filterbank.h

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/*
  Copyright (C) 2007-2013 Paul Brossier <piem@aubio.org>
                      and Amaury Hazan <ahazan@iua.upf.edu>
 
  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/>.
 
*/
 
/** \file
 
  Filterbank object
 
  General-purpose spectral filterbank object.
 
  \example spectral/test-filterbank.c
 
*/
 
#ifndef AUBIO_FILTERBANK_H
#define AUBIO_FILTERBANK_H
 
#ifdef __cplusplus
extern "C"
{
#endif
 
/** filterbank object
 
  This object stores a matrix of spectral filter coefficients.
 
 */
typedef struct _aubio_filterbank_t aubio_filterbank_t;
 
/** create filterbank object
 
  \param n_filters number of filters to create
  \param win_s size of analysis buffer (and length the FFT transform)
 
*/
aubio_filterbank_t *new_aubio_filterbank (uint_t n_filters, uint_t win_s);
 
/** destroy filterbank object
 
  \param f filterbank object, as returned by new_aubio_filterbank()
 
*/
void del_aubio_filterbank (aubio_filterbank_t * f);
 
/** compute filterbank
 
  \param f filterbank object, as returned by new_aubio_filterbank()
  \param in input spectrum containing an input spectrum of length `win_s`
  \param out output vector containing the energy found in each band, `nfilt` output values
 
*/
void aubio_filterbank_do (aubio_filterbank_t * f, const cvec_t * in, fvec_t * out);
 
/** return a pointer to the matrix object containing all filter coefficients
 
  \param f filterbank object, as returned by new_aubio_filterbank()
 
 */
fmat_t *aubio_filterbank_get_coeffs (const aubio_filterbank_t * f);
 
/** copy filter coefficients to the filterbank
 
  \param f filterbank object, as returned by new_aubio_filterbank()
  \param filters filter bank coefficients to copy from
 
 */
uint_t aubio_filterbank_set_coeffs (aubio_filterbank_t * f, const fmat_t * filters);
 
/** set norm parameter
 
  \param f filterbank object, as returned by new_aubio_filterbank()
  \param norm `1` to norm the filters, `0` otherwise.
 
  If set to `0`, the filters will not be normalized. If set to `1`,
  each filter will be normalized to one. Defaults to `1`.
 
  This function should be called *before* setting the filters with one of
  aubio_filterbank_set_triangle_bands(), aubio_filterbank_set_mel_coeffs(),
  aubio_filterbank_set_mel_coeffs_htk(), or
  aubio_filterbank_set_mel_coeffs_slaney().
 
 */
uint_t aubio_filterbank_set_norm (aubio_filterbank_t *f, smpl_t norm);
 
/** get norm parameter
 
  \param f filterbank object, as returned by new_aubio_filterbank()
  \returns `1` if norm is set, `0` otherwise. Defaults to `1`.
 
 */
smpl_t aubio_filterbank_get_norm (aubio_filterbank_t *f);
 
/** set power parameter
 
  \param f filterbank object, as returned by new_aubio_filterbank()
  \param power Raise norm of the input spectrum norm to this power before
  computing filterbank.  Defaults to `1`.
 
 */
uint_t aubio_filterbank_set_power (aubio_filterbank_t *f, smpl_t power);
 
/** get power parameter
 
  \param f filterbank object, as returned by new_aubio_filterbank()
  \return current power parameter. Defaults to `1`.
 
 */
smpl_t aubio_filterbank_get_power (aubio_filterbank_t *f);
 
#ifdef __cplusplus
}
#endif
 
#endif /* AUBIO_FILTERBANK_H */