[Feature Request] Ignore film grain in av1

[affectful]

Synthetic film grain artificially lowers SSIMULACRA2 score even though quality is visually improved. Add an option to disable film grain during decoding.

[Line-fr]

Hi, thank you for your interest
I am affraid I don't know a way to do that myself, it would also be misleading for the user. The user ask for a SSIMULACRA2 score and SSIMULACRA2 doesnt like grain, that is just a sad fact. Up to now, I have seen people needing to create a grainless intermediate for metrics and adding grain after using grav1synth.
However, I may also recommend CVVDP, which, unlike SSIMULACRA2 and Butteraugli is not severe on grain (depending on display type used of course)