Operating below the minimum refresh rate?
Posted: 24 Mar 2015, 21:12
Now that FreeSync/Adaptive-Sync is finally shipping, reviews have found some limitations when comparing it against G-Sync displays.
One of the main issues seems to be that once you get below the minimum refresh rate of the panel (40Hz TN/48Hz IPS) FreeSync is entirely disabled and you are left with the choice of a standard V-Sync on/off behavior operating at the minimum refresh rate.
I would not be happy if a game was running below 40 FPS, but a lot of people seem to be concerned about this.
Is this not something that AMD could fix in software if they simply repeat frames when operating below the minimum refresh rate of the panel?
E.g. To display 39 FPS on a 40-144Hz TN panel, output 78Hz or 117Hz instead and repeat the frame two or three times.
It would still be a problem for these first IPS panels which only have a range of 48-75Hz, but it seems entirely solvable in software for any display which has a maximum refresh rate of at least double its minimum.
As long as you have a flicker-free display, it seems like that should eliminate the problem, since LCDs are sample and hold.
I wonder if this might also be a partial solution for the overdriving issues that we are seeing, because you could keep the panel operating over a narrower range of frequencies. E.g. 73-144Hz rather than 40-144Hz.
One of the main issues seems to be that once you get below the minimum refresh rate of the panel (40Hz TN/48Hz IPS) FreeSync is entirely disabled and you are left with the choice of a standard V-Sync on/off behavior operating at the minimum refresh rate.
I would not be happy if a game was running below 40 FPS, but a lot of people seem to be concerned about this.
Is this not something that AMD could fix in software if they simply repeat frames when operating below the minimum refresh rate of the panel?
E.g. To display 39 FPS on a 40-144Hz TN panel, output 78Hz or 117Hz instead and repeat the frame two or three times.
It would still be a problem for these first IPS panels which only have a range of 48-75Hz, but it seems entirely solvable in software for any display which has a maximum refresh rate of at least double its minimum.
As long as you have a flicker-free display, it seems like that should eliminate the problem, since LCDs are sample and hold.
I wonder if this might also be a partial solution for the overdriving issues that we are seeing, because you could keep the panel operating over a narrower range of frequencies. E.g. 73-144Hz rather than 40-144Hz.