Waveform Quantization and Compression - Digital Signal Processing: Fundamentals and Applications - page 541

%

if tr ¼¼ 1
a ¼ zeros(1,2); b ¼ zeros(1,6);
tr ¼ 0;
td ¼ 0; % Set for the time being
else
% Update predictor poles
% Update a2 first
a2p (127.0/128.0)*a(2);

if abs(a(1)) <

¼

¼ 0.5

fa1 ¼ 4.0*a(1);

else
fa1

¼ 2.0*sgn(a(1));

end
a2p ¼ a2p þ (sign(pk1)*sgn(pk(1))-fa1*sign(pk1)*sgn(pk(2)))/128.0;
if abs(a2p) > 0.75
a2p ¼ 0.75*sgn(a2p);
end
a(2) ¼ a2p;

%
% Update a1
a1p ¼ (255.0/256.0)*a(1);
a1p ¼ a1p þ 3.0*sign(pk1)*sgn(pk(2))/256.0;
if abs(a1p) > 15.0/16.0-a2p
a1p ¼ 15.0/16.0 -a2p;
end
a(1) ¼ a1p;

%
% Update b coefficients
%

for i ¼ 1:6
b(i)

¼ (255.0/256.0)*b(i) þ sign(dqq)*sgn(dq(i))/128.0; % see Program 11.17 for sgn().

end
if a2p < -0.7185
td

¼ 1;

else
td

¼ 0;

end
if a2p < -0.7185 & abs(dq(6)) > 24.0*2^(yl)
tr ¼ 1;
else
tr ¼ 0;
end
for i ¼ 6:-1:2
dq(i) ¼ dq(i-1);
end
dq(1) ¼ dqq; pk(2) ¼ pk(1); pk(1) ¼ pk1; sr(2) ¼ sr(1); sr(1) ¼ srr;

%