CABACWriter.cpp

        {
          m_BinEncoder.encodeBin( remAbsLevel&1, cctx.parityCtxIdAbsTS() );
          DTRACE( g_trace_ctx, D_SYNTAX_RESI, "ts_par_flag() bin=%d ctx=%d\n", remAbsLevel&1, cctx.parityCtxIdAbsTS() );
        }
        else
        {
          m_BinEncoder.encodeBinEP( remAbsLevel&1 );
          DTRACE( g_trace_ctx, D_SYNTAX_RESI, "ts_par_flag() EPbin=%d\n", remAbsLevel&1 );
        }
      }
    }
  }

  int cutoffVal = 2;
  int numGtBins = 4;

  for( int i = 0; i < numGtBins; i++ )
  {
    for( int scanPos = firstSigPos; scanPos <= minSubPos; scanPos++ )
    {
      unsigned absLevel = abs( coeff[cctx.blockPos( scanPos )] );
      if( absLevel >= cutoffVal )
      {
        unsigned gt2 = ( absLevel >= ( cutoffVal + 2 ) );
        if( cctx.isContextCoded() )
        {
          m_BinEncoder.encodeBin( gt2, cctx.greaterXCtxIdAbsTS( cutoffVal>>1 ) );
          DTRACE( g_trace_ctx, D_SYNTAX_RESI, "ts_gt%d_flag() bin=%d ctx=%d sp=%d coeff=%d\n", i, gt2, cctx.greaterXCtxIdAbsTS( cutoffVal>>1 ), scanPos, min<int>( absLevel, cutoffVal+2 ) );
        }
        else
        {
          m_BinEncoder.encodeBinEP( gt2 );
          DTRACE( g_trace_ctx, D_SYNTAX_RESI, "ts_gt%d_flag() EPbin=%d sp=%d coeff=%d\n", i, gt2, scanPos, min<int>( absLevel, cutoffVal+2 ) );
        }
      }
    }
    cutoffVal += 2;
  }

  //===== coeff bypass ====
  for( int scanPos = firstSigPos; scanPos <= minSubPos; scanPos++ )
  {
    TCoeff    Coeff     = coeff[ cctx.blockPos( scanPos ) ];
    unsigned  absLevel  = abs( Coeff );
    if( absLevel >= cutoffVal )
    {
      int       rice = cctx.templateAbsSumTS( scanPos, coeff );
      unsigned  rem  = ( absLevel - cutoffVal ) >> 1;
      m_BinEncoder.encodeRemAbsEP( rem, rice, cctx.extPrec(), cctx.maxLog2TrDRange() );
      DTRACE( g_trace_ctx, D_SYNTAX_RESI, "ts_rem_val() bin=%d ctx=%d sp=%d\n", rem, rice, scanPos );
    }
  }
}
#endif





//================================================================================
//  clause 7.3.8.12
//--------------------------------------------------------------------------------
//    void  cross_comp_pred( tu, compID )
//================================================================================

void CABACWriter::cross_comp_pred( const TransformUnit& tu, ComponentID compID )
{
  CHECK(!( !isLuma( compID ) ), "Unspecified error");
  signed char alpha   = tu.compAlpha[compID];
  unsigned    ctxBase = ( compID == COMPONENT_Cr ? 5 : 0 );
  if( alpha == 0 )
  {
    m_BinEncoder.encodeBin( 0, Ctx::CrossCompPred( ctxBase ) );
    DTRACE( g_trace_ctx, D_SYNTAX, "cross_comp_pred() etype=%d pos=(%d,%d) alpha=%d\n", compID, tu.blocks[compID].x, tu.blocks[compID].y, tu.compAlpha[compID] );
    return;
  }

  static const unsigned log2AbsAlphaMinus1Table[8] = { 0, 1, 1, 2, 2, 2, 3, 3 };
  unsigned sign = ( alpha < 0 );
  if( sign )
  {
    alpha = -alpha;
  }
  CHECK(!( alpha <= 8 ), "Unspecified error");
  m_BinEncoder.encodeBin( 1, Ctx::CrossCompPred(ctxBase) );
  if( alpha > 1)
  {
     m_BinEncoder.encodeBin( 1, Ctx::CrossCompPred(ctxBase+1) );
     unary_max_symbol( log2AbsAlphaMinus1Table[alpha-1]-1, Ctx::CrossCompPred(ctxBase+2), Ctx::CrossCompPred(ctxBase+3), 2 );
  }
  else
  {
     m_BinEncoder.encodeBin( 0, Ctx::CrossCompPred(ctxBase+1) );
  }
  m_BinEncoder.encodeBin( sign, Ctx::CrossCompPred(ctxBase+4) );

  DTRACE( g_trace_ctx, D_SYNTAX, "cross_comp_pred() etype=%d pos=(%d,%d) alpha=%d\n", compID, tu.blocks[compID].x, tu.blocks[compID].y, tu.compAlpha[compID] );
}




//================================================================================
//  helper functions
//--------------------------------------------------------------------------------
//    void  unary_max_symbol  ( symbol, ctxId0, ctxIdN, maxSymbol )
//    void  unary_max_eqprob  ( symbol,                 maxSymbol )
//    void  exp_golomb_eqprob ( symbol, count )
//================================================================================

void CABACWriter::unary_max_symbol( unsigned symbol, unsigned ctxId0, unsigned ctxIdN, unsigned maxSymbol )
{
  CHECK( symbol > maxSymbol, "symbol > maxSymbol" );
  const unsigned totalBinsToWrite = std::min( symbol + 1, maxSymbol );
  for( unsigned binsWritten = 0; binsWritten < totalBinsToWrite; ++binsWritten )
  {
    const unsigned nextBin = symbol > binsWritten;
    m_BinEncoder.encodeBin( nextBin, binsWritten == 0 ? ctxId0 : ctxIdN );
  }
}


void CABACWriter::unary_max_eqprob( unsigned symbol, unsigned maxSymbol )
{
  if( maxSymbol == 0 )
  {
    return;
  }
  bool     codeLast = ( maxSymbol > symbol );
  unsigned bins     = 0;
  unsigned numBins  = 0;
  while( symbol-- )
  {
    bins   <<= 1;
    bins   ++;
    numBins++;
  }
  if( codeLast )
  {
    bins  <<= 1;
    numBins++;
  }
  CHECK(!( numBins <= 32 ), "Unspecified error");
  m_BinEncoder.encodeBinsEP( bins, numBins );
}


void CABACWriter::exp_golomb_eqprob( unsigned symbol, unsigned count )
{
  unsigned bins    = 0;
  unsigned numBins = 0;
  while( symbol >= (unsigned)(1<<count) )
  {
    bins <<= 1;
    bins++;
    numBins++;
    symbol -= 1 << count;
    count++;
  }
  bins <<= 1;
  numBins++;
  bins = (bins << count) | symbol;
  numBins += count;
  CHECK(!( numBins <= 32 ), "Unspecified error");
  m_BinEncoder.encodeBinsEP( bins, numBins );
}

void CABACWriter::codeAlfCtuEnableFlags( CodingStructure& cs, ChannelType channel, AlfSliceParam* alfParam)
{
  if( isLuma( channel ) )
  {
    if (alfParam->enabledFlag[COMPONENT_Y])
      codeAlfCtuEnableFlags( cs, COMPONENT_Y, alfParam );
  }
  else
  {
    if (alfParam->enabledFlag[COMPONENT_Cb])
      codeAlfCtuEnableFlags( cs, COMPONENT_Cb, alfParam );
    if (alfParam->enabledFlag[COMPONENT_Cr])
      codeAlfCtuEnableFlags( cs, COMPONENT_Cr, alfParam );
  }
}
void CABACWriter::codeAlfCtuEnableFlags( CodingStructure& cs, ComponentID compID, AlfSliceParam* alfParam)
{
  uint32_t numCTUs = cs.pcv->sizeInCtus;

  for( int ctuIdx = 0; ctuIdx < numCTUs; ctuIdx++ )
  {
    codeAlfCtuEnableFlag( cs, ctuIdx, compID, alfParam );
  }
}

void CABACWriter::codeAlfCtuEnableFlag( CodingStructure& cs, uint32_t ctuRsAddr, const int compIdx, AlfSliceParam* alfParam)
{
  const AlfSliceParam& alfSliceParam = alfParam ? (*alfParam) : cs.aps->getAlfAPSParam();

  if( cs.sps->getALFEnabledFlag() && alfSliceParam.enabledFlag[compIdx] )
  {
    const PreCalcValues& pcv = *cs.pcv;
    int                 frame_width_in_ctus = pcv.widthInCtus;
    int                 ry = ctuRsAddr / frame_width_in_ctus;
    int                 rx = ctuRsAddr - ry * frame_width_in_ctus;
    const Position      pos( rx * cs.pcv->maxCUWidth, ry * cs.pcv->maxCUHeight );
    const uint32_t          curSliceIdx = cs.slice->getIndependentSliceIdx();
    const uint32_t          curTileIdx = cs.picture->tileMap->getTileIdxMap( pos );
    bool                leftAvail = cs.getCURestricted( pos.offset( -(int)pcv.maxCUWidth, 0 ), curSliceIdx, curTileIdx, CH_L ) ? true : false;
    bool                aboveAvail = cs.getCURestricted( pos.offset( 0, -(int)pcv.maxCUHeight ), curSliceIdx, curTileIdx, CH_L ) ? true : false;

    int leftCTUAddr = leftAvail ? ctuRsAddr - 1 : -1;
    int aboveCTUAddr = aboveAvail ? ctuRsAddr - frame_width_in_ctus : -1;

    if( alfSliceParam.enabledFlag[compIdx] )
    {
      uint8_t* ctbAlfFlag = cs.slice->getPic()->getAlfCtuEnableFlag( compIdx );
      int ctx = 0;
      ctx += leftCTUAddr > -1 ? ( ctbAlfFlag[leftCTUAddr] ? 1 : 0 ) : 0;
      ctx += aboveCTUAddr > -1 ? ( ctbAlfFlag[aboveCTUAddr] ? 1 : 0 ) : 0;
      m_BinEncoder.encodeBin( ctbAlfFlag[ctuRsAddr], Ctx::ctbAlfFlag( compIdx * 3 + ctx ) );
    }
  }
}

//! \}