A SW bug in VTM for MPM generation when multiline is used for intra CU prediction

[ezhizng]

It looks as if there is a potential bug in intra prediction from multi reference line, please double check.

The code below is used for multi reference line intra prediction MPM generation. To avoid insert duplicated modes in MPM, the red marked code:

if (aboveIntraDir > DC_IDX)

should be changed to:

if (aboveIntraDir > DC_IDX && aboveIntraDir != leftIntraDir)

Code snip below:
UtilTools.cpp
Line 333

int PU::getIntraMPMs()
{
#if JVET_L0283_MULTI_REF_LINE
    if (extendRefLine)
    {
      int modeIdx = 0;
      int angularMode[2] = { 0, 0 };
 
      if (leftIntraDir > DC_IDX)
      {
        angularMode[modeIdx++] = leftIntraDir;
      }
      if (aboveIntraDir > DC_IDX)
      {
        angularMode[modeIdx++] = aboveIntraDir;
      }
}

[fbossen]

This looks like an oversight when combining multi reference lines with 6 MPMs. Suggested fix submitted in ​https://vcgit.hhi.fraunhofer.de/jvet/VVCSoftware_VTM/merge_requests/81