aubio 0.4.9

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a_weighting.h
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1/*
2 Copyright (C) 2003-2015 Paul Brossier <piem@aubio.org>
3
4 This file is part of aubio.
5
6 aubio is free software: you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation, either version 3 of the License, or
9 (at your option) any later version.
10
11 aubio is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
15
16 You should have received a copy of the GNU General Public License
17 along with aubio. If not, see <http://www.gnu.org/licenses/>.
18
19*/
20
21#ifndef AUBIO_FILTER_A_DESIGN_H
22#define AUBIO_FILTER_A_DESIGN_H
23
24/** \file
25
26 A-weighting filter coefficients
27
28 This file creates an A-weighting digital filter, which reduces low and high
29 frequencies and enhance the middle ones to reflect the ability of the human
30 hearing.
31
32 The implementation is based on the following standard:
33
34 - IEC/CD 1672: Electroacoustics-Sound Level Meters, IEC, Geneva, Nov. 1996,
35 for A- and C-weighting filters.
36
37 See also:
38
39 - <a href="http://en.wikipedia.org/wiki/A-weighting">A-Weighting on
40 Wikipedia</a>
41 - <a href="http://en.wikipedia.org/wiki/Weighting_filter">Weighting filter on
42 Wikipedia</a>
43 - <a href="http://www.mathworks.com/matlabcentral/fileexchange/69">Christophe
44 Couvreur's 'octave' toolbox</a>
45
46 The coefficients in this file have been computed using Christophe Couvreur's
47 scripts in octave 3.0 (debian package 1:3.0.5-6+b2 with octave-signal
48 1.0.9-1+b1 on i386), with <pre> [b, a] = adsign(1/Fs) </pre> for various
49 sampling frequencies (8000, 11025, 16000, 22050, 24000, 32000, 44100, 48000,
50 88200, 96000, and 192000 Hz).
51
52 The sampling frequency should normally be higher than 20kHz, but most common
53 file sampling rates have been included for completeness.
54
55 \example temporal/test-a_weighting.c
56
57*/
58
59#ifdef __cplusplus
60 extern "C" {
61#endif
62
63/** create new A-design filter
64
65 \param samplerate sampling frequency of the signal to filter. Should be one of
66 8000, 11025, 16000, 22050, 24000, 32000, 44100, 48000, 88200, 96000, and
67 192000 Hz
68
69 \return a new filter object
70
71*/
72 aubio_filter_t *new_aubio_filter_a_weighting (uint_t samplerate);
73
74/** set feedback and feedforward coefficients of a A-weighting filter
75
76 \param f filter object to get coefficients from
77 \param samplerate sampling frequency of the signal to filter. Should be one of
78 8000, 11025, 16000, 22050, 24000, 32000, 44100, 48000, 88200, 96000, and
79 192000 Hz
80
81*/
82 uint_t aubio_filter_set_a_weighting (aubio_filter_t * f, uint_t samplerate);
83
84#ifdef __cplusplus
85}
86#endif
87
88#endif /* AUBIO_FILTER_A_DESIGN_H */
new_aubio_filter_a_weighting
aubio_filter_t * new_aubio_filter_a_weighting(uint_t samplerate)
create new A-design filter
aubio_filter_set_a_weighting
uint_t aubio_filter_set_a_weighting(aubio_filter_t *f, uint_t samplerate)
set feedback and feedforward coefficients of a A-weighting filter
aubio_filter_t
struct _aubio_filter_t aubio_filter_t
Digital filter.
Definition filter.h:72
uint_t
unsigned int uint_t
unsigned integer
Definition types.h:60