function [ccc] = mfcc(x)
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% function ccc=mfcc(x);
%对输入的语音序列x进行MFCC参数的提取,返回MFCC参数和一阶
%差分MFCC参数,Mel滤波器的阶数为24
%fft变换的长度为256,采样频率为8000Hz,对x 256点分为一帧
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
bank=melbankm(24,256,11025,0,0.5,'m');
% 归一化mel滤波器组系数 Initialisierung coefficient of Mel-filter-bank
bank=full(bank);
bank=bank/max(bank(:));
% DCT系数,12*24 coefficient of DCT
for k=1:12
n=0:23;
dctcoef(k,:)=cos((2*n+1)*k*pi/(2*24));
end
% 归一化倒谱提升窗口 Initialisierung Cepstral?????????
w = 1 + 6 * sin(pi * [1:12] ./ 12);
w = w/max(w);
% 预加重滤波器 Pre-emphasis
xx=double(x);
xx=filter([1 -0.9375],1,xx);
% 语音信号分帧
xx=enframe(xx,256,80);
% 计算每帧的MFCC参数 rechnen jedem Frame's coefficient
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
%差分系数 coefficient of first-order difference
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参数和一阶差分mfcc参数 conflation coefficient of MFCC and first-order
%difference vom MFCC
ccc = [m dtm];
%去除首尾两帧,因为这两帧的一阶差分参数为0 weglassen erster und letzter Frame, wegen
%first-order difference = 0
ccc = ccc(3:size(m,1)-2,:);