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13th Meeting: Marrakech, January 2019 2019-01-17 00:27
CE8-related: CPR mode signaling and interaction with inter coding tools
Authors: W.-J. Chien Qualcomm Vadim Seregin Qualcomm Marta Karczewicz Qualcomm Shurui Ye Hikvision Fangdong Chen Hikvision Liqiang Wang Hikvision
Abstract
This contribution proposes two schemes to align the interaction between CPR mode with all other inter coding tools. The method is implemented on top of VTM-3.0 with CPR enabled. The first scheme removes CPR dependency in motion derivation process. It results in negligible BD-rate difference for all test configurations on regular or screen content materials. The second scheme uses CPR mode as a third mode other than intra or inter modes. Motion predictor for CPR mode and inter mode would be derived mutual-exclusively from each other. The simulations show 1.1% in RA configuration and 1.5% in LDB configuration in screen content coding materials.
Meeting Notes
JVET-M0483 CE8-related: CPR mode signalling and interaction with inter coding tools [W.-J. Chien, V. Seregin, M. Karczewicz (Qualcomm)]

This contribution proposes two schemes to align the interaction between CPR mode with all other inter coding tools. The method is implemented on top of VTM-3.0 with CPR enabled. The first scheme removes CPR dependency in motion derivation process. It results in negligible BD-rate difference for all test configurations on regular or screen content materials. The second scheme uses CPR mode as a third mode other than intra or inter modes. Motion predictor for CPR mode and inter mode would be derived mutual-exclusively from each other. The simulations show 1.1% in RA configuration and 1.5% in LDB configuration in screen content coding materials.

(see also discussion under JVET-M0327)

In Track B, the general consensus is that it is a right direction to signal CPR as a separate mode rather than using a special reference picture index. As this is a fundamental conceptual decision, this was later discussed and decided in the JVET plenary.

JVET-M0483 comes with spec text (“method 3”), which would probably need more careful inspection and modifications (also alignment with v9 of VVC draft 3).

This was further discussed in Track B Thursday 17 January 1730.

Generally, consensus that the text is appropriate. Open issues are raised as follows:

  • How to implement HMVP? It is agreed that separate HMVP buffers (5 candidates each) should be used for conventional MV and IBC.
  • How to implement merge? Share same process as in regular MV merge, but disallow TMVP, 0 vector means unavailable as it is invalid
  • Constraints to be implemented in bitstream, no invalid vectors, merge shall not be used if the merge candidate is invalid (out of range or 0)
  • For deblocking, IBC is handled as inter mode
  • CIIP does not use IBC
  • AMVP does not use quarterpel.
  • In dual tree, the mode is signalled both for luma and chroma, same derivation of chroma vector as in VTM3.

For the time being, the VTM4 encoder uses a maximum block size of 16x16, which may be released in the future. No normative impact.

Decision: Adopt JVET-M0483 (text in zip v4, “r1”, probably needs some more update along the lines above).

References:
JVET-L0293 JVET-L1028
Cited:
JVET-M0011 JVET-M0016 JVET-M0028 X JVET-M0860 X JVET-M1001 JVET-M1002 JVET-N0002 JVET-N0003 JVET-N0013 JVET-N0075 JVET-N0076 JVET-N0077 JVET-N0078 JVET-N0079 JVET-N0081 JVET-N0085 JVET-N0086 JVET-N0088 JVET-N0097 JVET-N0107 more than 20
ARCHIVE v4 :
JVET-L1001-v9-M0483_r1.docx JVET-M0483-source_method1_method2.zip JVET-M0483-source_method3.zip JVET-M0483.docx JVET-M0483_method1.xlsm JVET-M0483_method2.xlsm JVET-M0483_method3.xlsm JVET-M0483_method3_noHMVP_noPairwiseAverage.xlsm JVET-M0483_r1.docx JVET-M0483_r1.pptx JVET-M0483_r2.docx
Decisions
adopted
Adopt JVET-M0483 (text in zip v4, “r1”, probably needs some more update along the lines above)
Citation