source: src/musicutils.h @ c0a1906

feature/autosinkfeature/constantqfeature/pitchshiftfeature/timestretch
Last change on this file since c0a1906 was ff9c62a, checked in by Paul Brossier <piem@piem.org>, 10 months ago

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

  • Property mode set to 100644
File size: 6.7 KB
Line 
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/** @file
22 *  various functions useful in audio signal processing
23 */
24
25#ifndef AUBIO_MUSICUTILS_H
26#define AUBIO_MUSICUTILS_H
27
28#ifdef __cplusplus
29extern "C" {
30#endif
31
32/** create window
33
34  \param window_type type of the window to create
35  \param size length of the window to create (see fvec_set_window())
36
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
51  References:
52
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.
59  (<a href="http://www.cs.princeton.edu/courses/archive/spr09/cos325/Bernardini.pdf">
60  pdf</a>)
61
62 */
63uint_t fvec_set_window (fvec_t * window, char_t * window_type);
64
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$.
69
70  \param phase unwrapped phase to map to the unit circle
71
72  \return equivalent phase wrapped to the unit circle
73
74*/
75smpl_t aubio_unwrap2pi (smpl_t phase);
76
77/** convert frequency bin to midi value */
78smpl_t aubio_bintomidi (smpl_t bin, smpl_t samplerate, smpl_t fftsize);
79
80/** convert midi value to frequency bin */
81smpl_t aubio_miditobin (smpl_t midi, smpl_t samplerate, smpl_t fftsize);
82
83/** convert frequency bin to frequency (Hz) */
84smpl_t aubio_bintofreq (smpl_t bin, smpl_t samplerate, smpl_t fftsize);
85
86/** convert frequency (Hz) to frequency bin */
87smpl_t aubio_freqtobin (smpl_t freq, smpl_t samplerate, smpl_t fftsize);
88
89/** convert frequency (Hz) to mel
90
91  \param freq input frequency, in Hz
92
93  \return output mel
94
95  Converts a scalar from the frequency domain to the mel scale using Slaney
96  Auditory Toolbox's implementation:
97
98  If \f$ 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
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
195
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
214/** compute sound level on a linear scale
215
216  This gives the average of the square amplitudes.
217
218  \param v vector to compute level from
219
220  \return level of v
221
222*/
223smpl_t aubio_level_lin (const fvec_t * v);
224
225/** compute sound pressure level (SPL) in dB
226
227  This quantity is often wrongly called 'loudness'.
228
229  This gives ten times the log10 of the average of the square amplitudes.
230
231  \param v vector to compute dB SPL from
232
233  \return level of v in dB SPL
234
235*/
236smpl_t aubio_db_spl (const fvec_t * v);
237
238/** check if buffer level in dB SPL is under a given threshold
239
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*/
246uint_t aubio_silence_detection (const fvec_t * v, smpl_t threshold);
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*/
256smpl_t aubio_level_detection (const fvec_t * v, smpl_t threshold);
257
258/** clamp the values of a vector within the range [-abs(max), abs(max)]
259
260  \param in vector to clamp
261  \param absmax maximum value over which input vector elements should be clamped
262
263*/
264void fvec_clamp(fvec_t *in, smpl_t absmax);
265
266#ifdef __cplusplus
267}
268#endif
269
270#endif /* AUBIO_MUSICUTILS_H */
Note: See TracBrowser for help on using the repository browser.