function cps=mfcc_ifft(s,CPS_COEFFS);
% MFCC, [cps,dct]=mfcc(s,CPS_COEFFS)
% everything hard-wired inside. Reads mel fb from ~/matlab/fbanks/
% can eventually output also the dct
% CPS_COEFFS is the number of cps. coeffs including the 0-th one. 
% 1st and last channel repeated; uses the ifft instead of dct. 

load /u/honza/matlab/fbanks/mfb
%load /home/cernocky/OGI/PLP/mfb
N=size(mfb,2);
CPS_ORDER=15;

S = abs(specgram(s,256,8000,hamming(200),120)).^2;
Nfr = size(S,2);

fbout = mfb' * S;       

% log
fboutlog = log(fbout);

% ifft - better do it in a cycle.
R = zeros(2*(N+1),Nfr); 
for ii=1:Nfr,
  repeated = [fboutlog(1,ii); fboutlog(:,ii); fboutlog(N,ii)]; 
  x = [repeated; repeated(N+1:-1:2)]; % flip for the ifft
  X = real(ifft(x)); 
  R(:,ii) = X;  %pause 
end

% nothing more, R is the result ! 
cps = R(1:CPS_COEFFS,:);