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32nd Meeting: Hannover, DE, October 2023 2023-10-06 07:25
[AHG9] On order of output pictures when skipped candidate input pictures are present in NNPFGA
Authors: Hendry LGE Junghak Nam LGE S. Kim LGE J. Lim LGE
Abstract
It is asserted that the current text for neural-network post-filter group activation (NNPFGA) SEI message has problem when skipped input pictures are used and one or more filters in the target NNPFGC are filters that produce interpolated pictures. When one or more pictures are skipped from being used as input pictures, the skipped pictures may cause problem for decoder to determine where to put the interpolated output pictures from the filter that are supposed to be in between the two input pictures.
Meeting Notes
JVET-AF0095 [AHG9] On order of output pictures when skipped candidate input pictures are present in NNPFGA [Hendry, J. Nam, S. Kim, J. Lim (LGE)]

It was asserted that the current text for neural-network post-filter group activation (NNPFGA) SEI message has problem when skipped input pictures are used and one or more filters in the target NNPFGC are filters that produce interpolated pictures. When one or more pictures are skipped from being used as input pictures, the skipped pictures may cause problem for decoder to determine where to put the interpolated output pictures from the filter that are supposed to be in between the two input pictures.

This contribution proposes the following modification to overcome the asserted problem. The proposed modifications are as follows:

  1. For NNPFGA design, signal a flag for the i-th NNPF to specify whether or not the NNPF has interpolated picture(s) output. This flag is constrained to be equal to 1 when the NNPF includes picture rate upsampling purpose and be equal to 0 when the NNPF does not include picture rate upsampling purpose.
  2. When the value of nnpfga_input_pic_skip_count[ i ][ j ] is greater than 0, signal a new syntax element called nnpfga_num_interpolated_pic[ k ][ j ][ k ] for k ranges from 0 to nnpfga_input_pic_skip_count[ i ][ j ], inclusive, to specify the number of interpolated pictures generated by the i-th NNPF in the target NNPFG between the k-th and the ( k + 1 )-th pictures that are skipped in the list of candidate input pictures candInputPicList[ i ] after the j-th input picture of the NNPF
  3. It is constrained that when nnpfga_num_interpolated_pic[ k ][ j ][ k ] is present, the sum of nnpfga_num_interpolated_pic[ i ][ j ][ k ] for k ranges from 0 to nnpfga_input_pic_skip_count[ i ][ j ], inclusive, shall be equal to the value of nnpfc_interpolated_pics[ j ] of the NNPF.

It was commented that the example is an unusual cornercase with two different filters generating new pictures at different relative positions . Also, timing of output should be managed by systems level, where the system should know at which temporal positions pictures are generated. No need for action.

ARCHIVE :
JVET-AF0095_v1.docx
Decisions
It was commented that the example is an unusual cornercase with two different filters generating new pictures at different relative positions . Also, timing of output should be managed by systems level, where the system should know at which temporal positions pictures are generated. No need for action.
Citation