Opened 9 years ago

Closed 9 years ago

#912 closed defect (fixed)

CABAC context initialization at start of tile and dependent slice segment.

Reported by: bheng Owned by: bbross
Priority: minor Milestone:
Component: Text Version: D9 (K1003) v11
Keywords: Cc: bbross, wjhan, jct-vc@…

Description

If the current coding tree block is the first coding tree block in a tile and also the first coding tree block in a dependent slice segment (see example in Figure 6-5), the Initialization Process in Section 9.2.1 will fail to reinitialize the arithmetic decoding context. Instead, the state will be copied from the end of the previous tile, creating a cross-tile decoding dependency.

There should be an additional case here to check for the start of a tile. Something like the following:

The context variables of the arithmetic decoding engine are initialized as follows.

  • If the current coding tree block is the first coding tree block in a tile, the initialization process for context variables is invoked as specified in subclause 9.2.1.1.
  • Otherwise, if entropy_coding_sync_enabled_flag is equal to 1, ...

The HM-9.1 software has the same issue. A separate ticket will be filed for the software bug.

Change History (3)

comment:1 Changed 9 years ago by DefaultCC Plugin

  • Cc bbross wjhan jct-vc@… added

comment:2 Changed 9 years ago by ksuehring

A patch for HM has been committed in r3165 using the guard macro DEPSLICE_TILE_INDEPENDENT_BUGFIX. I didn't find the above mentioned software ticket.

Last edited 9 years ago by ksuehring (previous) (diff)

comment:3 Changed 9 years ago by bbross

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

Fixed in JCTVC-L0030.

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  • Benjamin Bross(Owner, Subscriber, Participant)
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  • Karsten Suehring(Participant, Always)
  • Woo-Jin Han(Subscriber)