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Diffstat (limited to 'src/temporal/a_weighting.h')
-rw-r--r-- | src/temporal/a_weighting.h | 88 |
1 files changed, 88 insertions, 0 deletions
diff --git a/src/temporal/a_weighting.h b/src/temporal/a_weighting.h new file mode 100644 index 0000000..49dd4d5 --- /dev/null +++ b/src/temporal/a_weighting.h @@ -0,0 +1,88 @@ +/* + 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_A_DESIGN_H +#define AUBIO_FILTER_A_DESIGN_H + +/** \file + + A-weighting filter coefficients + + This file creates an A-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] = adsign(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-a_weighting.c + +*/ + +#ifdef __cplusplus +extern "C" { +#endif + +/** create new A-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_a_weighting (uint_t samplerate); + +/** set feedback and feedforward coefficients of a A-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_a_weighting (aubio_filter_t * f, uint_t samplerate); + +#ifdef __cplusplus +} +#endif + +#endif /* AUBIO_FILTER_A_DESIGN_H */ |