HM编码器代码阅读(19)——量化

量化

理论和公式

    量化是指将信号的连续取值映射为有很多个离散幅值的过程。DCT之后，变换系数往往具有较大的动态范围，因此对变换系数进行量化可以有效减小信号取值空间，进而获得更好的压缩效果。
    量化是视频中产生失真的根本原因。

    量化器分为：标量量化器和矢量量化器两种，HEVC只使用标量量化器

    HEVC中的量化也分成两种，一种是传统的量化，另一种是率失真优化量化（RDOQ）

    更多量化方面的细节请参考 HEVC/H.265理论知识（6）——量化

传统的量化

量化的公式如下：
abs(x)=(abs(d) * MF + f_temp) >> (qbits + T_Shift)
qbits = + floor(QP/6)
MF = 2^qbits / Qstep
f_temp = f << (qbits + T_Shift)
一般情况下，对于I帧，f=1/3，对于P、B帧，f=1/6
x是量化后的系数
d是量化之前的系数

率失真优化量化

HEVC中除了普通的量化方法之外还有一种率失真优化量化（RDOQ）

变换和量化的入口函数

变换和量化的入口函数是TComTrQuant::transformNxN：
（1）首先判断是否确实需要变换量化
（2）如果使用了跳过变换的模式，那么调用xTransformSkip进行处理；否则调用xT进行变换处理
（3）调用xQuant函数进行量化

// 变换和量化！！！！！Void TComTrQuant::transformNxN( TComDataCU* pcCU, Pel*        pcResidual, UInt        uiStride, TCoeff*     rpcCoeff, #if ADAPTIVE_QP_SELECTIONInt*&       rpcArlCoeff, #endifUInt        uiWidth, UInt        uiHeight, UInt&       uiAbsSum, TextType    eTType, UInt        uiAbsPartIdx,Bool        useTransformSkip){// 判断是否跳过变换量化步骤，如果跳过的话，那么变换量化系数直接就是残差系数if (pcCU->getCUTransquantBypass(uiAbsPartIdx)){uiAbsSum=0;for (UInt k = 0; k<uiHeight; k++){for (UInt j = 0; j<uiWidth; j++){rpcCoeff[k*uiWidth+j]= pcResidual[k*uiStride+j];uiAbsSum += abs(pcResidual[k*uiStride+j]);}}return;}// 亮度块的帧内预测模式UInt uiMode;  //luma intra predif(eTType == TEXT_LUMA && pcCU->getPredictionMode(uiAbsPartIdx) == MODE_INTRA ){uiMode = pcCU->getLumaIntraDir( uiAbsPartIdx );}else{uiMode = REG_DCT;}uiAbsSum = 0;assert( (pcCU->getSlice()->getSPS()->getMaxTrSize() >= uiWidth) );Int bitDepth = eTType == TEXT_LUMA ? g_bitDepthY : g_bitDepthC;// 使用变换跳过模式if(useTransformSkip){// 变换xTransformSkip(bitDepth, pcResidual, uiStride, m_plTempCoeff, uiWidth, uiHeight );}else{// 变换xT(bitDepth, uiMode, pcResidual, uiStride, m_plTempCoeff, uiWidth, uiHeight );}// 量化函数xQuant( pcCU, m_plTempCoeff, rpcCoeff,#if ADAPTIVE_QP_SELECTIONrpcArlCoeff,#endifuiWidth, uiHeight, uiAbsSum, eTType, uiAbsPartIdx );}

量化操作

普通量化

/*** 量化操作*/Void TComTrQuant::xQuant( TComDataCU* pcCU, Int*        pSrc, TCoeff*     pDes, #if ADAPTIVE_QP_SELECTIONInt*&       pArlDes,#endifInt         iWidth, Int         iHeight, UInt&       uiAcSum, TextType    eTType, UInt        uiAbsPartIdx ){// 原始系数Int*   piCoef    = pSrc;// 变换后的系数TCoeff* piQCoef   = pDes;// 自适应量化系数选择#if ADAPTIVE_QP_SELECTIONInt*   piArlCCoef = pArlDes;#endifInt   iAdd = 0;Bool useRDOQ = pcCU->getTransformSkip(uiAbsPartIdx,eTType) ? m_useRDOQTS:m_useRDOQ;if ( useRDOQ && (eTType == TEXT_LUMA || RDOQ_CHROMA)){#if ADAPTIVE_QP_SELECTIONxRateDistOptQuant( pcCU, piCoef, pDes, pArlDes, iWidth, iHeight, uiAcSum, eTType, uiAbsPartIdx );#elsexRateDistOptQuant( pcCU, piCoef, pDes, iWidth, iHeight, uiAcSum, eTType, uiAbsPartIdx );#endif}else{/* ** 传统的量化方式** abs(x)=(abs(d) * MF + f_temp) >> (qbits + T_Shift)** qbits = + floor(QP/6)** MF = 2^qbits / Qstep** f_temp = f << (qbits + T_Shift)** 一般情况下，对于I帧，f=1/3，对于P、B帧，f=1/6** x是量化后的系数** d是量化之前的系数*/const UInt   log2BlockSize   = g_aucConvertToBit[ iWidth ] + 2;UInt scanIdx = pcCU->getCoefScanIdx(uiAbsPartIdx, iWidth, eTType==TEXT_LUMA, pcCU->isIntra(uiAbsPartIdx));const UInt *scan = g_auiSigLastScan[ scanIdx ][ log2BlockSize - 1 ];Int deltaU[32*32] ;#if ADAPTIVE_QP_SELECTIONQpParam cQpBase;Int iQpBase = pcCU->getSlice()->getSliceQpBase();Int qpScaled;Int qpBDOffset = (eTType == TEXT_LUMA)? pcCU->getSlice()->getSPS()->getQpBDOffsetY() : pcCU->getSlice()->getSPS()->getQpBDOffsetC();if(eTType == TEXT_LUMA){qpScaled = iQpBase + qpBDOffset;}else{Int chromaQPOffset;if(eTType == TEXT_CHROMA_U){chromaQPOffset = pcCU->getSlice()->getPPS()->getChromaCbQpOffset() + pcCU->getSlice()->getSliceQpDeltaCb();}else{chromaQPOffset = pcCU->getSlice()->getPPS()->getChromaCrQpOffset() + pcCU->getSlice()->getSliceQpDeltaCr();}iQpBase = iQpBase + chromaQPOffset;qpScaled = Clip3( -qpBDOffset, 57, iQpBase);if(qpScaled < 0){qpScaled = qpScaled +  qpBDOffset;}else{qpScaled = g_aucChromaScale[ qpScaled ] + qpBDOffset;}}cQpBase.setQpParam(qpScaled);#endifUInt uiLog2TrSize = g_aucConvertToBit[ iWidth ] + 2;Int scalingListType = (pcCU->isIntra(uiAbsPartIdx) ? 0 : 3) + g_eTTable[(Int)eTType];assert(scalingListType < SCALING_LIST_NUM);Int *piQuantCoeff = 0;// 存放MF值的地方（MF可以通过查表得到），其中MF = 2^qbits / QsteppiQuantCoeff = getQuantCoeff(scalingListType,m_cQP.m_iRem,uiLog2TrSize-2);UInt uiBitDepth = eTType == TEXT_LUMA ? g_bitDepthY : g_bitDepthC;// 即T_ShiftInt iTransformShift = MAX_TR_DYNAMIC_RANGE - uiBitDepth - uiLog2TrSize;  // Represents scaling through forward transform#if ADAPTIVE_QP_SELECTIONInt iQBits = QUANT_SHIFT + cQpBase.m_iPer + iTransformShift;iAdd = (pcCU->getSlice()->getSliceType()==I_SLICE ? 171 : 85) << (iQBits-9);Int iQBitsC = QUANT_SHIFT + cQpBase.m_iPer + iTransformShift - ARL_C_PRECISION;  Int iAddC   = 1 << (iQBitsC-1);#else// qbits的计算Int iQBits = QUANT_SHIFT + m_cQP.m_iPer + iTransformShift;                // Right shift of non-RDOQ quantizer;  level = (coeff*uiQ + offset)>>q_bits// 计算f_temp，f_temp就是iAddiAdd = (pcCU->getSlice()->getSliceType()==I_SLICE ? 171 : 85) << (iQBits-9);#endifInt qBits8 = iQBits-8;for( Int n = 0; n < iWidth*iHeight; n++ ){Int iLevel;Int  iSign;UInt uiBlockPos = n;iLevel  = piCoef[uiBlockPos];iSign   = (iLevel < 0 ? -1: 1);      #if ADAPTIVE_QP_SELECTIONInt64 tmpLevel = (Int64)abs(iLevel) * piQuantCoeff[uiBlockPos];if( m_bUseAdaptQpSelect ){piArlCCoef[uiBlockPos] = (Int)((tmpLevel + iAddC ) >> iQBitsC);}iLevel = (Int)((tmpLevel + iAdd ) >> iQBits);deltaU[uiBlockPos] = (Int)((tmpLevel - (iLevel<<iQBits) )>> qBits8);#else// 量化的核心：abs(x)=(abs(d) * MF + f_temp) >> (qbits + T_Shift)iLevel = ((Int64)abs(iLevel) * piQuantCoeff[uiBlockPos] + iAdd ) >> iQBits;deltaU[uiBlockPos] = (Int)( ((Int64)abs(piCoef[uiBlockPos]) * piQuantCoeff[uiBlockPos] - (iLevel<<iQBits) )>> qBits8 );#endifuiAcSum += iLevel;iLevel *= iSign;        piQCoef[uiBlockPos] = Clip3( -32768, 32767, iLevel );} // for n// 是否需要隐藏符号if( pcCU->getSlice()->getPPS()->getSignHideFlag() ){if(uiAcSum>=2){signBitHidingHDQ( piQCoef, piCoef, scan, deltaU, iWidth, iHeight ) ;}}} //if RDOQ//return;}

率失真优化量化RDOQ

1、把量化与率失真优化过程结合，给定多个可选的量化值，利用RDO（率失真优化）选出最优的值

2、操作步骤：

     （1）确定当前TU每个系数的可选量化值，利用下面公式进行预量化：

          

     （2）利用RDO准则确定当前TU所有系数的最优量化值QP（注意是每个系数的QP）

     （3）利用RDO准则确定当前TU每一个系数块组（CG，4x4的块）是否量化成全零组。如果当前的CG是全零CG，那么只需要编码全零标志；否则，要编码所有的系数。具体是：遍历所有的CG，计算其量化为全零CG时的率失真代价，与原来的率失真代价比较，如果全零CG对应的率失真代价较小，那么令当前CG为全零CG

     （4）利用RDO准则准确确定当前TU最后一个非零系数的位置

/*** 率失真优化量化** 细节方面还没有完全弄清楚*/Void TComTrQuant::xRateDistOptQuant                 ( TComDataCU*                     pcCU,Int*                            plSrcCoeff,TCoeff*                         piDstCoeff,#if ADAPTIVE_QP_SELECTIONInt*&                           piArlDstCoeff,#endifUInt                            uiWidth,UInt                            uiHeight,UInt&                           uiAbsSum,TextType                        eTType,UInt                            uiAbsPartIdx ){UInt uiLog2TrSize = g_aucConvertToBit[ uiWidth ] + 2;// 比特深度UInt uiBitDepth = eTType == TEXT_LUMA ? g_bitDepthY : g_bitDepthC;// 表示通过前向转换Int iTransformShift = MAX_TR_DYNAMIC_RANGE - uiBitDepth - uiLog2TrSize;  // Represents scaling through forward transformUInt       uiGoRiceParam       = 0;Double     d64BlockUncodedCost = 0;const UInt uiLog2BlkSize       = g_aucConvertToBit[ uiWidth ] + 2;// 系数的个数const UInt uiMaxNumCoeff       = uiWidth * uiHeight;// 扫描的方式Int scalingListType = (pcCU->isIntra(uiAbsPartIdx) ? 0 : 3) + g_eTTable[(Int)eTType];assert(scalingListType < SCALING_LIST_NUM);Int iQBits = QUANT_SHIFT + m_cQP.m_iPer + iTransformShift;                   // Right shift of non-RDOQ quantizer;  level = (coeff*uiQ + offset)>>q_bitsDouble *pdErrScaleOrg = getErrScaleCoeff(scalingListType,uiLog2TrSize-2,m_cQP.m_iRem);// 获取量化系数Int *piQCoefOrg = getQuantCoeff(scalingListType,m_cQP.m_iRem,uiLog2TrSize-2);Int *piQCoef = piQCoefOrg;Double *pdErrScale = pdErrScaleOrg;#if ADAPTIVE_QP_SELECTIONInt iQBitsC = iQBits - ARL_C_PRECISION;Int iAddC =  1 << (iQBitsC-1);#endif// 获取系数的扫描的索引UInt uiScanIdx = pcCU->getCoefScanIdx(uiAbsPartIdx, uiWidth, eTType==TEXT_LUMA, pcCU->isIntra(uiAbsPartIdx));#if ADAPTIVE_QP_SELECTIONmemset(piArlDstCoeff, 0, sizeof(Int) *  uiMaxNumCoeff);#endif// 系数的代价Double pdCostCoeff [ 32 * 32 ];Double pdCostSig   [ 32 * 32 ];Double pdCostCoeff0[ 32 * 32 ];::memset( pdCostCoeff, 0, sizeof(Double) *  uiMaxNumCoeff );::memset( pdCostSig,   0, sizeof(Double) *  uiMaxNumCoeff );Int rateIncUp   [ 32 * 32 ];Int rateIncDown [ 32 * 32 ];Int sigRateDelta[ 32 * 32 ];Int deltaU      [ 32 * 32 ];::memset( rateIncUp,    0, sizeof(Int) *  uiMaxNumCoeff );::memset( rateIncDown,  0, sizeof(Int) *  uiMaxNumCoeff );::memset( sigRateDelta, 0, sizeof(Int) *  uiMaxNumCoeff );::memset( deltaU,       0, sizeof(Int) *  uiMaxNumCoeff );const UInt * scanCG;{scanCG = g_auiSigLastScan[ uiScanIdx ][ uiLog2BlkSize > 3 ? uiLog2BlkSize-2-1 : 0  ];if( uiLog2BlkSize == 3 )// 8的情况{scanCG = g_sigLastScan8x8[ uiScanIdx ];}else if( uiLog2BlkSize == 5 )// 32的情况{scanCG = g_sigLastScanCG32x32;}}const UInt uiCGSize = (1 << MLS_CG_SIZE);         // 16Double pdCostCoeffGroupSig[ MLS_GRP_NUM ];UInt uiSigCoeffGroupFlag[ MLS_GRP_NUM ];UInt uiNumBlkSide = uiWidth / MLS_CG_SIZE;Int iCGLastScanPos = -1;UInt    uiCtxSet            = 0;Int     c1                  = 1;Int     c2                  = 0;Double  d64BaseCost         = 0;Int     iLastScanPos        = -1;UInt    c1Idx     = 0;UInt    c2Idx     = 0;Int     baseLevel;const UInt *scan = g_auiSigLastScan[ uiScanIdx ][ uiLog2BlkSize - 1 ];::memset( pdCostCoeffGroupSig,   0, sizeof(Double) * MLS_GRP_NUM );::memset( uiSigCoeffGroupFlag,   0, sizeof(UInt) * MLS_GRP_NUM );UInt uiCGNum = uiWidth * uiHeight >> MLS_CG_SIZE;Int iScanPos;coeffGroupRDStats rdStats;     for (Int iCGScanPos = uiCGNum-1; iCGScanPos >= 0; iCGScanPos--){UInt uiCGBlkPos = scanCG[ iCGScanPos ];UInt uiCGPosY   = uiCGBlkPos / uiNumBlkSide;UInt uiCGPosX   = uiCGBlkPos - (uiCGPosY * uiNumBlkSide);::memset( &rdStats, 0, sizeof (coeffGroupRDStats));const Int patternSigCtx = TComTrQuant::calcPatternSigCtx(uiSigCoeffGroupFlag, uiCGPosX, uiCGPosY, uiWidth, uiHeight);for (Int iScanPosinCG = uiCGSize-1; iScanPosinCG >= 0; iScanPosinCG--){iScanPos = iCGScanPos*uiCGSize + iScanPosinCG;//===== quantization =====UInt    uiBlkPos          = scan[iScanPos];// set coeffInt uiQ  = piQCoef[uiBlkPos];Double dTemp = pdErrScale[uiBlkPos];Int lLevelDouble          = plSrcCoeff[ uiBlkPos ];lLevelDouble              = (Int)min<Int64>((Int64)abs((Int)lLevelDouble) * uiQ , MAX_INT - (1 << (iQBits - 1)));#if ADAPTIVE_QP_SELECTIONif( m_bUseAdaptQpSelect ){piArlDstCoeff[uiBlkPos]   = (Int)(( lLevelDouble + iAddC) >> iQBitsC );}#endifUInt uiMaxAbsLevel        = (lLevelDouble + (1 << (iQBits - 1))) >> iQBits;Double dErr               = Double( lLevelDouble );pdCostCoeff0[ iScanPos ]  = dErr * dErr * dTemp;d64BlockUncodedCost      += pdCostCoeff0[ iScanPos ];piDstCoeff[ uiBlkPos ]    = uiMaxAbsLevel;if ( uiMaxAbsLevel > 0 && iLastScanPos < 0 ){iLastScanPos            = iScanPos;uiCtxSet                = (iScanPos < SCAN_SET_SIZE || eTType!=TEXT_LUMA) ? 0 : 2;iCGLastScanPos          = iCGScanPos;}if ( iLastScanPos >= 0 ){//===== coefficient level estimation =====UInt  uiLevel;UInt  uiOneCtx         = 4 * uiCtxSet + c1;UInt  uiAbsCtx         = uiCtxSet + c2;if( iScanPos == iLastScanPos ){uiLevel              = xGetCodedLevel( pdCostCoeff[ iScanPos ], pdCostCoeff0[ iScanPos ], pdCostSig[ iScanPos ], lLevelDouble, uiMaxAbsLevel, 0, uiOneCtx, uiAbsCtx, uiGoRiceParam, c1Idx, c2Idx, iQBits, dTemp, 1 );}else{UInt   uiPosY        = uiBlkPos >> uiLog2BlkSize;UInt   uiPosX        = uiBlkPos - ( uiPosY << uiLog2BlkSize );UShort uiCtxSig      = getSigCtxInc( patternSigCtx, uiScanIdx, uiPosX, uiPosY, uiLog2BlkSize, eTType );uiLevel              = xGetCodedLevel( pdCostCoeff[ iScanPos ], pdCostCoeff0[ iScanPos ], pdCostSig[ iScanPos ],lLevelDouble, uiMaxAbsLevel, uiCtxSig, uiOneCtx, uiAbsCtx, uiGoRiceParam, c1Idx, c2Idx, iQBits, dTemp, 0 );sigRateDelta[ uiBlkPos ] = m_pcEstBitsSbac->significantBits[ uiCtxSig ][ 1 ] - m_pcEstBitsSbac->significantBits[ uiCtxSig ][ 0 ];}deltaU[ uiBlkPos ]        = (lLevelDouble - ((Int)uiLevel << iQBits)) >> (iQBits-8);if( uiLevel > 0 ){Int rateNow = xGetICRate( uiLevel, uiOneCtx, uiAbsCtx, uiGoRiceParam, c1Idx, c2Idx );rateIncUp   [ uiBlkPos ] = xGetICRate( uiLevel+1, uiOneCtx, uiAbsCtx, uiGoRiceParam, c1Idx, c2Idx ) - rateNow;rateIncDown [ uiBlkPos ] = xGetICRate( uiLevel-1, uiOneCtx, uiAbsCtx, uiGoRiceParam, c1Idx, c2Idx ) - rateNow;}else // uiLevel == 0{rateIncUp   [ uiBlkPos ] = m_pcEstBitsSbac->m_greaterOneBits[ uiOneCtx ][ 0 ];}piDstCoeff[ uiBlkPos ] = uiLevel;d64BaseCost           += pdCostCoeff [ iScanPos ];baseLevel = (c1Idx < C1FLAG_NUMBER) ? (2 + (c2Idx < C2FLAG_NUMBER)) : 1;if( uiLevel >= baseLevel ){if(uiLevel  > 3*(1<<uiGoRiceParam)){uiGoRiceParam = min<UInt>(uiGoRiceParam+ 1, 4);}}if ( uiLevel >= 1){c1Idx ++;}//===== update bin model =====if( uiLevel > 1 ){c1 = 0; c2 += (c2 < 2);c2Idx ++;}else if( (c1 < 3) && (c1 > 0) && uiLevel){c1++;}//===== context set update =====if( ( iScanPos % SCAN_SET_SIZE == 0 ) && ( iScanPos > 0 ) ){c2                = 0;uiGoRiceParam     = 0;c1Idx   = 0;c2Idx   = 0; uiCtxSet          = (iScanPos == SCAN_SET_SIZE || eTType!=TEXT_LUMA) ? 0 : 2;if( c1 == 0 ){uiCtxSet++;}c1 = 1;}}else{d64BaseCost    += pdCostCoeff0[ iScanPos ];}rdStats.d64SigCost += pdCostSig[ iScanPos ];if (iScanPosinCG == 0 ){rdStats.d64SigCost_0 = pdCostSig[ iScanPos ];}if (piDstCoeff[ uiBlkPos ] ){uiSigCoeffGroupFlag[ uiCGBlkPos ] = 1;rdStats.d64CodedLevelandDist += pdCostCoeff[ iScanPos ] - pdCostSig[ iScanPos ];rdStats.d64UncodedDist += pdCostCoeff0[ iScanPos ];if ( iScanPosinCG != 0 ){rdStats.iNNZbeforePos0++;}}} //end for (iScanPosinCG)if (iCGLastScanPos >= 0) {if( iCGScanPos ){if (uiSigCoeffGroupFlag[ uiCGBlkPos ] == 0){UInt  uiCtxSig = getSigCoeffGroupCtxInc( uiSigCoeffGroupFlag, uiCGPosX, uiCGPosY, uiWidth, uiHeight);d64BaseCost += xGetRateSigCoeffGroup(0, uiCtxSig) - rdStats.d64SigCost;;  pdCostCoeffGroupSig[ iCGScanPos ] = xGetRateSigCoeffGroup(0, uiCtxSig);  } else{if (iCGScanPos < iCGLastScanPos) //skip the last coefficient group, which will be handled together with last position below.{if ( rdStats.iNNZbeforePos0 == 0 ) {d64BaseCost -= rdStats.d64SigCost_0;rdStats.d64SigCost -= rdStats.d64SigCost_0;}// rd-cost if SigCoeffGroupFlag = 0, initializationDouble d64CostZeroCG = d64BaseCost;// add SigCoeffGroupFlag cost to total costUInt  uiCtxSig = getSigCoeffGroupCtxInc( uiSigCoeffGroupFlag, uiCGPosX, uiCGPosY, uiWidth, uiHeight);if (iCGScanPos < iCGLastScanPos){d64BaseCost  += xGetRateSigCoeffGroup(1, uiCtxSig); d64CostZeroCG += xGetRateSigCoeffGroup(0, uiCtxSig);  pdCostCoeffGroupSig[ iCGScanPos ] = xGetRateSigCoeffGroup(1, uiCtxSig); }// try to convert the current coeff group from non-zero to all-zerod64CostZeroCG += rdStats.d64UncodedDist;  // distortion for resetting non-zero levels to zero levelsd64CostZeroCG -= rdStats.d64CodedLevelandDist;   // distortion and level cost for keeping all non-zero levelsd64CostZeroCG -= rdStats.d64SigCost;     // sig cost for all coeffs, including zero levels and non-zerl levels// if we can save cost, change this block to all-zero blockif ( d64CostZeroCG < d64BaseCost )      {uiSigCoeffGroupFlag[ uiCGBlkPos ] = 0;d64BaseCost = d64CostZeroCG;if (iCGScanPos < iCGLastScanPos){pdCostCoeffGroupSig[ iCGScanPos ] = xGetRateSigCoeffGroup(0, uiCtxSig); }// reset coeffs to 0 in this block                for (Int iScanPosinCG = uiCGSize-1; iScanPosinCG >= 0; iScanPosinCG--){iScanPos      = iCGScanPos*uiCGSize + iScanPosinCG;UInt uiBlkPos = scan[ iScanPos ];if (piDstCoeff[ uiBlkPos ]){piDstCoeff [ uiBlkPos ] = 0;pdCostCoeff[ iScanPos ] = pdCostCoeff0[ iScanPos ];pdCostSig  [ iScanPos ] = 0;}}} // end if ( d64CostAllZeros < d64BaseCost )      }} // end if if (uiSigCoeffGroupFlag[ uiCGBlkPos ] == 0)}else{uiSigCoeffGroupFlag[ uiCGBlkPos ] = 1;}}} //end for (iCGScanPos)//===== estimate last position =====if ( iLastScanPos < 0 ){return;}Double  d64BestCost         = 0;Int     ui16CtxCbf          = 0;Int     iBestLastIdxP1      = 0;if( !pcCU->isIntra( uiAbsPartIdx ) && eTType == TEXT_LUMA && pcCU->getTransformIdx( uiAbsPartIdx ) == 0 ){ui16CtxCbf   = 0;d64BestCost  = d64BlockUncodedCost + xGetICost( m_pcEstBitsSbac->blockRootCbpBits[ ui16CtxCbf ][ 0 ] );d64BaseCost += xGetICost( m_pcEstBitsSbac->blockRootCbpBits[ ui16CtxCbf ][ 1 ] );}else{ui16CtxCbf   = pcCU->getCtxQtCbf( eTType, pcCU->getTransformIdx( uiAbsPartIdx ) );ui16CtxCbf   = ( eTType ? TEXT_CHROMA : eTType ) * NUM_QT_CBF_CTX + ui16CtxCbf;d64BestCost  = d64BlockUncodedCost + xGetICost( m_pcEstBitsSbac->blockCbpBits[ ui16CtxCbf ][ 0 ] );d64BaseCost += xGetICost( m_pcEstBitsSbac->blockCbpBits[ ui16CtxCbf ][ 1 ] );}Bool bFoundLast = false;for (Int iCGScanPos = iCGLastScanPos; iCGScanPos >= 0; iCGScanPos--){UInt uiCGBlkPos = scanCG[ iCGScanPos ];d64BaseCost -= pdCostCoeffGroupSig [ iCGScanPos ]; if (uiSigCoeffGroupFlag[ uiCGBlkPos ]){     for (Int iScanPosinCG = uiCGSize-1; iScanPosinCG >= 0; iScanPosinCG--){iScanPos = iCGScanPos*uiCGSize + iScanPosinCG;if (iScanPos > iLastScanPos) continue;UInt   uiBlkPos     = scan[iScanPos];if( piDstCoeff[ uiBlkPos ] ){UInt   uiPosY       = uiBlkPos >> uiLog2BlkSize;UInt   uiPosX       = uiBlkPos - ( uiPosY << uiLog2BlkSize );Double d64CostLast= uiScanIdx == SCAN_VER ? xGetRateLast( uiPosY, uiPosX ) : xGetRateLast( uiPosX, uiPosY );Double totalCost = d64BaseCost + d64CostLast - pdCostSig[ iScanPos ];if( totalCost < d64BestCost ){iBestLastIdxP1  = iScanPos + 1;d64BestCost     = totalCost;}if( piDstCoeff[ uiBlkPos ] > 1 ){bFoundLast = true;break;}d64BaseCost      -= pdCostCoeff[ iScanPos ];d64BaseCost      += pdCostCoeff0[ iScanPos ];}else{d64BaseCost      -= pdCostSig[ iScanPos ];}} //end for if (bFoundLast){break;}} // end if (uiSigCoeffGroupFlag[ uiCGBlkPos ])} // end for for ( Int scanPos = 0; scanPos < iBestLastIdxP1; scanPos++ ){Int blkPos = scan[ scanPos ];Int level  = piDstCoeff[ blkPos ];uiAbsSum += level;piDstCoeff[ blkPos ] = ( plSrcCoeff[ blkPos ] < 0 ) ? -level : level;}//===== clean uncoded coefficients =====for ( Int scanPos = iBestLastIdxP1; scanPos <= iLastScanPos; scanPos++ ){piDstCoeff[ scan[ scanPos ] ] = 0;}if( pcCU->getSlice()->getPPS()->getSignHideFlag() && uiAbsSum>=2){Int64 rdFactor = (Int64) (g_invQuantScales[m_cQP.rem()] * g_invQuantScales[m_cQP.rem()] * (1<<(2*m_cQP.m_iPer))/ m_dLambda / 16 / (1<<DISTORTION_PRECISION_ADJUSTMENT(2*(uiBitDepth-8)))+ 0.5);Int lastCG = -1;Int absSum = 0 ;Int n ;for( Int subSet = (uiWidth*uiHeight-1) >> LOG2_SCAN_SET_SIZE; subSet >= 0; subSet-- ){Int  subPos     = subSet << LOG2_SCAN_SET_SIZE;Int  firstNZPosInCG=SCAN_SET_SIZE , lastNZPosInCG=-1 ;absSum = 0 ;for(n = SCAN_SET_SIZE-1; n >= 0; --n ){if( piDstCoeff[ scan[ n + subPos ]] ){lastNZPosInCG = n;break;}}for(n = 0; n <SCAN_SET_SIZE; n++ ){if( piDstCoeff[ scan[ n + subPos ]] ){firstNZPosInCG = n;break;}}for(n = firstNZPosInCG; n <=lastNZPosInCG; n++ ){absSum += piDstCoeff[ scan[ n + subPos ]];}if(lastNZPosInCG>=0 && lastCG==-1){lastCG = 1; } if( lastNZPosInCG-firstNZPosInCG>=SBH_THRESHOLD ){UInt signbit = (piDstCoeff[scan[subPos+firstNZPosInCG]]>0?0:1);if( signbit!=(absSum&0x1) )  // hide but need tune{// calculate the cost Int64 minCostInc = MAX_INT64, curCost=MAX_INT64;Int minPos =-1, finalChange=0, curChange=0;for( n = (lastCG==1?lastNZPosInCG:SCAN_SET_SIZE-1) ; n >= 0; --n ){UInt uiBlkPos   = scan[ n + subPos ];if(piDstCoeff[ uiBlkPos ] != 0 ){Int64 costUp   = rdFactor * ( - deltaU[uiBlkPos] ) + rateIncUp[uiBlkPos] ;Int64 costDown = rdFactor * (   deltaU[uiBlkPos] ) + rateIncDown[uiBlkPos] -   ((abs(piDstCoeff[uiBlkPos]) == 1) ? sigRateDelta[uiBlkPos] : 0);if(lastCG==1 && lastNZPosInCG==n && abs(piDstCoeff[uiBlkPos])==1){costDown -= (4<<15) ;}if(costUp<costDown){  curCost = costUp;curChange =  1 ;}else               {curChange = -1 ;if(n==firstNZPosInCG && abs(piDstCoeff[uiBlkPos])==1){curCost = MAX_INT64 ;}else{curCost = costDown ; }}}else{curCost = rdFactor * ( - (abs(deltaU[uiBlkPos])) ) + (1<<15) + rateIncUp[uiBlkPos] + sigRateDelta[uiBlkPos] ; curChange = 1 ;if(n<firstNZPosInCG){UInt thissignbit = (plSrcCoeff[uiBlkPos]>=0?0:1);if(thissignbit != signbit ){curCost = MAX_INT64;}}}if( curCost<minCostInc){minCostInc = curCost ;finalChange = curChange ;minPos = uiBlkPos ;}}if(piDstCoeff[minPos] == 32767 || piDstCoeff[minPos] == -32768){finalChange = -1;}if(plSrcCoeff[minPos]>=0){piDstCoeff[minPos] += finalChange ;}else{piDstCoeff[minPos] -= finalChange ; }          }}if(lastCG==1){lastCG=0 ;  }}}}