v_ccwarpf

V_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

0001 function m=v_ccwarpf(f,n,s)
0002 %V_CCWARPF  Warp cepstral coefficients M=(F,N,S)
0003 % f(1) is the original sample freq, f(2) is the new sample freq
0004 % n(1) is the original number of coefficients, n(2) is the new number
0005 % s is a string: s(1),s(2) =l for linear, m for mel frequency, use capitals if c0 included
0006 
0007 
0008 %      Copyright (C) Mike Brookes 1998
0009 %      Version: $Id: v_ccwarpf.m 10865 2018-09-21 17:22:45Z dmb $
0010 %
0011 %   VOICEBOX is a MATLAB toolbox for speech processing.
0012 %   Home page: http://www.ee.ic.ac.uk/hp/staff/dmb/voicebox/voicebox.html
0013 %
0014 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
0015 %   This program is free software; you can redistribute it and/or modify
0016 %   it under the terms of the GNU General Public License as published by
0017 %   the Free Software Foundation; either version 2 of the License, or
0018 %   (at your option) any later version.
0019 %
0020 %   This program is distributed in the hope that it will be useful,
0021 %   but WITHOUT ANY WARRANTY; without even the implied warranty of
0022 %   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
0023 %   GNU General Public License for more details.
0024 %
0025 %   You can obtain a copy of the GNU General Public License from
0026 %   http://www.gnu.org/copyleft/gpl.html or by writing to
0027 %   Free Software Foundation, Inc.,675 Mass Ave, Cambridge, MA 02139, USA.
0028 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
0029 
0030 if nargin<3
0031    s='ll';
0032 end
0033 if length(f)<2
0034    f(2)=1;
0035 end
0036 if length(n)<2
0037    n(2)=n(1);
0038 end
0039 z=s<'a';
0040 s=s+32*z;
0041 if all(s=='l')
0042    k=1:n(2)-z(2);
0043    ff=((1:n(1)).'-z(1))*f(2)/f(1);
0044    fa=2*sin(ff*pi).*ff/pi;
0045    fb=ff.^2;
0046    ka=1-2*rem(k,2);
0047    kb=k.^2;
0048    r1=ones(n(1),1);
0049    c1=ones(1,n(2)-z(2));
0050    a=fa(:,c1).*ka(r1,:);
0051    b=fb(:,c1)-kb(r1,:);
0052    f0=find(fix(ff)==ff);
0053    if length(f0)
0054       a(f0,:)=ff(f0,c1)==k(ones(length(f0),1),:);
0055       b(f0,:)=1;
0056    end
0057    m=a./b;
0058    if z(2)
0059       m=[[1; 0.5*fa(2:n(1))./fb(2:n(1))] m];
0060    end
0061 end
0062 
0063 
0064