Opened 6 years ago

Closed 17 months ago

#1402 closed defect (fixed)

Ambiguous semantic for constrained_intra_prediction_flag

Reported by: xiuxx Owned by:
Priority: minor Milestone:
Component: SCC text Version:
Keywords: CIP, HEVC SCC Cc: rajan_joshi, jct-vc@…

Description

In section 7.4.3.3.1 of HEVC SCC draft 3, the semantic of constrained_intra_prediction_flag is as follows:

"constrained_intra_pred_flag equal to 0 specifies that intra prediction allows usage of residual data and decoded samples of neighbouring coding blocks coded with or without using a reference picture that is not the current picture. constrained_intra_pred_flag equal to 1 specifies constrained intra prediction, in which case the general intra prediction process only uses residual data and decoded samples from neighbouring coding blocks coded without using a reference picture that is not the current picture."

However, there is ambiguity about the definition of "general intra prediction". It can be interpreted as either intra prediction only or intra and IBC prediction. In current SCM-4.0, it should refer to the second case, i.e., intra and IBC prediction. It is recommended to improve the text to match SCM-4.0.

Change History (3)

comment:1 Changed 6 years ago by DefaultCC Plugin

  • Cc rajan_joshi jct-vc@… added

comment:2 Changed 17 months ago by crosewarne

In H.265 11/19, the semantic is now:

constrained_intra_pred_flag equal to 0 specifies that intra prediction allows usage of residual data and decoded samples of neighbouring coding blocks coded using either intra or inter prediction modes. constrained_intra_pred_flag equal to 1 specifies constrained intra prediction, in which case intra prediction only uses residual data and decoded samples from neighbouring coding blocks coded using intra prediction modes.

Given the definition of inter prediction to include referencing the current picture, I think the ambiguity is resolved.

comment:3 Changed 17 months ago by crosewarne

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