ALWIP的MPM构建

getMipMPMs

int PU::getMipMPMs(const PredictionUnit &pu, unsigned *mpm)
{
  const CompArea &area = pu.block( getFirstComponentOfChannel( CHANNEL_TYPE_LUMA ) );
  const Position &pos = area.pos();

  bool realMode = false;

  // Get intra mode of left PU
  int leftIntraMode = -1;
  const PredictionUnit *puLeft = pu.cs->getPURestricted( pos.offset( -1, 0 ), pu, CHANNEL_TYPE_LUMA );

  if( puLeft && CU::isIntra( *puLeft->cu ) )
  {
    if( PU::isMIP( *puLeft ) )
    {
      if (getMipSizeId(*puLeft) == getMipSizeId(pu))
      {
        leftIntraMode = puLeft->intraDir[CHANNEL_TYPE_LUMA];//如果左参考为ALWIP模式，直接取用
        realMode = true;
      }
    }
    else
    {
      leftIntraMode = g_mapAngular33ToMip[getMipSizeId(pu)][g_intraMode65to33AngMapping[puLeft->intraDir[CHANNEL_TYPE_LUMA]]];//如果左参考传统模式，映射
    }
  }

  // Get intra mode of above PU
  int aboveIntraMode = -1;
  const PredictionUnit *puAbove = pu.cs->getPURestricted( pos.offset( 0, -1 ), pu, CHANNEL_TYPE_LUMA );

  if( puAbove && CU::isIntra( *puAbove->cu ) && CU::isSameCtu(*pu.cu, *puAbove->cu) )
  {
    if( PU::isMIP( *puAbove ) )
    {
      if (getMipSizeId(*puAbove) == getMipSizeId(pu))
      {
        aboveIntraMode = puAbove->intraDir[CHANNEL_TYPE_LUMA];//如果上参考为ALWIP模式，直接取用
        realMode = true;
      }
    }
    else
    {
      aboveIntraMode = g_mapAngular33ToMip[getMipSizeId(pu)][g_intraMode65to33AngMapping[puAbove->intraDir[CHANNEL_TYPE_LUMA]]];//如果上参考传统模式，映射
    }
  }

  // derive MPMs
  CHECKD(NUM_MPM_MIP != 3, "Error: wrong number of MPMs for MIP");

  const int* modeList = g_sortedMipMpms[getMipSizeId(pu)];//getMipSizeId：4*4--0;8*8--1;其他--2；
                                                                                          //g_sortedMipMpms：0-  { 17, 34, 5 },
 int numCand = 0;                                                                         //                 1-  { 0, 7, 16 },
  if( leftIntraMode == aboveIntraMode )//左和上相同预测模式，numCand = 1                      //                 2-  { 1,  4,  6 }, 
  {
    if( leftIntraMode > -1 )//ex：在leftIntraMode和17，34，5中选三个不同的，顺序依次
    {
      mpm[0] = leftIntraMode;
      numCand = 1;

      if( leftIntraMode != modeList[0] )
      {
        mpm[1] = modeList[0];
        mpm[2] = (leftIntraMode != modeList[1]) ? modeList[1] : modeList[2];
      }
      else
      {
        mpm[1] = modeList[1];
        mpm[2] = modeList[2];
      }
    }
    else
    {
      mpm[0] = modeList[0];
      mpm[1] = modeList[1];
      mpm[2] = modeList[2];
    }
  }
  else//左和上预测模式不同，numCand = 2
  {
    if( leftIntraMode > -1 && aboveIntraMode > -1 )//ex：在leftIntraMode，aboveIntraMode和17，34，5中选三个不同的，顺序依次
    {
      mpm[0] = leftIntraMode;
      mpm[1] = aboveIntraMode;
      numCand = 2;

      int index = 0;
      for( int i = 0; i < 3; i++ )
      {
        if( (leftIntraMode != modeList[i]) && (aboveIntraMode != modeList[i]) )
        {
          index = i;
          break;
        }
      }
      CHECK( index > 2, "Error" );
      mpm[2] = modeList[index];
    }
    else
    {
      mpm[0] = leftIntraMode > -1 ? leftIntraMode : aboveIntraMode;
      numCand = 1;

      if( mpm[0] != modeList[0] )
      {
        mpm[1] = modeList[0];
        mpm[2] = (mpm[0] != modeList[1]) ? modeList[1] : modeList[2];
      }
      else
      {
        mpm[1] = modeList[1];
        mpm[2] = modeList[2];
      }
    }
  }

  return (realMode ? numCand : 0);
}