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/* libxtract feature extraction library
*
* Copyright (C) 2006 Jamie Bullock
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
* USA.
*/
/* xtract_scalar.h: declares functions that extract a feature as a vector from an input vector */
#ifndef XTRACT_VECTOR
#define XTRACT_VECTOR
#ifdef __cplusplus
extern "C" {
#endif
/**
* \defgroup vector extraction functions
*
* Defines vectorr extraction functions, and their parameters.
* @{
*/
/** \brief Extract normalized (0-1) frequency domain magnitude spectrum from time domain signal
*
* \param *data: a pointer to the first element in an array of floats representing an audio vector
* \param N: the number of array elements to be considered
* \param *argv: a pointer to NULL
* \param *result: the magnitude spectrum of N values from the array pointed to by *data
*/
int xtract_magnitude_spectrum(const float *data, const int N, const void *argv, float *result);
/** \brief Extract autocorrelation from time domain signal using FFT based method
*
* \param *data: a pointer to the first element in an array of floats representing an audio vector
* \param N: the number of array elements to be considered
* \param *argv: a pointer to NULL
* \param *result: the autocorrelation of N values from the array pointed to by *data
*/
int xtract_autocorrelation_fft(const float *data, const int N, const void *argv, float *result);
/** \brief Extract Mel Frequency Cepstral Coefficients based on a method described by Rabiner
*
* \param *data: a pointer to the first element in an array of floats
* \param N: the number of array elements to be considered
* \param *argv: a pointer to a data structure of type xtract_mel_filter, containing n_filters coefficient tables to make up a mel-spaced filterbank
* \param *result: a pointer to an array containing the resultant MFCC
*
* The data structure pointed to by *argv must be obtained by first calling xtract_init_mfcc
*/
int xtract_mfcc(const float *data, const int N, const void *argv, float *result);
/** \brief Extract the Discrete Cosine transform of a time domain signal
* \param *data: a pointer to the first element in an array of floats representing an audio vector
* \param N: the number of array elements to be considered
* \param *argv: a pointer to NULL
* \param *result: a pointer to an array containing resultant dct coefficients
*/
int xtract_dct(const float *data, const int N, const void *argv, float *result);
/** \brief Extract autocorrelation from time domain signal using time-domain autocorrelation technique
*
* \param *data: a pointer to the first element in an array of floats representing an audio vector
* \param N: the number of array elements to be considered
* \param *argv: a pointer to NULL
* \param *result: the autocorrelation of N values from the array pointed to by *data
*/
int xtract_autocorrelation(const float *data, const int N, const void *argv, float *result);
/** \brief Extract Average Magnitude Difference Function from time domain signal
*
* \param *data: a pointer to the first element in an array of floats
* \param N: the number of array elements to be considered
* \param *argv: a pointer to NULL
* \param *result: the AMDF of N values from the array pointed to by *data
*/
int xtract_amdf(const float *data, const int N, const void *argv, float *result);
/** \brief Extract Average Squared Difference Function from time domain signal
*
* \param *data: a pointer to the first element in an array of floats representing an audio vector
* \param N: the number of array elements to be considered
* \param *argv: a pointer to NULL
* \param *result: the ASDF of N values from the array pointed to by *data
*/
int xtract_asdf(const float *data, const int N, const void *argv, float *result);
/** \brief Extract Bark band coefficients based on a method
* \param *data: a pointer to the first element in an array of floats representing the magnitude spectrum of an audio vector
* \param N: the number of array elements to be considered
* \param *argv: a pointer to an array of ints representing the limits of each bark band. This can be obtained by calling xtract_init_bark.
* \param *result: a pointer to an array containing resultant bark coefficients
*
* The limits array pointed to by *argv must be obtained by first calling xtract_init_bark
*
*/
int xtract_bark_coefficients(const float *data, const int N, const void *argv, float *result);
/** \brief Extract the frequency and amplitude of spectral peaks from a magnitude spectrum
* \param *data: a pointer to the first element in an array of floats representing the magnitude spectrum of an audio vector
* \param N: the number of array elements to be considered
* \param *argv: a pointer to an array containing peak threshold as percentage below max peak, and sample rate
* \param *result: a pointer to an array of size N, containing N/2 freqs and N/2 amplitudes, amplitudes are on a decibel scale with dbFS = 0
*/
int xtract_peaks(const float *data, const int N, const void *argv, float *result);
/** \brief Extract the harmonic spectrum of from a of a peak spectrum
* \param *data: a pointer to the first element in an array of floats representing the peak spectrum of an audio vector (e.g. *result from xtract_peaks). It is expected that the first half of the array pointed to by *data will contain frequencies for each peak considered, and the the second half will contain the respective amplitudes
* \param N: the size of the array pointed to by *data
* \param *argv: a pointer to an array containing the fundamental (f0) of the spectrum, and a threshold (t) where 0<=t<=1.0, and t determines the distance from the nearest harmonic number within which a partial can be considered harmonic.
* \param *result: a pointer to an array of size N containing N/2 freqs and N/2 amplitudes, amplitudes are on a decibel scale with dbFS = 0
*/
int xtract_harmonics(const float *data, const int N, const void *argv, float *result);
/** @} */
#ifdef __cplusplus
}
#endif
#endif
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