JVET-R0122 AHG9: On picture output for non-reference pictures [B. Choi, S. Wenger, S. Liu (Tencent)]
In this contribution, it is proposed that the pic_output_flag is not signalled in picture header and inferred to be equal to 1, when the value of non_reference_picture_flag is equal to 1. A coded picture with non_reference_picture_flag equal to 1 and pic_output_flag equal to 0 should not be included in the bitstream, becaue such a picture is never outputted and never used as a reference.
It was commented that, when a picture with pic_output_flag equal to 0 and Temporald less than the highest Temporald was referenced only by the highest temporal layer, and if that temproal layer is dropped, it becomes a "non-reference picture", although the "non-reference picture" flag is still equal to 0.
It was commented that the proposal would disallow a bitstream rewriter to mark a "non-reference picture" that has pic_output_flag equal to 1 to have pic_output_flag equal to 0 instead.
On the other hand, for that use case, the bitstream rewriter could set non_reference_picture_flag equal to 0 and set pic_output_flag equal to 0 for such a use case.
Decision (sensibility cleanup): Adopt. The NOTE needs to be rephased (delegated to the editor).