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maint: Update copyright dates.
author John W. Eaton <jwe@octave.org>
date Wed, 22 Feb 2017 12:39:29 -0500
parents e9a0469dedd9
children 092078913d54 93714122ed59
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1 ## Copyright (C) 1995-2017 John W. Eaton
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2 ##
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3 ## This file is part of Octave.
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4 ##
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5 ## Octave is free software; you can redistribute it and/or modify it
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6 ## under the terms of the GNU General Public License as published by
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7 ## the Free Software Foundation; either version 3 of the License, or (at
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8 ## your option) any later version.
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9 ##
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10 ## Octave is distributed in the hope that it will be useful, but
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11 ## WITHOUT ANY WARRANTY; without even the implied warranty of
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12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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13 ## General Public License for more details.
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14 ##
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15 ## You should have received a copy of the GNU General Public License
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16 ## along with Octave; see the file COPYING. If not, see
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17 ## <http://www.gnu.org/licenses/>.
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18
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19 ## -*- texinfo -*-
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20 ## @deftypefn {} {} mu2lin (@var{x}, @var{n})
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21 ## Convert audio data from mu-law to linear.
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22 ##
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23 ## Mu-law values are 8-bit unsigned integers. Linear values use @var{n}-bit
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24 ## signed integers or floating point values in the range -1@leq{}y@leq{}1 if
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25 ## @var{n} is 0.
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26 ##
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27 ## If @var{n} is not specified it defaults to 0.
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28 ## @seealso{lin2mu}
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29 ## @end deftypefn
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30
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31 ## Author: Andreas Weingessel <Andreas.Weingessel@ci.tuwien.ac.at>
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32 ## Created: 18 October 1994
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33 ## Adapted-By: jwe
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34
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35 function y = mu2lin (x, n = 0)
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36
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37 if (nargin == 2)
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38 if (n != 0 && n != 8 && n != 16)
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39 error ("mu2lin: N must be either 0, 8, or 16");
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40 endif
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41 elseif (nargin != 1)
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42 print_usage ();
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43 endif
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44
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45 ulaw = [32124, 31100, 30076, 29052, 28028, 27004, 25980, 24956, ...
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60 56, 48, 40, 32, 24, 16, 8, 0 ];
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61
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62 ulaw = [ -ulaw, ulaw ];
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64 ## Set the shape of y to that of x overwrites the contents of y with
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65 ## ulaw of x.
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66 y = x;
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67 y(:) = ulaw(x + 1);
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69 ## Convert to real or 8-bit.
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70 if (n == 0)
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71 ## [ -32768, 32767 ] -> [ -1, 1)
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72 y /= 32768;
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73 elseif (n == 8)
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74 ld = max (abs (y (:)));
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75 if (ld < 16384 && ld > 0)
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76 sc = 64 / ld;
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77 else
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78 sc = 1 / 256;
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79 endif
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80 y = fix (y * sc);
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81 endif
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82
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83 endfunction