source: src/mathutils.h @ 1111de1

feature/autosinkfeature/cnnfeature/cnn_orgfeature/constantqfeature/crepefeature/crepe_orgfeature/pitchshiftfeature/pydocstringsfeature/timestretchfix/ffmpeg5pitchshiftsamplertimestretchyinfft+
Last change on this file since 1111de1 was 83963b3, checked in by Paul Brossier <piem@piem.org>, 15 years ago

strip down stable public API, defining add AUBIO_UNSTABLE to access unstable API

  • Property mode set to 100644
File size: 7.0 KB
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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/** @file
22 *  various math functions
23 */
24
25#ifndef MATHUTILS_H
26#define MATHUTILS_H
27
28#include "fvec.h"
29#include "musicutils.h"
30
31#ifdef __cplusplus
32extern "C" {
33#endif
34
35/** compute the mean of a vector
36
37  \param s vector to compute mean from
38
39  \return the mean of v
40
41*/
42smpl_t fvec_mean (fvec_t * s);
43
44/** compute the mean of a vector channel
45
46  \param s vector to compute mean from
47  \param i channel to compute mean from
48
49  \return the mean of v
50
51*/
52smpl_t fvec_mean_channel (fvec_t * s, uint_t i);
53
54/** find the max of a vector
55
56  \param s vector to get the max from
57
58  \return the value of the minimum of v
59
60*/
61smpl_t fvec_max (fvec_t * s);
62
63/** find the min of a vector
64
65  \param s vector to get the min from
66
67  \return the value of the maximum of v
68
69*/
70smpl_t fvec_min (fvec_t * s);
71
72/** find the index of the min of a vector
73
74  \param s vector to get the index from
75
76  \return the index of the minimum element of v
77
78*/
79uint_t fvec_min_elem (fvec_t * s);
80
81/** find the index of the max of a vector
82
83  \param s vector to get the index from
84
85  \return the index of the maximum element of v
86
87*/
88uint_t fvec_max_elem (fvec_t * s);
89
90/** swap the left and right halves of a vector
91 
92  This function swaps the left part of the signal with the right part of the
93signal. Therefore
94
95  \f$ a[0], a[1], ..., a[\frac{N}{2}], a[\frac{N}{2}+1], ..., a[N-1], a[N] \f$
96 
97  becomes
98 
99  \f$ a[\frac{N}{2}+1], ..., a[N-1], a[N], a[0], a[1], ..., a[\frac{N}{2}] \f$
100
101  This operation, known as 'fftshift' in the Matlab Signal Processing Toolbox,
102can be used before computing the FFT to simplify the phase relationship of the
103resulting spectrum. See Amalia de Götzen's paper referred to above.
104 
105*/
106void fvec_shift (fvec_t * v);
107
108/** compute the sum of all elements of a vector
109
110  \param v vector to compute the sum of
111
112  \return the sum of v
113
114*/
115smpl_t fvec_sum (fvec_t * v);
116
117/** compute the energy of a vector
118
119  This function compute the sum of the squared elements of a vector.
120 
121  \param v vector to get the energy from
122
123  \return the energy of v
124 
125*/
126smpl_t fvec_local_energy (fvec_t * v);
127
128/** compute the High Frequency Content of a vector
129
130  The High Frequency Content is defined as \f$ \sum_0^{N-1} (k+1) v[k] \f$.
131 
132  \param v vector to get the energy from
133
134  \return the HFC of v
135 
136*/
137smpl_t fvec_local_hfc (fvec_t * v);
138
139/** computes the p-norm of a vector
140 
141  Computes the p-norm of a vector for \f$ p = \alpha \f$
142
143  \f$ L^p = ||x||_p = (|x_1|^p + |x_2|^p + ... + |x_n|^p ) ^ \frac{1}{p} \f$
144 
145  If p = 1, the result is the Manhattan distance.
146
147  If p = 2, the result is the Euclidean distance.
148
149  As p tends towards large values, \f$ L^p \f$ tends towards the maximum of the
150input vector.
151
152  References:
153 
154    - <a href="http://en.wikipedia.org/wiki/Lp_space">\f$L^p\f$ space</a> on
155  Wikipedia
156
157  \param v vector to compute norm from
158  \param p order of the computed norm
159
160  \return the p-norm of v
161 
162*/
163smpl_t fvec_alpha_norm (fvec_t * v, smpl_t p);
164
165/**  alpha normalisation
166
167  This function divides all elements of a vector by the p-norm as computed by
168fvec_alpha_norm().
169
170  \param v vector to compute norm from
171  \param p order of the computed norm
172
173*/
174void fvec_alpha_normalise (fvec_t * v, smpl_t p);
175
176/** add a constant to each elements of a vector
177
178  \param v vector to add constant to
179  \param c constant to add to v
180
181*/
182void fvec_add (fvec_t * v, smpl_t c);
183
184/** remove the minimum value of the vector to each elements
185 
186  \param v vector to remove minimum from
187
188*/
189void fvec_min_removal (fvec_t * v);
190
191/** compute moving median theshold of a vector
192
193  This function computes the moving median threshold value of at the given
194position of a vector, taking the median amongs post elements before and up to
195pre elements after pos.
196 
197  \param v input vector
198  \param tmp temporary vector of length post+1+pre
199  \param post length of causal part to take before pos
200  \param pre length of anti-causal part to take after pos
201  \param pos index to compute threshold for
202
203  \return moving median threshold value
204
205*/
206smpl_t fvec_moving_thres (fvec_t * v, fvec_t * tmp, uint_t post, uint_t pre,
207    uint_t pos, uint_t channel);
208
209/** apply adaptive threshold to a vector
210
211  For each points at position p of an input vector, this function remove the
212moving median threshold computed at p.
213
214  \param v input vector
215  \param tmp temporary vector of length post+1+pre
216  \param post length of causal part to take before pos
217  \param pre length of anti-causal part to take after pos
218
219*/
220void fvec_adapt_thres (fvec_t * v, fvec_t * tmp, uint_t post, uint_t pre, 
221    uint_t channel);
222
223/** returns the median of a vector
224
225  The QuickSelect routine is based on the algorithm described in "Numerical
226recipes in C", Second Edition, Cambridge University Press, 1992, Section 8.5,
227ISBN 0-521-43108-5
228
229  This implementation of the QuickSelect routine is based on Nicolas
230Devillard's implementation, available at http://ndevilla.free.fr/median/median/
231and in the Public Domain.
232
233  \param v vector to get median from
234  \param channel channel to get median from
235
236  \return the median of v
237 
238*/
239smpl_t fvec_median_channel (fvec_t * v, uint_t channel);
240
241/** finds exact peak index by quadratic interpolation*/
242smpl_t fvec_quadint (fvec_t * x, uint_t pos, uint_t channel);
243
244/** Quadratic interpolation using Lagrange polynomial.
245 
246  Inspired from ``Comparison of interpolation algorithms in real-time sound
247processing'', Vladimir Arnost,
248 
249  \param s0,s1,s2 are 3 consecutive samples of a curve
250  \param pf is the floating point index [0;2]
251 
252  \return s0 + (pf/2.)*((pf-3.)*s0-2.*(pf-2.)*s1+(pf-1.)*s2);
253
254*/
255smpl_t aubio_quadfrac (smpl_t s0, smpl_t s1, smpl_t s2, smpl_t pf);
256
257/** return 1 if v[p] is a peak and positive, 0 otherwise
258
259  This function returns 1 if a peak is found at index p in the vector v. The
260peak is defined as follows:
261
262  - v[p] is positive
263  - v[p-1] < v[p]
264  - v[p] > v[p+1]
265
266  \param v input vector
267  \param p position of supposed for peak
268
269  \return 1 if a peak is found, 0 otherwise
270
271*/
272uint_t fvec_peakpick (fvec_t * v, uint_t p);
273
274/** return 1 if a is a power of 2, 0 otherwise */
275uint_t aubio_is_power_of_two(uint_t a);
276
277/** return the next power of power of 2 greater than a */
278uint_t aubio_next_power_of_two(uint_t a);
279
280/** compute normalised autocorrelation function
281
282  \param input vector to compute autocorrelation from
283  \param output vector to store autocorrelation function to
284
285*/
286void aubio_autocorr (fvec_t * input, fvec_t * output);
287
288#ifdef __cplusplus
289}
290#endif
291
292#endif
293
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