First, most of the movies are done in CMV4.0 but exported in CMV2.9.jayper wrote: ↑Tue Mar 07, 2023 9:54 pmThanks so much! Apologies, but I am not yet well-read on the CMV4.0 vs CMV2.9 discussion. Is there a reason one would prefer one versus the other? I'm guessing it is more future-proof, but at this time most hardware doesn't support it? Is there a downside to keeping it?
CMV4.0 is backward compatible with cmv2.9. The trim passes (100-600-1000nits) are done in the level 8 for cmv4.0 and level 2 for cmv2.9.
When a device and the rpu are CMV4.0, the L2 trims are ignored because it will use the L8 trims which is the proper behavior.
Now the problem is that most of the CMv4.0 movies only have a 100nits L8 trim pass which is obviously not used in DV playback but they do have proper L2 trims that are ignored on cmv4.0 devices (shield/firestick/appletv/internal tv ). So you get inferior quality on those devices unless you remove the CMV4.0 block. The test files (made with original metadata from the movie Puss in boots) show exactly the problem and I bet this is the reason why we do not see a lot of CMV4.0 movies because the colorist has to do the trim passes two times (L8 + L2).
In my script, you can use 2-6 to export the trims to a text file and verify the raw data. So if you use a CMV4.0 devices, you might want to inspect your movies for cmv4.0 metadata (mostly amazon DV and movie anywhere web-dl ) .