Opened 4 weeks ago

Last modified 4 weeks ago

#1523 new defect

Wrong update of prevTid0Pic

Reported by: kolya Owned by:
Priority: critical Milestone: HM-next
Component: HM Version:
Keywords: longterm, prevTid0Pic, decoder Cc: ksuehring, karlsharman, jvet@…

Description

There is wrong update of POC in Void TDecTop::xCreateLostPicture(Int iLostPoc) line 370 of TDecTop.cpp caling xUpdatePreviousTid0POC.

When missing frame is after first POC MSB cycle, and that missing frame is coded as a LT reference with syntax delta_poc_msb_present_flag[i] == 0 and and used_by_curr_pic_lt_flag[i] == 1, the lost pic handling routine sets the POC of the missing pic by POC LSB only and full POC correct recovering is not possible in that case. Nevertheless, that is not the problem by itself and does not make the bitstream non-compliant with spec, but lost pic copying routine erroneously updates the common value of prevTid0Pic which is used for next POC derivation.

According to spec, prevTidOPic should be a value for the pic in decoding order, not for the lost pic.

The bug appears as POC number going crazy after first POC MSB cycle provided there is a referenced but lost pic in DPB.

N.Shlyakhov _at_ ieee -dot- org

Change History (1)

comment:1 Changed 4 weeks ago by kolya

  • Keywords decoder added
  • Summary changed from Wrong update of to Wrong update of prevTid0Pic
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