H.266/VVC代码学习13：VTM4.0中的CU层操作（compressCtu 、 xCompressCU）

从H.266/VVC代码学习3：VTM4.0中的CTU层操作（encodeCtus）我们了解到了视频最基本的操作块为CTU，现在我们进一步学习CU层的操作。有两个十分重要的函数：

1 compressCtu:

是对encodeCtu中拿到的单个ctu进行操作，是进行CU划分预测等处理的入口。内部一共会调用两次 xCompressCU ，一次是对亮度进行处理，一次是对色度进行处理。可见compressCtu是开始划分亮度和色度的开始，处理完一个CTU的亮度分量后，紧接着处理这个CTU的色度分量，之后处理下个 CTU。。

2 xCompressCU:

主要目的是选择预测模式和进行深一层的预测操作。其中xCheckModeSplit会用递归调用xCompressCU的方式遍历全部可能的划分方式，如64x64的亮度块（32x32的色度块）都会进行帧内模式、四叉树、两种二叉树这四种划分，如32x32的亮度块（16x16的色度块）都会进行帧内模式、四叉树、两种二叉树、两种三叉树这六种划分。下图为basketballdrill序列的色度划分信息可供理解：

以这样的方式，一步步划分到最底层，最后计算总RD代价确定究竟使用何种划分，并根据后面的预测记录最优模式信息，完成这个CTU的划分预测以及内部深层次的变换量化重建等部分。

VTM4.0中EncCu::compressCtu代码如下：

void EncCu::compressCtu( CodingStructure& cs, const UnitArea& area, const unsigned ctuRsAddr, const int prevQP[], const int currQP[] )
{
#if !JVET_M0255_FRACMMVD_SWITCH
  if (m_pcEncCfg->getIBCHashSearch() && ctuRsAddr == 0 && cs.slice->getSPS()->getIBCMode())
  {
#if JVET_M0427_INLOOP_RESHAPER
    if (cs.slice->getSPS()->getUseReshaper() && m_pcReshape->getCTUFlag())
      cs.picture->getOrigBuf(COMPONENT_Y).rspSignal(m_pcReshape->getFwdLUT());
#endif
    m_ibcHashMap.rebuildPicHashMap(cs.picture->getOrigBuf());
#if JVET_M0427_INLOOP_RESHAPER
    if (cs.slice->getSPS()->getUseReshaper() && m_pcReshape->getCTUFlag())
      cs.picture->getOrigBuf().copyFrom(cs.picture->getTrueOrigBuf());
#endif
  }
#endif
  /*************************** 初始化 ***************************/
  m_modeCtrl->initCTUEncoding( *cs.slice );

#if ENABLE_SPLIT_PARALLELISM
  if( m_pcEncCfg->getNumSplitThreads() > 1 )
  {
    for( int jId = 1; jId < NUM_RESERVERD_SPLIT_JOBS; jId++ )
    {
      EncCu*            jobEncCu  = m_pcEncLib->getCuEncoder( cs.picture->scheduler.getSplitDataId( jId ) );
      CacheBlkInfoCtrl* cacheCtrl = dynamic_cast< CacheBlkInfoCtrl* >( jobEncCu->m_modeCtrl );
      if( cacheCtrl )
      {
        cacheCtrl->init( *cs.slice );
      }
    }
  }

  if( auto* cacheCtrl = dynamic_cast<CacheBlkInfoCtrl*>( m_modeCtrl ) ) { cacheCtrl->tick(); }
#endif
  // init the partitioning manager 划分
  
  Partitioner *partitioner = PartitionerFactory::get( *cs.slice );
  partitioner->initCtu( area, CH_L, *cs.slice );
  
    if (m_pcEncCfg->getIBCMode())
  {
    if (area.lx() == 0 && area.ly() == 0)
    {
      m_pcInterSearch->resetIbcSearch();
    }
    m_pcInterSearch->resetCtuRecord();
    m_ctuIbcSearchRangeX = m_pcEncCfg->getIBCLocalSearchRangeX();
    m_ctuIbcSearchRangeY = m_pcEncCfg->getIBCLocalSearchRangeY();
  }
  if (m_pcEncCfg->getIBCMode() && m_pcEncCfg->getIBCHashSearch() && (m_pcEncCfg->getIBCFastMethod() & IBC_FAST_METHOD_ADAPTIVE_SEARCHRANGE))
  {
    const int hashHitRatio = m_ibcHashMap.getHashHitRatio(area.Y()); // in percent
    if (hashHitRatio < 5) // 5%
    {
      m_ctuIbcSearchRangeX >>= 1;
      m_ctuIbcSearchRangeY >>= 1;
    }
#if JVET_M0483_IBC
    if (cs.slice->getNumRefIdx(REF_PIC_LIST_0) > 0)
#else
    if (cs.slice->getNumRefIdx(REF_PIC_LIST_0) > 1)
#endif
    {
      m_ctuIbcSearchRangeX >>= 1;
      m_ctuIbcSearchRangeY >>= 1;
    }
  }
  // init current context pointer 当前上下文指针
  m_CurrCtx = m_CtxBuffer.data();

  CodingStructure *tempCS = m_pTempCS[gp_sizeIdxInfo->idxFrom( area.lumaSize().width )][gp_sizeIdxInfo->idxFrom( area.lumaSize().height )];
  CodingStructure *bestCS = m_pBestCS[gp_sizeIdxInfo->idxFrom( area.lumaSize().width )][gp_sizeIdxInfo->idxFrom( area.lumaSize().height )];
  LutMotionCand *tempMotCandLUTs = m_pTempMotLUTs[gp_sizeIdxInfo->idxFrom(area.lumaSize().width)][gp_sizeIdxInfo->idxFrom(area.lumaSize().height)];
  LutMotionCand *bestMotCandLUTs = m_pBestMotLUTs[gp_sizeIdxInfo->idxFrom(area.lumaSize().width)][gp_sizeIdxInfo->idxFrom(area.lumaSize().height)];
  cs.slice->copyMotionLUTs(cs.slice->getMotionLUTs(), tempMotCandLUTs);
  cs.slice->copyMotionLUTs(cs.slice->getMotionLUTs(), bestMotCandLUTs);

  /******************************* 对亮度进行操作 ******************************/
  cs.initSubStructure( *tempCS, partitioner->chType, partitioner->currArea(), false );
  cs.initSubStructure( *bestCS, partitioner->chType, partitioner->currArea(), false );
  tempCS->currQP[CH_L] = bestCS->currQP[CH_L] =
  tempCS->baseQP       = bestCS->baseQP       = currQP[CH_L];
  tempCS->prevQP[CH_L] = bestCS->prevQP[CH_L] = prevQP[CH_L];

  xCompressCU( tempCS, bestCS, *partitioner//进行CU处理
    , tempMotCandLUTs
    , bestMotCandLUTs
  );

  // all signals were already copied during compression if the CTU was split - at this point only the structures are copied to the top level CS
#if JVET_M0427_INLOOP_RESHAPER
  const bool copyUnsplitCTUSignals = bestCS->cus.size() == 1;
#else
  const bool copyUnsplitCTUSignals = bestCS->cus.size() == 1 && KEEP_PRED_AND_RESI_SIGNALS;
#endif
  cs.useSubStructure( *bestCS, partitioner->chType, CS::getArea( *bestCS, area, partitioner->chType ), copyUnsplitCTUSignals, false, false, copyUnsplitCTUSignals );
  cs.slice->copyMotionLUTs(bestMotCandLUTs, cs.slice->getMotionLUTs());

#if !REVERSAL_LUMA_AND_CHROMA
  /**************************** 对色度进行操作 ****************************/
  if (!cs.pcv->ISingleTree && cs.slice->isIRAP() && cs.pcv->chrFormat != CHROMA_400)
  {
	  m_CABACEstimator->getCtx() = m_CurrCtx->start;

	  partitioner->initCtu(area, CH_C, *cs.slice);

	  cs.initSubStructure(*tempCS, partitioner->chType, partitioner->currArea(), false);
	  cs.initSubStructure(*bestCS, partitioner->chType, partitioner->currArea(), false);
	  tempCS->currQP[CH_C] = bestCS->currQP[CH_C] =
		  tempCS->baseQP = bestCS->baseQP = currQP[CH_C];
	  tempCS->prevQP[CH_C] = bestCS->prevQP[CH_C] = prevQP[CH_C];

	  xCompressCU(tempCS, bestCS, *partitioner//进行CU处理
		  , tempMotCandLUTs
		  , bestMotCandLUTs
	  );

#if JVET_M0427_INLOOP_RESHAPER
	  const bool copyUnsplitCTUSignals = bestCS->cus.size() == 1;
#else
	  const bool copyUnsplitCTUSignals = bestCS->cus.size() == 1 && KEEP_PRED_AND_RESI_SIGNALS;
#endif
	  cs.useSubStructure(*bestCS, partitioner->chType, CS::getArea(*bestCS, area, partitioner->chType), copyUnsplitCTUSignals, false, false, copyUnsplitCTUSignals);
  }
#endif 


  /**************************** 重置上下文等后续操作 **************************/
  if (m_pcEncCfg->getUseRateCtrl())
  {
    (m_pcRateCtrl->getRCPic()->getLCU(ctuRsAddr)).m_actualMSE = (double)bestCS->dist / (double)m_pcRateCtrl->getRCPic()->getLCU(ctuRsAddr).m_numberOfPixel;
  }
  // reset context states and uninit context pointer
  m_CABACEstimator->getCtx() = m_CurrCtx->start;
  m_CurrCtx                  = 0;
  delete partitioner;

#if ENABLE_SPLIT_PARALLELISM && ENABLE_WPP_PARALLELISM
  if( m_pcEncCfg->getNumSplitThreads() > 1 && m_pcEncCfg->getNumWppThreads() > 1 )
  {
    cs.picture->finishCtuPart( area );
  }
#endif

  // Ensure that a coding was found
  // Selected mode's RD-cost must be not MAX_DOUBLE.
  CHECK( bestCS->cus.empty()                                   , "No possible encoding found" );
  CHECK( bestCS->cus[0]->predMode == NUMBER_OF_PREDICTION_MODES, "No possible encoding found" );
  CHECK( bestCS->cost             == MAX_DOUBLE                , "No possible encoding found" );

#if PRINT
  //printf("(%d,%d) %d %d: sum bits is %lld\n", bestCS->area.blocks[0].x, bestCS->area.blocks[0].y, bestCS->area.blocks[0].width, bestCS->area.blocks[0].height, bestCS->fracBits);
//  static uint64_t sum = 0;
//  sum += (bestCS->fracBits >> 15);
//  printf("(%d,%d) %d %d: chroma bits is %lld\n", bestCS->area.blocks[1].x, bestCS->area.blocks[1].y, bestCS->area.blocks[1].width, bestCS->area.blocks[1].height, sum);
#endif
}

VTM4.0中EncCu::xCompressCU代码如下：

void EncCu::xCompressCU( CodingStructure *&tempCS, CodingStructure *&bestCS, Partitioner &partitioner
  , LutMotionCand *&tempMotCandLUTs
  , LutMotionCand *&bestMotCandLUTs
)
{
	/*************************************** 初始化 ****************************************/
#if JVET_M0170_MRG_SHARELIST
  if (m_shareState == NO_SHARE)
  {
    tempCS->sharedBndPos = tempCS->area.Y().lumaPos();
    tempCS->sharedBndSize.width = tempCS->area.lwidth();
    tempCS->sharedBndSize.height = tempCS->area.lheight();
    bestCS->sharedBndPos = bestCS->area.Y().lumaPos();
    bestCS->sharedBndSize.width = bestCS->area.lwidth();
    bestCS->sharedBndSize.height = bestCS->area.lheight();
  }
#endif
#if ENABLE_SPLIT_PARALLELISM
  CHECK( m_dataId != tempCS->picture->scheduler.getDataId(), "Working in the wrong dataId!" );

  if( m_pcEncCfg->getNumSplitThreads() != 1 && tempCS->picture->scheduler.getSplitJobId() == 0 )
  {
    if( m_modeCtrl->isParallelSplit( *tempCS, partitioner ) )
    {
      m_modeCtrl->setParallelSplit( true );
      xCompressCUParallel( tempCS, bestCS, partitioner );
      return;
    }
  }

#endif

  Slice&   slice      = *tempCS->slice;//当前所处slice
  const PPS &pps      = *tempCS->pps;//当前所处pps
  const SPS &sps      = *tempCS->sps;//当前所处sps
  const uint32_t uiLPelX  = tempCS->area.Y().lumaPos().x;//左上x
  const uint32_t uiTPelY  = tempCS->area.Y().lumaPos().y;//左上y

  const unsigned wIdx = gp_sizeIdxInfo->idxFrom( partitioner.currArea().lwidth()  );

  const UnitArea currCsArea = clipArea( CS::getArea( *bestCS, bestCS->area, partitioner.chType ), *tempCS->picture );
#if JVET_M0483_IBC
  if (m_pImvTempCS && (!slice.isIntra() || slice.getSPS()->getIBCFlag()))
#else
  if( m_pImvTempCS && !slice.isIntra() )
#endif
  {
    tempCS->initSubStructure( *m_pImvTempCS[wIdx], partitioner.chType, partitioner.currArea(), false );
  }

  tempCS->chType = partitioner.chType;
  bestCS->chType = partitioner.chType;
  m_modeCtrl->initCULevel( partitioner, *tempCS );
#if JVET_M0140_SBT
  if( partitioner.currQtDepth == 0 && partitioner.currMtDepth == 0 && !tempCS->slice->isIntra() && ( sps.getUseSBT() || sps.getUseInterMTS() ) )
  {
    auto slsSbt = dynamic_cast<SaveLoadEncInfoSbt*>( m_modeCtrl );
    int maxSLSize = sps.getUseSBT() ? tempCS->slice->getSPS()->getMaxSbtSize() : MTS_INTER_MAX_CU_SIZE;
    slsSbt->resetSaveloadSbt( maxSLSize );
  }
  m_sbtCostSave[0] = m_sbtCostSave[1] = MAX_DOUBLE;
#endif

  m_CurrCtx->start = m_CABACEstimator->getCtx();

  /************************* 处理色度QP ***************************/
  m_cuChromaQpOffsetIdxPlus1 = 0;

  if( slice.getUseChromaQpAdj() )
  {
    int lgMinCuSize = sps.getLog2MinCodingBlockSize() +
      std::max<int>( 0, sps.getLog2DiffMaxMinCodingBlockSize() - int( pps.getPpsRangeExtension().getDiffCuChromaQpOffsetDepth() ) );
    m_cuChromaQpOffsetIdxPlus1 = ( ( uiLPelX >> lgMinCuSize ) + ( uiTPelY >> lgMinCuSize ) ) % ( pps.getPpsRangeExtension().getChromaQpOffsetListLen() + 1 );
  }

  if( !m_modeCtrl->anyMode() )
  {
    m_modeCtrl->finishCULevel( partitioner );
    return;
  }
  /********************* 处理亮度运动信息的LUT ********************/
#if JVET_M0483_IBC
  if ((!slice.isIntra() || slice.getSPS()->getIBCFlag())
#else
  if (!slice.isIntra()
#endif
    && tempCS->chType == CHANNEL_TYPE_LUMA
    )//如果是亮度帧内预测，要用运动信息的LUT
  {
    tempCS->slice->copyMotionLUTs(tempMotCandLUTs, tempCS->slice->getMotionLUTs());
  }

  DTRACE_UPDATE( g_trace_ctx, std::make_pair( "cux", uiLPelX ) );
  DTRACE_UPDATE( g_trace_ctx, std::make_pair( "cuy", uiTPelY ) );
  DTRACE_UPDATE( g_trace_ctx, std::make_pair( "cuw", tempCS->area.lwidth() ) );
  DTRACE_UPDATE( g_trace_ctx, std::make_pair( "cuh", tempCS->area.lheight() ) );
  DTRACE( g_trace_ctx, D_COMMON, "@(%4d,%4d) [%2dx%2d]\n", tempCS->area.lx(), tempCS->area.ly(), tempCS->area.lwidth(), tempCS->area.lheight() );


#if JVET_M0170_MRG_SHARELIST
  int startShareThisLevel = 0;
#endif
#if JVET_M0246_AFFINE_AMVR
  m_pcInterSearch->resetSavedAffineMotion();
#endif
  /***************************对当前ctu进行预测及划分，循环结束时划分预测全部完成****************************/
  do//尝试当前编码器各种可用的模式：如skip，帧间，帧内，PCM等，进行预测及划分。
  {
    EncTestMode currTestMode = m_modeCtrl->currTestMode();
#if PRINT
	//printf("(%2d,%2d) %2d %2d : mode:%2d chan:%d\n", tempCS->area.blocks[1].x, tempCS->area.blocks[1].y, tempCS->area.blocks[1].width, tempCS->area.blocks[1].height, currTestMode.type, partitioner.chType);
#endif
    if (tempCS->pps->getUseDQP() && CS::isDualITree(*tempCS) && isChroma(partitioner.chType))
    {
      const Position chromaCentral(tempCS->area.Cb().chromaPos().offset(tempCS->area.Cb().chromaSize().width >> 1, tempCS->area.Cb().chromaSize().height >> 1));
      const Position lumaRefPos(chromaCentral.x << getComponentScaleX(COMPONENT_Cb, tempCS->area.chromaFormat), chromaCentral.y << getComponentScaleY(COMPONENT_Cb, tempCS->area.chromaFormat));
      const CodingStructure* baseCS = bestCS->picture->cs;
      const CodingUnit* colLumaCu = baseCS->getCU(lumaRefPos, CHANNEL_TYPE_LUMA);

      if (colLumaCu)
      {
        currTestMode.qp = colLumaCu->qp;
      }
    }

#if SHARP_LUMA_DELTA_QP
    if( m_pcEncCfg->getLumaLevelToDeltaQPMapping().isEnabled() && partitioner.currDepth <= pps.getMaxCuDQPDepth() )
    {
#if ENABLE_SPLIT_PARALLELISM
      CHECK( tempCS->picture->scheduler.getSplitJobId() > 0, "Changing lambda is only allowed in the master thread!" );
#endif
      if (currTestMode.qp >= 0)
      {
        updateLambda(&slice, currTestMode.qp);
      }
    }
#endif

	/************ 先看帧间模式 ************/
    if( currTestMode.type == ETM_INTER_ME )//1.帧间
    {
      if( ( currTestMode.opts & ETO_IMV ) != 0 )
      {
#if JVET_M0246_AFFINE_AMVR
        tempCS->bestCS = bestCS;
        xCheckRDCostInterIMV( tempCS, bestCS, partitioner, currTestMode );
        tempCS->bestCS = nullptr;
#else
        xCheckRDCostInterIMV(tempCS, bestCS, partitioner, currTestMode);
#endif
      }
      else
      {
#if JVET_M0246_AFFINE_AMVR
        tempCS->bestCS = bestCS;
        xCheckRDCostInter( tempCS, bestCS, partitioner, currTestMode );
        tempCS->bestCS = nullptr;
#else
        xCheckRDCostInter( tempCS, bestCS, partitioner, currTestMode );
#endif
      }

    }
#if JVET_M0253_HASH_ME
    else if (currTestMode.type == ETM_HASH_INTER)//2.帧间：哈希
    {
      xCheckRDCostHashInter( tempCS, bestCS, partitioner, currTestMode );
    }
#endif
    else if( currTestMode.type == ETM_AFFINE )//3.帧间：AFFINE
    {
      xCheckRDCostAffineMerge2Nx2N( tempCS, bestCS, partitioner, currTestMode );
    }
#if REUSE_CU_RESULTS
    else if( currTestMode.type == ETM_RECO_CACHED )
    {
      xReuseCachedResult( tempCS, bestCS, partitioner );//4.重建？
    }
#endif
    else if( currTestMode.type == ETM_MERGE_SKIP )//5.帧间：MERGE中的SKIP 
    {
      xCheckRDCostMerge2Nx2N( tempCS, bestCS, partitioner, currTestMode );
      CodingUnit* cu = bestCS->getCU(partitioner.chType);
      if (cu)
      cu->mmvdSkip = cu->skip == false ? false : cu->mmvdSkip;
    }
    else if( currTestMode.type == ETM_MERGE_TRIANGLE )//6.帧间：MERGE中的TRIANGLE
    {
      xCheckRDCostMergeTriangle2Nx2N( tempCS, bestCS, partitioner, currTestMode );
    }
	/************ 再看帧内模式 ***********/
    else if( currTestMode.type == ETM_INTRA )
    {
      xCheckRDCostIntra( tempCS, bestCS, partitioner, currTestMode );//7.帧内
    }
	/************* 特殊的模式 *************/
    else if( currTestMode.type == ETM_IPCM )//PCM：直接传像素值的模式
    {
      xCheckIntraPCM( tempCS, bestCS, partitioner, currTestMode );
    }
    else if (currTestMode.type == ETM_IBC)//IBC：帧内块用帧间预测方式的模式
    {
      xCheckRDCostIBCMode(tempCS, bestCS, partitioner, currTestMode);
    }
    else if (currTestMode.type == ETM_IBC_MERGE)//IBC：merge模式
    {
      xCheckRDCostIBCModeMerge2Nx2N(tempCS, bestCS, partitioner, currTestMode);
    }
	/******** 划分：用于递归的模式 *********/
    else if( isModeSplit( currTestMode ) )//划分模式，这里会递归调用xcompressCu
    {

      xCheckModeSplit( tempCS, bestCS, partitioner, currTestMode
        , tempMotCandLUTs
        , bestMotCandLUTs
        , partitioner.currArea()
      );
    }
    else
    {
      THROW( "Don't know how to handle mode: type = " << currTestMode.type << ", options = " << currTestMode.opts );
    }
  } while( m_modeCtrl->nextMode( *tempCS, partitioner ) );//进行完所有尝试，找到了最好的划分

#if JVET_M0170_MRG_SHARELIST
  if(startShareThisLevel == 1)
  {
    m_shareState = NO_SHARE;
    m_pcInterSearch->setShareState(m_shareState);
    setShareStateDec(m_shareState);
  }
#endif

  /********************************** CTU划分及CU处理完成，记录最佳信息 **********************************/
  //////////////////////////////////////////////////////////////////////////
  // Finishing CU
#if ENABLE_SPLIT_PARALLELISM
  if( bestCS->cus.empty() )
  {
    CHECK( bestCS->cost != MAX_DOUBLE, "Cost should be maximal if no encoding found" );
    CHECK( bestCS->picture->scheduler.getSplitJobId() == 0, "Should always get a result in serial case" );

    m_modeCtrl->finishCULevel( partitioner );
    return;
  }

#endif
  // set context states 上下文状态
  m_CABACEstimator->getCtx() = m_CurrCtx->best;

  // QP from last processed CU for further processing QP进一步处理
  bestCS->prevQP[partitioner.chType] = bestCS->cus.back()->qp;
#if JVET_M0483_IBC
  if ((!slice.isIntra() || slice.getSPS()->getIBCFlag())
#else
  if (!slice.isIntra()
#endif
    && bestCS->chType == CHANNEL_TYPE_LUMA
#if JVET_M0483_IBC
    && bestCS->cus.size() == 1 && (bestCS->cus.back()->predMode == MODE_INTER || bestCS->cus.back()->predMode == MODE_IBC)
#else
    && bestCS->cus.size() == 1 && bestCS->cus.back()->predMode == MODE_INTER
#endif
    && bestCS->area.Y() == (*bestCS->cus.back()).Y()
    )
  {
    bestCS->slice->updateMotionLUTs(bestMotCandLUTs, (*bestCS->cus.back()));
  }
#if JVET_M0427_INLOOP_RESHAPER
  bestCS->picture->getPredBuf(currCsArea).copyFrom(bestCS->getPredBuf(currCsArea));
#endif
  bestCS->picture->getRecoBuf( currCsArea ).copyFrom( bestCS->getRecoBuf( currCsArea ) );
  m_modeCtrl->finishCULevel( partitioner );

#if ENABLE_SPLIT_PARALLELISM
  if( tempCS->picture->scheduler.getSplitJobId() == 0 && m_pcEncCfg->getNumSplitThreads() != 1 )
  {
    tempCS->picture->finishParallelPart( currCsArea );
  }

#endif
  // Assert if Best prediction mode is NONE
  // Selected mode's RD-cost must be not MAX_DOUBLE.  错误信息
  CHECK( bestCS->cus.empty()                                   , "No possible encoding found" );
  CHECK( bestCS->cus[0]->predMode == NUMBER_OF_PREDICTION_MODES, "No possible encoding found" );
  CHECK( bestCS->cost             == MAX_DOUBLE                , "No possible encoding found" );
}

笔者也只是对帧内预测有一定的了解，对于帧间等部分只有初步了解，尚未系统的学习。如果想了解帧内预测(xCheckRDCostIntra)的其他相关知识，请点击：H.266/VVC代码学习1：帧内预测框架，欢迎查看或指教，笔者会不断更新博客并对之前理解不深处进行勘误，以防老年痴呆，嘿嘿。