Update Common LUT Format to v4 (SMPTE version)

[doug-walker]

SMPTE is working on a standard for the Academy/ASC Common LUT Format. This will include some minor changes and the OCIO implementation will need to be adjusted accordingly.

This task is on hold while we wait for the FCD from the SMPTE working group.

[zachlewis]

Just out of curiosity, what kind of changes are we anticipating? And how would this affect ownership of further development?
(Like, would an Academy working group be in charge of making changes for v5? Would SMPTE have to make further changes for v6?)

[doug-walker]

@zachlewis , the working group discussions are private to SMPTE members with standards participation membership so I'm not allowed to discuss details, but I am anticipating that there will be a decision to do a "public FCD" in the next month, which would mean we would make a draft of the new spec publicly available. You would be able to see and comment on the specific minor changes at that point.

In terms of ownership of the spec, in my view, SMPTE now "owns" the CLF spec. However, that would not preclude the Academy or someone else to propose revisions to the spec. In terms of future revisions to the spec, SMPTE has a process in place for that. There is a lot of info on their website about how the process works.

In terms of ownership of the code development, OCIO is the only complete open source implementation of CLF I'm aware of (though I know colour has done some work towards implementing it as well with your help). No one from SMPTE or the Academy has signed up to update the OCIO implementation. Anyone is welcome to submit a PR to upgrade the OCIO parser for CLF. We will definitely ensure someone takes it on in time for the 2.5 release.

There is a guide for CLF implementers on the AMPAS site (that I led the development of). I'm guessing that will remain there unless SMPTE decides to make an RP or EG document out of it.

The CTF format, which is essentially CLF with extensions, will continue to be an OCIO format and will continue to be developed and versioned independently.

[doug-walker]

Closing as completed via PR #2265.