www.pudn.com > voicebox2.zip > LPCCC2DB.M

function db=lpccc2db(cc,np,nc) 
%LPCCC2DBf Convert complex cepstrum to dB power spectrum DB=(CC,NP,NC) 
% cc = complex cepstrum coefs 
% np+2 = number of frequency values 0 to nyquist (default: np=size(cc,2)) 
% nc = number of cepstral coefs to use (default: nc=np); 
% for high speed make np one less than a power of 2 
 
 
%      Copyright (C) Mike Brookes 1998 
% 
%      Last modified Tue May 12 16:02:11 1998 
% 
%   VOICEBOX home page: http://www.ee.ic.ac.uk/hp/staff/dmb/voicebox/voicebox.html 
% 
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%   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 2 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 can obtain a copy of the GNU General Public License from 
%   ftp://prep.ai.mit.edu/pub/gnu/COPYING-2.0 or by writing to 
%   Free Software Foundation, Inc.,675 Mass Ave, Cambridge, MA 02139, USA. 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
 
[nf,mc]=size(cc); 
if nargin<2 np=mc+2; end 
if nargin<3 nc=np; end 
k=10/log(10); 
if nc==mc 
   db=k*rsfft([zeros(nf,1) cc].',2*np+2).'; 
else 
   db=k*rsfft([zeros(nf,1) lpccc2cc(cc,nc)].',2*np+2).'; 
end 
if nargout==0 
   plot((0:np+1)/(2*np+2),db.'); 
   ylabel('dB'); 
end