source: src/musicutils.h @ 4edba9d

feature/autosinkfeature/constantqfeature/pitchshiftfeature/timestretch
Last change on this file since 4edba9d was ff9c62a, checked in by Paul Brossier <piem@piem.org>, 12 months ago

[api] add meltohz and hztomel, Slaney and Htk versions

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[83963b3]1/*
[0683ee2]2  Copyright (C) 2003-2015 Paul Brossier <piem@aubio.org>
[83963b3]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/** @file
[a17e8c9]22 *  various functions useful in audio signal processing
[83963b3]23 */
24
[6f42c16]25#ifndef AUBIO_MUSICUTILS_H
26#define AUBIO_MUSICUTILS_H
[83963b3]27
28#ifdef __cplusplus
29extern "C" {
30#endif
31
[0683ee2]32/** create window
[e84ab04]33
34  \param window_type type of the window to create
35  \param size length of the window to create (see fvec_set_window())
[0683ee2]36
[e84ab04]37*/
38fvec_t *new_aubio_window (char_t * window_type, uint_t size);
39
40/** set elements of a vector to window coefficients
41
42  \param window exsting ::fvec_t to use
43  \param window_type type of the window to create
44
45  List of available window types: "rectangle", "hamming", "hanning",
46  "hanningz", "blackman", "blackman_harris", "gaussian", "welch", "parzen",
47  "default".
48
49  "default" is equivalent to "hanningz".
50
[83963b3]51  References:
[0683ee2]52
[83963b3]53    - <a href="http://en.wikipedia.org/wiki/Window_function">Window
54function</a> on Wikipedia
55    - Amalia de Götzen, Nicolas Bernardini, and Daniel Arfib. Traditional (?)
56implementations of a phase vocoder: the tricks of the trade. In Proceedings of
57the International Conference on Digital Audio Effects (DAFx-00), pages 37–44,
58Uni- versity of Verona, Italy, 2000.
[2e69640]59  (<a href="http://www.cs.princeton.edu/courses/archive/spr09/cos325/Bernardini.pdf">
60  pdf</a>)
[83963b3]61
[33cd81f]62 */
63uint_t fvec_set_window (fvec_t * window, char_t * window_type);
64
[83963b3]65/** compute the principal argument
66
67  This function maps the input phase to its corresponding value wrapped in the
68range \f$ [-\pi, \pi] \f$.
69
70  \param phase unwrapped phase to map to the unit circle
[0683ee2]71
[83963b3]72  \return equivalent phase wrapped to the unit circle
73
74*/
75smpl_t aubio_unwrap2pi (smpl_t phase);
76
77/** convert frequency bin to midi value */
78smpl_t aubio_bintomidi (smpl_t bin, smpl_t samplerate, smpl_t fftsize);
79
80/** convert midi value to frequency bin */
81smpl_t aubio_miditobin (smpl_t midi, smpl_t samplerate, smpl_t fftsize);
82
83/** convert frequency bin to frequency (Hz) */
84smpl_t aubio_bintofreq (smpl_t bin, smpl_t samplerate, smpl_t fftsize);
85
86/** convert frequency (Hz) to frequency bin */
87smpl_t aubio_freqtobin (smpl_t freq, smpl_t samplerate, smpl_t fftsize);
88
[ff9c62a]89/** convert frequency (Hz) to mel
90
91  \param freq input frequency, in Hz
92
93  \return output mel
94
95  Converts a scalar from the frequency domain to the mel scale using Slaney
96  Auditory Toolbox's implementation:
97
98  If \f$ f < 1000 \f$, \f$ m = 3 f / 200 \f$.
99
100  If \f$ f >= 1000 \f$, \f$ m = 1000 + 27 \frac{{ln}(f) - ln(1000))}
101  {{ln}(6400) - ln(1000)}
102  \f$
103
104  See also
105  --------
106
107  aubio_meltohz(), aubio_hztomel_htk().
108
109*/
110smpl_t aubio_hztomel (smpl_t freq);
111
112/** convert mel to frequency (Hz)
113
114  \param mel input mel
115
116  \return output frequency, in Hz
117
118  Converts a scalar from the mel scale to the frequency domain using Slaney
119  Auditory Toolbox's implementation:
120
121  If \f$ f < 1000 \f$, \f$ f = 200 m/3 \f$.
122
123  If \f$ f \geq 1000 \f$, \f$ f = 1000 + \left(\frac{6400}{1000}\right)
124  ^{\frac{m - 1000}{27}} \f$
125
126  See also
127  --------
128
129  aubio_hztomel(), aubio_meltohz_htk().
130
131  References
132  ----------
133
134  Malcolm Slaney, *Auditory Toolbox Version 2, Technical Report #1998-010*
135  https://engineering.purdue.edu/~malcolm/interval/1998-010/
136
137*/
138smpl_t aubio_meltohz (smpl_t mel);
139
140/** convert frequency (Hz) to mel
141
142  \param freq input frequency, in Hz
143
144  \return output mel
145
146  Converts a scalar from the frequency domain to the mel scale, using the
147  equation defined by O'Shaughnessy, as implemented in the HTK speech
148  recognition toolkit:
149
150  \f$ m = 1127 + ln(1 + \frac{f}{700}) \f$
151
152  See also
153  --------
154
155  aubio_meltohz_htk(), aubio_hztomel().
156
157  References
158  ----------
159
160  Douglas O'Shaughnessy (1987). *Speech communication: human and machine*.
161  Addison-Wesley. p. 150. ISBN 978-0-201-16520-3.
162
163  HTK Speech Recognition Toolkit: http://htk.eng.cam.ac.uk/
164
165 */
166smpl_t aubio_hztomel_htk (smpl_t freq);
167
168/** convert mel to frequency (Hz)
169
170  \param mel input mel
171
172  \return output frequency, in Hz
173
174  Converts a scalar from the mel scale to the frequency domain, using the
175  equation defined by O'Shaughnessy, as implemented in the HTK speech
176  recognition toolkit:
177
178  \f$ f = 700 * {e}^\left(\frac{f}{1127} - 1\right) \f$
179
180  See also
181  --------
182
183  aubio_hztomel_htk(), aubio_meltohz().
184
185*/
186smpl_t aubio_meltohz_htk (smpl_t mel);
187
[83963b3]188/** convert frequency (Hz) to midi value (0-128) */
189smpl_t aubio_freqtomidi (smpl_t freq);
190
191/** convert midi value (0-128) to frequency (Hz) */
192smpl_t aubio_miditofreq (smpl_t midi);
193
194/** clean up cached memory at the end of program
[0683ee2]195
[83963b3]196  This function should be used at the end of programs to purge all cached
197  memory. So far it is only useful to clean FFTW's cache.
198
199*/
200void aubio_cleanup (void);
201
202/** zero-crossing rate (ZCR)
203
204  The zero-crossing rate is the number of times a signal changes sign,
205  divided by the length of this signal.
206
207  \param v vector to compute ZCR from
208
209  \return zero-crossing rate of v
210
211*/
212smpl_t aubio_zero_crossing_rate (fvec_t * v);
213
[4b891e9]214/** compute sound level on a linear scale
[5b41ef9]215
216  This gives the average of the square amplitudes.
217
[4b891e9]218  \param v vector to compute level from
[5b41ef9]219
220  \return level of v
221
222*/
[e9bd022]223smpl_t aubio_level_lin (const fvec_t * v);
[5b41ef9]224
[83963b3]225/** compute sound pressure level (SPL) in dB
226
227  This quantity is often wrongly called 'loudness'.
228
[5b41ef9]229  This gives ten times the log10 of the average of the square amplitudes.
230
[83963b3]231  \param v vector to compute dB SPL from
232
233  \return level of v in dB SPL
234
235*/
[e9bd022]236smpl_t aubio_db_spl (const fvec_t * v);
[83963b3]237
238/** check if buffer level in dB SPL is under a given threshold
[0683ee2]239
[83963b3]240  \param v vector to get level from
241  \param threshold threshold in dB SPL
242
243  \return 0 if level is under the given threshold, 1 otherwise
244
245*/
[e9bd022]246uint_t aubio_silence_detection (const fvec_t * v, smpl_t threshold);
[83963b3]247
248/** get buffer level if level >= threshold, 1. otherwise
249
250  \param v vector to get level from
251  \param threshold threshold in dB SPL
252
253  \return level in dB SPL if level >= threshold, 1. otherwise
254
255*/
[24e9b0a]256smpl_t aubio_level_detection (const fvec_t * v, smpl_t threshold);
[83963b3]257
[b799241]258/** clamp the values of a vector within the range [-abs(max), abs(max)]
259
260  \param in vector to clamp
[1136442]261  \param absmax maximum value over which input vector elements should be clamped
[b799241]262
263*/
264void fvec_clamp(fvec_t *in, smpl_t absmax);
265
[83963b3]266#ifdef __cplusplus
267}
268#endif
269
[6f42c16]270#endif /* AUBIO_MUSICUTILS_H */
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