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* \file
* \brief Implementation of linear prediction functions, and conversion
* between common representations of linear predictive parameters
* \author Thomas Eriksson
*
* -------------------------------------------------------------------------
*
* Copyright (C) 1995-2010 (see AUTHORS file for a list of contributors)
*
* This file is part of IT++ - a C++ library of mathematical, signal
* processing, speech processing, and communications classes and functions.
*
* IT++ 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 3 of the License, or (at your option) any
* later version.
*
* IT++ 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 IT++. If not, see <http://www.gnu.org/licenses/>.
*
* -------------------------------------------------------------------------
* Here we define functions for linear predictive analysis and
* coding. Several functions for computation of lpc parameters are
* given, together with functions to convert between various common
* representations of the lpc polynomial coefficients. The
* functionality is the same as in the MATLAB functions with the same
* names.
*
* The short term for the various parameter types are:
* poly - LPC polynomial coefficients
* ac - autocorrelation coefficients
* rc - reflection coefficients
* lar - log area ratios
* is - inverse sine parameters
* lsf - line spectral frequencies
*/
#ifndef LPCFUNC_H
#define LPCFUNC_H
#include <itpp/base/vec.h>
#include <itpp/itexports.h>
namespace itpp
{
/*! \addtogroup lpc
*/
//!@{
//! Returns a chirped version of the input vector
ITPP_EXPORT vec chirp(const vec &a, double factor);
//! Spectral distortion between two vectors, in dB.
ITPP_EXPORT double sd(const vec &In1, const vec &In2);
//! Spectral distortion between two vectors, in dB, up to highest frequency highestfreq.
ITPP_EXPORT double sd(const vec &In1, const vec &In2, double highestfreq);
//! Computes reflection coefficients from autocorrelation, using the Le-Roux-Guegen algorithm.
ITPP_EXPORT vec lerouxguegenrc(const vec &R, int order);
//! Levinson - Levinson-Durbin recursion.
ITPP_EXPORT vec levinson(const vec &R2, int order);
//! Computes the autocorrelation function
ITPP_EXPORT vec autocorr(const vec &x, int order);
//! lpc - Linear Predictive Coefficients using autocorrelation method.
ITPP_EXPORT vec lpc(const vec &x, int order);
//! schurrc - Schur algorithm.
ITPP_EXPORT vec schurrc(const vec &R, int order);
//! ac2rc - Autocorrelation sequence to reflection coefficients conversion.
ITPP_EXPORT vec ac2rc(const vec &ac);
//! ac2poly - Autocorrelation sequence to prediction polynomial conversion.
ITPP_EXPORT vec ac2poly(const vec &ac);
//! is2rc - Inverse sine parameters to reflection coefficients conversion.
ITPP_EXPORT vec is2rc(const vec &is);
//! lar2rc - Log area ratios to reflection coefficients conversion.
ITPP_EXPORT vec lar2rc(const vec &lar);
//! lsf2poly - Line spectral frequencies to prediction polynomial conversion.
ITPP_EXPORT vec lsf2poly(const vec &lsf);
//! poly2ac - Prediction polynomial to autocorrelation sequence conversion.
ITPP_EXPORT vec poly2ac(const vec &poly);
//! poly2lsf - Prediction polynomial to line spectral frequencies conversion.
ITPP_EXPORT vec poly2lsf(const vec &poly);
//! poly2rc - Prediction polynomial to reflection coefficients conversion.
ITPP_EXPORT vec poly2rc(const vec &poly);
//! poly2cepstrum - Prediction polynomial to cepstrum conversion.
ITPP_EXPORT vec poly2cepstrum(const vec &a);
//! poly2cepstrum - Prediction polynomial to cepstrum conversion, to the specified order.
ITPP_EXPORT vec poly2cepstrum(const vec &a, int num);
//! cepstrum2poly - Cepstrum to prediction polynomial conversion.
ITPP_EXPORT vec cepstrum2poly(const vec &c);
//! rc2ac - Reflection coefficients to autocorrelation sequence conversion.
ITPP_EXPORT vec rc2ac(const vec &rc);
//! rc2is - Reflection coefficients to inverse sine parameters conversion.
ITPP_EXPORT vec rc2is(const vec &rc);
//! rc2lar - Reflection coefficients to log area ratios conversion.
ITPP_EXPORT vec rc2lar(const vec &rc);
//! rc2poly - Reflection coefficients to prediction polynomial conversion.
ITPP_EXPORT vec rc2poly(const vec &rc);
//!@}
} // namespace itpp
#endif // #ifndef LPCFUNC_H
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