根据代码 详细分析JM8.6

L1 = 0.1;L2 = 0.3;L3 = 0.6;}else if (img->width == 352) 如果是cif格式门限L1 L2 L3取值如下{L1 = 0.2;L2 = 0.6;L3 = 1.2;}else 其他格式取值{L1 = 0.6;L2 = 1.4;L3 = 2.4;}根据bpp门限求出对应的初始Qpif (input->SeinitialQP==0){if(bpp<= L1)qp = 35;elseif(bpp<=L2)qp = 25;elseif(bpp<=L3)qp = 20;elseqp =10;input->SeinitialQP = qp;}作者: kingdexing 时间: 2008-9-17 18:44有空还会继续写,不会排版请见谅!作者: kingdexing 时间: 2008-9-17 20:31rc_init_GOP目的就是求出GOP的QP初始值void rc_init_GOP(int np, int nb)输入未编码的p数目np 未编码的b数目nb{if(R<0)当然R<0说明流量小于了编码位数Overum=TRUE;OverBits=-R;/*initialize the lower bound and the upper bound for the target bits of each frame, HRD consideration*/考虑到hrd（假设参考解码）来决定R中可用位数的上限和下限LowerBound=(long)(R+bit_rate/frame_rate);UpperBound1=(long)(R+InitialDelayOffset);/*compute the total number of bits for the current GOP*/ 计算当前gop的可用位AllocatedBits = (int) floor((1 + np + nb) * bit_rate / frame_rate + 0.5);np nb未编码的p b桢按当前流量流出的位数R +=AllocatedBits; R表示当前gop可用位数考虑gop的桢数算出流量和以前R相加因为以前R<0可能存在，说明上1个gop还有未流出的数据必须降低当前gop目标位数Np = np;Nb = nb;OverDuantQp=(int)(8*OverBits/AllocatedBits+0.5);原因就是R<0未流出的量求出修正OverDuantQp 8*Tr(i-1,Ngop)/Tr(i,0)上次剩余的位数处以当前分配的位数 GOPOverdue=FALSE; 用来控制gop是否迟到，过期可能由于网络原因有些gop阻塞了后来才收到/*field coding*/img->IFLAG=1; 场TotalPFrame=np;P桢数目等于未编码的np数目，因为调用此函数 gop内搜有图像都未编码img->NumberofGOP++;gop数目加1if(img->NumberofGOP==1)第1个GOP取由bpp初始设定的QP值{MyInitialQp=input->SeinitialQP;PreviousQp2=MyInitialQp-1; //recent change -0;QPLastGOP=MyInitialQp;}else{其他GOP的Qp计算公式如下QP=SumPqp/Np-8*Tr(i-1,Ngop)/Tr(i,0)-min{2,Ngop/15}=img->TotalQpforPPicture/img->NumberofPPicture-OverDuantQp-min{2,Ngop/15}/*adaptive field/frame coding*/自适应桢场编码if((input->;PicInterlace==ADAPTIVE_CODING)\||(input->MbInterlace))如何是图像自适应桢场编码，或者宏块是场模式或者宏块是桢场自适应模式{if (img->FieldFrame == 1)如果是幀编码 TotalQpforPPicture加上桢的FrameQPBuffer TotalQpforPPicture表示所有P图像的QP和{img->TotalQpforPPicture += FrameQPBuffer;QPLastPFrame = FrameQPBuffer;}else 场编码{img->TotalQpforPPicture += FieldQPBuffer;QPLastPFrame = FieldQPBuffer;}}/*compute the average QP of P frames in the previous GOP*/计算之前GOP所有P图像中的QP平均值 NumberofPPicture表示P图像数目PAverageQp=(int)(1.0*img->TotalQpforPPicture/img->NumberofPPicture+0.5);GOPDquant=(int)(0.5+1.0*(np+nb+1)/15);对应min{2,Ngop/15}if(GOPDquant>2)GOPDquant=2;PAverageQp-=GOPDquant;if (PAverageQp > (QPLastPFrame - 2)) 为了图像相关性考虑如果平均的QP大于之前P图像的QP-2，减少PAverageQpPAverageQp--;PAverageQp = MAX(QPLastGOP-2, PAverageQp);限定范围在上个GOP的QP值+-2范围内PAverageQp = MIN(QPLastGOP+2, PAverageQp);PAverageQp = MIN(RC_MAX_QUANT, PAverageQp);限定范围在0-51PAverageQp = MAX(RC_MIN_QUANT, PAverageQp);MyInitialQp=PAverageQp;QPLastGOP = MyInitialQp;更新上一个gop的QPPm_Qp=PAverageQp;PAveFrameQP=PAverageQp;PreviousQp1=PreviousQp2;PreviousQp2=MyInitialQp-1;}img->TotalQpforPPicture=0;清TotalQpforPPicture为当前GOP重新QP重新累加用img->NumberofPPicture=0; 当前GOP还没编码编码的P图像数目 NumberofPPicture为0NumberofBFrames=0; 当前GOP还没编码编码的B图像数目 NumberofPPicture为0}作者: kingdexing 时间: 2008-9-18 10:07初始化图像层输入fieldpic＝０场编码图像　１　桢编码图像　topfield １　是顶场void rc_init_pict(int fieldpic,int topfield,int targetcomputation)targetcomputation是否计算目标缓冲等级为1表示计算{int i;/*compute the total number of basic units in a frame*/计算１桢中BU（基本单元）的数目，用１桢中总宏块数目除BU中宏块数　这里说下图像img->BasicUnit和输入参数　input->basicunit区别毕竟在在场模式和桢场自适应模式img->BasicUnit=input->basicunit*2;只有桢模式img->BasicUnit=input->basicunit;也就是说在场模式和桢场自适应模式中BU中宏块数目是２倍只有在桢模式中BU宏块数目if(input->MbInterlace)在场模式和桢场自适应模式TotalNumberofBasicUnit=img->Frame_Total_Number_MB/img->BasicUnit;img->NumberofCodedMacroBlocks=0;当前图像还未编码　所以编码的宏块数目为０/*Normally, the bandwith for the VBR case is estimated bya congestion control algorithm. A bandwidth curve can be predefined if we only want totest the proposed algorithm*/这里为了做VBR（变速率）逻辑测试　定义个带宽的曲线设置　当第５９个已编码P图像时候速率　上升到1.5倍　当第６０个P图像速率恢复以前 if(input->channel_type==1){if(img->NumberofCodedPFrame==58)bit_rate *=1.5;else if(img->NumberofCodedPFrame==59)PreviousBit_Rate=bit_rate;}/*predefine a target buffer level for each frame*/为每桢图像　预先设置目标缓冲水平if((fieldpic||topfield)&&targetcomputation){switch (img->type){case P_SLICE:P图像因为带宽是实时变化地，所以R中可用位数必须１个图像１个图像地更新按照原理公式Tr(i,j)=Tr(i,j-1)+ (u(i,j)-u(i,j-1))*(Ngop-j)/Fr-b(i,j-1)　i代表第i个gop　j代表第j个图像Tr是gop中可分配的位元，u是带宽,Fr桢速率，b是已编码产生的位数上面公式这样理解，当前图像可用的位数，等于上一个图像可用位数减去带宽变化和上个图像产生的编码位数/*Since the available bandwidth may vary at any time, the total number ofbits is updated picture by picture*/if(PreviousBit_Rate!=bit_rate)R +=(int) floor((bit_rate-PreviousBit_Rate)*(Np+Nb)/frame_rate+0.5); 是 (u(i,j)-u(i,j-1))*(Ngop-j)/Fr/* predefine the target buffer level for each picture.frame layer rate control*/设定桢层速率控制为每个图像设定缓冲水平TargetBufferLevelTbl(i,2)=Bc(i,2) Bc(i,2)是第i个gop第1个P图像编码完毕后实际缓冲占有率TBL(i,j+1)=TBL(i,j)-Tbl(i,2)/Np-1+AWp(i,j)*(L+1)*u(i,j)/Fr*AWp(i,j)*AWb(i,j)*L-u(i,j)/Fr AWp AWb为了计算复杂度的权if(img->BasicUnit==img->Frame_Total_Number_MB)如果BU内宏块数目等于桢中宏块数目{if(img->NumberofPPicture==1)已经编码一个P图像目标缓冲水平等于当前缓冲占有率 Tbl(i,2)=Bc(i,2){因为起始CurrentBufferFullness=0 GOPTargetBufferLevel=0 更新 CurrentBufferFullness += nbits - bit_rate/frame_rate;编码位数减去流出其实也可以CurrentBufferFullness=BufferSize/8 GOPTargetBufferLevel=BufferSize/8 在带宽波动的情况下留点裕度这样可以保证流体流动通信模型（fluid flow traffic model）HRD缓存是不会向上或者向下溢出的TargetBufferLevel=CurrentBufferFullness;DeltaP=(CurrentBufferFullness-GOPTargetBufferLevel)/(TotalPFrame-1); 这里DeltaP=-Tbl(i,2)/Np-1 GOPTargetBufferLevel=0不考虑了 TargetBufferLevel -=DeltaP; TBL(i,j)-DeltaP}else if(img->NumberofPPicture>1)TargetBufferLevel -=DeltaP; TBL(i,j)-DeltaP}/*basic unit layer rate control*/else{if(img->NumberofCodedPFrame>0)已编码P图像的数目大于0{/*adaptive frame/filed coding*/if(((input->;PicInterlace==ADAPTIVE_CODING)||(input->MbInterlace))\&&(img->FieldControl==1))在图像桢场自适应和宏块场编码或宏块桢场自适应且FieldControl=1场编码情况一句话宏块场编码情况{ TotalNumberofBasicUnit是图像中BU数目注意这里的图像即可以指场图像也可以指桢图像for(i=0;i<TotalNumberofBasicUnit;i++)FCBUPFMAD是之前场控制编码mad,FCBUCFMAD是当前场控制编码madFCBUPFMAD=FCBUCFMAD; 更新之前场控制编码mad,因为该图像已经编码完毕}else{for(i=0;i<TotalNumberofBasicUnit;i++) 桢编码模式 BUPFMAD是之前mad,BUCFMAD是当前madBUPFMAD=BUCFMAD;}}if(img->NumberofGOP==1)第1个gop第2个p图像开始计算tbl{if(img->NumberofPPicture==1)已经编码一个P图像目标缓冲水平等于当前缓冲占有率 Tbl(i,2)=Bc(i,2){因为起始CurrentBufferFullness=0 GOPTargetBufferLevel=0 更新 CurrentBufferFullness += nbits - bit_rate/frame_rate;编码位数减去流出其实也可以CurrentBufferFullness=BufferSize/8 GOPTargetBufferLevel=BufferSize/8 在带宽波动的情况下留点裕度这样可以保证流体流动通信模型（fluid flow traffic model）HRD缓存是不会向上或者向下溢出的TargetBufferLevel=CurrentBufferFullness;DeltaP=(CurrentBufferFullness-GOPTargetBufferLevel)/(TotalPFrame-1);这里DeltaP=-Tbl(i,2)/Np-1 GOPTargetBufferLevel=0不考虑了TargetBufferLevel -=DeltaP; TBL(i,j)-DeltaP}else if(img->NumberofPPicture>1)已当前GOP编码P图像数目大于1个TargetBufferLevel -=DeltaP; TBL(i,j)-DeltaP}else if(img->NumberofGOP>1)第2 3....个GOP第1个P开始就计算tbl用来自GOP的I桢编码后的当前缓冲占有率{if(img->NumberofPPicture==0){TargetBufferLevel=CurrentBufferFullness;DeltaP=(CurrentBufferFullness-GOPTargetBufferLevel)/TotalPFrame;TargetBufferLevel -=DeltaP;}else if(img->NumberofPPicture>0)TargetBufferLevel -=DeltaP;}}AWp和AWb的更新公式AWP=AWp/8+7*Wp/8 AWb=AWb/8+7*Wb/8 Wb=b(i,j)*QPb(i,j)/1.3636 Wp=b(i,j)*QPp(i,j)if(img->NumberofCodedPFrame==1)如果第1个P图像已编码AWp=WpAWp=Wp;如果以编码P图像小于8且大于1 用已编码图像1/NumberofCodedPFrame做加权毕竟已编码P数目小于8,用1/8加权平滑不合适if((img->NumberofCodedPFrame<8)&&(img->NumberofCodedPFrame>1))AWp=Wp*(img->NumberofCodedPFrame-1)/img->NumberofCodedPFrame+\AWp/img->NumberofCodedPFrame;else if(img->NumberofCodedPFrame>1)已编码P图像大于8的话用已编码图像1/8做加权AWP=AWp/8+7*Wp/8AWp=Wp/8+7*AWp/8;//compute the average complexity of B frames这里tbl+=AWp(i,j)*(L+1)*u(i,j)/Fr*AWp(i,j)*AWb(i,j)*L L表示后续B桢数目理解成2个P图像之间B的数目就好input->successive_Bframe就是Lif(input->successive_Bframe>0){//compute the target buffer levelTargetBufferLevel +=(AWp*(input->successive_Bframe+1)*bit_rate\/(frame_rate*(AWp+AWb*input->successive_Bframe))-bit_rate/frame_rate);}break;case B_SLICE:/* update the total number of bits if the bandwidth is changed*/按照原理公式Tr(i,j)=Tr(i,j-1)+ (u(i,j)-u(i,j-1))*(Ngop-j)/Fr-b(i,j-1)　if(PreviousBit_Rate!=bit_rate)带宽变动情况下Gop中可用位数R必须修正,修正值u(i,j)-u(i,j-1))*(Ngop-j)/FrR +=(int) floor((bit_rate-PreviousBit_Rate)*(Np+Nb)/frame_rate+0.5);if((img->NumberofCodedPFrame==1)&&(img->NumberofCodedBFrame==1))编码第1个P和编码第1个B图像后如下初始化复杂度参数AWp {AWp=Wp;AWb=Wb;}else if(img->NumberofCodedBFrame>1)如果已编码的B数目大于1{//compute the average weightAWb的更新公式AWb=AWb/8+7*Wb/8 在已编码的B数目大小于8 加权系数取1/NumberofCodedBFrameif(img->NumberofCodedBFrame<8)AWb=Wb*(img->NumberofCodedBFrame-1)/img->NumberofCodedBFrame+\AWb/img->NumberofCodedBFrame;elseAWb=Wb/8+7*AWb/8;}break;}/*Compute the target bit for each frame*/计算每个桢的目标位数,为什么要这一步呢,理解如下如果实际缓冲的等级等同于我们的目标缓冲等级,当然可以保证每个GOP都精确分配到位数,但是R-D模型和mad预测模型是不精确地,导致实际缓冲水平和目标位元等级的误差较大,那么我们需要计算每张图像的目标位数用来降低实际缓冲水平和目标位元之间的误差,这就是细节控制如同往杯子里面倒水,如果要正好倒1升水, 当然1滴1滴倒最好了!if(img->type==P_SLICE) P图像模式{/*frame layer rate control*/if(img->BasicUnit==img->Frame_Total_Number_MB)BU中宏块数目等于桢中宏块数目{if(img->NumberofCodedPFrame>0)已编码的P数目大于1{通过Gop中R可用位数计算T是图像可用位数,公式如下f(i,j)=Wp(i,j-1)*Tr/(Wp(i,j-1)*Np+Wb(i,j-1)*Nb)也就是T = Wp*R/(Np*Wp+Nb*Wb)T = (long) floor(Wp*R/(Np*Wp+Nb*Wb) + 0.5);T是图像可用位数,当然是Gop中R可用位数下面考虑到第i个Gop的第J个图像的目标分配位数由目标缓冲等级Tbl=TargetBufferLevel 实际缓冲区占有率Bc(i,j)=CurrentBufferFullness 频宽u(i,j)=bit_rateGAMMAP在有B图像的情况下GAMMAP=0.25; 无B图像的情况下GAMMAP=0.5;为什么有B图像比无B图像GAMMAP要小,我这样理解,B编码产生位数少,当然需要减去的实际和目标的误差系数小公式f1=u(i,j)/Fr+gamma*(Tbl(i,j)-Bc(i,j))T1 = (long) floor(bit_rate/frame_rate-GAMMAP*(CurrentBufferFullness-TargetBufferLevel)+0.5);T1=MAX(0,T1);目标可用位数f(i,j)由f(i,j)和f1加权得到f(i,j)=beta*f(i,j)+(1-beta)*f1beta在没有B图像情况下beta=0.5 有B图像的情况下是0.9这说明有B图像情况主要由f(i,j)自身决定T = (long)(floor(BETAP*T+(1.0-BETAP)*T1+0.5));}}/*basic unit layer rate control*/基本单元层控制else{if((img->NumberofGOP==1)&&(img->NumberofCodedPFrame>0))第1个GOP并且已编码P数目大于0{通过Gop中R可用位数计算T是图像可用位数,公式如下:f(i,j)=Wp(i,j-1)*Tr/(Wp(i,j-1)*Np+Wb(i,j-1)*Nb)T = (int) floor(Wp*R/(Np*Wp+Nb*Wb) + 0.5);T1 = (int) floor(bit_rate/frame_rate-GAMMAP*(CurrentBufferFullness-TargetBufferLevel)+0.5);T1=MAX(0,T1);T = (int)(floor(BETAP*T+(1.0-BETAP)*T1+0.5));}else if(img->NumberofGOP>1)第2 3 .....个GOP{T = (long) floor(Wp*R/(Np*Wp+Nb*Wb) + 0.5);T1 = (long) floor(bit_rate/frame_rate-GAMMAP*(CurrentBufferFullness-TargetBufferLevel)+0.5);T1 = MAX(0,T1);T = (long)(floor(BETAP*T+(1.0-BETAP)*T1+0.5));}}/*reserve some bits for smoothing*/保留一些位数为了平滑很荒唐吧0.0*input->successive_Bframe估计0.0是个可调系数调整T中可用位数T=(long)((1.0-0.0*input->successive_Bframe)*T);/*HRD consideration*/保证图像可用位数T永远在[LowerBound,UpperBound2]范围内//这里的LowerBound和UpperBound2在图像编码结束后会调用rc_update_pict更新地//通过流出减去编码位数,如果流出大于流入(图像编码位数),瓶子空的更多了表示有更多可用的位数那么当前图像可用位数上下限应该增加 //如果流出大于流入(图像编码位数),表示有可用的位数减少瓶子空间更少了那么当前图像可用位数上下限应该减少//LowerBound +=(long)(bit_rate/frame_rate-nbits);//UpperBound1 +=(long)(bit_rate/frame_rate-nbits); UpperBound2 = (long)(OMEGA*UpperBound1); OMEGA=0.9保证裕度T = MAX(T, (long) LowerBound);T = MIN(T, (long) UpperBound2);if((topfield)||(fieldpic&&((input->;PicInterlace==ADAPTIVE_CODING)\||(input->MbInterlace))))场编码情况T_field=T;}}if(fieldpic||topfield)桢编码或者顶场编码{/*frame layer rate control*/图像层速率控制也叫桢层速率控制img->NumberofHeaderBits=0;还未编码先把头信息位数NumberofHeaderBits和纹理信息位数NumberofTextureBits清0img->NumberofTextureBits=0;/*basic unit layer rate control*/只有在BU中宏块小于桢中宏块数目才存在BU基本单元控制if(img->BasicUnit<img->Frame_Total_Number_MB){TotalFrameQP=0; 图像内所有BU的QP和img->NumberofBasicUnitHeaderBits=0; 头信息位数NumberofHeaderBitsimg->NumberofBasicUnitTextureBits=0;纹理信息位数NumberofTextureBitsimg->TotalMADBasicUnit=0; 图像内所有BU的MAD和TotalMADBasicUnitif(img->FieldControl==0)桢编码NumberofBasicUnit=TotalNumberofBasicUnit;else 场编码NumberofBasicUnit=TotalNumberofBasicUnit/2;}}if((img->type==P_SLICE)&&(img->BasicUnit<img->Frame_Total_Number_MB)\&&(img->FieldControl==1)){/*top filed at basic unit layer rate control*/顶场编码在BU层速率控制if(topfield){bits_topfield=0;T=(long)(T_field*0.6);顶场可用位数//顶场和底场的一共的可用位数T_field 0.6系数说明顶场编码重要性可能作参考场}/*bottom filed at basic unit layer rate control*/else{T=T_field-bits_topfield;场可用的位数T_field减去顶场编码产生的位数bits_topfield得到底场可用的位数img->NumberofBasicUnitHeaderBits=0;头信息位数NumberofHeaderBitsimg->NumberofBasicUnitTextureBits=0;纹理信息位数NumberofTextureBitsimg->TotalMADBasicUnit=0;图像内所有BU的MAD和TotalMADBasicUnitNumberofBasicUnit=TotalNumberofBasicUnit/2;场编码每个场中BU数目自然为桢BU数目的1半}}}作者: kingdexing 时间: 2008-9-18 11:46//calculate MAD for the current macroblock 计算当前宏块的MAD,diff是像素Y原值减去预测值MAD=sum(abs(diff))/256double calc_MAD(){int k,l;int s = 0;double MAD;for (k = 0; k < 16; k++)for (l = 0; l < 16; l++)s+= abs(diffy[k][l]);MAD=s*1.0/256;return MAD;}// update one picture after frame/field encoding在桢场编码后更新一个图像参数void rc_update_pict(int nbits){R-= nbits; /* remaining # of bits in GOP */GOP中剩余可用位数R,必须减去上个图像编码产生位数CurrentBufferFullness += nbits - bit_rate/frame_rate;当前缓冲满度用流入减去流出修正/*update the lower bound and the upper bound for the target bits of each frame, HRD consideration*///通过流出减去编码位数,如果流出大于流入(图像编码位数),瓶子空的更多了表示有更多可用的位数那么当前图像可用位数上下限应该增加 //如果流出大于流入(图像编码位数),表示有可用的位数减少瓶子空间更少了那么当前图像可用位数上下限应该减少LowerBound +=(long)(bit_rate/frame_rate-nbits);UpperBound1 +=(long)(bit_rate/frame_rate-nbits);OMEGA=0.9保证裕度UpperBound2 = (long)(OMEGA*UpperBound1);return;}// update after frame encoding 在桢编码后更新RCvoid rc_update_pict_frame(int nbits){/*update thecomplexity weight of I, P, B frame*/更新I P B的复杂度权int Avem_Qc; Avem_Qc是所有BU的QP平均值int X;/*frame layer rate control*/图象层速率控制I P B的复杂度权Wb=b(i,j)*QPb(i,j)/1.3636 Wp=b(i,j)*QPp(i,j) nbits=b(i,j)if(img->BasicUnit==img->Frame_Total_Number_MB)BU的宏块数目等于桢内宏块数目X = (int) floor(nbits*m_Qc+ 0.5);注意是m_Qc nbits编码产生位数/*basic unit layer rate control*/基本单元层速率控制else{if(img->type==P_SLICE)P图像模式{if(((img->IFLAG==0)&&(img->FieldControl==1))\场编码且不是第1个GOP的第1个I场图像 IFLAG=1可能代表seq的第1个场 ||(img->FieldControl==0))桢编码{Avem_Qc=TotalFrameQP/TotalNumberofBasicUnit;求出平均基本单元QcX=(int)floor(nbits*Avem_Qc+0.5);}}else if(img->type==B_SLICE)B图像模式X = (int) floor(nbits*m_Qc+ 0.5);}//I P B的复杂度权Wb=b(i,j)*QPb(i,j)/1.3636 Wp=b(i,j)*QPp(i,j) nbits=b(i,j)switch (img->type){case P_SLICE:/*filed coding*/if(((img->IFLAG==0)&&(img->FieldControl==1))\\场编码且不是第1个GOP的第1个I场图像||(img->FieldControl==0))桢图像{Xp = X;Np--; 已编码P图像了所以未编码P图像减1Wp=Xp;Pm_Hp=img->NumberofHeaderBits;头信息位数img->NumberofCodedPFrame++;已编码P图像数目NumberofCodedPFrameimg->NumberofPPicture++; 已编码P图像数目NumberofPPicture}else if((img->IFLAG!=0)&&(img->FieldControl==1))第1个GOP的第1个I场图像已经编码,那么此标志清0img->IFLAG=0;break;case B_SLICE:Xb = X;Nb--;已编码B图像了所以未编码P图像减1Wb=Xb/THETA; 来自Wb=b(i,j)*QPb(i,j)/1.3636 THETA=1.3636img->NumberofCodedBFrame++;已编码B图像数目NumberofCodedBFrameNumberofBFrames++; 已编码P图像数目NumberofCodedBFramebreak;}}// coded bits for top field 顶场编码产生的位数bits_topfieldvoid setbitscount(int nbits){bits_topfield = nbits;}作者: kingdexing 时间: 2008-9-18 11:47先休息下,估计要1星期才能把上10万行的代码,完全详细分析完毕!作者: kingdexing 时间: 2008-9-19 13:40//compute a quantization parameter for each frame计算每桢量化参数int updateQuantizationParameter(int topfield){double dtmp;记得初中学过的二次方程式吧其实就是delta=sqrt(b*b-4*a*c)int m_Bits;int BFrameNumber;int StepSize;int PAverageQP;int SumofBasicUnit;int i;/*frame layer rate control*/桢层速率控制if(img->BasicUnit==img->Frame_Total_Number_MB)BU内宏块数目等于桢内宏块数目自然不存在BU控制问题啦{/*fixed quantization parameter is used to coded I frame, the first P frame and the first B framethe quantization parameter is adjusted according the available channel bandwidth andthe type of vide*//*top field*/if((topfield)||(img->FieldControl==0))是顶场或者场控制信号为0{if(img->type==I_SLICE)I条带情况 m_qc取初始值{m_Qc=MyInitialQp;return m_Qc;}else if(img->type==B_SLICE)B条带{if(input->successive_Bframe==1)P与P之间只有1个B情况{successive_Bframe=1对1求余任何整数都是0阿下面的就可笑了,毫无意义BFrameNumber=(NumberofBFrames+1)%input->successive_Bframe;if(BFrameNumber==0)在这里又修正BFrameNumber=1说明BFrameNumber表示在2个P图像中的第几个Ｂ图像　真垃圾代码阿BFrameNumber=input->successive_Bframe;因为successive_Bframe＝１说明在2个P图像中只有１个Ｂ图像BFrameNumber只可能为１/*adaptive field/frame coding*/else if(BFrameNumber==1){当L=1表示2个P图像之间有1个B图像公式如下:QB1=(QP1+QP2+2)/2 当QP1!=QP2QB1=QP1+2 当QP1 =QP2if((input->icInterlace==ADAPTIVE_CODING)\||(input->MbInterlace)){if(img->FieldControl==0)场控制关闭{/*previous choice is frame coding*/if(img->FieldFrame==1)之前选择是桢编码{PreviousQp1=PreviousQp2;例如P1B1P2B2P3当前是B1则PreviousQp1代表P1图像,PreviousQp2=P2PreviousQp2=FrameQPBuffer;}/*previous choice is field coding*/else之前选择是场编码{PreviousQp1=PreviousQp2;PreviousQp2=FieldQPBuffer;}}}}// m_Qc=QB1=(QP1+QP2+2)/2 当QP1!=QP2// m_Qc=QB1=QP1+2 当QP1 =QP2if(PreviousQp1==PreviousQp2)m_Qc=PreviousQp1+2;elsem_Qc=(PreviousQp1+PreviousQp2)/2+1;m_Qc = MIN(m_Qc, RC_MAX_QUANT); // clipping钳位0-51m_Qc = MAX(RC_MIN_QUANT, m_Qc);//clipping}else{//L=successive_Bframe>1 下面求余就有意义了说明BFrameNumber表示在2个P图像中的第几个Ｂ图像这样举例把L=2 PB1B2PB3B4P那么NumberofBFrames=2已编码的B数目是2那么当前是第3个B实际B3,BFrameNumber=1在实际P与P的位置是1已编码的B数目是3那么当前是第3个B实际B3,BFrameNumber=2通过对后续B的数目求余求得当前B在P 与P的位置BFrameNumber=(NumberofBFrames+1)%input->successive_Bframe;if(BFrameNumber==0)上面再NumberofBFrames=3时候求于地BFrameNumber＝０必须修正为２BFrameNumber=input->successive_Bframe;/*adaptive field/frame coding*/else if(BFrameNumber==1){　更新之前两个P图像的QP值因为是第１个B所以需要更新，其他B与第１个B采用的参考P是一致的作考虑if((input->icInterlace==ADAPTIVE_CODING)\||(input->MbInterlace))图像自适应编码或帧编码{if(img->FieldControl==0)场控制信号关闭当前图像可以使桢编码也可以是场编码{　更新之前两个P图像的QP值/*previous choice is frame coding*/if(img->FieldFrame==1)图像选择是桢编码　{PreviousQp1=PreviousQp2;PreviousQp2=FrameQPBuffer;}/*previous choice is field coding*/else图像选择是场编码{PreviousQp1=PreviousQp2;PreviousQp2=FieldQPBuffer;}}}}当L>1表示两张P图像插入多张B图像公式如下:QBi=QP1+alpha+max{min{(QP2-QP1)/(L-1),2*(i-1)},-2*(i-1)}alpha取值如下:alpha=-3 if QP2-QP1<=-2*L-3alpha=-2 if QP2-QP1=-2*L-2alpha=-1 if QP2-QP1=-2*L-1alpha=0 if QP2-QP1=-2*Lalpha=1 if QP2-QP1=-2*L+1alpha=2 其他情况为什么需要alpha=StepSize修正QB,估计是按照２个P图像的Qp差deltaQ和L的关系，做个平滑处理，避免图像质量差别过大if((PreviousQp2-PreviousQp1)<=(-2*input->successive_Bframe-3))StepSize=-3;else if((PreviousQp2-PreviousQp1)==(-2*input->successive_Bframe-2))StepSize=-2;else if((PreviousQp2-PreviousQp1)==(-2*input->successive_Bframe-1))StepSize=-1;else if((PreviousQp2-PreviousQp1)==(-2*input->successive_Bframe))StepSize=0;else if((PreviousQp2-PreviousQp1)==(-2*input->successive_Bframe+1))StepSize=1;elseStepSize=2;m_Qc=PreviousQp1+StepSize;下面按照max{min{(QP2-QP1)/(L-1),2*(i-1)},-2*(i-1)}修正　估计保证播放顺序靠近第１个P的修正更加接近第１个P的Qp,接近第２个P图像的修正更加接近第２个P的Qp，也是为了做个平滑处理，避免图像质量差别过大m_Qc +=MIN(2*(BFrameNumber-1),MAX(-2*(BFrameNumber-1), \(BFrameNumber-1)*(PreviousQp2-PreviousQp1)/(input->successive_Bframe-1)));m_Qc = MIN(m_Qc, RC_MAX_QUANT); // clipping钳位0-51m_Qc = MAX(RC_MIN_QUANT, m_Qc);//clipping}return m_Qc;}else if((img->type==P_SLICE)&&(img->NumberofPPicture==0))当前是P图像并且已编码的P图像数目是０{m_Qc=MyInitialQp; MyInitialQp是GOP的QPif(img->FieldControl==0)场控制关闭{if(active_sps->frame_mbs_only_flag)只有桢模式桢宏块编码{img->TotalQpforPPicture +=m_Qc;TotalQpforPPicture表示GOP内已编码P图像Qp和PreviousQp1=PreviousQp2;更新2个P图像QcPreviousQp2=m_Qc;Pm_Qp=m_Qc;}/*adaptive field/frame coding*/自适应桢场模式elseFrameQPBuffer=m_Qc; FrameQPBuffer桢QP缓冲}return m_Qc;}else{/*adaptive field/frame coding*/if(((input->icInterlace==ADAPTIVE_CODING)\图像自适应桢场模式||(input->MbInterlace))\宏块场模式或自适应桢场模式&&(img->FieldControl==0))场控制关闭{/*previous choice is frame coding*/if(img->FieldFrame==1)桢模式{img->TotalQpforPPicture +=FrameQPBuffer;TotalQpforPPicture表示GOP内已编码P图像Qp和Pm_Qp=FrameQPBuffer;}/*previous choice is field coding*/else场模式{img->TotalQpforPPicture +=FieldQPBuffer;Pm_Qp=FieldQPBuffer;}}下面是2次r-d模型系数具体模型推导由taylor级数推导以后有时间相信写个RD模型推导(R-H)/MAD=C1/Qstep+C2/(Qstep*Qstep) 这里m_X1 m_X2就是C1 C2这里是(T-H)/MAD=MADPictureC1/Qstep+MADPictureC2/(Qstep*Qstep)m_X1=Pm_X1;m_X2=Pm_X2;m_Hp=PPreHeader;之前的头信息位数m_Qp=Pm_Qp;m_QP是m_可能代表宏块，因为BU宏块等于桢宏块数目，所以m_qp等于P图像Pm_Qp//PDuantQp=2;估计可用于对图像Qpc=min{Qpp+2,max(Qpp-2,Qpc)}进行clip，保证图像层Qpc在之前图像Qpp+-2范围内//保证当前和之前图像质量相差不大DuantQp=PDuantQp;MADPictureC1=PMADPictureC1; PMADPictureC1是预测MADMADPictureC2=PMADPictureC2; PMADPictureC2是预测MADPreviousPictureMAD=PPictureMAD[0]reviousPictureMAD之前图像MAD/* predict the MAD of current picture*/预测当前图像MADMADc=a1*MADp+a2 MADPictureC1=a1 MADPictureC2=a2 MADp是前1张图像对应位置的MAD,预测待编码基本单元的MAD 因为BU宏块等于桢宏块数目，所以直接用图像的MAD值PreviousPictureMADCurrentFrameMAD=MADPictureC1*PreviousPictureMAD+MADPictureC2;/*compute the number of bits for the texture*/if(T<0)T是图像可用位数，如果小于0，需要调大当前图像QP，减少位数{m_Qc=m_Qp+DuantQp;调大当前图像QPm_Qc = MIN(m_Qc, RC_MAX_QUANT); // clipping保证不大于最大量化步长51}else{公式(T-H)/MAD=MADPictureC1/Qstep+MADPictureC2/(Qstep*Qstep)m_Bits =T-m_Hp;去除头信息//MINVALUE=4.0; 在基本单元层分配基本单元的位数R R= MAX(R, (int)(bit_rate/(MINVALUE*frame_rate*TotalNumberofBasicUnit))); //这里TotalNumberofBasicUnit=1所以不存在基本单元层直接如下拉m_Bits = MAX(m_Bits, (int)(bit_rate/(MINVALUE*frame_rate)));dtmp = CurrentFrameMAD * m_X1 * CurrentFrameMAD * m_X1 \ //dtmp是2次方程式delta如果这都不懂回去练初中+ 4 * m_X2 * CurrentFrameMAD * m_Bits;//下面是2次方程式求解初中数学不详细推了if ((m_X2 == 0.0) || (dtmp < 0) || ((sqrt (dtmp) - m_X1 * CurrentFrameMAD) <= 0.0)) // fall back 1st order modem_Qstep = (float) (m_X1 * CurrentFrameMAD / (double) m_Bits);else // 2nd order modem_Qstep = (float) ((2 * m_X2 * CurrentFrameMAD) / (sqrt (dtmp) - m_X1 * CurrentFrameMAD));量化步长m_Qstep和量化索引QP关系：量化索引+6那么量化步长翻倍！量化索引+1那么量化索引增加12.5%和我们的uniform均一量化有区别吧具体为什么可能由于概率密度函数决定地量化概率分布和失真的关系吧求出0-51的量化索引m_qc吧m_Qc=Qstep2QP(m_Qstep);下面是保证+-2和1-51量化钳位保证图像质量前后差别不大，量化参数不超过上下限m_Qc = MIN(m_Qp+DuantQp, m_Qc); // control variationm_Qc = MIN(m_Qc, RC_MAX_QUANT); // clippingm_Qc = MAX(m_Qp-DuantQp, m_Qc); // control variationm_Qc = MAX(RC_MIN_QUANT, m_Qc);}if(img->FieldControl==0)场信号控制关闭{/*frame coding*/if(active_sps->frame_mbs_only_flag)只有宏块桢模式{img->TotalQpforPPicture +=m_Qc;TotalQpforPPicture表示GOP内已编码P图像Qp和 PreviousQp1=PreviousQp2;2个P图像的QP中间参数更新PreviousQp2=m_Qc;Pm_Qp=m_Qc;}/*adaptive field/frame coding*/自适应桢场模式elseFrameQPBuffer=m_Qc;}return m_Qc;}}/*bottom field*/底场不说了写到手麻else{if((img->type==P_SLICE)&&(img->IFLAG==0)){/*field coding*/if(input->icInterlace==FIELD_CODING){img->TotalQpforPPicture +=m_Qc;PreviousQp1=PreviousQp2+1;PreviousQp2=m_Qc;//+0 Recent change 13/1/2003Pm_Qp=m_Qc;}/*adaptive field/frame coding*/elseFieldQPBuffer=m_Qc;}return m_Qc;}}/*basic unit layer rate control*/基本单元速率控制下面和前面基本相似不多少说了作者: kingdexing 时间: 2008-9-19 13:46看我写的h.264代码理解基本每句都能帮助你理解把代码当小说看就不会累了人为什么看小说1天能1本看代码不行呢就是因为你是热爱喜欢还是功利性质地想懂!作者: kingdexing 时间: 2008-9-19 21:25/*basic unit layer rate control*/基本单元速率控制下面和前面基本相似不多少说了else{/*top filed of I frame*/if(img->type==I_SLICE)I图像{m_Qc=MyInitialQp;直接用GOP的QPreturn m_Qc;}/*bottom field of I frame*/是P条带场控制开启//还有待修改注释else if((img->type==P_SLICE)&&(img->IFLAG==1)&&(img->FieldControl==1)){m_Qc=MyInitialQp;直接用GOP的QPreturn m_Qc;}else if(img->type==B_SLICE)B条带{/*top filed of B frame*/顶场if((topfield)||(img->FieldControl==0))场控制关闭{if(input->successive_Bframe==1){BFrameNumber只能为1前面已经分析过了BFrameNumber=(NumberofBFrames+1)%input->successive_Bframe;if(BFrameNumber==0)BFrameNumber=input->successive_Bframe;/*adaptive field/frame coding*/else if(BFrameNumber==1){if((input->PicInterlace==ADAPTIVE_CODING)\图像自适应桢场编码||(input->MbInterlace))宏块自适应或场编码{if(img->FieldControl==0){ 更新之前两个P图像的QP值/*previous choice is frame coding*/if(img->FieldFrame==1)当前图像是桢编码{PreviousQp1=PreviousQp2;PreviousQp2=FrameQPBuffer;}/*previous choice is field coding*/else当前图像是场编码{PreviousQp1=PreviousQp2;PreviousQp2=FieldQPBuffer;}}}}// m_Qc=QB1=(QP1+QP2+2)/2 当QP1!=QP2// m_Qc=QB1=QP1+2 当QP1 =QP2if(PreviousQp1==PreviousQp2)m_Qc=PreviousQp1+2;elsem_Qc=(PreviousQp1+PreviousQp2)/2+1;m_Qc = MIN(m_Qc, RC_MAX_QUANT); // clipping钳位0-51m_Qc = MAX(RC_MIN_QUANT, m_Qc);//clipping}else后续B桢大于1的情况{//BFrameNumber只能为1-successive_Bframe前面已经分析过了,代表2个P之间第几个B图像BFrameNumber=(NumberofBFrames+1)%input->successive_Bframe;if(BFrameNumber==0)BFrameNumber=input->successive_Bframe;/*adaptive field/frame coding*/else if(BFrameNumber==1){if((input->PicInterlace==ADAPTIVE_CODING)\||(input->MbInterlace))图像自适应编码或帧编码{更新之前两个P图像的QP值if(img->FieldControl==0){/*previous choice is frame coding*/if(img->FieldFrame==1){PreviousQp1=PreviousQp2;PreviousQp2=FrameQPBuffer;}/*previous choice is field coding*/else{PreviousQp1=PreviousQp2;PreviousQp2=FieldQPBuffer;}}}}参见前面写的alpha取值和为什么要这样取值if((PreviousQp2-PreviousQp1)<=(-2*input->successive_Bframe-3))StepSize=-3;else if((PreviousQp2-PreviousQp1)==(-2*input->successive_Bframe-2))StepSize=-2;else if((PreviousQp2-PreviousQp1)==(-2*input->successive_Bframe-1))StepSize=-1;else if((PreviousQp2-PreviousQp1)==(-2*input->successive_Bframe))StepSize=0;//0else if((PreviousQp2-PreviousQp1)==(-2*input->successive_Bframe+1))StepSize=1;//1elseStepSize=2;//2m_Qc=PreviousQp1+StepSize;//保证播放顺序靠近第１个P的修正更加接近第１个P的Qp,//接近第２个P图像的修正更加接近第２个P的Qp，也是为了做个平滑处理，避免图像质量差别过大m_Qc +=MIN(2*(BFrameNumber-1),MAX(-2*(BFrameNumber-1), \(BFrameNumber-1)*(PreviousQp2-PreviousQp1)/(input->successive_Bframe-1)));m_Qc = MIN(m_Qc, RC_MAX_QUANT); // clipping钳位0-51m_Qc = MAX(RC_MIN_QUANT, m_Qc);//clipping}return m_Qc;}/*bottom field of B frame*/elsereturn m_Qc;}else if(img->type==P_SLICE)P条带{if((img->NumberofGOP==1)&&(img->NumberofPPicture==0))第1个GOP并且已经编码P数目为0,也就是GOP中所有P图像都还没编码时候 {if((img->FieldControl==0)||((img->FieldControl==1)\&&(img->IFLAG==0))){/*top field of the first P frame*/第1个P的顶场,取GOP的QP初始值,因为P未编码,索以把基本单元内头信息NumberofBasicUnitHeaderBits和纹理信息NumberofBasicUnitTextureBits都清零m_Qc=MyInitialQp;img->NumberofBasicUnitHeaderBits=0;img->NumberofBasicUnitTextureBits=0;NumberofBasicUnit--;BU数目减1/*bottom field of the first P frame*/第1个P的底场if((!topfield)&&(NumberofBasicUnit==0)){/*frame coding or field coding*/if((active_sps->frame_mbs_only_flag)||(input->PicInterlace==FIELD_CODING))只有宏块桢编码或者图像场编码{img->TotalQpforPPicture +=m_Qc;当前P的Qc总数和更新PreviousQp1=PreviousQp2;PreviousQp2=m_Qc;PAveFrameQP=m_Qc;介绍下PAveHeaderBits2 PAveHeaderBits3 PAveHeaderBits1吧用于计算所有单元的头信息的位数Mhdrl第l个基本单元实际产生的头信息位数AveMhdrl=AveMhdrl*(1-1/l)+Mhdrl/l 可见l=1时AveMhdrl=MhdrlPMhdrl是前一章图像所有基本单元预测得到地 PMhdrl=AveMhdrl/Nunit+PMhdrl*(1-1/Nunit)初始化PMhdrl=0PAveHeaderBits2是表示预测BU的头信息位数也就是平均BU的头信息位数PAveHeaderBits3=PAveHeaderBits2;}/*adaptive frame/field coding*/else if((input->PicInterlace==ADAPTIVE_CODING)\||(input->MbInterlace)){if(img->FieldControl==0){FrameQPBuffer=m_Qc;FrameAveHeaderBits=PAveHeaderBits2;平均BU的头信息位数}else{FieldQPBuffer=m_Qc;FieldAveHeaderBits=PAveHeaderBits2;平均BU的头信息位数}}}Pm_Qp=m_Qc;。