语音信号_实验_语音信号分析_语音编解码_语音信号_语音采集

function [voice,pitcha,rms,rc]=decode1(ipitch,irms,irc,rcn) % This program provides error correction and decoding for all LPC parameters. % INPUTS: % ORDER - Number of RC's % IPITV - Index value of pitch % IRMS - Coded Energy % IRC - Coded Reflection Coefficients % CORRP - Error correction: % If FALSE, parameters are decoded directly with no delay. If TRUE, % most important parameter bits are protected by Hamming code and % median smoothed. This requires an additional frame of delay. % OUTPUTS: % VOICE - Half frame voicing decisions % PITCH - Decoded pitch % RMS - Energy % RC - Reflection coefficients % % NOTE: Zero RC's should be done more directly, but this would affect % coded parameter printout. rmst=[1024,936,856,784,718,656,600,550,502,460,420,384,352,328,294,270,246,226,206,188,172,158,144,132,120,110,102,92,84,78,70,64,60,54,50,46,42,38,34,32,30,26,24,22,20,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,0]; ivtab =[24960,24960,24960,24960,25480,25480,25483,25480,16640,1560,1560,1560,16640,1816,1563,1560,24960,24960,24859,24856,26001,25881,25915,25913,1560,1560,7800,3640,1561,1561,3643,3641]; corth=[32767.0, 32767.0, 32.0, 32.0, 32.0, 32.0, 16.0, 16.0;10.0, 8.0, 6.4, 6.4, 11.2, 11.2, 5.6, 5.6;5.0, 4.0, 3.2, 3.2, 6.4, 6.4, 3.2, 3.2;0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]; detau=[0,0,0,3,0,3,3,31, 0,3,3,21,3,3,29,30,0,3,3,20,3,25,27,26, 3,23,58,22,3,24,28,3,0,3,3,3,3,39,33,32, 3,37,35,36,3,38,34,3,3,42,46,44,50,40,48,3, 54,3,56,3,52,3,3,1,0,3,3,108,3,78,100,104, 3,84,92,88,156,80,96,3,3,74,70,72,66,76,68,3, 62,3,60,3,64,3,3,1,3,116,132,112,148,152,3,3, 140,3,136,3,144,3,3,1,124,120,128,3,3,3,3,1, 3,3,3,1,3,1,1,1]; detab7=[4,11,18,25,32,39,46,53,60,66,72,77,82,87,92,96,101,104,108,111,114,115,117,119,121,122,123,124,125,126,127,127]; descl=[0.6953,0.6250,0.5781,0.5469,0.5312,0.5391,0.4688,0.3828]; deadd=[1152,-2816,-1536,-3584,-1280,-2432,768,-1920]; qb=[511,511,1023,1023,1023,1023,2047,4095]; nbit=[8,8,5,5,4,4,4,4,3,2]; zrc=[0,0,0,0,0,3,0,2,0,0]; abit=[2,4,8,16,32]; ivp2h=0; erate=0; iovoic=0; iavgp=60; ethrs=2048; ethrs1=128; ethrs2=1024; ethrs3=2048; fut=1; pres=1; past=2; first=1; rcn=length(irc); pitcha=0; % If no error correction, do pitch and voicing then jump to decode % i4 = detau(ipitch); i4=ipitch; % Do error correction pitch and voicing if(i4>4) dpit(fut) = i4; ivoic = 2; iavgp =fix((15*iavgp+i4+8)*0.0625); else ivoic = i4; dpit(fut) = iavgp; end drms(fut)=irms; for n1=1:rcn drc(fut,n1) = irc(n1); end % Determine index to IVTAB from V/UV decision % If error rate is high then use alternate table index = 16*ivp2h + 4*iovoic + ivoic + 1; i1 = ivtab(index); ipit = bitand(i1,3); icorf = fix(i1*0.125); if erate<ethrs icorf =fix(icorf * 0.015625); end % Determine error rate: 4=high 1=low ixcor = 4; if(erate<ethrs3) ixcor = 3; end if(erate<ethrs2) ixcor = 2; end if(erate<ethrs1) ixcor = 1; end % Voice/unvoice decision determined from bits 0 and 1 of IVTAB voice(1) = bitand(fix(icorf*0.5),1); voice(2) = bitand(icorf,1); % Skip decoding on first frame because present data not yet available if(first) first = 0; else % If bit 4 of ICORF is set then correct RMS and RC(1) - RC(4). % Determine error rate and correct errors using a Hamming 8,4 code % during transition or unvoiced frame. If IOUT is negative, % more than 1 error occurred, use previous frame's parameters. if(bitand(icorf,abit(3))~=0) errcnt = 0; lsb = bitand(drms(pres),1); index = fix(drc(pres,7)*16 + drms(pres) * 0.5); % ham84(index,&iout,&errcnt); drms(pres) = drms(past); if(iout>=0) drms(pres) = iout*2 + lsb; end for n1=1:4 if n1==1 i1= bitand(drc(pres,8),7)*2+bitand(drc(pres,9),1); else i1 = drc(pres,8-n1)&15; end i2 = bitand(drc(pres,4-n1),31); lsb = bitand(i2,1); index = fix(16*i1 + i2*0.5); % ham84(index,&iout,&errcnt); if iout>=0 iout = iout*2+lsb; if(bitand(iout,16)==16) iout = iout-32; end else iout = drc(past,4-n2); end drc(pres,4-n2) = iout; end % Determine error rate erate = fix(erate*0.96875 + errcnt*102); end % Get unsmoothed RMS, RC's, and PITCH irms = drms(pres); for n1=1;rcn irc(n1)= drc(pres,n1); end if ipit==1 dpit(pres) = dpit(past); end if ipit==3 dpit(pres) = dpit(fut); end pitcha= dpit(pres); % If bit 2 of ICORF is set then smooth RMS and RC's if(bitand(icorf,abit(1))~=0) if (abs(drms(pres)-drms(fut))>=corth(ixcor-1,1))&(abs(drms(res)-drms(past))>= corth(ixcor-1,1)) temp1=[drms(past),drms(pres),drms(fut)]; irms=median(temp1); end for n1=1:6 if( abs(drc(pres,n1-1)-drc(fut,n1-1))>=corth(ixcor-1,n1+1)&abs(drc(pres,n1-1)-drc(past,n1-1))>= corth(ixcor-1,n1+1)) temp1=[drc(past,n1-1),drc(pres,n1-1),drc(fut,n1-1)]; irc(n1)=median(temp1); end end end % If bit 3 of ICORF is set then smooth pitch if(bitand(icorf,abit(2))~=0) if(abs(dpit(pres)-dpit(fut)) >= corth(ixcor-1,0)&abs(dpit(pres)-dpit(past))>= corth(ixcor-1,0)) temp1=[dpit(past), dpit(pres), dpit(fut)]; pitch = median(temp1); end end end % If bit 5 of ICORF is set then RC(5) - RC(10) are loaded with % values so that after quantization bias is removed in decode % the values will be zero. % end if first if(bitand(icorf,abit(4))~=0) for(n1=5:rcn) irc(n1)=zrc(n1); end end % House keeping - one frame delay iovoic = ivoic; ivp2h = voice(2); dpit(past) = dpit(pres); dpit(pres) = dpit(fut); drms(past) = drms(pres); drms(pres) = drms(fut); for(n1=1:rcn) drc(past,n1) = drc(pres,n1); drc(pres,n1) = drc(fut,n1); end % Decode RMS irms = rmst((31-irms)*2); % Decode RC(1) and RC(2) from log-area-ratios % Protect from illegal coded value (-16) caused by bit errors for(n1=1:2) i2 = irc(n1); i1 = 0; if(i2<0) i1 = 1; i2 = -i2; if(i2>15) i2 = 0; end end i2 = detab7(2*i2+1); if(i1==1) i2 = -i2; end ishift = 15 - nbit(n1); irc(n1) = i2*bitshift((ishift-1),2); end % Decode RC(3)-RC(10) to sign plus 14 bits for(n1=3:rcn) i2 = irc(n1); ishift = 15 - nbit(n1-1); i2 = i2*bitshift((ishift-1),2); i2 = i2+qb(n1-2); ftemp = i2*descl(n1-2) + deadd(n1-2); % rounding problem if(ftemp < 0) ftemp = - ftemp; itemp = fix(ftemp); irc(n1) = -itemp; else irc(n1) = fix(ftemp); end end % Scale RMS and RC's to reals rms=double(irms); for(n1=1:rcn) rc(n1)= double(irc(n1)* 6.103515625e-05); ,384 = 2^14 end