Hello! Me and a friend were discussing this, the question is, does LFC make a wide VRR range irrelevant?
Example:
Same panel performance, same settings, same everything (for the sake of argument)
Monitor 1: Game runs at 35 FPS, monitor refreshes at 70Hz (VRR range 60-144)
Monitor 2: Game runs at 35 FPS, monitor refreshes at 35Hz (VRR range 30-144)
Would the experience be the same? Down to input lag?
If they offer the same result, would that only be at a locked framerate? Or would the effect still be the same at a variable frame rate? (varying between 35 FPS and 50 FPS for example).
Thank you!
Does LFC make a wide VRR range irrelevant?
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Re: Does LFC make a wide VRR range irrelevant?
The real answer is "it depends"ArrowLynx wrote: ↑16 Feb 2023, 11:50Hello! Me and a friend were discussing this, the question is, does LFC make a wide VRR range irrelevant?
Example:
Same panel performance, same settings, same everything (for the sake of argument)
Monitor 1: Game runs at 35 FPS, monitor refreshes at 70Hz (VRR range 60-144)
Monitor 2: Game runs at 35 FPS, monitor refreshes at 35Hz (VRR range 30-144)
Would the experience be the same? Down to input lag?
If they offer the same result, would that only be at a locked framerate? Or would the effect still be the same at a variable frame rate? (varying between 35 FPS and 50 FPS for example).
1. LCD GtG decay
2. Flicker
3. Scrolling chessboard artifacts (inversion artifact)
3. LFC Stutter or lack thereof.
A higher min Hz actually can be better quality because LCD GtG differences between 60Hz and 240Hz is smaller than 30Hz vs 240Hz. The problem with LFC is frame collision-related stutter, where a new frame is stalled due to monitor being busy repeat-refreshing. However, if your VRR(max) is very high, e.g. 360Hz, then the monitor-busy is only 1/360sec. So LFC penalty is almost negligible for monitors 240Hz and up, and completely invisible at 360Hz and up, in theory at least. A native non-LFC-assisted VRR range of 65Hz-360Hz can be better quality than 48Hz-360Hz, as an example, if it minimizes flicker and other artifacts such as scrolling chessboard-pixel artifacts (especially on TN panels, which are prone to that artifact).
Ultra-low-Hz has a nasty tendancy to make this artifact visible on TN panels, so minimizing this with a higher VRR(min) and using LFC instead, can eliminate this from being blatantly visible.
OLED is immune to this, but OLED has a gamma flicker issue which can be more visible with low min-Hz. On the other hand, the rapid cycling of LFC=on / LFC=off from wildly gyrating frame rates, can amplify gamma-related flicker, but that may not happen if the graphics driver has a LFC-stiction behavior that forces LFC until the frame rate is much higher (e.g. back into triple digits).
It's a game of pick-poison. Personally, as long as VRR(min) and VRR(max) is still minimum 4x-5x apart, I prefer LFC over native VRR(min). 2.77ms of LFC stutter (1/360sec) is much more invisible than 21ms of MPRT (1/48sec of motion blur). As long as erratic-stutter is much smaller than the motion blur amplitude, the LFC stutter is rendered essentially invisible. On the other hand, LFC is a software-driven algorithm on all VRR panels (other than G-SYNC native chipped with the FPGA/ASICs) which is subject to computer-performance-jitter error margins...
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