source: src/spectral/filterbank_mel.h @ fa713bd

feature/autosinkfeature/constantqfeature/pitchshiftfeature/pydocstringsfeature/timestretch
Last change on this file since fa713bd was fa713bd, checked in by Paul Brossier <piem@piem.org>, 23 months ago

[filterbank] add set_mel_coeffs

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1/*
2  Copyright (C) 2007-2013 Paul Brossier <piem@aubio.org>
3                      and Amaury Hazan <ahazan@iua.upf.edu>
4
5  This file is part of aubio.
6
7  aubio is free software: you can redistribute it and/or modify
8  it under the terms of the GNU General Public License as published by
9  the Free Software Foundation, either version 3 of the License, or
10  (at your option) any later version.
11
12  aubio is distributed in the hope that it will be useful,
13  but WITHOUT ANY WARRANTY; without even the implied warranty of
14  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15  GNU General Public License for more details.
16
17  You should have received a copy of the GNU General Public License
18  along with aubio.  If not, see <http://www.gnu.org/licenses/>.
19
20*/
21
22/** \file
23
24  Filterbank object coefficients initialization
25
26  Functions to create set the ::aubio_filterbank_t coefficients to
27    - ::aubio_filterbank_set_triangle_bands: overlapping triangular bands,
28    - ::aubio_filterbank_set_mel_coeffs_slaney: Mel frequency bands.
29
30  \example spectral/test-filterbank_mel.c
31
32*/
33
34#ifndef AUBIO_FILTERBANK_MEL_H
35#define AUBIO_FILTERBANK_MEL_H
36
37#ifdef __cplusplus
38extern "C"
39{
40#endif
41
42/** filterbank initialization with triangular and overlapping bands
43
44  \param fb filterbank object
45  \param freqs arbitrary array of boundary frequencies
46  \param samplerate audio sampling rate
47
48  This function computes the coefficients of the filterbank based on the
49  boundaries found in freqs, in Hz, and using triangular overlapping bands.
50
51*/
52uint_t aubio_filterbank_set_triangle_bands (aubio_filterbank_t * fb,
53    const fvec_t * freqs, smpl_t samplerate);
54
55/** filterbank initialization for Mel filters using Slaney's coefficients
56
57  \param fb filterbank object
58  \param samplerate audio sampling rate
59
60  The filter coefficients are built to match exactly Malcolm Slaney's Auditory
61  Toolbox implementation (see file mfcc.m). The number of filters should be 40.
62
63  References
64  ----------
65
66  Malcolm Slaney, *Auditory Toolbox Version 2, Technical Report #1998-010*
67  https://engineering.purdue.edu/~malcolm/interval/1998-010/
68
69*/
70uint_t aubio_filterbank_set_mel_coeffs_slaney (aubio_filterbank_t * fb,
71    smpl_t samplerate);
72
73/** Mel filterbank initialization
74
75  \param fb filterbank object
76  \param samplerate audio sampling rate
77  \param fmin start frequency, in Hz
78  \param fmax end frequency, in Hz
79
80  The filterbank will be initialized with bands linearly spaced in the mel
81  scale, from `fmin` to `fmax`.
82
83  References
84  ----------
85
86  Malcolm Slaney, *Auditory Toolbox Version 2, Technical Report #1998-010*
87  https://engineering.purdue.edu/~malcolm/interval/1998-010/
88
89*/
90uint_t aubio_filterbank_set_mel_coeffs(aubio_filterbank_t * fb,
91    smpl_t samplerate, smpl_t freq_min, smpl_t freq_max);
92
93/** Mel filterbank initialization
94
95  \param fb filterbank object
96  \param samplerate audio sampling rate
97  \param fmin start frequency, in Hz
98  \param fmax end frequency, in Hz
99
100  The bank of filters will be initalized to to cover linearly spaced bands in
101  the Htk mel scale, from `fmin` to `fmax`.
102
103  References
104  ----------
105
106  Douglas O'Shaughnessy (1987). *Speech communication: human and machine*.
107  Addison-Wesley. p. 150. ISBN 978-0-201-16520-3.
108
109  HTK Speech Recognition Toolkit: http://htk.eng.cam.ac.uk/
110
111*/
112uint_t aubio_filterbank_set_mel_coeffs_htk(aubio_filterbank_t * fb,
113    smpl_t samplerate, smpl_t freq_min, smpl_t freq_max);
114
115#ifdef __cplusplus
116}
117#endif
118
119#endif /* AUBIO_FILTERBANK_MEL_H */
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