Add potential for PTL::general_frame_only_constraint_flag to set true

[Former user]

Currently m_vps.ptl.frameOnlyConstraintFlag is initialized to false and is never given a chance to become true. If possible, and please, can frameOnlyConstraintFlag be set accordingly once vui.fieldSeqFlag is known? Even though it is not misleading to clamp frameOnlyConstraintFlag to false.

Relevant spec info:

profile_tier_level() general_frame_only_constraint_flag equal to 1 specifies that field_seq_flag is equal to 0. general_frame_only_constraint_flag equal to 0 indicates that field_seq_flag may or may not be equal to 0.

vui_parameters() field_seq_flag equal to 1 indicates that the CVS conveys pictures that represent fields, and specifies that a picture timing SEI message shall be present in every access unit of the current CVS. field_seq_flag equal to 0 indicates that the CVS conveys pictures that represent frames and that a picture timing SEI message may or may not be present in any access unit of the current CVS. When field_seq_flag is not present, it is inferred to be equal to 0. When general_frame_only_constraint_flag is equal to 1, the value of field_seq_flag shall be equal to 0.

[Deepthi Nandakumar]

Thanks, patch pushed.

Curious about this though - is this to make the decoder logic simpler?

[Former user]

My client's container has a soft requirement for this field and tests will always result in a warning of non-compliance. Code to infer correctness of more useful fields, like field_seq_flag, is in place but, I can't change what customers choose to worry about.

Appreciate it!

[Former user]

nandaku2 @ https://bitbucket.org/multicoreware/x265/commits/194eeb121e45ba495b3cfb1de4faa1cf51690215

New videos generated with general_frame_only_constraint_flag set as desired, when permitted.