Opened 9 years ago

Closed 7 years ago

#499 closed defect (wontfix)

Decoding transform subdiv flag at depth 0 uses CNU context

Reported by: pieterkapsenberg Owned by:
Priority: major Milestone: HM-6.2
Component: HM Version: HM-6.1
Keywords: transform context cabac subdiv Cc: fbossen, ksuehring, davidf, jct-vc@…

Description

In a stream with 32x32 LCUs, it is possible to call the function TDecSbac::parseTransformSubdivFlag with a depth of 0. The context selection is done with this depth, and in HM right now this context is not used, so the bistream gets coded and decoded with the dummy init value of 154:

static const UChar
INIT_TRANS_SUBDIV_FLAG[3][NUM_TRANS_SUBDIV_FLAG_CTX] =
{
{ CNU, 224, 167, 122, CNU, CNU, CNU, CNU, CNU, CNU, },
{ CNU, 124, 138, 94, CNU, CNU, CNU, CNU, CNU, CNU, },
{ CNU, 153, 138, 138, CNU, CNU, CNU, CNU, CNU, CNU, },
};

Incidentally, the parameter name uiLog2TransformBlockSize of the TDecSbac::parseTransformSubdivFlag function should really be called uiDepth, since that is what it used for.

Change History (3)

comment:1 Changed 9 years ago by DefaultCC Plugin

  • Cc fbossen ksuehring davidf jct-vc@… added

comment:2 Changed 9 years ago by ksuehring

Also here: This is related to issue #436. Context initializations were only run for common test conditions.

comment:3 Changed 7 years ago by fbossen

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

Doesn't apply to final spec

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  • David Flynn(Subscriber)
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