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12th Meeting: Macao, October 2018 2018-10-04 19:49
CE15-related: Palette mode when dual-tree is enabled
Authors: J. Ye Tencent Xinwei Li Tencent Shan Liu Tencent Xiaozhong Xu Tencent
Abstract
In this contribution, the modification on palette mode when dual tree is enabled is proposed. In VTM 2.0.1, for I slice, the dual tree is enabled, and luma CTU and chroma CTU have different tree structure. In the HEVC SCC palette mode, the luma sample and chroma sample are interleaved coded. In this case, the HEVC SCC palette mode cannot directly be applied on VTM 2.0.1. In this contribution, two methods are proposed to solve this issue. The proposed method 1 reports -11.64%, -7.75%, -7.55% luma and chroma BD rate changing for AI configuration on class F over VTM 2.0.1. And reports -9.00%, -7.07%, -7.14% luma and chroma BD rate changing for RA configuration on class F over VTM 2.0.1. The proposed method 2 reports -11.60%,-8.56%, -8.35% luma and chroma BD rate changing for AI configuration on class F over VTM 2.0.1. And reports -8.88%,-7.75%, -8.12% luma and chroma BD rate changing for RA configuration on class F over VTM 2.0.1.
Meeting Notes
JVET-L0308 CE15-related: Palette mode when dual-tree is enabled [J. Ye, X. Li, S. Liu, X. Xu (Tencent)]

In this contribution, the modification on palette mode when dual tree is enabled is proposed. In VTM 2.0.1, for I slice, the dual tree is enabled, and luma CTU and chroma CTU have different tree structure. In the HEVC SCC palette mode, the luma sample and chroma sample are interleaved coded. In this case, the HEVC SCC palette mode cannot directly be applied on VTM 2.0.1. In this contribution, two methods are proposed to solve this issue. The proposed method 1 reports -11.64%, -7.75%, -7.55% luma and chroma BD rate changing for AI configuration on class F over VTM 2.0.1. And reports -9.00%, -7.07%, -7.14% luma and chroma BD rate changing for RA configuration on class F over VTM 2.0.1. The proposed method 2 reports -11.60%, -8.56%, -8.35% luma and chroma BD rate changing for AI configuration on class F over VTM 2.0.1. And reports -8.88%, -7.75%, -8.12% luma and chroma BD rate changing for RA configuration on class F over VTM 2.0.1.

Two methods are proposed for palette mode when dual tree is enabled:

  • Method 1: only apply palette mode to luma plane when dual tree is enabled. In this case, only one palette table and one index map for luma CU will be signaled. When coding chroma plane separately, palette mode will not be used. The other available modes, such as intra chroma mode coding, will be used.
  • Method 2: apply palette mode to luma plane when dual tree is enabled. When coding chroma plane, if the co-located luma blocks are all coded in palette mode, the chroma block are also have the flexibility to use palette mode. A flag is signaled whether the chroma block using palette mode or not. If the chroma block using palette mode, the corresponding palette mode syntax will be signaled.

It was reported that some loss is observed in Method 1, and the loss is less in Method 2.

In Method 2, there is no syntax for the chroma CU if any of collocated luma CU is not coded in palette mode.

It was commented that the chroma CU could be set to palette mode without syntax if the collocated luma CUs are coded by the palette mode.

The BoG recommended to study this in the next CE.

References:
JVET-K1010 JVET-K1028 JVET-K1035
Cited:
JVET-L0011 JVET-L0526 X JVET-L0688 JVET-L1028
ARCHIVE v3 :
JVET-L0308-v2.docx JVET-L0308.pptx JVET-L0308_method1.xlsm JVET-L0308_method2.xlsm
Decisions
The BoG recommended to study this in the next CE.
Citation