source: src/temporal/adesign.h @ a4364b8

feature/autosinkfeature/cnnfeature/cnn_orgfeature/constantqfeature/crepefeature/crepe_orgfeature/pitchshiftfeature/pydocstringsfeature/timestretchfix/ffmpeg5pitchshiftsamplertimestretchyinfft+
Last change on this file since a4364b8 was a4364b8, checked in by Paul Brossier <piem@piem.org>, 15 years ago

src/temporal: revamp filter object, clarify API for A- and C-weighting filters,
add coefficients for 8000 16000 22050 44100 96000 192000, improve documentation,
remove unneeded filter_priv.h, add A and C weighting tests.

  • Property mode set to 100644
File size: 2.2 KB
Line 
1/*
2  Copyright (C) 2003-2009 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 _ADESIGN_H
22#define _ADESIGN_H
23
24/** \file
25
26  Create an A-weighting filter
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.
50
51*/
52
53#ifdef __cplusplus
54extern "C" {
55#endif
56
57/** create new A-design filter
58
59  \param samplerate sampling frequency of the signal to filter. Should be one of
60  8000, 16000, 22050, 44100, 96000, 192000.
61  \param channels number of channels to allocate
62
63  \return a new filter object
64
65*/
66aubio_filter_t * new_aubio_filter_adsgn (uint_t samplerate, uint_t channels);
67
68/** set feedback and feedforward coefficients of a A-weighting filter
69
70  \param f filter object to get coefficients from
71
72*/
73void aubio_filter_set_adsgn (aubio_filter_t *f);
74
75#ifdef __cplusplus
76}
77#endif
78
79#endif /* _ADESIGN_H */
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