function ccc = mfcc(x)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                 function ccc=mfcc(x);
%對輸入的語音序列x進行MFCC參數的提取，返回MFCC參數和一階
%差分MFCC參數，Mel濾波器的階數為24
%fft變換的長度為256，采樣頻率為8000Hz，對x 256點分為一幀
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


bank=melbankm(24,256,8000,0,0.5,'m');
% 歸一化mel濾波器組系數
bank=full(bank);
bank=bank/max(bank(:));

% DCT系數,12*24
for k=1:12
  n=0:23;
  dctcoef(k,:)=cos((2*n+1)*k*pi/(2*24));
end

% 歸一化倒譜提升窗口
w = 1 + 6 * sin(pi * [1:12] ./ 12);
w = w/max(w);

% 預加重濾波器
xx=double(x);
xx=filter([1 -0.9375],1,xx);

% 語音信號分幀
xx=enframe(xx,256,80);

% 計算每幀的MFCC參數
for i=1:size(xx,1)
  y = xx(i,:);
  s = y' .* hamming(256);
  t = abs(fft(s));
  t = t.^2;
  c1=dctcoef * log(bank * t(1:129));
  c2 = c1.*w';
  m(i,:)=c2';
end

%差分系數
dtm = zeros(size(m));
for i=3:size(m,1)-2
  dtm(i,:) = -2*m(i-2,:) - m(i-1,:) + m(i+1,:) + 2*m(i+2,:);
end
dtm = dtm / 3;

%合并mfcc參數和一階差分mfcc參數
ccc = [m dtm];
%去除首尾兩幀，因為這兩幀的一階差分參數為0
ccc = ccc(3:size(m,1)-2,:);