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12th Meeting: Macao, October 2018 2018-10-02 03:26
CE8-related: Restrictions for the search area of the IBC blocks in CPR
Authors: Luong Pham Van Qualcomm Vadim Seregin Qualcomm W.-J. Chien Qualcomm T. Hsieh Qualcomm Marta Karczewicz Qualcomm
Abstract
This contribution proposes the restrictions to the search area for IBC blocks. The search area is restricted to the current CTU and few CTUs to the left of the current CTU. Additionally, this proposal also proposes to extend the search area to 10 lines above these CTUs. It is reported that with the proposed restricted search area, the Luma BD-rate changes for [CTC, Class F, class SCC 1080p] over BMS2.1-VTM configuration are:
Meeting Notes
JVET-L0404 CE8-related: Restrictions for the search area of the CPR blocks in CPR [L. Pham Van, V. Seregin, W.-J. Chien, T. Hsieh, M. Karczewicz (Qualcomm)]

This contribution proposes the restrictions to the search area for IBC blocks. The search area is restricted to the current CTU and few CTUs to the left of the current CTU. Additionally, this proposal also proposes to extend the search area to 10 lines above these CTUs. It is reported that with the proposed restricted search area, the Luma BD-rate changes for [CTC, Class F, class SCC 1080p] over BMS2.1-VTM configuration are:

The current and 1 left CTU without and with extended lines, respectively:

  • AI: (-0.29%, -15.55%, -46.10%) and (-0.32%, -15.79%, -46.99%).
  • RA: (-0.10%, -12.67%, -29.42%) and (-0.11%, -12.88%, -30.17%).
  • LB: (0.02%, -7.19%, -19.70%) and (-0.32%, -7.38%, -20.18%).

The current and 2 left CTUs without and with extended lines, respectively:

  • AI: (-0.29%, -15.76%, -46.68%) and (-0.32%, -15.98%, -47.56%).
  • RA: (-0.10%, -12.84%, -30.23%) and (-0.11%, -13.06%, -30.99%).
  • LB: (0.02%, -7.30%, -20.39%) and (0.02%, -7.62%, -20.96%).

The current and 3 left CTUs without and with extended lines, respectively:

  • AI: (-0.29, -15.84%, -46.98%) and (-0.32%, -16.06%, -47.85%).
  • RA: (-0.10, -12.91%, -30.63%) and (-0.11%, -13.14%, -31.35%).
  • LB: (0.02%, -7.52%, -20.94%) and (0.02, -7.67%, -21.52%).

Based on CPR with local search range (current CTU + x left CTUs), this proposal proposes to extend the search area to N lines above these CTUs. N is set to be 10 in the proposal, but the proposal also proposed that the number of N should be set accoding to the VVC design. Coding performance using these extra N lines was reported.

It was commented that the reference pixels in N lines are before deblocking stage. It was suggestesd to test N=4 in the next CE.

It was commented that there are different approaches: (1) extend reference to the left CTU (2) top N line.

It was commented that multiple tools can share the same additional required resource.

It was commented that it is better that the required line memory could be in the same memory as the one to store the reference samples in the current and left CTUs.

The BoG recommended to study this in the next CE.

Note: During discussion about palette mode, it was suggested that the upcoming CE8 should test CPR technology also in a configuration where the CE15 reference palette mode is enabled.

CE9 related – Decoder-side motion vector derivation (26)

Decoder motion vector refinement

A BoG was formed, with results reported in JVET-L0693. The BoG results were reviewed 1415-1500 Track B Monday (GJS).

References:
JVET-K0076
Cited:
JVET-L0011 JVET-L0028 X JVET-L0688 JVET-L1028
ARCHIVE v2 :
JVET-L0404.docx JVET-L0404_Compare_TestBoverTestA.xlsm JVET-L0404_TestA_1LeftCTUandCurrentCTU.xlsm JVET-L0404_TestB_1LeftCTUandCurrentCTU_10Lines.xlsm JVET-L0404_TestC_2LeftCTUandCurrentCTU.xlsm JVET-L0404_TestD_2LeftCTUandCurrentCTU_10Lines.xlsm JVET-L0404_TestE_3LeftCTUandCurrentCTU.xlsm JVET-L0404_TestF_3LeftCTUandCurrentCTU_10Lines.xlsm
Decisions
A BoG was formed, with results reported in JVET-L0693. The BoG results were reviewed 1415-1500 Track B Monday (GJS).
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