melp_qgain.m

语音编码中的MELP的经典估计

%Quantize the gain
%Input:
%        G2p(the previous frame Gain)
%        G(G1 and G2)
%Output:
%        Q(quantized Gains)
function Q=melp_Qgain(G2p,G)
if G(1)<10
   G(1)=10;
end
if G(1)>77
   G(1)=77;
end

if (abs(G2p-G(2))<5)&(abs(G(1)-0.5*(G(2)+G2p))<3)
   Q(1)=0;
else
   gain_max=max(G2p,G(2))+6;
   gain_min=min(G2p,G(2))-6;
   if gain_min<10
      gain_min=10;
   end
   if gain_max>77
      gain_max=77;
   end
   delta=(gain_max-gain_min)/7;
   temp=G(1)-gain_min;
   Q(1)=1+fix(temp/delta);
   if Q(1)>7
      Q(1)=7;
   end
end

delta=67/32;
Q(2)=fix((G(2)-10)/delta);
if Q(2)>31
   Q(2)=31;
end