/* Copyright (C) 2003-2009 Paul Brossier 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 . */ #ifndef _ADESIGN_H #define _ADESIGN_H /** \file Create an A-weighting filter 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-Weighting on Wikipedia - Weighting filter on Wikipedia - Christophe Couvreur's 'octave' toolbox 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
 [b, a] = adsign(1/Fs) 
for various sampling frequencies (8000, 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 A-design filter \param samplerate sampling frequency of the signal to filter. Should be one of 8000, 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_a_weighting (uint_t samplerate, uint_t channels); /** set feedback and feedforward coefficients of a A-weighting filter \param f filter object to get coefficients from */ void aubio_filter_set_a_weighting (aubio_filter_t *f); #ifdef __cplusplus } #endif #endif /* _ADESIGN_H */