mula_pcm.m

模拟信号数字化的PCM量化以及哈夫曼编码

function[sqnr,a_quan,code]=mula_pcm(a,n,mu)
%MULA_PCM MU-LAW PCM encoding of a sequence.
%[SQNR,A_QUAN,CODE]=MULA_PCM(A,N,MU)
%a=input sequence
%n=number of quantization levels(even)
%sqnr=output SQNR(in db)
%a_quan=quantized output before encoding.
%code=the encoded output.
[y,maximum]=mulaw(a,mu);%经过压缩曲线处理
[sqnr,y_q,code]=u_pcm(y,n);%把处理后的结果均匀量化
a_quan=invmulaw(y_q,mu);%把处理后的结果对应到压缩之前
a_quan=maximum*a_quan;%在调用mulaw时曾归一化,现在进行复原
sqnr=20*log10(norm(a)/norm(a-a_quan));%求量化信噪比