source: src/temporal/a_weighting.h @ 6f42c16

feature/autosinkfeature/constantqfeature/pitchshiftfeature/pydocstringsfeature/timestretchpitchshiftsamplertimestretchyinfft+
Last change on this file since 6f42c16 was 6f42c16, checked in by Paul Brossier <piem@piem.org>, 3 years ago

src/: change c header identifiers (see #35)

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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
60extern "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*/
72aubio_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*/
82uint_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 */
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