Originally Posted by mbunio
Have you experienced quick bright blink when scene changes from brighter to darker? It is very quick, but still it can be noticed, at least by me.
I tried switch to different modes, but only on game mode it does not appear. However, on game mode motion is far from good when watching movies (I mean watching movies with lower frame rate, when testing YouTube video in 60fps motion is excellent...). Btw, I've noticed also that when on game mode picture seems to be crispier compared to any other mode and I think there is not to much blooming at least around subtitles....
This is an issue caused between an incompatibility between the A/V Sync mode and the Auto Local Dimming feature of the TV. The A/V Sync uses software to sync the video to the audio to ensure that the lips sync up to the sound. For some reason, the Auto Local Dimming, which controls the dimming zones of the TV to produce deeper blacks, is not also controlled by this software, so it gets out of sync from what is being displayed on screen, thus it brightens or dims the screen for the next scene before your image cuts to it.
There are two options to fix this problem, the easiest is to go to the settings menu on the TV Home screen, go to sound, and find the A/V Sync setting and turn it off (it's also possible that Auto fixes it as well, but I can't confirm that currently). Go back and check that this works for you. If, however you now find that your setup has lip sync issues, you may need to try the other option, which is turning A/V Sync back on, and then turning Auto Local Dimming to off in your picture settings for the applicable input. This is the more annoying way to do it, because the Auto Local Dimming picture setting is input specific, but the A/V Sync option, unfortunately, is a universal setting that applies to all inputs. I have to use A/V Sync for my DirecTV box, as I find that the audio delay on it is unacceptable for many channels, it's a problem with the source. I wish that i could just leave the setting alone, but when I watch from Apple TV 4K, I much prefer to use local dimming, so have to always drill down into the settings to turn A/V Sync back off before I switch inputs.