Opened 7 years ago

Closed 7 years ago

#1351 closed defect (fixed)

error in parsing terminating bit that ends slice_segment_data

Reported by: dthoang Owned by:
Priority: minor Milestone: HM-16.3
Component: HM Version: HM-16.2
Keywords: Cc: ksuehring, davidf, karlsharman, jct-vc@…

Description

A recent change in TDecSlice.cpp introduced an error in the parsing of the terminating bit at the end of slice_segment_data.

    // Should the sub-stream/stream be terminated after this CTU?
    // (end of slice-segment, end of tile, end of wavefront-CTU-row)
    if (isLastCtuOfSliceSegment ||
         (  ctuXPosInCtus + 1 == tileXPosInCtus + currentTile.getTileWidthInCtus() &&
          ( ctuYPosInCtus + 1 == tileYPosInCtus + currentTile.getTileHeightInCtus() || wavefrontsEnabled)
         )
       )

Should be changed to:

    // Should the sub-stream/stream be terminated after this CTU?
    // (end of slice-segment, end of tile, end of wavefront-CTU-row)
    if (!isLastCtuOfSliceSegment &&
         (  ctuXPosInCtus + 1 == tileXPosInCtus + currentTile.getTileWidthInCtus() &&
          ( ctuYPosInCtus + 1 == tileYPosInCtus + currentTile.getTileHeightInCtus() || wavefrontsEnabled)
         )
       )

Please refer to syntax table 7.3.8.1 of the specification.

Change History (2)

comment:1 Changed 7 years ago by DefaultCC Plugin

  • Cc ksuehring davidf karlsharman jct-vc@… added

comment:2 Changed 7 years ago by karlsharman

  • Milestone set to HM-16.3
  • Resolution set to fixed
  • Status changed from new to closed

This would have had no actual effect on decoding since parseTerminatingBit
can be called multiple times for the last terminating-1 bit, and still get
the same result:

m_uiRange is deremented, but not used after the call to TDecBinCABAC::decodeBinTrm,
and m_uiValue is not updated by TDecBinCABAC::decodeBinTrm.

However, fixed for clarity.

Fixed in r4237.

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These roles will be notified: Reporter, Owner, Subscriber, Participant

  • David Flynn(Subscriber)
  • Dzung Hoang(Reporter)
  • jct-vc@…(Subscriber)
  • Karl Sharman(Subscriber, Participant)
  • karl.sharman@…(Always)
  • Karsten Suehring(Subscriber, Always)