|
2847
|
1 ## Copyright (C) 1996, 1997 John W. Eaton |
|
2313
|
2 ## |
|
|
3 ## This file is part of Octave. |
|
|
4 ## |
|
|
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 2, or (at your option) |
|
|
8 ## any later version. |
|
|
9 ## |
|
|
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. |
|
|
14 ## |
|
|
15 ## You should have received a copy of the GNU General Public License |
|
|
16 ## along with Octave; see the file COPYING. If not, write to the Free |
|
|
17 ## Software Foundation, 59 Temple Place - Suite 330, Boston, MA |
|
|
18 ## 02111-1307, USA. |
|
2303
|
19 |
|
3332
|
20 ## -*- texinfo -*- |
|
|
21 ## @deftypefn {Function File} {} mu2lin (@var{x}, @var{bps}) |
|
3911
|
22 ## Converts audio data from linear to mu-law. Mu-law values are 8-bit |
|
|
23 ## unsigned integers. Linear values use @var{n}-bit signed integers |
|
|
24 ## or floating point values in the range -1<=y<=1 if @var{n} is 0. If |
|
|
25 ## @var{n} is not specified it defaults to 8. |
|
3332
|
26 ## @end deftypefn |
|
5053
|
27 ## |
|
3408
|
28 ## @seealso{lin2mu, loadaudio, saveaudio, playaudio, setaudio, and record} |
|
2311
|
29 |
|
3911
|
30 ## Author: Andreas Weingessel <Andreas.Weingessel@ci.tuwien.ac.at> |
|
2312
|
31 ## Created: 18 October 1994 |
|
|
32 ## Adapted-By: jwe |
|
|
33 |
|
1636
|
34 function y = mu2lin (x, bit) |
|
2325
|
35 |
|
1636
|
36 if (nargin == 1) |
|
3911
|
37 ## XXX COMPATIBILITY XXX: bps defaults to 8 for octave, 0 for Matlab |
|
1636
|
38 bit = 8; |
|
|
39 elseif (nargin == 2) |
|
3911
|
40 if (bit != 0 && bit != 8 && bit != 16) |
|
|
41 error ("mu2lin: bit must be either 0, 8 or 16"); |
|
1636
|
42 endif |
|
|
43 else |
|
3456
|
44 usage ("y = mu2lin (x, bit)"); |
|
1636
|
45 endif |
|
|
46 |
|
3911
|
47 ulaw = [32124, 31100, 30076, 29052, 28028, 27004, 25980, 24956, \ |
|
|
48 23932, 22908, 21884, 20860, 19836, 18812, 17788, 16764, \ |
|
|
49 15996, 15484, 14972, 14460, 13948, 13436, 12924, 12412, \ |
|
|
50 11900, 11388, 10876, 10364, 9852, 9340, 8828, 8316, \ |
|
|
51 7932, 7676, 7420, 7164, 6908, 6652, 6396, 6140, \ |
|
|
52 5884, 5628, 5372, 5116, 4860, 4604, 4348, 4092, \ |
|
|
53 3900, 3772, 3644, 3516, 3388, 3260, 3132, 3004, \ |
|
|
54 2876, 2748, 2620, 2492, 2364, 2236, 2108, 1980, \ |
|
|
55 1884, 1820, 1756, 1692, 1628, 1564, 1500, 1436, \ |
|
|
56 1372, 1308, 1244, 1180, 1116, 1052, 988, 924, \ |
|
|
57 876, 844, 812, 780, 748, 716, 684, 652, \ |
|
|
58 620, 588, 556, 524, 492, 460, 428, 396, \ |
|
|
59 372, 356, 340, 324, 308, 292, 276, 260, \ |
|
|
60 244, 228, 212, 196, 180, 164, 148, 132, \ |
|
|
61 120, 112, 104, 96, 88, 80, 72, 64, \ |
|
|
62 56, 48, 40, 32, 24, 16, 8, 0 ]; |
|
1636
|
63 |
|
3911
|
64 ulaw = [ -ulaw, ulaw ]; |
|
|
65 |
|
|
66 ## Set the shape of y to that of x overwrites the contents of y with |
|
|
67 ## ulaw of x. |
|
|
68 y = x; |
|
|
69 y(:) = ulaw (x + 1); |
|
1636
|
70 |
|
3911
|
71 ## Convert to real or 8-bit. |
|
|
72 if (bit == 0) |
|
|
73 ## [ -32768, 32767 ] -> [ -1, 1) |
|
|
74 y = y/32768; |
|
|
75 elseif (bit == 8) |
|
|
76 ld = max (abs (y (:))); |
|
|
77 if (ld < 16384 && ld > 0) |
|
1636
|
78 sc = 64 / ld; |
|
|
79 else |
|
|
80 sc = 1 / 256; |
|
|
81 endif |
|
|
82 y = fix (y * sc); |
|
|
83 endif |
|
|
84 |
|
|
85 endfunction |
