Of itu-t sg16 wp3 and iso/iec jtc1/SC29/WG11

6.5.2Slice/picture skipping (4)

This category reviewed Tues. 29th (GJS).

It was remarked that skipping can only be done using low-level syntax in version 1 decoders, so skipping might not be considered only to be a high-level-syntax modification. It can hypothetically be expressed as high-level syntax, but is a low-level operation in a version 1 decoder.

JCTVC-O0055 MV-HEVC/SHVC HLS: Skipped slice and use case [T. Yamamoto, T. Ikai, T. Tsukuba (Sharp)]

This contribution introduces an ROI-capable scalable video applications using skipped tile. In the application, 1) media box transfers modified EL bitstream corresponding to the region requested by the users, 2) EL data is modified so that the outside-of-region part of the bitstream includes less data by replacing the outside-of-region with skipped tile, and 3) SHVC decoder could receive whole BL bitstream and partial EL sub bitstream corresponding to the requested ROI.

This contribution proposes modified syntax for signalling skipped slice/tile:

• 
  SPS-level syntax to indicate whether all tiles included in CVS are motion constrained.
  
• 
  Slice-level non-significant slice/tile indication flag signalled when multiple tiles are used and when either all tiles are motion constrained or all tiles are inter-layer constrained.
  
• 
  Slice-level syntax for the number of skipped CTUs in skipped slice/tile based on maximum number of CTUs included in the slice/tile
  
• 
  Bitstream constraint on conformance cropping window to include only non-skipped tiles.
  

The proposal is focused on using tile-constrained decoding operations so that a middle box could replace an existing tile in the bitstream with an instruction to generate that tile by another process.

No action taken due to the general concern expressed above (about contributions in the category of partial-picture operations currently expressed only in low-level syntax for version 1).