HEVC代码追踪（十四）:解码之xDecodeSlice

Bool TDecTop::decode(InputNALUnit& nalu, Int& iSkipFrame, Int& iPOCLastDisplay)
{
  // Initialize entropy decoder
  m_cEntropyDecoder.setEntropyDecoder (&m_cCavlcDecoder);
  m_cEntropyDecoder.setBitstream      (nalu.m_Bitstream);

  switch (nalu.m_nalUnitType)
  {
    case NAL_UNIT_VPS:
      xDecodeVPS();
      return false;
      
    case NAL_UNIT_SPS:
      xDecodeSPS();
      return false;

    case NAL_UNIT_PPS:
      xDecodePPS();
      return false;
      
    case NAL_UNIT_PREFIX_SEI:
    case NAL_UNIT_SUFFIX_SEI:
      xDecodeSEI( nalu.m_Bitstream, nalu.m_nalUnitType );
      return false;

    case NAL_UNIT_CODED_SLICE_TRAIL_R:
    case NAL_UNIT_CODED_SLICE_TRAIL_N:
    case NAL_UNIT_CODED_SLICE_TSA_R:
    case NAL_UNIT_CODED_SLICE_TSA_N:
    case NAL_UNIT_CODED_SLICE_STSA_R:
    case NAL_UNIT_CODED_SLICE_STSA_N:
    case NAL_UNIT_CODED_SLICE_BLA_W_LP:
    case NAL_UNIT_CODED_SLICE_BLA_W_RADL:
    case NAL_UNIT_CODED_SLICE_BLA_N_LP:
    case NAL_UNIT_CODED_SLICE_IDR_W_RADL:
    case NAL_UNIT_CODED_SLICE_IDR_N_LP:
    case NAL_UNIT_CODED_SLICE_CRA:
    case NAL_UNIT_CODED_SLICE_RADL_N:
    case NAL_UNIT_CODED_SLICE_RADL_R:
    case NAL_UNIT_CODED_SLICE_RASL_N:
    case NAL_UNIT_CODED_SLICE_RASL_R:
      return xDecodeSlice(nalu, iSkipFrame, iPOCLastDisplay);
      break;
      
    case NAL_UNIT_EOS:
      m_associatedIRAPType = NAL_UNIT_INVALID;
      m_pocCRA = 0;
      m_pocRandomAccess = MAX_INT;
      m_prevPOC = MAX_INT;
      m_bFirstSliceInPicture = true;
      m_bFirstSliceInSequence = true;
      m_prevSliceSkipped = false;
      m_skippedPOC = 0;
      return false;
      
    case NAL_UNIT_ACCESS_UNIT_DELIMITER:
      // TODO: process AU delimiter
      return false;
      
    case NAL_UNIT_EOB:
      return false;

    case NAL_UNIT_FILLER_DATA:
      return false;
      
    case NAL_UNIT_RESERVED_VCL_N10:
    case NAL_UNIT_RESERVED_VCL_R11:
    case NAL_UNIT_RESERVED_VCL_N12:
    case NAL_UNIT_RESERVED_VCL_R13:
    case NAL_UNIT_RESERVED_VCL_N14:
    case NAL_UNIT_RESERVED_VCL_R15:
      
    case NAL_UNIT_RESERVED_IRAP_VCL22:
    case NAL_UNIT_RESERVED_IRAP_VCL23:
      
    case NAL_UNIT_RESERVED_VCL24:
    case NAL_UNIT_RESERVED_VCL25:
    case NAL_UNIT_RESERVED_VCL26:
    case NAL_UNIT_RESERVED_VCL27:
    case NAL_UNIT_RESERVED_VCL28:
    case NAL_UNIT_RESERVED_VCL29:
    case NAL_UNIT_RESERVED_VCL30:
    case NAL_UNIT_RESERVED_VCL31:
      
    case NAL_UNIT_RESERVED_NVCL41:
    case NAL_UNIT_RESERVED_NVCL42:
    case NAL_UNIT_RESERVED_NVCL43:
    case NAL_UNIT_RESERVED_NVCL44:
    case NAL_UNIT_RESERVED_NVCL45:
    case NAL_UNIT_RESERVED_NVCL46:
    case NAL_UNIT_RESERVED_NVCL47:
    case NAL_UNIT_UNSPECIFIED_48:
    case NAL_UNIT_UNSPECIFIED_49:
    case NAL_UNIT_UNSPECIFIED_50:
    case NAL_UNIT_UNSPECIFIED_51:
    case NAL_UNIT_UNSPECIFIED_52:
    case NAL_UNIT_UNSPECIFIED_53:
    case NAL_UNIT_UNSPECIFIED_54:
    case NAL_UNIT_UNSPECIFIED_55:
    case NAL_UNIT_UNSPECIFIED_56:
    case NAL_UNIT_UNSPECIFIED_57:
    case NAL_UNIT_UNSPECIFIED_58:
    case NAL_UNIT_UNSPECIFIED_59:
    case NAL_UNIT_UNSPECIFIED_60:
    case NAL_UNIT_UNSPECIFIED_61:
    case NAL_UNIT_UNSPECIFIED_62:
    case NAL_UNIT_UNSPECIFIED_63:

    default:
      assert (0);
  }

  return false;
}

Bool TDecTop::xDecodeSlice(InputNALUnit &nalu, Int &iSkipFrame, Int iPOCLastDisplay )
{
  TComPic*& pcPic = m_pcPic;
  m_apcSlicePilot->initSlice();

  if (m_bFirstSliceInPicture)
  {
    m_uiSliceIdx = 0;
  }
  else
  {
    m_apcSlicePilot->copySliceInfo( pcPic->getPicSym()->getSlice(m_uiSliceIdx-1) );
  }
  m_apcSlicePilot->setSliceIdx(m_uiSliceIdx);

  m_apcSlicePilot->setNalUnitType(nalu.m_nalUnitType);
  Bool nonReferenceFlag = (m_apcSlicePilot->getNalUnitType() == NAL_UNIT_CODED_SLICE_TRAIL_N ||
                           m_apcSlicePilot->getNalUnitType() == NAL_UNIT_CODED_SLICE_TSA_N   ||
                           m_apcSlicePilot->getNalUnitType() == NAL_UNIT_CODED_SLICE_STSA_N  ||
                           m_apcSlicePilot->getNalUnitType() == NAL_UNIT_CODED_SLICE_RADL_N  ||
                           m_apcSlicePilot->getNalUnitType() == NAL_UNIT_CODED_SLICE_RASL_N);
  m_apcSlicePilot->setTemporalLayerNonReferenceFlag(nonReferenceFlag);
  
  m_apcSlicePilot->setReferenced(true); // Putting this as true ensures that picture is referenced the first time it is in an RPS
  m_apcSlicePilot->setTLayerInfo(nalu.m_temporalId);

  m_cEntropyDecoder.decodeSliceHeader (m_apcSlicePilot, &m_parameterSetManagerDecoder);
  
  // set POC for dependent slices in skipped pictures
  if(m_apcSlicePilot->getDependentSliceSegmentFlag() && m_prevSliceSkipped) 
  {
    m_apcSlicePilot->setPOC(m_skippedPOC);
  }

  m_apcSlicePilot->setAssociatedIRAPPOC(m_pocCRA);
  m_apcSlicePilot->setAssociatedIRAPType(m_associatedIRAPType);

#if SETTING_NO_OUT_PIC_PRIOR
  //For inference of NoOutputOfPriorPicsFlag
  if (m_apcSlicePilot->getRapPicFlag())
  {
    if ((m_apcSlicePilot->getNalUnitType() >= NAL_UNIT_CODED_SLICE_BLA_W_LP && m_apcSlicePilot->getNalUnitType() <= NAL_UNIT_CODED_SLICE_IDR_N_LP) || 
        (m_apcSlicePilot->getNalUnitType() == NAL_UNIT_CODED_SLICE_CRA && m_bFirstSliceInSequence) ||
        (m_apcSlicePilot->getNalUnitType() == NAL_UNIT_CODED_SLICE_CRA && m_apcSlicePilot->getHandleCraAsBlaFlag()))
    {
      m_apcSlicePilot->setNoRaslOutputFlag(true);
    }
    //the inference for NoOutputPriorPicsFlag
    if (!m_bFirstSliceInBitstream && m_apcSlicePilot->getRapPicFlag() && m_apcSlicePilot->getNoRaslOutputFlag())
    {
      if (m_apcSlicePilot->getNalUnitType() == NAL_UNIT_CODED_SLICE_CRA)
      {
        m_apcSlicePilot->setNoOutputPriorPicsFlag(true);
      }
    }
    else
    {
      m_apcSlicePilot->setNoOutputPriorPicsFlag(false);
    }

    if(m_apcSlicePilot->getNalUnitType() == NAL_UNIT_CODED_SLICE_CRA)
    {
      m_craNoRaslOutputFlag = m_apcSlicePilot->getNoRaslOutputFlag();
    }
  }
  if (m_apcSlicePilot->getRapPicFlag() && m_apcSlicePilot->getNoOutputPriorPicsFlag())
  {
    m_lastPOCNoOutputPriorPics = m_apcSlicePilot->getPOC();
    m_isNoOutputPriorPics = true;
  }
  else
  {
    m_isNoOutputPriorPics = false;
  }

  //For inference of PicOutputFlag
  if (m_apcSlicePilot->getNalUnitType() == NAL_UNIT_CODED_SLICE_RASL_N || m_apcSlicePilot->getNalUnitType() == NAL_UNIT_CODED_SLICE_RASL_R)
  {
    if ( m_craNoRaslOutputFlag )
    {
      m_apcSlicePilot->setPicOutputFlag(false);
    }
  }
#endif

#if FIX_POC_CRA_NORASL_OUTPUT
  if (m_apcSlicePilot->getNalUnitType() == NAL_UNIT_CODED_SLICE_CRA && m_craNoRaslOutputFlag) //Reset POC MSB when CRA has NoRaslOutputFlag equal to 1
  {
    Int iMaxPOClsb = 1 << m_apcSlicePilot->getSPS()->getBitsForPOC();
    m_apcSlicePilot->setPOC( m_apcSlicePilot->getPOC() & (iMaxPOClsb - 1) );
  }
#endif

  // Skip pictures due to random access
  if (isRandomAccessSkipPicture(iSkipFrame, iPOCLastDisplay))
  {
    m_prevSliceSkipped = true;
    m_skippedPOC = m_apcSlicePilot->getPOC();
    return false;
  }
  // Skip TFD pictures associated with BLA/BLANT pictures
  if (isSkipPictureForBLA(iPOCLastDisplay))
  {
    m_prevSliceSkipped = true;
    m_skippedPOC = m_apcSlicePilot->getPOC();
    return false;
  }
  
  // clear previous slice skipped flag
  m_prevSliceSkipped = false;

  //we should only get a different poc for a new picture (with CTU address==0)
  if (m_apcSlicePilot->isNextSlice() && m_apcSlicePilot->getPOC()!=m_prevPOC && !m_bFirstSliceInSequence && (m_apcSlicePilot->getSliceCurStartCUAddr()!=0))
  {
    printf ("Warning, the first slice of a picture might have been lost!\n");
  }
  // exit when a new picture is found
  if (m_apcSlicePilot->isNextSlice() && (m_apcSlicePilot->getSliceCurStartCUAddr() == 0 && !m_bFirstSliceInPicture) && !m_bFirstSliceInSequence )
  {
    if (m_prevPOC >= m_pocRandomAccess)
    {
      m_prevPOC = m_apcSlicePilot->getPOC();
      return true;
    }
    m_prevPOC = m_apcSlicePilot->getPOC();
  }

  // actual decoding starts here
  xActivateParameterSets();

  if (m_apcSlicePilot->isNextSlice()) 
  {
    m_prevPOC = m_apcSlicePilot->getPOC();
  }
  m_bFirstSliceInSequence = false;
#if SETTING_NO_OUT_PIC_PRIOR  
  m_bFirstSliceInBitstream  = false;
#endif
  //detect lost reference picture and insert copy of earlier frame.
  Int lostPoc;
  while((lostPoc=m_apcSlicePilot->checkThatAllRefPicsAreAvailable(m_cListPic, m_apcSlicePilot->getRPS(), true, m_pocRandomAccess)) > 0)
  {
    xCreateLostPicture(lostPoc-1);
  }
  if (m_bFirstSliceInPicture)
  {
    // Buffer initialize for prediction.
    m_cPrediction.initTempBuff();
    m_apcSlicePilot->applyReferencePictureSet(m_cListPic, m_apcSlicePilot->getRPS());
    //  Get a new picture buffer
    xGetNewPicBuffer (m_apcSlicePilot, pcPic);

    Bool isField = false;
    Bool isTff = false;
    
    if(!m_SEIs.empty())
    {
      // Check if any new Picture Timing SEI has arrived
      SEIMessages pictureTimingSEIs = extractSeisByType (m_SEIs, SEI::PICTURE_TIMING);
      if (pictureTimingSEIs.size()>0)
      {
        SEIPictureTiming* pictureTiming = (SEIPictureTiming*) *(pictureTimingSEIs.begin());
        isField = (pictureTiming->m_picStruct == 1) || (pictureTiming->m_picStruct == 2);
        isTff =  (pictureTiming->m_picStruct == 1);
      }
    }
    
    //Set Field/Frame coding mode
    m_pcPic->setField(isField);
    m_pcPic->setTopField(isTff);
    
    // transfer any SEI messages that have been received to the picture
    pcPic->setSEIs(m_SEIs);
    m_SEIs.clear();

    // Recursive structure
    m_cCuDecoder.create ( g_uiMaxCUDepth, g_uiMaxCUWidth, g_uiMaxCUHeight );
    m_cCuDecoder.init   ( &m_cEntropyDecoder, &m_cTrQuant, &m_cPrediction );
    m_cTrQuant.init     ( g_uiMaxCUWidth, g_uiMaxCUHeight, m_apcSlicePilot->getSPS()->getMaxTrSize());

    m_cSliceDecoder.create();
  }
  else
  {
    // Check if any new SEI has arrived
    if(!m_SEIs.empty())
    {
      // Currently only decoding Unit SEI message occurring between VCL NALUs copied
      SEIMessages &picSEI = pcPic->getSEIs();
      SEIMessages decodingUnitInfos = extractSeisByType (m_SEIs, SEI::DECODING_UNIT_INFO);
      picSEI.insert(picSEI.end(), decodingUnitInfos.begin(), decodingUnitInfos.end());
      deleteSEIs(m_SEIs);
    }
  }
  
  //  Set picture slice pointer
  TComSlice*  pcSlice = m_apcSlicePilot;
  Bool bNextSlice     = pcSlice->isNextSlice();

  UInt i;
  pcPic->getPicSym()->initTiles(pcSlice->getPPS());

  //generate the Coding Order Map and Inverse Coding Order Map
  UInt uiEncCUAddr;
  for(i=0, uiEncCUAddr=0; i<pcPic->getPicSym()->getNumberOfCUsInFrame(); i++, uiEncCUAddr = pcPic->getPicSym()->xCalculateNxtCUAddr(uiEncCUAddr))
  {
    pcPic->getPicSym()->setCUOrderMap(i, uiEncCUAddr);
    pcPic->getPicSym()->setInverseCUOrderMap(uiEncCUAddr, i);
  }
  pcPic->getPicSym()->setCUOrderMap(pcPic->getPicSym()->getNumberOfCUsInFrame(), pcPic->getPicSym()->getNumberOfCUsInFrame());
  pcPic->getPicSym()->setInverseCUOrderMap(pcPic->getPicSym()->getNumberOfCUsInFrame(), pcPic->getPicSym()->getNumberOfCUsInFrame());

  //convert the start and end CU addresses of the slice and dependent slice into encoding order
  pcSlice->setSliceSegmentCurStartCUAddr( pcPic->getPicSym()->getPicSCUEncOrder(pcSlice->getSliceSegmentCurStartCUAddr()) );
  pcSlice->setSliceSegmentCurEndCUAddr( pcPic->getPicSym()->getPicSCUEncOrder(pcSlice->getSliceSegmentCurEndCUAddr()) );
  if(pcSlice->isNextSlice())
  {
    pcSlice->setSliceCurStartCUAddr(pcPic->getPicSym()->getPicSCUEncOrder(pcSlice->getSliceCurStartCUAddr()));
    pcSlice->setSliceCurEndCUAddr(pcPic->getPicSym()->getPicSCUEncOrder(pcSlice->getSliceCurEndCUAddr()));
  }

  if (m_bFirstSliceInPicture) 
  {
    if(pcPic->getNumAllocatedSlice() != 1)
    {
      pcPic->clearSliceBuffer();
    }
  }
  else
  {
    pcPic->allocateNewSlice();
  }
  assert(pcPic->getNumAllocatedSlice() == (m_uiSliceIdx + 1));
  m_apcSlicePilot = pcPic->getPicSym()->getSlice(m_uiSliceIdx); 
  pcPic->getPicSym()->setSlice(pcSlice, m_uiSliceIdx);

  pcPic->setTLayer(nalu.m_temporalId);

  if (bNextSlice)
  {
    pcSlice->checkCRA(pcSlice->getRPS(), m_pocCRA, m_associatedIRAPType, m_cListPic );
    // Set reference list
    pcSlice->setRefPicList( m_cListPic, true );
    
    // For generalized B
    // note: maybe not existed case (always L0 is copied to L1 if L1 is empty)
    if (pcSlice->isInterB() && pcSlice->getNumRefIdx(REF_PIC_LIST_1) == 0)
    {
      Int iNumRefIdx = pcSlice->getNumRefIdx(REF_PIC_LIST_0);
      pcSlice->setNumRefIdx        ( REF_PIC_LIST_1, iNumRefIdx );

      for (Int iRefIdx = 0; iRefIdx < iNumRefIdx; iRefIdx++)
      {
        pcSlice->setRefPic(pcSlice->getRefPic(REF_PIC_LIST_0, iRefIdx), REF_PIC_LIST_1, iRefIdx);
      }
    }
    if (!pcSlice->isIntra())
    {
      Bool bLowDelay = true;
      Int  iCurrPOC  = pcSlice->getPOC();
      Int iRefIdx = 0;

      for (iRefIdx = 0; iRefIdx < pcSlice->getNumRefIdx(REF_PIC_LIST_0) && bLowDelay; iRefIdx++)
      {
        if ( pcSlice->getRefPic(REF_PIC_LIST_0, iRefIdx)->getPOC() > iCurrPOC )
        {
          bLowDelay = false;
        }
      }
      if (pcSlice->isInterB())
      {
        for (iRefIdx = 0; iRefIdx < pcSlice->getNumRefIdx(REF_PIC_LIST_1) && bLowDelay; iRefIdx++)
        {
          if ( pcSlice->getRefPic(REF_PIC_LIST_1, iRefIdx)->getPOC() > iCurrPOC )
          {
            bLowDelay = false;
          }
        }        
      }

      pcSlice->setCheckLDC(bLowDelay);            
    }

    //---------------
    pcSlice->setRefPOCList();
  }

  pcPic->setCurrSliceIdx(m_uiSliceIdx);
  if(pcSlice->getSPS()->getScalingListFlag())
  {
    pcSlice->setScalingList ( pcSlice->getSPS()->getScalingList()  );
    if(pcSlice->getPPS()->getScalingListPresentFlag())
    {
      pcSlice->setScalingList ( pcSlice->getPPS()->getScalingList()  );
    }
    if(!pcSlice->getPPS()->getScalingListPresentFlag() && !pcSlice->getSPS()->getScalingListPresentFlag())
    {
      pcSlice->setDefaultScalingList();
    }
    m_cTrQuant.setScalingListDec(pcSlice->getScalingList());
    m_cTrQuant.setUseScalingList(true);
  }
  else
  {
    m_cTrQuant.setFlatScalingList();
    m_cTrQuant.setUseScalingList(false);
  }

  //  Decode a picture
  m_cGopDecoder.decompressSlice(nalu.m_Bitstream, pcPic);

  m_bFirstSliceInPicture = false;
  m_uiSliceIdx++;

  return false;
}