JVET-AP0106 AHG9: On signalling packed channels in ECFI SEI message [H. Tan, C. Kim, J. Lee, J. Nam, J. Lim, S. Kim (LGE)]

This contribution asserts that the signalling for the mapping between partition and channel component in the ECFI SEI message has the following two problems:

1. The current semantics does not specify that at least one of the value of ecfi_packed_channel_id[ i ][ j ][ k ] shall not be equal to 0.
2. The signalling method to assign the partitions to channel components are not efficient. A more efficient signalling would simply signal the partition index / id and what channel component it is associated with. That way the maximum we have to loop is only as many as the defined channel, not as many as the partitions in which some of them may be unused.

It was suggested that the proposed constraint is unnecessary.

No action on item 1.

It was noted that HEIF has a similar functionality using the same syntax.

No action.