PCM编解码的MATLAB实现

1、clc% clear allclose all fs=1OO; t=1/fs:1/fs:1;n=8;s1=cos(2*pi*t);s=s1/max(abs(s1); % 信号归一化 y=Alaw(s); %A 律量化qu c = u_qua ntize( y,n);qu仁decode(c,le ngth(s),ceil(log2( n) )+1);x=i nv Alaw(qu1);x=x*max(abs(s1);plot(t,s1)hold on plot(t,x,'r')figure(2) fun cti on y=Alaw(sO)A=87.6;A0=1/A;s=abs(s0

2、);y=zeros(1,le ngth(s);y(fin d(s<=A0)=(A*s(fi nd(s<=A0)”(1+log(A).*sig n( s0(s<=A0);y(fi nd(s>A0)=(1+log(A*s(fi nd(s>A0)”(1+log(A).*sig n(s0(s>A0 );fun cti on x=inv Alaw(y)A=87.6;A0=1/A;yO=abs(y);in dex=fi nd(y0<=1/(log(A)+1);% x(i ndex)=(log(A)+1)/A*y0(i ndex).*sig n(y(i ndex);

3、x(in dex) = yO(i ndex)*(1+log(A)/A.*sig n(y(i ndex);in dex=fi nd(y0>1/(log(A)+1);x(in dex) = 1/A*exp(y0(i ndex)*(1+log(A)-1).*sig n(y(i ndex);%x(i ndex)=1/A*exp(y0(i ndex)/(1/(log(A)+1)-1).*sig n(y(i ndex);fun cti on qu c = u_qua ntize(y 0,n)%均量化m=0:1/n:1;q=m(1: n)+1/(2* n);n仁ceil(log2( n);y=abs(

4、y0);for i=1: nqu(fin d(y>=m(i) & y<=m(i+1) = q(i);codi(fi nd(y>=m(i) & y<=m(i+1) = i-1;endqu=qu.*sig n(y 0);%编码c=zeros(1,le ngth(y0)* (n 1+1);for k=1:le ngth(y0)c(k-1)*( n1+1)+2:k*( n1+1) = dectobi n( codi(k), n1);if y0(k)>0c(k-1)*( n1+1)+1) = 1;endend% cod=dec2b in( codi);% r

5、 l=size(cod);% for k=1:r%c(k-1)*(l+1)+1)=sig n(y0(k)+abs(y0(k);% for k1=2:l+1%c(k-1)*(l+1)+k1)=str2 num(cod(k,k1-1);% end% end% % cod = str2 nu m(cod);% %将符号数组转换为数字% r=ceil(log2( n+1);% c=zeros(1,le ngth(codi)*r);% for k=1:le ngth(codi)%l=le ngth(cod(k,:);%for j=1:le ngth(cod(k,:)%c(k-1)*r+j)=str2 nu m(cod(k,j);% end% end fun cti on qu仁decode(c, N,nO)% N=le ngth(c)/8;n=2A( nO-1);m=0:1/n:1;q=m(1: n)+1/(2* n);% mi=zeros(1,N);for i=1:Nmi=bi ntodec(c(i-1)* n0+2:i*