新人上路，请多多指教。 一直想写博客，今天才开始写第一篇。
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这次来讲一下VTM9.0中关于CU划分的部分，主要是两个函数xCompressCU和xCheckModeSplit。
xCompressCU主要针对当前CU可能进行的预测划分模式，完成相应的操作。主要分为以下几种模式（后面两种暂时还没学习，后面如果接触到会补充）
1划分模式：四叉树划分，水平二叉树划分，垂直二叉树划分，水平三叉树划分，垂直三叉树划分。通过调用函数xCompressCU完成。
2帧内预测：调用函数xCheckRDCostIntra完成。
3帧间预测：。。。。
4屏幕内容编码：。。。。
xCompressCU函数流程:初始化，调用函数initCULevel()，获取当前CU可能的预测和编码模式，并且按照顺序推入栈中。然后进入一循环，改循环会不断调取栈顶模式，将CU按照相应模式进行编码或划分，直至栈内不储存模式为止。具体代码如下：
void EncCu::xCompressCU( CodingStructure*& tempCS, CodingStructure*& bestCS, Partitioner& partitioner, double maxCostAllowed )
{
/*************************************** 初始化 ****************************************/
CHECK(maxCostAllowed < 0, "Wrong value of maxCostAllowed!");
#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
uint32_t compBegin;
uint32_t numComp;
bool jointPLT = false;
if (partitioner.isSepTree( *tempCS ))
{
#if JVET_Q0504_PLT_NON444
if( !CS::isDualITree(*tempCS) && partitioner.treeType != TREE_D )
{
compBegin = COMPONENT_Y;
numComp = (tempCS->area.chromaFormat != CHROMA_400)?3: 1;
jointPLT = true;
}
else
{
#endif
if (isLuma(partitioner.chType))
{
compBegin = COMPONENT_Y;
numComp = 1;
}
else
{
compBegin = COMPONENT_Cb;
numComp = 2;
}
#if JVET_Q0504_PLT_NON444
}
#endif
}
else
{
compBegin = COMPONENT_Y;
#if JVET_Q0504_PLT_NON444
numComp = (tempCS->area.chromaFormat != CHROMA_400) ? 3 : 1;
#else
numComp = 3;
#endif
jointPLT = true;
}
SplitSeries splitmode = -1;
uint8_t bestLastPLTSize[MAX_NUM_CHANNEL_TYPE];
Pel bestLastPLT[MAX_NUM_COMPONENT][MAXPLTPREDSIZE]; // store LastPLT for
uint8_t curLastPLTSize[MAX_NUM_CHANNEL_TYPE];
Pel curLastPLT[MAX_NUM_COMPONENT][MAXPLTPREDSIZE]; // store LastPLT if no partition
for (int i = compBegin; i < (compBegin + numComp); i++)
{
ComponentID comID = jointPLT ? (ComponentID)compBegin : ((i > 0) ? COMPONENT_Cb : COMPONENT_Y);
bestLastPLTSize[comID] = 0;
curLastPLTSize[comID] = tempCS->prevPLT.curPLTSize[comID];
memcpy(curLastPLT[i], tempCS->prevPLT.curPLT[i], tempCS->prevPLT.curPLTSize[comID] * sizeof(Pel));
}
Slice& slice = *tempCS->slice;
const PPS &pps = *tempCS->pps;
const SPS &sps = *tempCS->sps;
const uint32_t uiLPelX = tempCS->area.Y().lumaPos().x;
const uint32_t uiTPelY = tempCS->area.Y().lumaPos().y;
const ModeType modeTypeParent = partitioner.modeType;
const TreeType treeTypeParent = partitioner.treeType;
const ChannelType chTypeParent = partitioner.chType;
const UnitArea currCsArea = clipArea( CS::getArea( *bestCS, bestCS->area, partitioner.chType ), *tempCS->picture );
m_modeCtrl->initCULevel( partitioner, *tempCS );//初始化所有编码划分模式，为CU设置可能的编码划分模式
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()->getMaxTbSize() : MTS_INTER_MAX_CU_SIZE;
slsSbt->resetSaveloadSbt( maxSLSize );
#if ENABLE_SPLIT_PARALLELISM
CHECK( tempCS->picture->scheduler.getSplitJobId() != 0, "The SBT search reset need to happen in sequential region." );
if (m_pcEncCfg->getNumSplitThreads() > 1)
{
for (int jId = 1; jId < NUM_RESERVERD_SPLIT_JOBS; jId++)
{
auto slsSbt = dynamic_cast<SaveLoadEncInfoSbt *>(m_pcEncLib->getCuEncoder(jId)->m_modeCtrl);
slsSbt->resetSaveloadSbt(maxSLSize);
}
}
#endif
}
m_sbtCostSave[0] = m_sbtCostSave[1] = MAX_DOUBLE;
m_CurrCtx->start = m_CABACEstimator->getCtx();
/************************* 处理色度QP ***************************/
m_cuChromaQpOffsetIdxPlus1 = 0;
if( slice.getUseChromaQpAdj() )
{
// TODO M0133 : double check encoder decisions with respect to chroma QG detection and actual encode
int lgMinCuSize = sps.getLog2MinCodingBlockSize() +
#if JVET_Q0468_Q0469_MIN_LUMA_CB_AND_MIN_QT_FIX
std::max<int>(0, floorLog2(sps.getCTUSize()) - sps.getLog2MinCodingBlockSize() - int(slice.getCuChromaQpOffsetSubdiv() / 2));
#else
std::max<int>( 0, sps.getLog2DiffMaxMinCodingBlockSize() - int( slice.getCuChromaQpOffsetSubdiv()/2 ) );
#endif
#if JVET_Q0267_RESET_CHROMA_QP_OFFSET
if( partitioner.currQgChromaEnable() )
{
m_cuChromaQpOffsetIdxPlus1 = ( ( uiLPelX >> lgMinCuSize ) + ( uiTPelY >> lgMinCuSize ) ) % ( pps.getChromaQpOffsetListLen() + 1 );
}
#else
m_cuChromaQpOffsetIdxPlus1 = ( ( uiLPelX >> lgMinCuSize ) + ( uiTPelY >> lgMinCuSize ) ) % ( pps.getChromaQpOffsetListLen() + 1 );
#endif
}
if( !m_modeCtrl->anyMode() )
{
m_modeCtrl->finishCULevel( partitioner );
return;
}
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() );
m_pcInterSearch->resetSavedAffineMotion();
double bestIntPelCost = MAX_DOUBLE;
if (tempCS->slice->getSPS()->getUseColorTrans())
{
tempCS->tmpColorSpaceCost = MAX_DOUBLE;
bestCS->tmpColorSpaceCost = MAX_DOUBLE;
tempCS->firstColorSpaceSelected = true;
bestCS->firstColorSpaceSelected = true;
}
if (tempCS->slice->getSPS()->getUseColorTrans() && !CS::isDualITree(*tempCS))
{
tempCS->firstColorSpaceTestOnly = false;
bestCS->firstColorSpaceTestOnly = false;
tempCS->tmpColorSpaceIntraCost[0] = MAX_DOUBLE;
tempCS->tmpColorSpaceIntraCost[1] = MAX_DOUBLE;
bestCS->tmpColorSpaceIntraCost[0] = MAX_DOUBLE;
bestCS->tmpColorSpaceIntraCost[1] = MAX_DOUBLE;
if (tempCS->bestParent && tempCS->bestParent->firstColorSpaceTestOnly)
{
tempCS->firstColorSpaceTestOnly = bestCS->firstColorSpaceTestOnly = true;
}
}
/***************************按照堆栈中的模式进行循环预测编码或划分，当循环结束时当前CU已选择最小的RDcost进行划分与编码****************************/
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。
{
for (int i = compBegin; i < (compBegin + numComp); i++)
{
ComponentID comID = jointPLT ? (ComponentID)compBegin : ((i > 0) ? COMPONENT_Cb : COMPONENT_Y);
tempCS->prevPLT.curPLTSize[comID] = curLastPLTSize[comID];
memcpy(tempCS->prevPLT.curPLT[i], curLastPLT[i], curLastPLTSize[comID] * sizeof(Pel));
}
EncTestMode currTestMode = m_modeCtrl->currTestMode();//获得本次循环的编码或划分模式
currTestMode.maxCostAllowed = maxCostAllowed;
if (pps.getUseDQP() && partitioner.isSepTree(*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 || ENABLE_QPA_SUB_CTU
if (partitioner.currQgEnable() && (
#if SHARP_LUMA_DELTA_QP
(m_pcEncCfg->getLumaLevelToDeltaQPMapping().isEnabled()) ||
#endif
#if ENABLE_QPA_SUB_CTU
(m_pcEncCfg->getUsePerceptQPA() && !m_pcEncCfg->getUseRateCtrl() && pps.getUseDQP())
#else
false
#endif
))
{
#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,
#if WCG_EXT && ER_CHROMA_QP_WCG_PPS
m_pcEncCfg->getWCGChromaQPControl().isEnabled(),
#endif
CS::isDualITree (*tempCS) || (partitioner.currDepth == 0));
}
}
#endif
if( currTestMode.type == ETM_INTER_ME )//帧间运动估计-运动搜索（wan）
{
if( ( currTestMode.opts & ETO_IMV ) != 0 )
{
const bool skipAltHpelIF = ( int( ( currTestMode.opts & ETO_IMV ) >> ETO_IMV_SHIFT ) == 4 ) && ( bestIntPelCost > 1.25 * bestCS->cost );
if (!skipAltHpelIF)
{
tempCS->bestCS = bestCS;
xCheckRDCostInterIMV(tempCS, bestCS, partitioner, currTestMode, bestIntPelCost);
tempCS->bestCS = nullptr;
}
}
else
{
tempCS->bestCS = bestCS;
xCheckRDCostInter( tempCS, bestCS, partitioner, currTestMode );
tempCS->bestCS = nullptr;
}
}
else if (currTestMode.type == ETM_HASH_INTER)// IBC？
{
xCheckRDCostHashInter( tempCS, bestCS, partitioner, currTestMode );
}
else if( currTestMode.type == ETM_AFFINE )// 仿射，旋转（266）
{
xCheckRDCostAffineMerge2Nx2N( tempCS, bestCS, partitioner, currTestMode );
}
#if REUSE_CU_RESULTS
else if( currTestMode.type == ETM_RECO_CACHED )//快速算法，内存级别
{
xReuseCachedResult( tempCS, bestCS, partitioner );
}
#endif
else if( currTestMode.type == ETM_MERGE_SKIP )//MERGE，SKIP（wan）
{
xCheckRDCostMerge2Nx2N( tempCS, bestCS, partitioner, currTestMode );
CodingUnit* cu = bestCS->getCU(partitioner.chType);
if (cu)
cu->mmvdSkip = cu->skip == false ? false : cu->mmvdSkip;
}
#if !JVET_Q0806
else if( currTestMode.type == ETM_MERGE_TRIANGLE )
{
xCheckRDCostMergeTriangle2Nx2N( tempCS, bestCS, partitioner, currTestMode );
}
#else
else if( currTestMode.type == ETM_MERGE_GEO )//一个CU划分成两个，分别找
{
xCheckRDCostMergeGeo2Nx2N( tempCS, bestCS, partitioner, currTestMode );
}
#endif
else if( currTestMode.type == ETM_INTRA )//帧内
{
#if SPLIT_TEST
printf("intra: (%2d,%2d) %2d %2d : mode:%2d chan:%d\n", tempCS->area.blocks[0].x, tempCS->area.blocks[0].y, tempCS->area.blocks[0].width, tempCS->area.blocks[0].height, currTestMode.type, partitioner.chType);
#endif
if (slice.getSPS()->getUseColorTrans() && !CS::isDualITree(*tempCS))
{
bool skipSecColorSpace = false;
skipSecColorSpace = xCheckRDCostIntra(tempCS, bestCS, partitioner, currTestMode, (m_pcEncCfg->getRGBFormatFlag() ? true : false));//帧内预测编码
#if JVET_Q0820_ACT
if ((m_pcEncCfg->getCostMode() == COST_LOSSLESS_CODING) && !m_pcEncCfg->getRGBFormatFlag())
{
skipSecColorSpace = true;
}
#endif
if (!skipSecColorSpace && !tempCS->firstColorSpaceTestOnly)
{
xCheckRDCostIntra(tempCS, bestCS, partitioner, currTestMode, (m_pcEncCfg->getRGBFormatFlag() ? false : true));
}
if (!tempCS->firstColorSpaceTestOnly)
{
if (tempCS->tmpColorSpaceIntraCost[0] != MAX_DOUBLE && tempCS->tmpColorSpaceIntraCost[1] != MAX_DOUBLE)
{
double skipCostRatio = m_pcEncCfg->getRGBFormatFlag() ? 1.1 : 1.0;
if (tempCS->tmpColorSpaceIntraCost[1] > (skipCostRatio*tempCS->tmpColorSpaceIntraCost[0]))
{
tempCS->firstColorSpaceTestOnly = bestCS->firstColorSpaceTestOnly = true;
}
}
}
else
{
CHECK(tempCS->tmpColorSpaceIntraCost[1] != MAX_DOUBLE, "the RD test of the second color space should be skipped");
}
}
else
{
xCheckRDCostIntra(tempCS, bestCS, partitioner, currTestMode, false);
}
}
else if (currTestMode.type == ETM_PALETTE)//调色板
{
xCheckPLT( tempCS, bestCS, partitioner, currTestMode );
}
else if (currTestMode.type == ETM_IBC)//IBC
{
xCheckRDCostIBCMode(tempCS, bestCS, partitioner, currTestMode);
}
else if (currTestMode.type == ETM_IBC_MERGE)
{
xCheckRDCostIBCModeMerge2Nx2N(tempCS, bestCS, partitioner, currTestMode);
}
else if( isModeSplit( currTestMode ) )//compresscu-先判断能否继续划分-xCheckModeSplit-compresscu
{//如果判断type是五种划分模式其中一种
#if SPLIT_TEST
printf("split: (%2d,%2d) %2d %2d : mode:%2d chan:%d\n", tempCS->area.blocks[0].x, tempCS->area.blocks[0].y, tempCS->area.blocks[0].width, tempCS->area.blocks[0].height, currTestMode.type, partitioner.chType);
#endif
if (bestCS->cus.size() != 0)
{
splitmode = bestCS->cus[0]->splitSeries;
}
assert( partitioner.modeType == tempCS->modeType );
int signalModeConsVal = tempCS->signalModeCons( getPartSplit( currTestMode ), partitioner, modeTypeParent );
int numRoundRdo = signalModeConsVal == LDT_MODE_TYPE_SIGNAL ? 2 : 1;
bool skipInterPass = false;
for( int i = 0; i < numRoundRdo; i++ )
{
//change cons modes
if( signalModeConsVal == LDT_MODE_TYPE_SIGNAL )
{
CHECK( numRoundRdo != 2, "numRoundRdo shall be 2 - [LDT_MODE_TYPE_SIGNAL]" );
tempCS->modeType = partitioner.modeType = (i == 0) ? MODE_TYPE_INTER : MODE_TYPE_INTRA;
}
else if( signalModeConsVal == LDT_MODE_TYPE_INFER )
{
CHECK( numRoundRdo != 1, "numRoundRdo shall be 1 - [LDT_MODE_TYPE_INFER]" );
tempCS->modeType = partitioner.modeType = MODE_TYPE_INTRA;
}
else if( signalModeConsVal == LDT_MODE_TYPE_INHERIT )
{
CHECK( numRoundRdo != 1, "numRoundRdo shall be 1 - [LDT_MODE_TYPE_INHERIT]" );
tempCS->modeType = partitioner.modeType = modeTypeParent;
}
//for lite intra encoding fast algorithm, set the status to save inter coding info
//对于精简帧内编码快速算法，设置状态以保存帧间编码信息
if( modeTypeParent == MODE_TYPE_ALL && tempCS->modeType == MODE_TYPE_INTER )
{
m_pcIntraSearch->setSaveCuCostInSCIPU( true );
m_pcIntraSearch->setNumCuInSCIPU( 0 );
}
else if( modeTypeParent == MODE_TYPE_ALL && tempCS->modeType != MODE_TYPE_INTER )
{
m_pcIntraSearch->setSaveCuCostInSCIPU( false );
if( tempCS->modeType == MODE_TYPE_ALL )
{
m_pcIntraSearch->setNumCuInSCIPU( 0 );
}
}
xCheckModeSplit( tempCS, bestCS, partitioner, currTestMode, modeTypeParent, skipInterPass );//划分函数
//recover cons modes
tempCS->modeType = partitioner.modeType = modeTypeParent;
tempCS->treeType = partitioner.treeType = treeTypeParent;
partitioner.chType = chTypeParent;
if( modeTypeParent == MODE_TYPE_ALL )
{
m_pcIntraSearch->setSaveCuCostInSCIPU( false );
if( numRoundRdo == 2 && tempCS->modeType == MODE_TYPE_INTRA )
{
m_pcIntraSearch->initCuAreaCostInSCIPU();
}
}
if( skipInterPass )
{
break;
}
}
if (splitmode != bestCS->cus[0]->splitSeries)
{
splitmode = bestCS->cus[0]->splitSeries;
const CodingUnit& cu = *bestCS->cus.front();
cu.cs->prevPLT = bestCS->prevPLT;
for (int i = compBegin; i < (compBegin + numComp); i++)
{
ComponentID comID = jointPLT ? (ComponentID)compBegin : ((i > 0) ? COMPONENT_Cb : COMPONENT_Y);
bestLastPLTSize[comID] = bestCS->cus[0]->cs->prevPLT.curPLTSize[comID];
memcpy(bestLastPLT[i], bestCS->cus[0]->cs->prevPLT.curPLT[i], bestCS->cus[0]->cs->prevPLT.curPLTSize[comID] * sizeof(Pel));
}
}
}
else
{
THROW( "Don't know how to handle mode: type = " << currTestMode.type << ", options = " << currTestMode.opts );
}
} while( m_modeCtrl->nextMode( *tempCS, partitioner ) );//开始删掉栈顶的模式与接下来栈内不会存在的模式，进入CU下一个编码/划分模式
//////////////////////////////////////////////////////////////////////////
// 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
//如果划分失败，则删除m_ComprCUCtxList栈顶，结束划分
if( tempCS->cost == MAX_DOUBLE && bestCS->cost == MAX_DOUBLE )
{
//although some coding modes were planned to be tried in RDO, no coding mode actually finished encoding due to early termination
//thus tempCS->cost and bestCS->cost are both MAX_DOUBLE; in this case, skip the following process for normal case
m_modeCtrl->finishCULevel( partitioner );
return;
}
// set context states
m_CABACEstimator->getCtx() = m_CurrCtx->best;
// QP from last processed CU for further processing
//copy the qp of the last non-chroma CU
int numCUInThisNode = (int)bestCS->cus.size();
if( numCUInThisNode > 1 && bestCS->cus.back()->chType == CHANNEL_TYPE_CHROMA && !CS::isDualITree( *bestCS ) )
{
CHECK( bestCS->cus[numCUInThisNode-2]->chType != CHANNEL_TYPE_LUMA, "wrong chType" );
bestCS->prevQP[partitioner.chType] = bestCS->cus[numCUInThisNode-2]->qp;
}
else
{
bestCS->prevQP[partitioner.chType] = bestCS->cus.back()->qp;
}
if ((!slice.isIntra() || slice.getSPS()->getIBCFlag())
&& partitioner.chType == CHANNEL_TYPE_LUMA
&& bestCS->cus.size() == 1 && (bestCS->cus.back()->predMode == MODE_INTER || bestCS->cus.back()->predMode == MODE_IBC)
&& bestCS->area.Y() == (*bestCS->cus.back()).Y()
)
{
const CodingUnit& cu = *bestCS->cus.front();
bool isIbcSmallBlk = CU::isIBC(cu) && (cu.lwidth() * cu.lheight() <= 16);
CU::saveMotionInHMVP( cu, isIbcSmallBlk );
}
bestCS->picture->getPredBuf(currCsArea).copyFrom(bestCS->getPredBuf(currCsArea));
bestCS->picture->getRecoBuf( currCsArea ).copyFrom( bestCS->getRecoBuf( currCsArea ) );
m_modeCtrl->finishCULevel( partitioner );//删除m_ComprCUCtxList栈顶
if( m_pcIntraSearch->getSaveCuCostInSCIPU() && bestCS->cus.size() == 1 )
{
m_pcIntraSearch->saveCuAreaCostInSCIPU( Area( partitioner.currArea().lumaPos(), partitioner.currArea().lumaSize() ), bestCS->cost );
}
#if ENABLE_SPLIT_PARALLELISM
if( tempCS->picture->scheduler.getSplitJobId() == 0 && m_pcEncCfg->getNumSplitThreads() != 1 )
{
tempCS->picture->finishParallelPart( currCsArea );
}
#endif
if (bestCS->cus.size() == 1) // no partition
{
CHECK(bestCS->cus[0]->tileIdx != bestCS->pps->getTileIdx(bestCS->area.lumaPos()), "Wrong tile index!");
if (bestCS->cus[0]->predMode == MODE_PLT)
{
for (int i = compBegin; i < (compBegin + numComp); i++)
{
ComponentID comID = jointPLT ? (ComponentID)compBegin : ((i > 0) ? COMPONENT_Cb : COMPONENT_Y);
bestCS->prevPLT.curPLTSize[comID] = curLastPLTSize[comID];
memcpy(bestCS->prevPLT.curPLT[i], curLastPLT[i], curLastPLTSize[comID] * sizeof(Pel));
}
bestCS->reorderPrevPLT(bestCS->prevPLT, bestCS->cus[0]->curPLTSize, bestCS->cus[0]->curPLT, bestCS->cus[0]->reuseflag, compBegin, numComp, jointPLT);
}
else
{
for (int i = compBegin; i<(compBegin + numComp); i++)
{
ComponentID comID = jointPLT ? (ComponentID)compBegin : ((i > 0) ? COMPONENT_Cb : COMPONENT_Y);
bestCS->prevPLT.curPLTSize[comID] = curLastPLTSize[comID];
memcpy(bestCS->prevPLT.curPLT[i], curLastPLT[i], bestCS->prevPLT.curPLTSize[comID] * sizeof(Pel));
}
}
}
else
{
for (int i = compBegin; i<(compBegin + numComp); i++)
{
ComponentID comID = jointPLT ? (ComponentID)compBegin : ((i > 0) ? COMPONENT_Cb : COMPONENT_Y);
bestCS->prevPLT.curPLTSize[comID] = bestLastPLTSize[comID];
memcpy(bestCS->prevPLT.curPLT[i], bestLastPLT[i], bestCS->prevPLT.curPLTSize[comID] * sizeof(Pel));
}
}
const CodingUnit& cu = *bestCS->cus.front();
cu.cs->prevPLT = bestCS->prevPLT;
// Assert if Best prediction mode is NONE
// 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" );
}划分主要时调用函数xCheckModeSplit完成。函数xCheckModeSplit流程如下
- 首先完成初始化操作，设置上下文，判断当前划分模式是否可用。
- 调用splitCurrArea对子块进行划分，主要是计算划分后各个子块高宽与坐标。
- 进入循环，该循环会遍历每一个子块，调用函数xCompressCU，完成对子块的划分与预测编码。获得该子块划分编码后的RDcost，划分结构等相关信息。
- 结束循环后将划分前的RDcost与划分后进行对比，判断该CU是否进行划分
函数xCheckModeSplit具体代码如下：
void EncCu::xCheckModeSplit(CodingStructure *&tempCS, CodingStructure *&bestCS, Partitioner &partitioner, const EncTestMode& encTestMode, const ModeType modeTypeParent, bool &skipInterPass )
{
const int qp = encTestMode.qp;
const Slice &slice = *tempCS->slice;
const int oldPrevQp = tempCS->prevQP[partitioner.chType];
const auto oldMotionLut = tempCS->motionLut;
#if ENABLE_QPA_SUB_CTU
const PPS &pps = *tempCS->pps;
const uint32_t currDepth = partitioner.currDepth;
#endif
const auto oldPLT = tempCS->prevPLT;
const PartSplit split = getPartSplit( encTestMode );//获得cu划分方式
const ModeType modeTypeChild = partitioner.modeType;
CHECK( split == CU_DONT_SPLIT, "No proper split provided!" );
tempCS->initStructData( qp );//初始化tempCS
m_CABACEstimator->getCtx() = m_CurrCtx->start;
const TempCtx ctxStartSP( m_CtxCache, SubCtx( Ctx::SplitFlag, m_CABACEstimator->getCtx() ) );
const TempCtx ctxStartQt( m_CtxCache, SubCtx( Ctx::SplitQtFlag, m_CABACEstimator->getCtx() ) );
const TempCtx ctxStartHv( m_CtxCache, SubCtx( Ctx::SplitHvFlag, m_CABACEstimator->getCtx() ) );
const TempCtx ctxStart12( m_CtxCache, SubCtx( Ctx::Split12Flag, m_CABACEstimator->getCtx() ) );
const TempCtx ctxStartMC( m_CtxCache, SubCtx( Ctx::ModeConsFlag, m_CABACEstimator->getCtx() ) );
m_CABACEstimator->resetBits();
m_CABACEstimator->split_cu_mode( split, *tempCS, partitioner );
m_CABACEstimator->mode_constraint( split, *tempCS, partitioner, modeTypeChild );
const double factor = ( tempCS->currQP[partitioner.chType] > 30 ? 1.1 : 1.075 );
tempCS->useDbCost = m_pcEncCfg->getUseEncDbOpt();
if (!tempCS->useDbCost)
CHECK(bestCS->costDbOffset != 0, "error");
const double cost = m_pcRdCost->calcRdCost( uint64_t( m_CABACEstimator->getEstFracBits() + ( ( bestCS->fracBits ) / factor ) ), Distortion( bestCS->dist / factor ) ) + bestCS->costDbOffset / factor;
m_CABACEstimator->getCtx() = SubCtx( Ctx::SplitFlag, ctxStartSP );
m_CABACEstimator->getCtx() = SubCtx( Ctx::SplitQtFlag, ctxStartQt );
m_CABACEstimator->getCtx() = SubCtx( Ctx::SplitHvFlag, ctxStartHv );
m_CABACEstimator->getCtx() = SubCtx( Ctx::Split12Flag, ctxStart12 );
m_CABACEstimator->getCtx() = SubCtx( Ctx::ModeConsFlag, ctxStartMC );
//停止划分，具体原因不清楚
if (cost > bestCS->cost + bestCS->costDbOffset
#if ENABLE_QPA_SUB_CTU
|| (m_pcEncCfg->getUsePerceptQPA() && !m_pcEncCfg->getUseRateCtrl() && pps.getUseDQP() && (slice.getCuQpDeltaSubdiv() > 0) && (split == CU_HORZ_SPLIT || split == CU_VERT_SPLIT) &&
(currDepth == 0)) // force quad-split or no split at CTU level在CTU级别强制四叉树分割或不分割
#endif
)
{
xCheckBestMode( tempCS, bestCS, partitioner, encTestMode );
return;
}
const bool chromaNotSplit = modeTypeParent == MODE_TYPE_ALL && modeTypeChild == MODE_TYPE_INTRA ? true : false;
if( partitioner.treeType != TREE_D )
{
tempCS->treeType = TREE_L;
}
else
{
if( chromaNotSplit )
{
CHECK( partitioner.chType != CHANNEL_TYPE_LUMA, "chType must be luma" );
tempCS->treeType = partitioner.treeType = TREE_L;
}
else
{
tempCS->treeType = partitioner.treeType = TREE_D;
}
}
partitioner.splitCurrArea( split, *tempCS );//进行划分，计算划分子块区域以及坐上坐标
bool qgEnableChildren = partitioner.currQgEnable(); // QG possible at children level
m_CurrCtx++;
tempCS->getRecoBuf().fill( 0 );
tempCS->getPredBuf().fill(0);
AffineMVInfo tmpMVInfo;
bool isAffMVInfoSaved;
m_pcInterSearch->savePrevAffMVInfo(0, tmpMVInfo, isAffMVInfoSaved);
BlkUniMvInfo tmpUniMvInfo;
bool isUniMvInfoSaved = false;
if (!tempCS->slice->isIntra())
{
m_pcInterSearch->savePrevUniMvInfo(tempCS->area.Y(), tmpUniMvInfo, isUniMvInfoSaved);
}
do
{
const auto &subCUArea = partitioner.currArea();//划分后的子块区域
if( tempCS->picture->Y().contains( subCUArea.lumaPos() ) )
{
const unsigned wIdx = gp_sizeIdxInfo->idxFrom( subCUArea.lwidth () );
const unsigned hIdx = gp_sizeIdxInfo->idxFrom( subCUArea.lheight() );
CodingStructure *tempSubCS = m_pTempCS[wIdx][hIdx];
CodingStructure *bestSubCS = m_pBestCS[wIdx][hIdx];
tempCS->initSubStructure( *tempSubCS, partitioner.chType, subCUArea, false );//子块cu初始化
tempCS->initSubStructure( *bestSubCS, partitioner.chType, subCUArea, false );
tempSubCS->bestParent = bestSubCS->bestParent = bestCS;
double newMaxCostAllowed = isLuma(partitioner.chType) ? std::min(encTestMode.maxCostAllowed, bestCS->cost - m_pcRdCost->calcRdCost(tempCS->fracBits, tempCS->dist)) : MAX_DOUBLE;
newMaxCostAllowed = std::max(0.0, newMaxCostAllowed);
xCompressCU(tempSubCS, bestSubCS, partitioner, newMaxCostAllowed);//递归调用
tempSubCS->bestParent = bestSubCS->bestParent = nullptr;
if( bestSubCS->cost == MAX_DOUBLE )
{
CHECK( split == CU_QUAD_SPLIT, "Split decision reusing cannot skip quad split" );
tempCS->cost = MAX_DOUBLE;
tempCS->costDbOffset = 0;
tempCS->useDbCost = m_pcEncCfg->getUseEncDbOpt();
m_CurrCtx--;
partitioner.exitCurrSplit();
xCheckBestMode( tempCS, bestCS, partitioner, encTestMode );
if( partitioner.chType == CHANNEL_TYPE_LUMA )
{
tempCS->motionLut = oldMotionLut;
}
return;
}
bool keepResi = KEEP_PRED_AND_RESI_SIGNALS;
tempCS->useSubStructure( *bestSubCS, partitioner.chType, CS::getArea( *tempCS, subCUArea, partitioner.chType ), KEEP_PRED_AND_RESI_SIGNALS, true, keepResi, keepResi );
//从子结构中复制编码数据，将bestSubCS的cu,pu,tu复制到tempCS中
if( partitioner.currQgEnable() )
{
tempCS->prevQP[partitioner.chType] = bestSubCS->prevQP[partitioner.chType];
}
if( partitioner.isConsInter() )
{
for( int i = 0; i < bestSubCS->cus.size(); i++ )
{
CHECK( bestSubCS->cus[i]->predMode != MODE_INTER, "all CUs must be inter mode in an Inter coding region (SCIPU)" );
}
}
else if( partitioner.isConsIntra() )
{
for( int i = 0; i < bestSubCS->cus.size(); i++ )
{
CHECK( bestSubCS->cus[i]->predMode == MODE_INTER, "all CUs must not be inter mode in an Intra coding region (SCIPU)" );
}
}
tempSubCS->releaseIntermediateData();//清空子节点数据
bestSubCS->releaseIntermediateData();
if( !tempCS->slice->isIntra() && partitioner.isConsIntra() )
{
tempCS->cost = m_pcRdCost->calcRdCost( tempCS->fracBits, tempCS->dist );
if( tempCS->cost > bestCS->cost )
{
tempCS->cost = MAX_DOUBLE;
tempCS->costDbOffset = 0;
tempCS->useDbCost = m_pcEncCfg->getUseEncDbOpt();
m_CurrCtx--;
partitioner.exitCurrSplit();
if( partitioner.chType == CHANNEL_TYPE_LUMA )
{
tempCS->motionLut = oldMotionLut;
}
return;
}
}
}
} while( partitioner.nextPart( *tempCS ) );//进行下一个子块的划分
partitioner.exitCurrSplit();//清除m_partStack栈顶，将深度减一
m_CurrCtx--;
if( chromaNotSplit )
{
//Note: In local dual tree region, the chroma CU refers to the central luma CU's QP.
//If the luma CU QP shall be predQP (no residual in it and before it in the QG), it must be revised to predQP before encoding the chroma CU
//Otherwise, the chroma CU uses predQP+deltaQP in encoding but is decoded as using predQP, thus causing encoder-decoded mismatch on chroma qp.
if( tempCS->pps->getUseDQP() )
{
//find parent CS that including all coded CUs in the QG before this node
CodingStructure* qgCS = tempCS;
bool deltaQpCodedBeforeThisNode = false;
if( partitioner.currArea().lumaPos() != partitioner.currQgPos )
{
int numParentNodeToQgCS = 0;
while( qgCS->area.lumaPos() != partitioner.currQgPos )
{
CHECK( qgCS->parent == nullptr, "parent of qgCS shall exsit" );
qgCS = qgCS->parent;
numParentNodeToQgCS++;
}
//check whether deltaQP has been coded (in luma CU or luma&chroma CU) before this node
CodingStructure* parentCS = tempCS->parent;
for( int i = 0; i < numParentNodeToQgCS; i++ )
{
//checking each parent
CHECK( parentCS == nullptr, "parentCS shall exsit" );
for( const auto &cu : parentCS->cus )
{
if( cu->rootCbf && !isChroma( cu->chType ) )
{
deltaQpCodedBeforeThisNode = true;
break;
}
}
parentCS = parentCS->parent;
}
}
//revise luma CU qp before the first luma CU with residual in the SCIPU to predQP
if( !deltaQpCodedBeforeThisNode )
{
//get pred QP of the QG
const CodingUnit* cuFirst = qgCS->getCU( CHANNEL_TYPE_LUMA );
CHECK( cuFirst->lumaPos() != partitioner.currQgPos, "First cu of the Qg is wrong" );
int predQp = CU::predictQP( *cuFirst, qgCS->prevQP[CHANNEL_TYPE_LUMA] );
//revise to predQP
int firstCuHasResidual = (int)tempCS->cus.size();
for( int i = 0; i < tempCS->cus.size(); i++ )
{
if( tempCS->cus[i]->rootCbf )
{
firstCuHasResidual = i;
break;
}
}
for( int i = 0; i < firstCuHasResidual; i++ )
{
tempCS->cus[i]->qp = predQp;
}
}
}
assert( tempCS->treeType == TREE_L );
uint32_t numCuPuTu[6];
tempCS->picture->cs->getNumCuPuTuOffset( numCuPuTu );
tempCS->picture->cs->useSubStructure( *tempCS, partitioner.chType, CS::getArea( *tempCS, partitioner.currArea(), partitioner.chType ), false, true, false, false );
#if JVET_Q0438_MONOCHROME_BUGFIXES
if (isChromaEnabled(tempCS->pcv->chrFormat))
{
#endif
partitioner.chType = CHANNEL_TYPE_CHROMA;
tempCS->treeType = partitioner.treeType = TREE_C;
m_CurrCtx++;
const unsigned wIdx = gp_sizeIdxInfo->idxFrom( partitioner.currArea().lwidth() );
const unsigned hIdx = gp_sizeIdxInfo->idxFrom( partitioner.currArea().lheight() );
CodingStructure *tempCSChroma = m_pTempCS2[wIdx][hIdx];
CodingStructure *bestCSChroma = m_pBestCS2[wIdx][hIdx];
tempCS->initSubStructure( *tempCSChroma, partitioner.chType, partitioner.currArea(), false );
tempCS->initSubStructure( *bestCSChroma, partitioner.chType, partitioner.currArea(), false );
tempCS->treeType = TREE_D;
xCompressCU( tempCSChroma, bestCSChroma, partitioner );
//attach chromaCS to luma CS and update cost
bool keepResi = KEEP_PRED_AND_RESI_SIGNALS;
//bestCSChroma->treeType = tempCSChroma->treeType = TREE_C;
CHECK( bestCSChroma->treeType != TREE_C || tempCSChroma->treeType != TREE_C, "wrong treeType for chroma CS" );
tempCS->useSubStructure( *bestCSChroma, partitioner.chType, CS::getArea( *bestCSChroma, partitioner.currArea(), partitioner.chType ), KEEP_PRED_AND_RESI_SIGNALS, true, keepResi, true );
//release tmp resource
tempCSChroma->releaseIntermediateData();
bestCSChroma->releaseIntermediateData();
//tempCS->picture->cs->releaseIntermediateData();
#if JVET_Q0438_MONOCHROME_BUGFIXES
m_CurrCtx--;
}
#endif
tempCS->picture->cs->clearCuPuTuIdxMap( partitioner.currArea(), numCuPuTu[0], numCuPuTu[1], numCuPuTu[2], numCuPuTu + 3 );
#if !JVET_Q0438_MONOCHROME_BUGFIXES
m_CurrCtx--;
#endif
//recover luma tree status
partitioner.chType = CHANNEL_TYPE_LUMA;
partitioner.treeType = TREE_D;
partitioner.modeType = MODE_TYPE_ALL;
}
// Finally, generate split-signaling bits for RD-cost check
const PartSplit implicitSplit = partitioner.getImplicitSplit( *tempCS );
{
bool enforceQT = implicitSplit == CU_QUAD_SPLIT;
// LARGE CTU bug
if( m_pcEncCfg->getUseFastLCTU() )
{
unsigned minDepth = 0;
unsigned maxDepth = floorLog2(tempCS->sps->getCTUSize()) - floorLog2(tempCS->sps->getMinQTSize(slice.getSliceType(), partitioner.chType));
if( auto ad = dynamic_cast<AdaptiveDepthPartitioner*>( &partitioner ) )
{
ad->setMaxMinDepth( minDepth, maxDepth, *tempCS );
}
if( minDepth > partitioner.currQtDepth )
{
// enforce QT
enforceQT = true;
}
}
if( !enforceQT )
{
m_CABACEstimator->resetBits();
m_CABACEstimator->split_cu_mode( split, *tempCS, partitioner );
partitioner.modeType = modeTypeParent;
m_CABACEstimator->mode_constraint( split, *tempCS, partitioner, modeTypeChild );
tempCS->fracBits += m_CABACEstimator->getEstFracBits(); // split bits加上划分的bit
}
}
tempCS->cost = m_pcRdCost->calcRdCost( tempCS->fracBits, tempCS->dist );//计算当前划分模式总的代价
// Check Delta QP bits for splitted structure
if( !qgEnableChildren ) // check at deepest QG level only
xCheckDQP( *tempCS, partitioner, true );
// If the configuration being tested exceeds the maximum number of bytes for a slice / slice-segment, then
// a proper RD evaluation cannot be performed. Therefore, termination of the
// slice/slice-segment must be made prior to this CTU.
// This can be achieved by forcing the decision to be that of the rpcTempCU.
// The exception is each slice / slice-segment must have at least one CTU.
if (bestCS->cost != MAX_DOUBLE)
{
}
else
{
bestCS->costDbOffset = 0;
}
tempCS->useDbCost = m_pcEncCfg->getUseEncDbOpt();
if( tempCS->cus.size() > 0 && modeTypeParent == MODE_TYPE_ALL && modeTypeChild == MODE_TYPE_INTER )
{
int areaSizeNoResiCu = 0;
for( int k = 0; k < tempCS->cus.size(); k++ )
{
areaSizeNoResiCu += (tempCS->cus[k]->rootCbf == false) ? tempCS->cus[k]->lumaSize().area() : 0;
}
if( areaSizeNoResiCu >= (tempCS->area.lumaSize().area() >> 1) )
{
skipInterPass = true;
}
}
// RD check for sub partitioned coding structure.
xCheckBestMode( tempCS, bestCS, partitioner, encTestMode );//比较当前划分方式与之前划分方式，然后选择代价较小的
if (isAffMVInfoSaved)
m_pcInterSearch->addAffMVInfo(tmpMVInfo);
if (!tempCS->slice->isIntra() && isUniMvInfoSaved)
{
m_pcInterSearch->addUniMvInfo(tmpUniMvInfo);
}
tempCS->motionLut = oldMotionLut;
tempCS->prevPLT = oldPLT;
tempCS->releaseIntermediateData();
tempCS->prevQP[partitioner.chType] = oldPrevQp;
}这部分代码稍微看的有点绕，是由于xCompressCU函数中调用了函数xCheckModeSplit，在函数xCheckModeSplit又调用了xCompressCU。这样CU递归划分直到不能划分为止。对CU进行RDO的逻辑是先对当前CU进行编码，再对其划分，对划分完的各个子块进行编码，若（不划分的RDcost）> (划分的RDcost+划分需要多传输的bit数)，那么就进行划分，否则不划分。可以在xCompressCU函数开头打印log判断cu划分与编码的顺序。如下图所示，其中模式5为帧内预测模式，其余为划分模式。
