id,summary,reporter,owner,description,type,status,priority,milestone,component,version,resolution,keywords,cc 573,skip_flag context derivation issue,zhyang123,,"According to Table 9-38, skip_flag uses left and above skip_flag to derive the context index for CABAC decoding. However, instead of storing the neighboring skip_flag, the current HM 7.0 uses the following condition to determine the value of the neighboring skip_flag {{{ if ( m_pcSlice->isIntra () ) { return false; } return ( getMergeFlag( uiPartIdx ) && getPartitionSize( uiPartIdx ) == SIZE_2Nx2N && !getQtRootCbf( uiPartIdx ) ); }}} On the other hand, the new cbf flag coding rules in HM 7.0 allows the top layer chroma cbf to be one while all child chroma cbf flags to be zero. Although the example may be useless for a smart encoder, if allowed, it will make the above mentioned condition no longer equivalent to skip_flag equal to one and hence cause inconsistency between HM and spec. Suggested fix may be either fix the spec to disallow such cases or fix the HM to use the real neighboring skip_flag value to derive the context.",defect,closed,minor,HM-7.0,HM,HM-7.0,invalid,,fbossen ksuehring davidf jct-vc@…