/*  Copyright (C) 2003-2015 Paul Brossier <piem@aubio.org>   This file is part of aubio.   aubio 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.   aubio 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 aubio.  If not, see <http://www.gnu.org/licenses/>. */ #ifndef AUBIO_FILTER_H#define AUBIO_FILTER_H /** \file   Digital filter   This object stores a digital filter of order \f$n\f$.  It contains the following data:    - \f$ n*1 b_i \f$ feedforward coefficients    - \f$ n*1 a_i \f$ feedback coefficients    - \f$ n*c x_i \f$ input signal    - \f$ n*c y_i \f$ output signal   For convenience, the samplerate of the input signal is also stored in the  object.   Feedforward and feedback parameters can be modified using  aubio_filter_get_feedback() and aubio_filter_get_feedforward().   The function aubio_filter_do_outplace() computes the following output signal  \f$ y[n] \f$ from the input signal \f$ x[n] \f$:   \f{eqnarray*}{     y[n] = b_0 x[n] & + & b_1 x[n-1] + b_2 x[n-2] + ... + b_P x[n-P] \\                     & - & a_1 y[n-1] - a_2 y[n-2] - ... - a_P y[n-P] \\  \f}   The function aubio_filter_do() executes the same computation but modifies  directly the input signal (in-place).   The function aubio_filter_do_filtfilt() version runs the filter twice, first  forward then backward, to compensate with the phase shifting of the forward  operation.   Some convenience functions are provided:    - new_aubio_filter_a_weighting() and aubio_filter_set_a_weighting(),    - new_aubio_filter_c_weighting() and aubio_filter_set_c_weighting().    - new_aubio_filter_biquad() and aubio_filter_set_biquad().   \example temporal/test-filter.c */ #ifdef __cplusplusextern "C" {#endif /** Digital filter */typedef struct _aubio_filter_t aubio_filter_t;#pragma incomplete aubio_filter_t /** filter input vector (in-place)   \param f filter object as returned by new_aubio_filter()  \param in input vector to filter */void aubio_filter_do (aubio_filter_t * f, fvec_t * in); /** filter input vector (out-of-place)   \param f filter object as returned by new_aubio_filter()  \param in input vector to filter  \param out output vector to store filtered input */void aubio_filter_do_outplace (aubio_filter_t * f, const fvec_t * in, fvec_t * out); /** filter input vector forward and backward   \param f ::aubio_filter_t object as returned by new_aubio_filter()  \param in ::fvec_t input vector to filter  \param tmp memory space to use for computation */void aubio_filter_do_filtfilt (aubio_filter_t * f, fvec_t * in, fvec_t * tmp); /** returns a pointer to feedback coefficients \f$ a_i \f$   \param f filter object to get parameters from   \return a pointer to the \f$ a_0 ... a_i ... a_P \f$ coefficients */lvec_t *aubio_filter_get_feedback (const aubio_filter_t * f); /** returns a pointer to feedforward coefficients \f$ b_i \f$   \param f filter object to get coefficients from   \return a pointer to the \f$ b_0 ... b_i ... b_P \f$ coefficients */lvec_t *aubio_filter_get_feedforward (const aubio_filter_t * f); /** get order of the filter   \param f filter to get order from   \return the order of the filter */uint_t aubio_filter_get_order (const aubio_filter_t * f); /** get sampling rate of the filter   \param f filter to get sampling rate from   \return the sampling rate of the filter, in Hz */uint_t aubio_filter_get_samplerate (const aubio_filter_t * f); /** get sampling rate of the filter   \param f filter to get sampling rate from  \param samplerate sample rate to set the filter to   \return the sampling rate of the filter, in Hz */uint_t aubio_filter_set_samplerate (aubio_filter_t * f, uint_t samplerate); /** reset filter memory   \param f filter object as returned by new_aubio_filter() */void aubio_filter_do_reset (aubio_filter_t * f); /** create new filter object   This function creates a new ::aubio_filter_t object, given the order of the  filter.   \param order order of the filter (number of coefficients)   \return the newly created filter object */aubio_filter_t *new_aubio_filter (uint_t order); /** delete a filter object   \param f filter object to delete */void del_aubio_filter (aubio_filter_t * f); #ifdef __cplusplus}#endif #endif /* AUBIO_FILTER_H */