Mercurial > octave-libtiff
view scripts/audio/mu2lin.m @ 31206:df8ee95752aa
imformats: moved Tiff logic to default_formats
* scripts/image/imformats.m: added logic in default_formats to use
Tiff functions for tiff images if available.
* scripts/io/Tiff.m: removed the PKG_ADD logic in favor of the imformats
logic to make the function handles valid.
author | magedrifaat <magedrifaat@gmail.com> |
---|---|
date | Sat, 03 Sep 2022 20:36:33 +0200 |
parents | 13a7af4ca0da |
children |
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######################################################################## ## ## Copyright (C) 1995-2022 The Octave Project Developers ## ## See the file COPYRIGHT.md in the top-level directory of this ## distribution or <https://octave.org/copyright/>. ## ## 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 ## <https://www.gnu.org/licenses/>. ## ######################################################################## ## -*- texinfo -*- ## @deftypefn {} {@var{y} =} mu2lin (@var{x}) ## @deftypefnx {} {@var{y} =} mu2lin (@var{x}, @var{n}) ## Convert audio data from mu-law to linear. ## ## Mu-law values are 8-bit unsigned integers in the range 0 @leq{} @var{y} ## @leq{} 255. Linear values use floating point values in the range ## -@var{linmax} @leq{} @var{x} @var{linmax} (where ## @code{@var{linmax} = 32124/32768 =~ 0.98}) when @var{n} is zero (default). ## If @var{n} is 8 or 16 then @var{n}-bit signed integers are used instead. ## ## Programming Note: @code{mu2lin} maps maximum mu-law inputs to values ## slightly below the maximum ([-0.98, +0.98]) representable with a linear ## scale. Because of this, @code{mu2lin (lin2mu (@var{x}))} might not ## reproduce the original input. ## @seealso{lin2mu} ## @end deftypefn function y = mu2lin (x, n = 0) if (nargin < 1) print_usage (); endif if (nargin == 2) if (! isscalar (n) && ! isreal (n) || (n != 0 && n != 8 && n != 16)) error ("lin2mu: N must be either 0, 8, or 16"); elseif (isempty (n)) n = 0; endif 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 /= 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 ## Test functionality %!shared linmax %! linmax = 32124 / 32768; %!test %! x = [0, 128, 255]; %! y = x'; %! assert (mu2lin (x), (mu2lin (y))'); %! assert (mu2lin (x), [-linmax, +linmax, 0]); %!assert (mu2lin ([]), []) %!assert (mu2lin (255), 0) %!assert (mu2lin (255, 0), 0) %!assert (mu2lin (255, 8), 0) %!assert (mu2lin (255, 16), 0) %!assert (mu2lin (128, []), linmax) %!assert (mu2lin (128, 8), 125) %!assert (mu2lin (128, 16), 32124) %!assert (mu2lin (zeros (1, 1000), 0), repmat (-linmax, 1, 1000)) %!assert (mu2lin (255*ones (2, 2), 0), zeros (2, 2)) ## Test input validation %!error <Invalid call> mu2lin () %!error <N must be either 0, 8, or 16> mu2lin (1, 2) %!error <N must be either 0, 8, or 16> mu2lin (1, [1,2]) %!error <N must be either 0, 8, or 16> mu2lin (1, ones (1, 2)) %!error mu2lin ({2:5})