ref: 0d434df5868fcf0f3cacfc22b6ddfc8355a18cd6
dir: /src/temporal/c_weighting.h/
/*
Copyright (C) 2003-2009 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 _CDESIGN_H
#define _CDESIGN_H
/** \file
Create a C-weighting filter
This file creates a C-weighting digital filter, which reduces low and high
frequencies and enhance the middle ones to reflect the ability of the human
hearing.
The implementation is based on the following standard:
- IEC/CD 1672: Electroacoustics-Sound Level Meters, IEC, Geneva, Nov. 1996,
for A- and C-weighting filters.
See also:
- <a href="http://en.wikipedia.org/wiki/A-weighting">A-Weighting on
Wikipedia</a>
- <a href="http://en.wikipedia.org/wiki/Weighting_filter">Weighting filter on
Wikipedia</a>
- <a href="http://www.mathworks.com/matlabcentral/fileexchange/69">Christophe
Couvreur's 'octave' toolbox</a>
The coefficients in this file have been computed using Christophe Couvreur's
scripts in octave 3.0 (debian package 1:3.0.5-6+b2 with octave-signal
1.0.9-1+b1 on i386), with <pre> [b, a] = cdsign(1/Fs) </pre> for various
sampling frequencies (8000, 11025, 16000, 22050, 24000, 32000, 44100, 48000,
88200, 96000, and 192000 Hz).
The sampling frequency should normally be higher than 20kHz, but most common
file sampling rates have been included for completeness.
*/
#ifdef __cplusplus
extern "C" {
#endif
/** create new C-design filter
\param samplerate sampling frequency of the signal to filter. Should be one of
8000, 11025, 16000, 22050, 24000, 32000, 44100, 48000, 88200, 96000, and
192000 Hz
\param channels number of channels to allocate
\return a new filter object
*/
aubio_filter_t * new_aubio_filter_c_weighting (uint_t samplerate, uint_t channels);
/** set feedback and feedforward coefficients of a C-weighting filter
\param f filter object to get coefficients from
*/
uint_t aubio_filter_set_c_weighting (aubio_filter_t *f);
#ifdef __cplusplus
}
#endif
#endif /* _CDESIGN_H */