close all
clear
clc
[x fs]=wavread('speech.wav');
bank=mel(24,256,fs,0,0.4,'m');%Mel濾波器的階數為24，fft變換的長度為256，采樣頻率為8000Hz
% 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);%對x 256點分為一幀

% 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

%求取差分系數
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,:);
subplot(211)
ccc_1=ccc(:,1);
plot(ccc_1);title('MFCC');
ylabel('幅值');
title('一維數組及其幅值的關系')
[h,w]=size(ccc);
A=size(ccc);
subplot(212)
plot([1,w],A);
xlabel('維數');
ylabel('幅值');
title('維數于幅值的關系')