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

function m=ccwarpf(f,n,s) 
%CCWARPF  Warp cepstral coefficients M=(F,N,S)  
% f(1) is the original sample freq, f(2) is the new sample freq 
% n(1) is the original number of coefficients, n(2) is the new number 
% s is a string: s(1),s(2) =l for linear, m for mel frequency, use capitals if c0 included 
 
 
%      Copyright (C) Mike Brookes 1998 
% 
%      Last modified Fri Apr  3 14:57:14 1998 
% 
%   VOICEBOX home page: http://www.ee.ic.ac.uk/hp/staff/dmb/voicebox/voicebox.html 
% 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
%   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. 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
 
if nargin<3 
   s='ll'; 
end 
if length(f)<2 
   f(2)=1; 
end 
if length(n)<2 
   n(2)=n(1); 
end 
z=s<'a'; 
s=s+32*z; 
if all(s=='l') 
   k=1:n(2)-z(2); 
   ff=((1:n(1)).'-z(1))*f(2)/f(1); 
   fa=2*sin(ff*pi).*ff/pi; 
   fb=ff.^2; 
   ka=1-2*rem(k,2); 
   kb=k.^2; 
   r1=ones(n(1),1); 
   c1=ones(1,n(2)-z(2)); 
   a=fa(:,c1).*ka(r1,:); 
   b=fb(:,c1)-kb(r1,:); 
   f0=find(fix(ff)==ff); 
   if length(f0) 
      a(f0,:)=ff(f0,c1)==k(ones(length(f0),1),:); 
      b(f0,:)=1; 
   end 
   m=a./b; 
   if z(2) 
      m=[[1; 0.5*fa(2:n(1))./fb(2:n(1))] m]; 
   end 
end