OK, I have the mystery of this partially solved (thanks to a post from nightantilli in the other thread), at least I think so, but I stress that it's a not a solution and AMD are going to have to fix this.
It does appear that Freesync isn't being correctly disengaged during video playback in MPC-BE and a whole host of other players; creating a profile override to force disable it doesn't work, so stop suggesting it. My monitor has a Freesync range of 40-75HZ, but unfortunately, this isn't enough for LFC to work. LFC on my monitor, seems to require a differential of at least 2x between the minimum and maximum, which this monitor (and I suspect any monitor affected by the problem) doesn't have. Either that or they handle LFC differently with different conditions for engaging it.
If you use CRU to expand the Freesync range to either 35-75 or 30-75, both creating a larger than 2x differential, this tearing and stuttering problem vanishes without any other user intervention. To test this at your own risk, you need to launch CRU, click "edit" next to the active monitor, enter a sensible minimum V rate value that creates a differential of least 2x between it and V rate max. So for instance, 35 works, but 38 doesn't.
Anybody not experiencing these problems with MPC, out-of-the-box, I suspect already has functioning LFC. So this problem could actually be much larger, it just isn't manifesting for most people because LFC is correcting for it.
As far I can tell, the driver changes introduced 18 months ago crippled video playback compatibility with monitors that don't by default support LFC. Again, the per-app ability to force disable Freesync does not work here; it has never worked so please stop suggesting it.
But here's the problem. amdmatt, you said that you tested on a Samsung U32E850R and didn't see any problem (did you try the second clip in MPC?). That monitor does not have a 2x differential in range and is only 60Hz, so there must be another mechanism by which this is being corrected for or by which LFC is being engaged. Or do some of these older monitors like mine just implement LFC very differently? I'm also wondering if the frame duplication pattern is a factor; 24p to 60Hz conversion is very specific and it's possible that the player, MPC, is handling that in a way that plays nice with your display.
We need a solution to this. I think we've all been very patient. I'm going to stress this one more time for the people in the back:
Creating a profile override for MPC in Radeon settings, to force disable Freesync, doesn't resolve the issue and Enhanced Sync is disabled. A profile override should work, but it doesn't and I don't know why. Something else is going on or not being fully disengaged, be that LFC or something undiscovered.
