2 Copyright (C) 2003-2015 Paul Brossier <piem@aubio.org>
4 This file is part of aubio.
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.
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.
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/>.
22 * various functions useful in audio signal processing
25 #ifndef _AUBIO__MUSICUTILS_H
26 #define _AUBIO__MUSICUTILS_H
34 \param window_type type of the window to create
35 \param size length of the window to create (see fvec_set_window())
38 fvec_t *new_aubio_window (char_t * window_type, uint_t size);
40 /** set elements of a vector to window coefficients
42 \param window exsting ::fvec_t to use
43 \param window_type type of the window to create
45 List of available window types: "rectangle", "hamming", "hanning",
46 "hanningz", "blackman", "blackman_harris", "gaussian", "welch", "parzen",
49 "default" is equivalent to "hanningz".
53 - <a href="http://en.wikipedia.org/wiki/Window_function">Window
54 function</a> on Wikipedia
55 - Amalia de Götzen, Nicolas Bernardini, and Daniel Arfib. Traditional (?)
56 implementations of a phase vocoder: the tricks of the trade. In Proceedings of
57 the International Conference on Digital Audio Effects (DAFx-00), pages 37–44,
58 Uni- versity of Verona, Italy, 2000.
59 (<a href="http://profs.sci.univr.it/%7Edafx/Final-Papers/ps/Bernardini.ps.gz">
63 uint_t fvec_set_window (fvec_t * window, char_t * window_type);
65 /** compute the principal argument
67 This function maps the input phase to its corresponding value wrapped in the
68 range \f$ [-\pi, \pi] \f$.
70 \param phase unwrapped phase to map to the unit circle
72 \return equivalent phase wrapped to the unit circle
75 smpl_t aubio_unwrap2pi (smpl_t phase);
77 /** convert frequency bin to midi value */
78 smpl_t aubio_bintomidi (smpl_t bin, smpl_t samplerate, smpl_t fftsize);
80 /** convert midi value to frequency bin */
81 smpl_t aubio_miditobin (smpl_t midi, smpl_t samplerate, smpl_t fftsize);
83 /** convert frequency bin to frequency (Hz) */
84 smpl_t aubio_bintofreq (smpl_t bin, smpl_t samplerate, smpl_t fftsize);
86 /** convert frequency (Hz) to frequency bin */
87 smpl_t aubio_freqtobin (smpl_t freq, smpl_t samplerate, smpl_t fftsize);
89 /** convert frequency (Hz) to midi value (0-128) */
90 smpl_t aubio_freqtomidi (smpl_t freq);
92 /** convert midi value (0-128) to frequency (Hz) */
93 smpl_t aubio_miditofreq (smpl_t midi);
95 /** clean up cached memory at the end of program
97 This function should be used at the end of programs to purge all cached
98 memory. So far it is only useful to clean FFTW's cache.
101 void aubio_cleanup (void);
103 /** zero-crossing rate (ZCR)
105 The zero-crossing rate is the number of times a signal changes sign,
106 divided by the length of this signal.
108 \param v vector to compute ZCR from
110 \return zero-crossing rate of v
113 smpl_t aubio_zero_crossing_rate (fvec_t * v);
115 /** compute sound level on a linear scale
117 This gives the average of the square amplitudes.
119 \param v vector to compute level from
124 smpl_t aubio_level_lin (fvec_t * v);
126 /** compute sound pressure level (SPL) in dB
128 This quantity is often wrongly called 'loudness'.
130 This gives ten times the log10 of the average of the square amplitudes.
132 \param v vector to compute dB SPL from
134 \return level of v in dB SPL
137 smpl_t aubio_db_spl (fvec_t * v);
139 /** check if buffer level in dB SPL is under a given threshold
141 \param v vector to get level from
142 \param threshold threshold in dB SPL
144 \return 0 if level is under the given threshold, 1 otherwise
147 uint_t aubio_silence_detection (fvec_t * v, smpl_t threshold);
149 /** get buffer level if level >= threshold, 1. otherwise
151 \param v vector to get level from
152 \param threshold threshold in dB SPL
154 \return level in dB SPL if level >= threshold, 1. otherwise
157 smpl_t aubio_level_detection (fvec_t * v, smpl_t threshold);
163 #endif /* _AUBIO__MUSICUTILS_H */