Opened 10 months ago

Closed 7 months ago

#152 closed defect (fixed)

Sub-PU TMVP can generate an invalid inter candidate

Reported by: bheng Owned by:
Priority: minor Milestone:
Component: VTM Version: VTM-3.0
Keywords: Cc: ksuehring, XiangLi, fbossen, jvet@…

Description (last modified by ksuehring)

In UnitTools.cpp, in the function getInterMergeSubPuMvpCand():

      if (colMi.isInter ... )
      {
        for (unsigned currRefListId = 0; currRefListId < (bBSlice ? 2 : 1); currRefListId++)
        {
          RefPicList currRefPicList = RefPicList(currRefListId);
          if (deriveScaledMotionTemporal(…))
          {
            …
          }
        }
      }
      else
      {
        // intra coded, in this case, no motion vector is available for list 0 or list 1, so use default
        …
      }

The code above can generate a inter motion vector with no valid reference frame (all refIdx = -1).

Assume the first if() condition passes (i.e. colMi.isInter) and the second if() condition fails. For example, if the current slice is a P-slice and deriveScaledMotionTemporal() returns false for List0 because colMi contains only List1 motion, getCheckLDC()=0, and bAllowMirrorMV=0.

In this situation, the code above will never run the else( ) condition that assigns the default motion instead. An inter motion vector will be assigned with no valid reference index (refIdxL0=-1 and refIdxL1=-1).

Change history (4)

comment:2 Changed 9 months ago by bheng

  • Resolution set to fixed
  • Status changed from new to closed

comment:3 Changed 9 months ago by ksuehring

  • Description modified (diff)
  • Resolution fixed deleted
  • Status changed from closed to reopened

comment:4 Changed 7 months ago by bheng

  • Resolution set to fixed
  • Status changed from reopened to closed
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