update packages

[CreaPhase.git] / octave_packages / m / audio / lin2mu.m

diff --git a/octave_packages/m/audio/lin2mu.m b/octave_packages/m/audio/lin2mu.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} {} lin2mu (@var{x}, @var{n})
+## Convert audio data from linear to mu-law.  Mu-law values use 8-bit
+## unsigned integers.  Linear values use @var{n}-bit signed integers or
+## floating point values in the range -1 @leq{} @var{x} @leq{} 1 if
+## @var{n} is 0.
+##
+## If @var{n} is not specified it defaults to 0, 8, or 16 depending on
+## the range of values in @var{x}.
+## @seealso{mu2lin, loadaudio, saveaudio}
+## @end deftypefn
+
+
+## Author: Andreas Weingessel <Andreas.Weingessel@ci.tuwien.ac.at>
+## Created: 17 October 1994
+## Adapted-By: jwe
+
+function y = lin2mu (x, n)
+
+  if (nargin == 1)
+    range = max (abs (x (:)));
+    if (range <= 1)
+      n = 0;
+    elseif (range <= 128)
+      n = 8;
+      warning ("lin2mu: no precision specified, so using %d", n);
+    else
+      n = 16;
+    endif
+  elseif (nargin == 2)
+    if (n != 0 && n != 8 && n != 16)
+      error ("lin2mu: N must be either 0, 8 or 16");
+    endif
+  else
+    print_usage ();
+  endif
+
+  ## Transform real and n-bit format to 16-bit.
+  if (n == 0)
+    ## [-1,1] -> [-32768, 32768]
+    x = 32768 * x;
+  elseif (n != 16)
+    x = 2^(16-n) .* x;
+  endif
+
+  ## Determine sign of x, set sign(0) = 1.
+  sig = sign(x) + (x == 0);
+
+  ## Take absolute value of x, but force it to be smaller than 32636;
+  ## add bias.
+  x = min (abs (x), 32635) + 132;
+
+  ## Find exponent and fraction of bineary representation.
+  [f, e] = log2 (x);
+
+  y = 64 * sig - 16 * e - fix (32 * f) + 335;
+
+endfunction