Mercurial > octave
view scripts/audio/lin2mu.m @ 31042:13a7af4ca0da
Update lin2mu, mu2lin functions.
* lin2mu.m: Rewrite docstring. Use default argument for input 'n' to simply
input validation. Eliminate warning abut no precision certified. Add stricter
input validation 'n' input. Use inplace operators for better performnace.
Update BIST tests.
* mu2lin.m: Rewrite docstring. Use default argument for input 'n' to simply
input validation. Add BIST tests for function.
author | Rik <rik@octave.org> |
---|---|
date | Sat, 28 May 2022 23:21:53 -0700 |
parents | e4f9db6543bd |
children | fd29c7a50a78 |
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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} =} lin2mu (@var{x}) ## @deftypefnx {} {@var{y} =} lin2mu (@var{x}, @var{n}) ## Convert audio data from linear to mu-law. ## ## Linear values use floating point values in the range -1 @leq{} @var{x} ## @leq{} 1 if @var{n} is 0 (default), or @var{n}-bit signed integers if @var{n} ## is 8 or 16. Mu-law values are 8-bit unsigned integers in the range ## 0 @leq{} @var{y} @leq{} 255. ## @seealso{mu2lin} ## @end deftypefn function y = lin2mu (x, n = 0) if (nargin < 1) print_usage (); endif ## Convert to floating point integers per Matlab. x = double (x); 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 ## Transform real and n-bit format to 16-bit. if (n == 0) ## [-1,1] -> [-32768, 32768] x *= 32768; elseif (n != 16) x *= 256; 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 binary representation. [f, e] = log2 (x); y = 64 * sig - 16 * e - fix (32 * f) + 335; endfunction ## Test functionality %!test %! x = -1:1; %! y = x'; %! assert (lin2mu (x), (lin2mu (y))') %! assert (lin2mu (x), [0, 255, 128]) %!assert (lin2mu ([0, 1, NaN, inf, -inf], 8), [255, 231, NaN, 128, 0]) %!assert (lin2mu ([]), []) %!assert (lin2mu (0), 255) %!assert (lin2mu (0, 0), 255) %!assert (lin2mu (0, 8), 255) %!assert (lin2mu (0, 16), 255) %!assert (lin2mu (2, 8), 219) %!assert (lin2mu (3, []), 128) %!assert (lin2mu (3, 16), 255) %!assert (lin2mu (repmat (-0.23, 1, 1000), 0), repmat (34, 1, 1000)) %!assert (lin2mu (ones (2, 2), 0), repmat (128, 2)) ## Test input validation %!error <Invalid call> lin2mu () %!error <N must be either 0, 8, or 16> lin2mu (1, 2) %!error <N must be either 0, 8, or 16> lin2mu (1, [1,2]) %!error <N must be either 0, 8, or 16> lin2mu (1, ones (1, 2)) %!error <invalid conversion> lin2mu ({2:5})