ref: 2f169662056f89e87829a2e356071d6098fbc13f
dir: /src/temporal/c_weighting.h/
/*
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_C_DESIGN_H
#define AUBIO_FILTER_C_DESIGN_H
/** \file
C-weighting filter coefficients
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.
\example temporal/test-c_weighting.c
*/
#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
\return a new filter object
*/
aubio_filter_t *new_aubio_filter_c_weighting (uint_t samplerate);
/** set feedback and feedforward coefficients of a C-weighting filter
\param f filter object to get coefficients from
\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
*/
uint_t aubio_filter_set_c_weighting (aubio_filter_t * f, uint_t samplerate);
#ifdef __cplusplus
}
#endif
#endif /* AUBIO_FILTER_C_DESIGN_H */