/* -----------------------------------------------------------------------------
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other Intellectual Property Rights other than the copyrights concerning 
the Software are granted under this license.

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------------------------------------------------------------------------------------------- */

/** \file     DecLib.cpp
    \brief    decoder wrapper class
*/

#include "DecLib.h"

#include "CommonLib/dtrace_next.h"
#include "CommonLib/dtrace_buffer.h"
#include "CommonLib/TimeProfiler.h"

#include "CommonLib/x86/CommonDefX86.h"

#include "NALread.h"


namespace vvdec
{

#ifdef TRACE_ENABLE_ITT
std::vector<__itt_domain*> itt_domain_decInst;
__itt_domain* itt_domain_dec           = __itt_domain_create( "Decode" );
__itt_domain* itt_domain_prs           = __itt_domain_create( "Parse" );
__itt_domain* itt_domain_oth           = __itt_domain_create( "Other" );

__itt_string_handle* itt_handle_alf    = __itt_string_handle_create( "ALF_CTU" );
__itt_string_handle* itt_handle_presao = __itt_string_handle_create( "PreSAO_Line" );
__itt_string_handle* itt_handle_sao    = __itt_string_handle_create( "SAO_CTU" );
__itt_string_handle* itt_handle_lfl    = __itt_string_handle_create( "LFL_CTU" );
__itt_string_handle* itt_handle_intra  = __itt_string_handle_create( "Intra_CTU" );
__itt_string_handle* itt_handle_inter  = __itt_string_handle_create( "Inter_CTU" );
__itt_string_handle* itt_handle_mider  = __itt_string_handle_create( "MI-Der_CTU" );
__itt_string_handle* itt_handle_lfcl   = __itt_string_handle_create( "Prep_ClearLF" );
__itt_string_handle* itt_handle_ext    = __itt_string_handle_create( "Prep_ExtBrdr" );
__itt_string_handle* itt_handle_dmvr   = __itt_string_handle_create( "MI-DMVR" );
__itt_string_handle* itt_handle_rsp    = __itt_string_handle_create( "Reshape_CTU" );

__itt_string_handle* itt_handle_parse  = __itt_string_handle_create( "Parse_Slice" );

__itt_string_handle* itt_handle_start  = __itt_string_handle_create( "Start_Pic" );
__itt_string_handle* itt_handle_done   = __itt_string_handle_create( "Pic_Done" );
__itt_string_handle* itt_handle_finish = __itt_string_handle_create( "Finish_Pic" );

__itt_string_handle* itt_handle_schedTasks = __itt_string_handle_create( "Scheduling_Tasks" );
__itt_string_handle* itt_handle_waitTasks  = __itt_string_handle_create( "Wait_for_Dec_Tasks" );


// create global domain for DecLib
__itt_domain* itt_domain_glb    = __itt_domain_create ( "Global" );
// create a global counter
__itt_counter itt_frame_counter = __itt_counter_create( "FrameNumber", "Global" );

#define ITT_TASKSTART( d, t ) __itt_task_begin( ( d ), __itt_null, __itt_null, ( t ) )
#define ITT_TASKEND( d, t )   __itt_task_end  ( ( d ) )
#else
#define ITT_TASKSTART( d, t )
#define ITT_TASKEND( d, t )
#endif

//! \ingroup DecoderLib
//! \{

DecLib::DecLib()
{
#ifdef TRACE_ENABLE_ITT
  itt_domain_dec->flags = 1;
  itt_domain_prs->flags = 1;
  itt_domain_glb->flags = 1;
  itt_domain_oth->flags = 1;
#endif
}

#if RPR_YUV_OUTPUT
void DecLib::create( int numDecThreads, int parserFrameDelay, const UserAllocator& userAllocator, ErrHandlingFlags errHandlingFlags, int upscaledOutput )
#else
void DecLib::create( int numDecThreads, int parserFrameDelay, const UserAllocator& userAllocator, ErrHandlingFlags errHandlingFlags )
#endif
{
  // run constructor again to ensure all variables, especially in DecLibParser have been reset
  this->~DecLib();
  new( this ) DecLib;

  if( numDecThreads < 0 )
  {
    numDecThreads = std::min<unsigned>( MAX_THREADS, std::thread::hardware_concurrency() );
  }

  m_decodeThreadPool.reset( new ThreadPool( numDecThreads, "DecThread" ) );

  if( parserFrameDelay < 0 )
  {
    CHECK( numDecThreads < 0, "invalid number of threads" );
    parserFrameDelay = numDecThreads;
  }
  m_parseFrameDelay = parserFrameDelay;

  bool upscalingEnabled = false;
#if RPR_YUV_OUTPUT
  m_upscaledOutput = upscaledOutput;
  upscalingEnabled = upscaledOutput;
#endif
  m_picListManager.create( m_parseFrameDelay, ( int ) m_decLibRecon.size(), upscalingEnabled, userAllocator );
  m_decLibParser.create  ( m_decodeThreadPool.get(), m_parseFrameDelay, ( int ) m_decLibRecon.size(), numDecThreads, errHandlingFlags );

  int id=0;
  for( auto &dec: m_decLibRecon )
  {
    dec.create( m_decodeThreadPool.get(), id++, upscalingEnabled );
  }

  std::stringstream cssCap;
  cssCap << "THREADS="     << numDecThreads << "; "
         << "PARSE_DELAY=" << parserFrameDelay << "; ";
#if ENABLE_SIMD_OPT
#  if defined( TARGET_SIMD_X86 )
  cssCap << "SIMD=" << read_x86_extension_name();
#  else
  cssCap << "SIMD=SCALAR";
#  endif
#else
  cssCap << "SIMD=NONE";
#endif

  m_sDecoderCapabilities = cssCap.str();

  DTRACE_UPDATE( g_trace_ctx, std::make_pair( "final", 1 ) );
}

void DecLib::destroy()
{
  if( m_decodeThreadPool )
  {
    m_decodeThreadPool->shutdown( true );
    m_decodeThreadPool.reset();
  }

  m_decLibParser.destroy();
  for( auto &dec: m_decLibRecon )
  {
    dec.destroy();
  }

  m_picListManager.deleteBuffers();
}

Picture* DecLib::decode( InputNALUnit& nalu )
{
  PROFILER_SCOPE_AND_STAGE( 1, g_timeProfiler, P_NALU_SLICE_PIC_HL );

  bool newPic = false;
  if( m_iMaxTemporalLayer < 0 || nalu.m_temporalId <= m_iMaxTemporalLayer )
  {
    newPic = m_decLibParser.parse( nalu );
  }

  if( newPic )
  {
    Picture* pcParsedPic = m_decLibParser.getNextDecodablePicture();
    if( pcParsedPic )
    {
      while( pcParsedPic->error || pcParsedPic->wasLost || pcParsedPic->parseDone.hasException() )
      {
        CHECK( pcParsedPic->progress >= Picture::reconstructing, "The error picture shouldn't be in reconstructing state yet." );

        std::exception_ptr parsing_exception = pcParsedPic->parseDone.hasException() ? pcParsedPic->parseDone.getException() : nullptr;
        if( parsing_exception )
        {   // the exception has not been thrown out of the library. Do that after preparing this picture for referencing
          pcParsedPic->error = true;
          pcParsedPic->waitForAllTasks();
          pcParsedPic->parseDone.clearException();
        }

        pcParsedPic->waitForAllTasks();

        if( pcParsedPic->progress < Picture::parsing )
        {
          // we don't know if all structures are there yet, so we init them
          pcParsedPic->ensureUsableAsRef();
        }
        pcParsedPic->fillGrey( m_decLibParser.getParameterSetManager().getFirstSPS() );

        // need to finish picture here, because it won't go through declibRecon
        finishPicture( pcParsedPic );

        // this exception has not been thrown outside (error must have happened in slice parsing task)
        if( parsing_exception )
        {
          CHECK( pcParsedPic->exceptionThrownOut, "The exception shouldn't have been thrown out already." );
          pcParsedPic->exceptionThrownOut = true;
          std::rethrow_exception( parsing_exception );
        }

        // try again to get a picture, that we can reconstruct now
        pcParsedPic = m_decLibParser.getNextDecodablePicture();
      }

      reconPicture( pcParsedPic );
    }
  }

  if( newPic || nalu.m_nalUnitType == NAL_UNIT_EOS )
  {
    Picture* outPic = getNextOutputPic( false );
    if( outPic )
    {
      CHECK_WARN( outPic->progress < Picture::finished, "Picture should have been finished by now. Blocking and finishing..." );
      if( outPic->progress < Picture::finished )
      {
        blockAndFinishPictures( outPic );

        CHECK_RECOVERABLE( outPic->progress < Picture::finished, "Picture still not finished. Something is really broken." );
      }

      m_checkMissingOutput = true;
    }

    // warn if we don't produce an output picture for every incoming picture
    CHECK_WARN( m_checkMissingOutput && !outPic, "missing output picture" ); // this CHECK is not needed in flushPic(), because in flushPic() the nullptr signals the end of the bitstream
    return outPic;
  }

  return nullptr;
}

Picture* DecLib::flushPic()
{
  Picture* outPic = getNextOutputPic( false );
  // at end of file, fill the decompression queue and decode pictures until the next output-picture is finished
  while( Picture* pcParsedPic = m_decLibParser.getNextDecodablePicture() )
  {
    // reconPicture() blocks and finishes one picture on each call
    reconPicture( pcParsedPic );

    if( !outPic )
    {
      outPic = getNextOutputPic( false );
    }
    if( outPic && outPic->progress == Picture::finished )
    {
      return outPic;
    }
  }

  if( outPic && outPic->progress == Picture::finished )
  {
    return outPic;
  }

  // if all pictures have been parsed, but not finished, iteratively wait for and finish next pictures
  blockAndFinishPictures( outPic );
  if( !outPic )
  {
    outPic = getNextOutputPic( false );
  }
  if( outPic && outPic->progress == Picture::finished )
  {
    return outPic;
  }

  CHECK_RECOVERABLE( outPic, "we shouldn't be holding an output picture here" );
  // flush remaining pictures without considering num reorder pics
  outPic = getNextOutputPic( true );
  if( outPic )
  {
    CHECK_RECOVERABLE( outPic->progress != Picture::finished, "all pictures should have been finished by now" );
    // outPic->referenced = false;
    return outPic;
  }

  // At the very end reset parser state
  InputNALUnit eosNAL;
  eosNAL.m_nalUnitType = NAL_UNIT_EOS;
  m_decLibParser.parse( eosNAL );
  m_checkMissingOutput = false;

  return nullptr;
}

#if JVET_R0270
int DecLib::finishPicture( Picture* pcPic, MsgLevel msgl, bool associatedWithNewClvs )
#else
int DecLib::finishPicture( Picture* pcPic, MsgLevel msgl )
#endif
{
#ifdef TRACE_ENABLE_ITT
  // increment Framecounter
  __itt_counter_inc( itt_frame_counter );
#endif

  Slice*  pcSlice = pcPic->slices[0];
  if( pcPic->wasLost || pcPic->error || pcPic->reconDone.hasException() )
  {
    msg( msgl, "POC %4d LId: %2d TId: %1d %s\n", pcPic->poc, pcPic->layerId, pcSlice->getTLayer(), pcPic->wasLost ? "LOST" : "ERROR" );
    pcPic->progress = Picture::finished;

    // if the picture has an exception set (originating from thread-pool tasks), don't return here, but rethrow the exception
    try
    {
      pcPic->parseDone.checkAndRethrowException();
      pcPic->reconDone.checkAndRethrowException();
    }
    catch( ... )
    {
      pcPic->waitForAllTasks();

      // need to clear exception so we can use it as reference picture
      pcPic->reconDone.clearException();
      pcPic->reconDone.unlock();
      pcPic->error = true;
      if( !pcPic->exceptionThrownOut )
      {
        pcPic->exceptionThrownOut = true;
        throw;
      }
    }

    return pcPic->poc;
  }

  ITT_TASKSTART( itt_domain_oth, itt_handle_finish );

  char c = ( pcSlice->isIntra() ? 'I' : pcSlice->isInterP() ? 'P' : 'B' );
  if( !pcPic->isReferencePic )
  {
    c += 32;  // tolower
  }

  //-- For time output for each slice
  msg( msgl, "POC %4d LId: %2d TId: %1d ( %c-SLICE, QP%3d ) ", pcPic->poc, pcPic->layerId,
         pcSlice->getTLayer(),
         c,
         pcSlice->getSliceQp() );
  msg( msgl, "[DT %6.3f] ", pcPic->getProcessingTime() );

  for (int iRefList = 0; iRefList < 2; iRefList++)
  {
    msg( msgl, "[L%d ", iRefList);
    for (int iRefIndex = 0; iRefIndex < pcSlice->getNumRefIdx(RefPicList(iRefList)); iRefIndex++)
    {
#if RPR_OUTPUT_MSG
      const std::pair<int, int>& scaleRatio = pcSlice->getScalingRatio( RefPicList( iRefList ), iRefIndex );
      
      if( pcSlice->getPicHeader()->getEnableTMVPFlag() && pcSlice->getColFromL0Flag() == bool(1 - iRefList) && pcSlice->getColRefIdx() == iRefIndex )
      {
        if( scaleRatio.first != 1 << SCALE_RATIO_BITS || scaleRatio.second != 1 << SCALE_RATIO_BITS )
        {
          msg( msgl, "%dc(%1.2lfx, %1.2lfx) ", pcSlice->getRefPOC( RefPicList( iRefList ), iRefIndex ), double( scaleRatio.first ) / ( 1 << SCALE_RATIO_BITS ), double( scaleRatio.second ) / ( 1 << SCALE_RATIO_BITS ) );
        }
        else
        {
          msg( msgl, "%dc ", pcSlice->getRefPOC( RefPicList( iRefList ), iRefIndex ) );
        }
      }
      else
      {
        if( scaleRatio.first != 1 << SCALE_RATIO_BITS || scaleRatio.second != 1 << SCALE_RATIO_BITS )
        {
          msg( msgl, "%d(%1.2lfx, %1.2lfx) ", pcSlice->getRefPOC( RefPicList( iRefList ), iRefIndex ), double( scaleRatio.first ) / ( 1 << SCALE_RATIO_BITS ), double( scaleRatio.second ) / ( 1 << SCALE_RATIO_BITS ) );
        }
        else
        {
      msg( msgl, "%d ", pcSlice->getRefPOC(RefPicList(iRefList), iRefIndex));
    }
      }
#else
      msg( msgl, "%d ", pcSlice->getRefPOC(RefPicList(iRefList), iRefIndex));
#endif
    }
    msg( msgl, "] ");
  }

  msg( msgl, "\n");

//  pcPic->neededForOutput = (pcSlice->getPicHeader()->getPicOutputFlag() ? true : false);
#if JVET_R0270
  if (associatedWithNewClvs && pcPic->neededForOutput)
  {
    if (!pcSlice->getPPS()->getMixedNaluTypesInPicFlag() && pcSlice->getNalUnitType() == NAL_UNIT_CODED_SLICE_RASL)
    {
      pcPic->neededForOutput = false;
    }
    else if (pcSlice->getPPS()->getMixedNaluTypesInPicFlag())
    {
      bool isRaslPic = true;
      for (int i = 0; isRaslPic && i < pcPic->numSlices; i++)
      {
        if (!(pcSlice->getNalUnitType() == NAL_UNIT_CODED_SLICE_RASL || pcSlice->getNalUnitType() == NAL_UNIT_CODED_SLICE_RADL))
        {
          isRaslPic = false;
        }
      }
      if (isRaslPic)
      {
        pcPic->neededForOutput = false;
      }
    }
  }
#endif

  m_picListManager.markUnusedPicturesReusable();

  if( m_parseFrameDelay > 0 )
  {
    checkPictureHashSEI( pcPic );
  }

  ITT_TASKEND( itt_domain_oth, itt_handle_finish );

  pcPic->progress = Picture::finished;

  return pcSlice->getPOC();
}

void DecLib::checkPictureHashSEI( Picture* pcPic )
{
  if( !m_decodedPictureHashSEIEnabled )
  {
    return;
  }

  CHECK_RECOVERABLE( pcPic->progress < Picture::reconstructed, "picture not reconstructed" );

  seiMessages pictureHashes = SEI_internal::getSeisByType( pcPic->seiMessageList, VVDEC_DECODED_PICTURE_HASH );

  if( !pictureHashes.empty() && !pcPic->picCheckedDPH && pcPic->neededForOutput )
  {
    if( pictureHashes.size() > 1 )
    {
      msg( WARNING, "Warning: Got multiple decoded picture hash SEI messages. Using first." );
    }

    const vvdecSEIDecodedPictureHash* hash = (vvdecSEIDecodedPictureHash*)pictureHashes.front()->payload;

    msg( INFO, "         " );
    m_numberOfChecksumErrorsDetected += calcAndPrintHashStatus( pcPic->getRecoBuf(), hash, pcPic->cs->sps->getBitDepths(), INFO );
    pcPic->picCheckedDPH = true;
    msg( INFO, "\n" );
  }
  else if( pcPic->neededForOutput )
  {
    if( pcPic->subPictures.empty() )
    {
      msg( WARNING, "Warning: missing decoded picture hash SEI message.\n" );
      return;
    }

    seiMessages scalableNestingSeis = SEI_internal::getSeisByType( pcPic->seiMessageList, VVDEC_SCALABLE_NESTING );
    for( auto* seiIt: scalableNestingSeis )
    {
      CHECK_RECOVERABLE( seiIt->payloadType != VVDEC_SCALABLE_NESTING, "expected nesting SEI" );

      const vvdecSEIScalableNesting* nestingSei = (vvdecSEIScalableNesting*)seiIt->payload;
      if( !nestingSei->snSubpicFlag )
      {
        continue;
      }

      for( int i = 0; i < nestingSei->snNumSEIs; ++i )
      {
        auto& nestedSei = nestingSei->nestedSEIs[i];
        CHECK_RECOVERABLE( nestedSei == nullptr, "missing nested sei" );
        if( nestedSei && nestedSei->payloadType != VVDEC_DECODED_PICTURE_HASH )
          continue;

        const vvdecSEIDecodedPictureHash* hash = (vvdecSEIDecodedPictureHash*)nestedSei->payload;

        if( pcPic->subpicsCheckedDPH.empty() )
        {
          pcPic->subpicsCheckedDPH.resize( pcPic->subPictures.size(), false );
        }
        else
        {
          CHECK_RECOVERABLE( pcPic->subpicsCheckedDPH.size() != pcPic->subPictures.size(), "Picture::subpicsCheckedDPH not properly initialized" );
        }

        for( int j = 0; j < nestingSei->snNumSubpics; ++j )
        {
          uint32_t subpicId = nestingSei->snSubpicId[j];

          for( auto& subPic: pcPic->subPictures )
          {
            if( subPic.getSubPicID() != subpicId )
              continue;

            auto subPicIdx = subPic.getSubPicIdx();
            if( pcPic->subpicsCheckedDPH[subPicIdx] )
              continue;

            const UnitArea area = UnitArea( pcPic->chromaFormat, subPic.getLumaArea() );
            m_numberOfChecksumErrorsDetected += calcAndPrintHashStatus( pcPic->cs->getRecoBuf( area ), hash, pcPic->cs->sps->getBitDepths(), INFO );
            pcPic->subpicsCheckedDPH[subPicIdx] = true;
            msg( INFO, "\n" );
          }
        }
      }
    }

    if( m_parseFrameDelay )
    {
      // this warning is only enabled, when running with parse delay enabled, because otherwise we don't know here if the last DPH Suffix-SEI has already been
      // parsed
      auto checkedSubpicCount = std::count( pcPic->subpicsCheckedDPH.cbegin(), pcPic->subpicsCheckedDPH.cend(), true );
      if( checkedSubpicCount != pcPic->subPictures.size() )
      {
        msg( WARNING, "Warning: missing decoded picture hash SEI message for SubPics (%u/%u).\n", checkedSubpicCount, pcPic->subPictures.size() );
      }
    }
  }
}

Picture* DecLib::getNextOutputPic( bool bFlush )
{
  if( m_picListManager.getFrontPic() == nullptr )
  {
    return nullptr;
  }

  const SPS* activeSPS      = m_picListManager.getFrontPic()->cs->sps.get();
  const int  maxNrSublayers = activeSPS->getMaxTLayers();

  int numReorderPicsHighestTid;
  int maxDecPicBufferingHighestTid;
  if( m_iMaxTemporalLayer == -1 || m_iMaxTemporalLayer >= maxNrSublayers )
  {
    numReorderPicsHighestTid     = activeSPS->getNumReorderPics( maxNrSublayers - 1 );
    maxDecPicBufferingHighestTid = activeSPS->getMaxDecPicBuffering( maxNrSublayers - 1 );
  }
  else
  {
    numReorderPicsHighestTid     = activeSPS->getNumReorderPics( m_iMaxTemporalLayer );
    maxDecPicBufferingHighestTid = activeSPS->getMaxDecPicBuffering( m_iMaxTemporalLayer );
  }

  return m_picListManager.getNextOutputPic( numReorderPicsHighestTid, maxDecPicBufferingHighestTid, bFlush );
}

void DecLib::reconPicture( Picture* pcPic )
{
  CHECK( std::any_of( m_decLibRecon.begin(), m_decLibRecon.end(), [=]( auto& rec ) { return rec.getCurrPic() == pcPic; } ),
         "(Reused) Picture structure is still in progress in decLibRecon." );

  DecLibRecon* reconInstance = &m_decLibRecon.front();
  move_to_end( m_decLibRecon.begin(), m_decLibRecon );

  Picture* donePic = reconInstance->waitForPrevDecompressedPic();
  try
  {
    reconInstance->decompressPicture( pcPic );
  }
  catch( ... )
  {
    pcPic->reconDone.setException( std::current_exception() );
    pcPic->error = true;
  }

  if( donePic )
  {
    finishPicture( donePic );
  }
}

void DecLib::blockAndFinishPictures( Picture* pcPic )
{
  // find Recon instance where current picture (if not null) is active and ensure the picture gets finished
  // otherwise all pictures get finished
  for( auto& recon: m_decLibRecon )
  {
    if( pcPic && recon.getCurrPic() != pcPic )
    {
      continue;
    }

    if( Picture* donePic = recon.waitForPrevDecompressedPic() )
    {
      finishPicture( donePic );
    }
  }
}

void DecLib::checkNalUnitConstraints( uint32_t naluType )
{
  const ConstraintInfo *cInfo = NULL;
  if (m_decLibParser.getParameterSetManager().getActiveSPS() != NULL && m_decLibParser.getParameterSetManager().getActiveSPS()->getProfileTierLevel() != NULL)
  {
    cInfo = m_decLibParser.getParameterSetManager().getActiveSPS()->getProfileTierLevel()->getConstraintInfo();
    if( cInfo != NULL )
    {
      xCheckNalUnitConstraintFlags( cInfo, naluType );
    }
  }
}

void DecLib::xCheckNalUnitConstraintFlags( const ConstraintInfo *cInfo, uint32_t naluType )
{
  if( cInfo != NULL )
  {
    CHECK_RECOVERABLE( cInfo->getNoTrailConstraintFlag() && naluType == NAL_UNIT_CODED_SLICE_TRAIL,
                       "Non-conforming bitstream. no_trail_constraint_flag is equal to 1 but bitstream contains NAL unit of type TRAIL_NUT." );
    CHECK_RECOVERABLE( cInfo->getNoStsaConstraintFlag()  && naluType == NAL_UNIT_CODED_SLICE_STSA,
                       "Non-conforming bitstream. no_stsa_constraint_flag is equal to 1 but bitstream contains NAL unit of type STSA_NUT." );
    CHECK_RECOVERABLE( cInfo->getNoRaslConstraintFlag()  && naluType == NAL_UNIT_CODED_SLICE_RASL,
                       "Non-conforming bitstream. no_rasl_constraint_flag is equal to 1 but bitstream contains NAL unit of type RASL_NUT." );
    CHECK_RECOVERABLE( cInfo->getNoRadlConstraintFlag()  && naluType == NAL_UNIT_CODED_SLICE_RADL,
                       "Non-conforming bitstream. no_radl_constraint_flag is equal to 1 but bitstream contains NAL unit of type RADL_NUT." );
    CHECK_RECOVERABLE( cInfo->getNoIdrConstraintFlag()   && naluType == NAL_UNIT_CODED_SLICE_IDR_W_RADL,
                       "Non-conforming bitstream. no_idr_constraint_flag is equal to 1 but bitstream contains NAL unit of type IDR_W_RADL." );
    CHECK_RECOVERABLE( cInfo->getNoIdrConstraintFlag()   && naluType == NAL_UNIT_CODED_SLICE_IDR_N_LP,
                       "Non-conforming bitstream. no_idr_constraint_flag is equal to 1 but bitstream contains NAL unit of type IDR_N_LP." );
    CHECK_RECOVERABLE( cInfo->getNoCraConstraintFlag()   && naluType == NAL_UNIT_CODED_SLICE_CRA,
                       "Non-conforming bitstream. no_cra_constraint_flag is equal to 1 but bitstream contains NAL unit of type CRA_NUT." );
    CHECK_RECOVERABLE( cInfo->getNoGdrConstraintFlag()   && naluType == NAL_UNIT_CODED_SLICE_GDR,
                       "Non-conforming bitstream. no_gdr_constraint_flag is equal to 1 but bitstream contains NAL unit of type GDR_NUT." );
    CHECK_RECOVERABLE( cInfo->getNoApsConstraintFlag()   && naluType == NAL_UNIT_PREFIX_APS,
                       "Non-conforming bitstream. no_aps_constraint_flag is equal to 1 but bitstream contains NAL unit of type APS_PREFIX_NUT." );
    CHECK_RECOVERABLE( cInfo->getNoApsConstraintFlag()   && naluType == NAL_UNIT_SUFFIX_APS,
                       "Non-conforming bitstream. no_aps_constraint_flag is equal to 1 but bitstream contains NAL unit of type APS_SUFFIX_NUT." );
  }
}

#define SEI_REPETITION_CONSTRAINT_LIST_SIZE  21

/**
 - Count the number of identical SEI messages in the current picture
 */
void DecLib::checkSeiInPictureUnit()
{
  std::vector<std::tuple<int, uint32_t, uint8_t*>> seiList;

  // payload types subject to constrained SEI repetition
  int picUnitRepConSeiList[SEI_REPETITION_CONSTRAINT_LIST_SIZE] = { 0, 1, 19, 45, 129, 132, 133, 137, 144, 145, 147, 148, 149, 150, 153, 154, 155, 156, 168, 203, 204};
  
  // extract SEI messages from NAL units
  for( auto &sei : m_pictureSeiNalus )
  {
    InputBitstream bs = sei.getBitstream();

    do
    {
      int payloadType = 0;
      uint32_t val = 0;

      do
      {
        bs.readByte(val);
        payloadType += val;
      } while (val==0xFF);

      uint32_t payloadSize = 0;
      do
      {
        bs.readByte(val);
        payloadSize += val;
      } while (val==0xFF);
    
      uint8_t *payload = new uint8_t[payloadSize];
      for( uint32_t i = 0; i < payloadSize; i++ )
      {
        bs.readByte(val);
        payload[i] = (uint8_t)val;
      }
      seiList.push_back(std::tuple<int, uint32_t, uint8_t*>(payloadType, payloadSize, payload));
    }
    while( bs.getNumBitsLeft() > 8 );
  }

  // count repeated messages in list
  for( uint32_t i = 0; i < seiList.size(); i++ )
  {
    int      k, count = 1;
    int      payloadType1 = std::get<0>(seiList[i]);
    uint32_t payloadSize1 = std::get<1>(seiList[i]);
    uint8_t  *payload1    = std::get<2>(seiList[i]);

    // only consider SEI payload types in the PicUnitRepConSeiList
    for( k=0; k<SEI_REPETITION_CONSTRAINT_LIST_SIZE; k++ )
    {
      if( payloadType1 == picUnitRepConSeiList[k] )
      {
        break;
      }
    }
    if( k >= SEI_REPETITION_CONSTRAINT_LIST_SIZE )
    {
      continue;
    }

    // compare current SEI message with remaining messages in the list
    for( uint32_t j = i+1; j < seiList.size(); j++ )
    {
      int      payloadType2 = std::get<0>(seiList[j]);
      uint32_t payloadSize2 = std::get<1>(seiList[j]);
      uint8_t  *payload2    = std::get<2>(seiList[j]);
      
      // check for identical SEI type, size, and payload
      if( payloadType1 == payloadType2 && payloadSize1 == payloadSize2 )
      {
        if( memcmp(payload1, payload2, payloadSize1*sizeof(uint8_t)) == 0 )
        {
          count++;
        }
      }
    }
    CHECK_RECOVERABLE(count > 4, "There shall be less than or equal to 4 identical sei_payload( ) syntax structures within a picture unit.");
  }

  // free SEI message list memory
  for( uint32_t i = 0; i < seiList.size(); i++ )
  {
    uint8_t *payload = std::get<2>(seiList[i]);
    delete   payload;
  }
  seiList.clear();
}

/**
 - Reset list of SEI NAL units from the current picture
 */
void DecLib::resetPictureSeiNalus()
{
  m_pictureSeiNalus.clear();
}

void DecLib::checkAPSInPictureUnit()
{
  bool firstVCLFound = false;
  bool suffixAPSFound = false;
  for (auto &nalu : m_pictureUnitNals)
  {
    if (NALUnit::isVclNalUnitType(nalu))
    {
      firstVCLFound = true;
      CHECK_RECOVERABLE( suffixAPSFound, "When any suffix APS NAL units are present in a PU, they shall follow the last VCL unit of the PU" );
    }
    else if (nalu == NAL_UNIT_PREFIX_APS)
    {
      CHECK_RECOVERABLE( firstVCLFound, "When any prefix APS NAL units are present in a PU, they shall precede the first VCL unit of the PU");
    }
    else if (nalu == NAL_UNIT_SUFFIX_APS)
    {
      suffixAPSFound = true;
    }
  }
}

}