Mercurial > octave
view scripts/audio/mu2lin.m @ 2312:204cc7db6f4a
[project @ 1996-07-11 21:20:36 by jwe]
author | jwe |
---|---|
date | Thu, 11 Jul 1996 21:20:36 +0000 |
parents | 2b5788792cad |
children | 5ca126254d15 |
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### Copyright (C) 1996 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 2, 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, write to the Free ### Software Foundation, 59 Temple Place - Suite 330, Boston, MA ### 02111-1307, USA. ## usage: y = mu2lin (x [, bit]) ## ## If x is a vector of audio data with mu-law encoding, mu2lin (x) ## holds the same data with linear encoding. ## The optional argument bit specifies whether the input data is ## 8 bit (default) or 16 bit. ## Author: AW <Andreas.Weingessel@ci.tuwien.ac.at> ## Created: 18 October 1994 ## Adapted-By: jwe function y = mu2lin (x, bit) if (nargin == 1) bit = 8; elseif (nargin == 2) if (bit != 8 && bit != 16) error ("mu2lin: bit must be either 8 or 16"); endif else usage ("y = mu2lin (x [, bit])"); endif if (! is_vector (x)) error ("mu2lin: x must be a vector"); endif exp_lut = [0; 132; 396; 924; 1980; 4092; 8316; 16764]; ## invert x bitwise x = 255 - x; ## determine sign of y sig = (x > 127); ## determine exponent and fraction of y e = fix (x / 16) - 8 .* sig + 1; f = rem (x, 16); sig = 1 - 2 .* sig; y = (pow2 (f, e + 2) + exp_lut (e)) .* sig; ## convert to 8-bit if (bit == 8) ld = max (abs (y)); if (ld < 16384) sc = 64 / ld; else sc = 1 / 256; endif y = fix (y * sc); endif endfunction