VVC/JEM代码学习1：estIntraPredChromaQT函数

       现在好像关于JEM的博客还很少，正好自己学习JEM，就把自己学习到的一点东西记录下来。省的学了就忘，先给自己定个目标，一天至少一篇吧。今天学习了色度帧内预测，先记录一下。estIntraPredChromaQT函数的主要功能是进行色度分量的帧内预测，在11种备选的预测模式中根据RD cost选择cost最小的一种模式作为最优预测模式。11种备选模式中，前6种是属于CCLM预测，用重建的亮度分量预测色度分量，后面5种是和HEVC中的色度预测模式一致。

Void
TEncSearch::estIntraPredChromaQT(TComDataCU* pcCU,
                                 TComYuv*    pcOrgYuv,
                                 TComYuv*    pcPredYuv,
                                 TComYuv*    pcResiYuv,
                                 TComYuv*    pcRecoYuv,
#if COM16_C806_LARGE_CTU
                                 Pel*        resiLuma[NUMBER_OF_STORED_RESIDUAL_TYPES]
#else
                                 Pel         resiLuma[NUMBER_OF_STORED_RESIDUAL_TYPES][MAX_CU_SIZE * MAX_CU_SIZE]
#endif
                                 DEBUG_STRING_FN_DECLARE(sDebug))
{
#if JVET_C0024_QTBT
  const UInt    uiInitTrDepth  =  0;
  UInt uiWIdx = g_aucConvertToBit[pcCU->getWidth(0)];
  UInt uiHIdx = g_aucConvertToBit[pcCU->getHeight(0)];
#else
  const UInt    uiInitTrDepth  = pcCU->getPartitionSize(0) != SIZE_2Nx2N && enable4ChromaPUsInIntraNxNCU(pcOrgYuv->getChromaFormat()) ? 1 : 0;
#endif

  TComTURecurse tuRecurseCU(pcCU, 0);
  TComTURecurse tuRecurseWithPU(tuRecurseCU, false, (uiInitTrDepth==0)?TComTU::DONT_SPLIT : TComTU::QUAD_SPLIT);
#if !JVET_C0024_QTBT
  const UInt    uiQNumParts    = tuRecurseWithPU.GetAbsPartIdxNumParts();
#endif
  const UInt    uiDepthCU=tuRecurseWithPU.getCUDepth();
  const UInt    numberValidComponents = pcCU->getPic()->getNumberValidComponents();
  do   while大循环/
  do
  {
#if JVET_E0077_LM_MF
      UInt auiSATDModeList[LM_FILTER_NUM];
      UInt auiSATDSortedcost[LM_FILTER_NUM];

      const UInt csx = getComponentScaleX(COMPONENT_Cb, pcCU->getSlice()->getSPS()->getChromaFormatIdc());
      const UInt csy = getComponentScaleY(COMPONENT_Cb, pcCU->getSlice()->getSPS()->getChromaFormatIdc());

      Int iBlockSize = (pcCU->getHeight(0) >> csy) + (pcCU->getWidth(0) >> csx);
#endif

    UInt       uiBestMode  = 0;
    Distortion uiBestDist  = 0;
    Double     dBestCost   = MAX_DOUBLE;

    //----- init mode list -----
    if (tuRecurseWithPU.ProcessChannelSection(CHANNEL_TYPE_CHROMA))
    {
#if JVET_E0062_MULTI_DMS
      UInt uiModeList[NUM_CHROMA_MODE];
#else
      UInt uiModeList[FAST_UDI_MAX_RDMODE_NUM];
#endif

#if !JVET_C0024_QTBT
      const UInt  uiQPartNum     = uiQNumParts;
#endif
      const UInt  uiPartOffset   = tuRecurseWithPU.GetAbsPartIdxTU();
      {
        UInt  uiMinMode = 0;
        UInt  uiMaxMode = NUM_CHROMA_MODE;//11;

        //----- check chroma modes -----
#if JVET_E0077_ENHANCED_LM
        uiMaxMode =
#endif//前6种67，68，69，70，71，72应该是CCLM的6种预测模式，后5种和HEVC里的一样;
        pcCU->getAllowedChromaDir( uiPartOffset, uiModeList );//获得可用的色度预测模式,uiModeList里有11种候选模式;
#if ENVIRONMENT_VARIABLE_DEBUG_AND_TEST
        if (DebugOptionList::ForceChromaMode.isSet())
        {
          uiMinMode=DebugOptionList::ForceChromaMode.getInt();
          if (uiModeList[uiMinMode]==34)
          {
            uiMinMode=4; // if the fixed mode has been renumbered because DM_CHROMA covers it, use DM_CHROMA.
          }
          uiMaxMode=uiMinMode+1;
        }
#endif

#if JVET_C0024_QTBT
        assert(uiPartOffset==0);     
        UInt uiShort, uiLong;
        UInt uiStr;
        if (pcCU->getHeight(0) > pcCU->getWidth(0))
        {
            uiShort = pcCU->getWidth(0);
            uiLong = pcCU->getHeight(0);
            uiStr = pcCU->getPic()->getNumPartInCtuWidth();
        }
        else
        {
            uiShort = pcCU->getHeight(0);