initsub.m

the implement of the encoder and the decoder of the CELP

function [b1,b2,b3,b4,sube]=initsub(spch,sube,l,b1,b2,b3,b4,flag)

global pcode pgain sub_cnt frame_count gamma1 olpc pdlyindx lpcMat TRUE FALSE 

if flag~=FALSE
    [sube,b1]=pitch_syn(sube,b1,pcode(sub_cnt),pgain(sub_cnt));     % Pitch synthesis routine
end

[voc,b2]=lpcr(lpcMat(frame_count,:),b2,sube);                       % LPC synthesis. Returned with voc

sube=spch-voc;                                                      % Get error signal (First error or second error)

[sube,b3]=FIRfilter(lpcMat(frame_count,:),b3,sube);                 % A(z) filter

wlpc=wcoff(gamma1,lpcMat(frame_count,:));                       % Weight LPC coefficients with 0.8

[sube,b4]=lpcr(wlpc,b4,sube);                     % Weighted filter error signal

% The last three steps realize weighting filtering: A(z)/A(z/gamma)