2 Copyright (C) 2003-2009 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 math functions
24 * \todo multichannel (each function should return -or set- an array sized to
25 * the number of channel in the input vector)
27 * \todo appropriate switches depending on types.h content
41 * - dafx : http://profs.sci.univr.it/%7Edafx/Final-Papers/ps/Bernardini.ps.gz
42 * - freqtweak : http://freqtweak.sf.net/
43 * - extace : http://extace.sf.net/
51 aubio_win_blackman_harris,
58 fvec_t * new_aubio_window(uint_t size, aubio_window_type wintype);
60 /** principal argument
62 * mod(phase+PI,-TWO_PI)+PI
64 smpl_t aubio_unwrap2pi (smpl_t phase);
66 /** calculates the mean of a vector
70 smpl_t vec_mean(fvec_t *s);
71 /** returns the max of a vector
75 smpl_t vec_max(fvec_t *s);
76 /** returns the min of a vector
80 smpl_t vec_min(fvec_t *s);
81 /** returns the index of the min of a vector
85 uint_t vec_min_elem(fvec_t *s);
86 /** returns the index of the max of a vector
90 uint_t vec_max_elem(fvec_t *s);
91 /** implement 'fftshift' like function
93 * a[0]...,a[n/2],a[n/2+1],...a[n]
97 * a[n/2+1],...a[n],a[0]...,a[n/2]
99 void vec_shift(fvec_t *s);
101 smpl_t vec_sum(fvec_t *s);
107 smpl_t vec_local_energy(fvec_t * f);
108 /** returns High Frequency Energy Content
111 smpl_t vec_local_hfc(fvec_t * f);
112 /** return alpha norm.
114 * alpha=2 means normalise variance.
115 * alpha=1 means normalise abs value.
116 * as alpha goes large, tends to normalisation
119 * \bug should not use POW :(
121 smpl_t vec_alpha_norm(fvec_t * DF, smpl_t alpha);
122 /** dc(min) removal */
123 void vec_dc_removal(fvec_t * mag);
124 /** alpha normalisation */
125 void vec_alpha_normalise(fvec_t * mag, uint_t alpha);
126 /** add a constant to all members of a vector */
127 void vec_add(fvec_t * mag, smpl_t threshold);
129 /** compute adaptive threshold of input vector */
130 void vec_adapt_thres(fvec_t * vec, fvec_t * tmp,
131 uint_t win_post, uint_t win_pre);
132 /** adaptative thresholding
134 * y=fn_thresh(fn,x,post,pre)
135 * compute adaptive threshold at each time
136 * fn : a function name or pointer, eg 'median'
138 * post: window length, causal part
139 * pre: window length, anti-causal part
141 * y: signal the same length as x
143 * Formerly median_thresh, used compute median over a
144 * window of post+pre+1 samples, but now works with any
145 * function that takes a vector or matrix and returns a
146 * 'representative' value for each column, eg
147 * medians=fn_thresh(median,x,8,8)
148 * minima=fn_thresh(min,x,8,8)
149 * see SPARMS for explanation of post and pre
151 smpl_t vec_moving_thres(fvec_t * vec, fvec_t * tmp,
152 uint_t win_post, uint_t win_pre, uint_t win_pos);
154 /** returns the median of the vector
156 * This Quickselect routine is based on the algorithm described in
157 * "Numerical recipes in C", Second Edition,
158 * Cambridge University Press, 1992, Section 8.5, ISBN 0-521-43108-5
160 * This code by Nicolas Devillard - 1998. Public domain,
161 * available at http://ndevilla.free.fr/median/median/
163 smpl_t vec_median(fvec_t * input);
165 /** finds exact peak index by quadratic interpolation*/
166 smpl_t vec_quadint(fvec_t * x, uint_t pos, uint_t span);
168 /** Quadratic interpolation using Lagrange polynomial.
170 * inspired from ``Comparison of interpolation algorithms in real-time sound
171 * processing'', Vladimir Arnost,
173 * estimate = s0 + (pf/2.)*((pf-3.)*s0-2.*(pf-2.)*s1+(pf-1.)*s2);
175 * \param s0,s1,s2 are 3 known points on the curve,
176 * \param pf is the floating point index [0;2]
178 smpl_t aubio_quadfrac(smpl_t s0, smpl_t s1, smpl_t s2, smpl_t pf);
180 /** returns 1 if X1 is a peak and positive */
181 uint_t vec_peakpick(fvec_t * input, uint_t pos);
183 /** convert frequency bin to midi value */
184 smpl_t aubio_bintomidi(smpl_t bin, smpl_t samplerate, smpl_t fftsize);
185 /** convert midi value to frequency bin */
186 smpl_t aubio_miditobin(smpl_t midi, smpl_t samplerate, smpl_t fftsize);
187 /** convert frequency bin to frequency (Hz) */
188 smpl_t aubio_bintofreq(smpl_t bin, smpl_t samplerate, smpl_t fftsize);
189 /** convert frequency (Hz) to frequency bin */
190 smpl_t aubio_freqtobin(smpl_t freq, smpl_t samplerate, smpl_t fftsize);
191 /** convert frequency (Hz) to midi value (0-128) */
192 smpl_t aubio_freqtomidi(smpl_t freq);
193 /** convert midi value (0-128) to frequency (Hz) */
194 smpl_t aubio_miditofreq(smpl_t midi);
196 /** check if current buffer level is under a given threshold */
197 uint_t aubio_silence_detection(fvec_t * ibuf, smpl_t threshold);
198 /** get the current buffer level */
199 smpl_t aubio_level_detection(fvec_t * ibuf, smpl_t threshold);
201 * calculate normalised autocorrelation function
203 void aubio_autocorr(fvec_t * input, fvec_t * output);
205 * zero-crossing rate (number of zero cross per sample)
207 smpl_t aubio_zero_crossing_rate(fvec_t * input);
209 * clean up cached memory at the end of program
211 * use this function at the end of programs to purge all
212 * cached memory. so far this function is only used to clean
215 void aubio_cleanup(void);