CABACWriter.cpp

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/** \file     CABACWriter.cpp
 *  \brief    Writer for low level syntax
 */

#include "CommonLib/Contexts.h"
#include "CABACWriter.h"

#include "EncLib.h"

#include "CommonLib/UnitTools.h"
#include "CommonLib/dtrace_buffer.h"
#include "CommonLib/BinaryDecisionTree.h"

#include <map>
#include <algorithm>
#include <limits>


//! \ingroup EncoderLib
//! \{

void CABACWriter::initCtxModels( const Slice& slice )
{
  int       qp                = slice.getSliceQp();
  SliceType sliceType         = slice.getSliceType();
  SliceType encCABACTableIdx  = slice.getEncCABACTableIdx();
  if( !slice.isIntra() && (encCABACTableIdx==B_SLICE || encCABACTableIdx==P_SLICE) && slice.getPPS()->getCabacInitPresentFlag() )
  {
    sliceType = encCABACTableIdx;
  }
  m_BinEncoder.reset( qp, (int)sliceType );
}



template <class BinProbModel>
SliceType xGetCtxInitId( const Slice& slice, const BinEncIf& binEncoder, Ctx& ctxTest )
{
  const CtxStore<BinProbModel>& ctxStoreTest = static_cast<const CtxStore<BinProbModel>&>( ctxTest );
  const CtxStore<BinProbModel>& ctxStoreRef  = static_cast<const CtxStore<BinProbModel>&>( binEncoder.getCtx() );
  int qp = slice.getSliceQp();
  if( !slice.isIntra() )
  {
    SliceType aSliceTypeChoices[] = { B_SLICE, P_SLICE };
    uint64_t  bestCost            = std::numeric_limits<uint64_t>::max();
    SliceType bestSliceType       = aSliceTypeChoices[0];
    for (uint32_t idx=0; idx<2; idx++)
    {
      uint64_t  curCost           = 0;
      SliceType curSliceType      = aSliceTypeChoices[idx];
      ctxTest.init( qp, (int)curSliceType );
      for( int k = 0; k < Ctx::NumberOfContexts; k++ )
      {
        if( binEncoder.getNumBins(k) > 0 )
        {
          curCost += uint64_t( binEncoder.getNumBins(k) ) * ctxStoreRef[k].estFracExcessBits( ctxStoreTest[k] );
        }
      }
      if (curCost < bestCost)
      {
        bestSliceType = curSliceType;
        bestCost      = curCost;
      }
    }
    return bestSliceType;
  }
  else
  {
    return I_SLICE;
  }
}


SliceType CABACWriter::getCtxInitId( const Slice& slice )
{
  switch( m_TestCtx.getBPMType() )
  {
  case BPM_Std:   return  xGetCtxInitId<BinProbModel_Std>   ( slice, m_BinEncoder, m_TestCtx );
  default:        return  NUMBER_OF_SLICE_TYPES;
  }
}



unsigned estBits( BinEncIf& binEnc, const std::vector<bool>& bins, const Ctx& ctx, const int ctxId, const uint8_t winSize )
{
  binEnc.initCtxAndWinSize( ctxId, ctx, winSize );
  binEnc.start();
  const std::size_t numBins   = bins.size();
  unsigned          startBits = binEnc.getNumWrittenBits();
  for( std::size_t binId = 0; binId < numBins; binId++ )
  {
    unsigned  bin = ( bins[binId] ? 1 : 0 );
    binEnc.encodeBin( bin, ctxId );
  }
  unsigned endBits    = binEnc.getNumWrittenBits();
  unsigned codedBits  = endBits - startBits;
  return   codedBits;
}





//================================================================================
//  clause 7.3.8.1
//--------------------------------------------------------------------------------
//    void  end_of_slice()
//================================================================================

void CABACWriter::end_of_slice()
{
  m_BinEncoder.encodeBinTrm ( 1 );
  m_BinEncoder.finish       ();
}




//================================================================================
//  clause 7.3.8.2
//--------------------------------------------------------------------------------
//    bool  coding_tree_unit( cs, area, qp, ctuRsAddr, skipSao )
//================================================================================

void CABACWriter::coding_tree_unit( CodingStructure& cs, const UnitArea& area, int (&qps)[2], unsigned ctuRsAddr, bool skipSao /* = false */ )
{
  CUCtx cuCtx( qps[CH_L] );
  Partitioner *partitioner = PartitionerFactory::get( *cs.slice );

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

  if( !skipSao )
  {
    sao( *cs.slice, ctuRsAddr );
  }

  for( int compIdx = 0; compIdx < MAX_NUM_COMPONENT; compIdx++ )
  {
    codeAlfCtuEnableFlag( cs, ctuRsAddr, compIdx );
  }

  if ( CS::isDualITree(cs) && cs.pcv->chrFormat != CHROMA_400 && cs.pcv->maxCUWidth > 64 )
  {
    CUCtx chromaCuCtx(qps[CH_C]);
    Partitioner *chromaPartitioner = PartitionerFactory::get(*cs.slice);
    chromaPartitioner->initCtu(area, CH_C, *cs.slice);
    coding_tree(cs, *partitioner, cuCtx, chromaPartitioner, &chromaCuCtx);
    qps[CH_L] = cuCtx.qp;
    qps[CH_C] = chromaCuCtx.qp;

    delete chromaPartitioner;
  }
  else
  {
    coding_tree( cs, *partitioner, cuCtx );
    qps[CH_L] = cuCtx.qp;
    if( CS::isDualITree( cs ) && cs.pcv->chrFormat != CHROMA_400 )
    {
      CUCtx cuCtxChroma( qps[CH_C] );
      partitioner->initCtu( area, CH_C, *cs.slice );
      coding_tree( cs, *partitioner, cuCtxChroma );
      qps[CH_C] = cuCtxChroma.qp;
    }
  }

  delete partitioner;