Improving Free Sync/G-Sync

[WhoDecidedThat]

The refresh rate range for G-Sync/Free Sync monitors is about 40-144 Hz on the TN panels or 6.94 to 25 ms refresh time/interval. My idea is that what if you alter how the behavior of variable refresh rate system like this: monitor gets the frame, renders it, waits for 15 ms, renders the same frame again, waits for the next frame to come in, renders it, waits for 15 ms and so on. This way we can change the effective Variable Refresh Rate window from 40-144 Hz to (15+25 ms to 15 ms) 25-65 Hz which is more useful in many scenarios. It’s not as wide a window as 40-144 but with more complex patterns better results can be obtained by others. Any thoughts?

 

[newconroer]

Neat idea, worth feeding back to AMD.

25-65hz is a much better spectrum. Anything over 60 is pretty much wasted with these advanced adaptive sync technologies.

 

[WhoDecidedThat]

Sigh. The calculations are wrong. If a frame misses the 15 ms window, frame display/refresh times will jump to 21.94 ms at minimum which is about 45.47 Hz so it will be 25-45 Hz and not 25-65 Hz. There isn't much you can do with a window of only 18.06 ms.

 

[Bill_Bright]

[rant on]

I wish they would come up with a different term than "refresh". "Refresh" came out of the CRT monitor world because the illuminated phosphors on the inside of the cathode ray "tube" would start to fade or "decay" or as soon as they were illuminated. So the red, green, and blue "ray guns" had to come back and "refresh" the entire screen pixel by pixel - and it did this, typically, 60 times a second. CRT monitors are "analog" devices.

But with LCD monitors, the lit up pixels don't need refreshing. They are diodes. They stay lit ("on") until told to turn off. They maintain the exact same color and luminance ("perceived" brightness) until the program changes the "frame" (area of the image that changes). LCD monitors are "digital" devices.

So with a LCD monitor, the image never - as in NEVER EVER needs to be "refreshed". It needs to be redrawn (re-programmed) to display the changes from the last image sent by the program. If no changes, it can just sit there for hours or days. If an "object" (a fired photon torpedo, for example) moves a micron across the screen, ONLY those pixels (not the entire screen image) that changed need to be re-programmed to the new colors and luminance.

So something else should be used instead of "refresh" and I think that should be "frame rate". Though frame rate came out of the video "recording" industry, it makes sense when applied to the capability of LCD monitors.

[rant off]

 

[Frag_Maniac]

The refresh ranges for both tech are far from equal as you imply. Freesync literally supports as low as 9Hz. A lot of people seem to have a misconception about Freesync's low frame capability based on a few misleading early reports based on tests limited to 48Hz monitors.

Freesync is new, yet has already seen lots of interest from manufacturers, and VESA as a new standard. It is likely we'll soon see displays that support at least down to 30Hz for Freesync. Once tests are conducted with new displays, I think you'll see your suggestion is not needed, at least for Freesync.

Furthermore 15ms is slow enough to drastically affect the response times of most made-for-gaming monitors, esp G-Sync ones. G-Sync ones pretty much have to be fast to be able to sell at their high price. Having the same frame repeated would probably only minimize the inherent flicker effect of G-Sync.

Lastly, this is a tech that has been available in TVs for some time to combat motion blur. The problem you run into is when it's enabled, processing invariably increases, as does input lag, significantly so. For instance Samsung TV's can have 44ms input lag in Game mode, but when the frame insertion tech is enabled, it doubles to about 88ms, which is WAY too much for gaming.