Opened 12 years ago

Closed 12 years ago

#699 closed defect (fixed)

Derivation process of chroma offset in WP when an input bit depth is beyond 8bit

Reported by: Tanizawa Owned by: bbross
Priority: minor Milestone: D8
Component: Text Version: D8 (J1003) d7
Keywords: Cc: bbross, wjhan, jct-vc@…

Description

When an input bit depth is beyond 8bit, the derivation process of chroma offset in the weighted prediction is incorrect. Since the value of chroma offset is always held in 8bit (see equations (8-224) and (8-225)), the predicted value of chroma offset must be also held in 8bit.
The original equation (7-48) in section 7.4.5.4 should be modified simply as follows:

Original;
shift = 1 << ( BitDepthC − 1 )
ChromaOffsetL0[ i ][ j ] = Clip3( −128, 127, (delta_chroma_offset_l0[ i ][ j ] – ( (shift*ChromaWeightL0[ i ][ j ]) >> ChromaLog2WeightDenom ) − shift ) ) (7-48)

Modified;
ChromaOffsetL0[ i ][ j ] = Clip3( −128, 127, (delta_chroma_offset_l0[ i ][ j ] – ( (128*ChromaWeightL0[ i ][ j ]) >> ChromaLog2WeightDenom ) − 128 ) ) (7-48)

Change History (2)

comment:1 Changed 12 years ago by DefaultCC Plugin

  • Cc bbross wjhan jct-vc@… added

comment:2 Changed 12 years ago by bbross

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

Will be fixed in JCTVC-K0030_v3 (to be released)

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