www.gusucode.com > 线性时频分析工具箱 - ltfat-1.0.1源码程序 > 线性时频分析工具箱 - LTFAT\auditory\rangeexpand.m

    function sig = rangeexpand(codedsig,mu,sigweight);
%RANGEEXPAND  Expand the dynamic range of a signal
%   Usage:  sig = rangeexpand(codedsig,mu,sigweight);
%
%   RANGEEXPAND(codedsig,mu,sigweight) inverts a previously
%   applied mu-law companding to the signal codedsig. The parameters
%   mu and sigweight must match those from the call to MULAWENCODE
%  
%   References:
%     S. Jayant and P. Noll. Digital Coding of Waveforms: Principles and
%     Applications to Speech and Video. Prentice Hall, 1990.
%     

% Copyright (C) 2005-2011 Peter L. Soendergaard.
% This file is part of LTFAT version 1.0.1
% This program 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.
% 
% This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.

% AUTHOR: Bruno Torresani and Peter Soendergaard

definput.flags.method={'mulaw','alaw'}
definput.keyvals.mu=255;
[flags,kv]=ltfatarghelper({'L'},definput,varargin);

if flags.do_mulaw

  cst = (1+kv.mu);
  sig = cst.^(abs(codedsig));
  sig = sign(codedsig) .* (sig-1);
  sig = sig * sigweight/kv.mu;

end;

if flags.do_alaw
  error('Not implemented yet.');
end;