JVET-AC0061 AHG9: Comments on Neural-network Post-filter Characteristics SEI Message [S. Deshpande (Sharp)]

Some modifications are proposed to the Neural-network post-filter characteristics SEI Message. Following is proposed:

• Proposal 1: It is proposed to move nnpfc_purpose syntax element to signal it earlier in the NNPFC SEI message.
• Proposal 2: Two bug-fixes are proposed related to variables in NNPFC SEI message.
  • Bug-fix A: It is asserted that the outermost for loop in equation 84 which defines the process StoreOutputTensors( ), should use the variable numOutputPics instead of numInputPics.
  • Bug-fix B: It is asserted that when nnpfc_purpose has a value other than value 5, the variable numOutputPics is not derived and it should be derived.
• Proposal 3: It is proposed to either define a new syntax element for specifying the bit depth of chroma sample values in the input integer tensor or to define the semantics of an existing syntax element to apply to chroma samples in addition to the luma samples.