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% rc = meanrc(filelist, ncoeffs [,framedur, defaultFs]) 
% 
%  MEANRC computes & displays the mean and s.d. reflection coefficients 
%  for a set of sound files. For each sound file, a 10ms analysis frame 
%  is chosen from the middle of the file, preemphasized & hamming-windowed. 
%  Its reflection (aka PARCOR) coefficients are computed for 1...ncoeffs. 
% 
%  MEAN also plots the average and stdev of the RCs. If rc(i,n) is the 
%  i'th reflection coeff for sound n, then for each i, MEANRC averages over 
%  rc(i,[1...numsounds]) and computes their s.d. The plot shows the 
%  means and a single s.d. for each i. 
%   
%   filelist: A list of filenames (can be a array of strings, or a cell 
%     array). If a single filename is given and it has an extension of 
%     .DAT or .TXT, it is taken to be a file containing the list of  
%     sound filenames (one on each line). Currently, .WAV, .AU,  
%     and .RAW files are supported. 
% 
%   ncoeffs  : number of coefficients to compute for each frame. 
%   
%   framedur : duration of the analysis frame (in msec).  
%              Default is 20ms. 
% 
%   defaultFs: The sampling rate to use for .RAW files (in Hz). 
%              Default is 10000. 
%        
%   rc       : Matrix of reflection coefficients. rc(:,n) are the  
%              coeffs for filelist{n}. 
% 
% Gautam Vallabha (vallabha@walt.ccs.fau.edu), NOV-15-2000 
% Center for Complex Systems, Florida Atlantic University. 
 
function rcout = meanrc(filelst, ncoeffs, framedur, defaultFs) 
 
if nargin < 4, defaultFs = 10000; end  % in msec  
if nargin < 3, framedur = 20; end  % in msec  
 
rc = []; 
Filelist = loadfilelist(filelst); 
if length(Filelist)==0,  
  fprintf(1, 'No sound files!\n'); 
  return;  
end 
 
% ------- 
 
for i=1:length(Filelist), 
 
  [sndfilename, datfilename, ext] = fixfilename(Filelist{i}); 
  [sig,Fs,err,msg] = getsound(sndfilename, ext, defaultFs); 
  if err, 
    fprintf(1, 'Error: %s\n', msg); 
  else 
   % pick a frame from the middle of the utterance 
    framelen = floor(Fs * (framedur/1000)); 
    framestart = floor(length(sig)/2 - framelen/2); 
    xprhm = preham( sig(framestart:framestart+framelen-1) ); 
    [a,k]=parcor(xprhm,ncoeffs); 
    rc(:,end+1) = k(:); 
  end 
 
end 
 
% ------- 
 
if isempty(rc), return; end 
if nargout > 0, rcout = rc; end 
 
figure; xval=1:ncoeffs; 
if size(rc,2)==1, 
 plot(xval, rc, '-x');  
else 
 m=mean(rc.'); sd = std(rc.'); 
 errorbar(1:ncoeffs,m,sd);  
end 
 
hold on; axis tight; ax=axis; 
plot(ax(1:2), [ 0    0  ], 'r--'); 
plot(ax(1:2), [ 0.2  0.2], 'r:'); 
plot(ax(1:2), [-0.2 -0.2], 'r:'); 
xlabel('lag (m)'); 
ylabel('mean k_m');