1 ## Copyright (C) 1995-2012 John W. Eaton
3 ## This file is part of Octave.
5 ## Octave is free software; you can redistribute it and/or modify it
6 ## under the terms of the GNU General Public License as published by
7 ## the Free Software Foundation; either version 3 of the License, or (at
8 ## your option) any later version.
10 ## Octave is distributed in the hope that it will be useful, but
11 ## WITHOUT ANY WARRANTY; without even the implied warranty of
12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 ## General Public License for more details.
15 ## You should have received a copy of the GNU General Public License
16 ## along with Octave; see the file COPYING. If not, see
17 ## <http://www.gnu.org/licenses/>.
20 ## @deftypefn {Function File} {} mu2lin (@var{x}, @var{n})
21 ## Convert audio data from mu-law to linear. Mu-law values are 8-bit
22 ## unsigned integers. Linear values use @var{n}-bit signed integers
23 ## or floating point values in the range -1@leq{}y@leq{}1 if @var{n}
26 ## If @var{n} is not specified it defaults to 0.
27 ## @seealso{lin2mu, loadaudio, saveaudio}
30 ## Author: Andreas Weingessel <Andreas.Weingessel@ci.tuwien.ac.at>
31 ## Created: 18 October 1994
34 function y = mu2lin (x, n = 0)
37 if (n != 0 && n != 8 && n != 16)
38 error ("mu2lin: N must be either 0, 8, or 16");
44 ulaw = [32124, 31100, 30076, 29052, 28028, 27004, 25980, 24956, \
45 23932, 22908, 21884, 20860, 19836, 18812, 17788, 16764, \
46 15996, 15484, 14972, 14460, 13948, 13436, 12924, 12412, \
47 11900, 11388, 10876, 10364, 9852, 9340, 8828, 8316, \
48 7932, 7676, 7420, 7164, 6908, 6652, 6396, 6140, \
49 5884, 5628, 5372, 5116, 4860, 4604, 4348, 4092, \
50 3900, 3772, 3644, 3516, 3388, 3260, 3132, 3004, \
51 2876, 2748, 2620, 2492, 2364, 2236, 2108, 1980, \
52 1884, 1820, 1756, 1692, 1628, 1564, 1500, 1436, \
53 1372, 1308, 1244, 1180, 1116, 1052, 988, 924, \
54 876, 844, 812, 780, 748, 716, 684, 652, \
55 620, 588, 556, 524, 492, 460, 428, 396, \
56 372, 356, 340, 324, 308, 292, 276, 260, \
57 244, 228, 212, 196, 180, 164, 148, 132, \
58 120, 112, 104, 96, 88, 80, 72, 64, \
59 56, 48, 40, 32, 24, 16, 8, 0 ];
61 ulaw = [ -ulaw, ulaw ];
63 ## Set the shape of y to that of x overwrites the contents of y with
68 ## Convert to real or 8-bit.
70 ## [ -32768, 32767 ] -> [ -1, 1)
73 ld = max (abs (y (:)));
74 if (ld < 16384 && ld > 0)