More on epilepsy in Cliffs of Dover

[Herra Tohtori]

Originally Posted by Shrike_UK

V-Sync is already in all games, as we know to reduce visual artifact, (they will also flicker)

Vertical synchronization prevents frame tearing. That means, it synchronizes the frame rate of the game to the frame rates that the display is compatible with.

If the game FPS is out of synch with the display, it is possible for the frame to change while it is drawing onto the screen, causing horizontal tearing to appear as the frame switches on the next, but previous frame is still displayed on the top of the screen while next frame is already rendered and sent to the display to render for the bottom half of the image.

For example, a display with vertical frequency of 60 Hz will be able to smoothly show image stream at 60, 30, 20, 15, 12, 10, 5, 4, 3, 2 and 1 frames per second without tearing up the frames, because the changes of the frames are in synch with the speed at which the display itself can switch between frames (or, in mathematical terms, these frame rates are factors of 60)


As a result, if your computer cannot achieve static frame rates of 60 - VSync will reduce frame rates to 30 to prevent tearing up the frames, technically anyway.

If your computer can't run at 30 FPS, VSync drops frame rate to next even number that fits into the VFreq of the monitor, in this case 20 FPS, etc.

Incidentally, this is why I would want monitors to support frame rates up to 120 FPS. Even if you wouldn't necessarily notice difference during smooth gameplay, you could have a wider range of applicable frame rates without frame tearing because the factors for 120 are {1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 20, 24, 30, 40, 60, 120}.

For example, if your computer couldn't quite render up to 60 FPS, it wouldn't drop all the way to 30, but to 40 FPS instead. Similarly if frame rates were just below 30, they would drop to 24 FPS instead of 20.



Now, this issue is somewhat similar in the sense that, ironically, low frame rate will cause more radical changes between frames, which will...

...wait for it...


...cause more flickering.

Which is what is supposed to be prevented by the anti-epilepsy measures.


So, yeah, way to go. I bet the low frame rates and especially the stuttering is much more aggravating to even the most photosensitive epileptics than a smooth frame rate with the original effects.

'Cause, you know, low stuttering frame rates essentially turn the whole GAME into flickering mess instead of individual effects.