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17th Meeting: Brussels, January 2020 2020-01-10 09:12
Clipping of minimum QP prime value
Authors: K. Unno KDDI K. Kawamura KDDI S. Naito KDDI Kyohei Unno
Abstract
In this contribution, it is proposed that the minimum value of Qp′ is clipped with 0 for non transform skip case and with 4 for transform skip case. The proposed clipping is applied to Qp′ after compensation depending on whether adaptive colour transform is applied.
Meeting Notes
JVET-Q0142 Clipping of minimum QP prime value [K. Unno, K. Kawamura, S. Naito (KDDI)]

In this contribution, it is proposed that the minimum value of Qp′ is clipped with 0 for non transform skip case and with 4 for transform skip case. The proposed clipping is applied to Qp′ after compensation depending on whether adaptive colour transform is applied.

Difference from JVET-Q0098: For TS blocks, clipping of QP’ is performed to minimum of 4 instead of QpPrimeTSMin. It is however raised that clipping to 4 would only be correct for the case of bit depth equal 10.

It is mentioned that also the case of ACT disabled should be considered, so the clipping should only be applied when ACT is on.

It is mentioned that there should be no difference to results of JVET-Q0098. However, the difference is observed, which may be due to the fact that handling of deblocking is wrong in the implementation of Q0098.

References:
JVET-P2001
Cited:
JVET-Q0015 JVET-Q0815 JVET-Q0820
PATENTS:
WO/2021/088835 0.34 20240129462 0.33 20220272335 0.32 20150016542 0.31 2013206815 0.30 2016200057 0.28 20170155903 0.27 20210281843 0.26
ARCHIVE v2 :
JVET-Q0142.docx JVET-Q0142.pdf JVET-Q0142_DraftText_Q0041-v1.docx JVET-Q0142_VTM-7.1.diff
Decisions
It is mentioned that there should be no difference to results of JVET-Q0098. However, the difference is observed, which may be due to the fact that handling of deblocking is wrong in the implementation of Q0098.
Citation