as 0.1 (openEAR) setting this option to 0 is required for comaptibility.

  • oldCompatCepstrum (numeric) [default: 0.0]

    1 = compatibility with old openEAR (0.1) cepstrum computation (absCepstrum = 1, acfCepsNormOutput = 0, and usePower should be 1 (not forced though)).

  • absCepstrum (numeric) [default: 0.0]

    1 = enable output of root of power cepstrum (absolute value)