Refresh rate doesn't appear to adjust to content frame rate

[hedgehog90 16]

I have a samsung UE50MU6120 and I've noticed there doesn't appear to be any refresh rate adjustment when I use the usb installed version of Emby, and there is a distinct lack of smoothness to videos with a frame rate of 24fps, most noticeable in what are supposed to be slow panning shots.

Supposing Emby sends a signal to the TV 'hey, I'm playing @ 24fps now', where in the TV settings can I make it listen and adapt the refresh rate accordingly?
I've got it set to Game Mode so it doesn't apply that horrible 'fake' interpolated smoothness for 60fps playback (it's insane that this was the default setting!)
According to the manual there is a setting for external devices with game mode called 'FreeSync'. It has 2 settings - Basic and Ultimate:
"Basic sets the refresh rate for 90 to 120Hz, while Ultimate opens up the range from 48 all the way up to 120Hz"
Which appears to be a really odd way of stating that it simply adapts the refresh rate to the external device's output signal, why there are 2 settings I have no idea. 48-120Hz (factoring 24-60Hz) is what I need, but this appears to be for external devices only.

I've got an old Philips TV that handles this without issue (with content delivered via HDMI), but for some reason my relatively new Samsung TV doesn't handle this.

I hope this isn't a basic limitation of the app as it's installed on the TV, rather than receiving an HDMI signal.

Edited October 2, 2020 by hedgehog90

[SamES 890]

What happens if you put the same file on a USB drive and connect it directly to the TV?  How does it play then?

The Emby app passes the video url directly to the native avplayer, and there is no option for the app to adjust the refresh rate.

Have you tried adjusting the Auto Motion settings in the advanced Picture settings menu on the TV?   Just be aware that these settings can be changed differently for each source, so even if you have turned smoothness off on HDMI sources, you will also need to adjust it while playing back content via the app. 

Not sure if anything in this forum is of interest https://www.avforums.com/threads/suggestions-for-a-replacement-to-my-ue50mu6120.2199903/