update packages

[CreaPhase.git] / octave_packages / m / audio / mu2lin.m

diff --git a/octave_packages/m/audio/mu2lin.m b/octave_packages/m/audio/mu2lin.m
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+## Copyright (C) 1995-2012 John W. Eaton
+##
+## This file is part of Octave.
+##
+## Octave is free software; you can redistribute it and/or modify it
+## under the terms of the GNU General Public License as published by
+## the Free Software Foundation; either version 3 of the License, or (at
+## your option) any later version.
+##
+## Octave is distributed in the hope that it will be useful, but
+## WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+## General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with Octave; see the file COPYING.  If not, see
+## <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {} mu2lin (@var{x}, @var{n})
+## Convert audio data from mu-law to linear.  Mu-law values are 8-bit
+## unsigned integers.  Linear values use @var{n}-bit signed integers
+## or floating point values in the range -1@leq{}y@leq{}1 if @var{n}
+## is 0.
+##
+## If @var{n} is not specified it defaults to 0.
+## @seealso{lin2mu, loadaudio, saveaudio}
+## @end deftypefn
+
+## Author:  Andreas Weingessel <Andreas.Weingessel@ci.tuwien.ac.at>
+## Created: 18 October 1994
+## Adapted-By: jwe
+
+function y = mu2lin (x, n = 0)
+
+  if (nargin == 2)
+    if (n != 0 && n != 8 && n != 16)
+      error ("mu2lin: N must be either 0, 8, or 16");
+    endif
+  elseif (nargin != 1)
+    print_usage ();
+  endif
+
+  ulaw = [32124, 31100, 30076, 29052, 28028, 27004, 25980, 24956, \
+          23932, 22908, 21884, 20860, 19836, 18812, 17788, 16764, \
+          15996, 15484, 14972, 14460, 13948, 13436, 12924, 12412, \
+          11900, 11388, 10876, 10364,  9852,  9340,  8828,  8316, \
+           7932,  7676,  7420,  7164,  6908,  6652,  6396,  6140, \
+           5884,  5628,  5372,  5116,  4860,  4604,  4348,  4092, \
+           3900,  3772,  3644,  3516,  3388,  3260,  3132,  3004, \
+           2876,  2748,  2620,  2492,  2364,  2236,  2108,  1980, \
+           1884,  1820,  1756,  1692,  1628,  1564,  1500,  1436, \
+           1372,  1308,  1244,  1180,  1116,  1052,   988,   924, \
+            876,   844,   812,   780,   748,   716,   684,   652, \
+            620,   588,   556,   524,   492,   460,   428,   396, \
+            372,   356,   340,   324,   308,   292,   276,   260, \
+            244,   228,   212,   196,   180,   164,   148,   132, \
+            120,   112,   104,    96,    88,    80,    72,    64, \
+             56,    48,    40,    32,    24,    16,     8,     0 ];
+
+  ulaw = [ -ulaw, ulaw ];
+
+  ## Set the shape of y to that of x overwrites the contents of y with
+  ## ulaw of x.
+  y = x;
+  y(:) = ulaw (x + 1);
+
+  ## Convert to real or 8-bit.
+  if (n == 0)
+    ## [ -32768, 32767 ] -> [ -1, 1)
+    y = y/32768;
+  elseif (n == 8)
+    ld = max (abs (y (:)));
+    if (ld < 16384 && ld > 0)
+      sc = 64 / ld;
+    else
+      sc = 1 / 256;
+    endif
+    y = fix (y * sc);
+  endif
+
+endfunction