Forum Discussion
Oculus & Nvidia G-Sync
I was wondering if the Oculus team has been keeping an eye on the new G-Sync tech that Nvidia has been talking about lately, which allows the display to refresh in sync with the graphics cards frame r...
Carmack has answered this: https://twitter.com/id_aa_carmack/status/391299110344867841, quote: "G-Sync won't work on any of the display panels Oculus is considering right now, but it will probably be influencing many future panels."
G-Sync will not work with any panel, ideally you want a 120Hz panel to get the lowest possible latency: The frame redraw takes only 8ms instead of 16ms. You also have a minimal refresh-rate with G-Sync: You can't drive the display a 1 FPS, instead the lower limit might be 40. This means when you are running between the minimal and maximal frame-rate you won't have tearing and a latency of the screen update rate (8 vs 16 ms). If you drop below, the screen has to refresh and will refresh the last frame. If you are just below that limit (e.g. 39 FPS) that means you have to wait one refresh before you can display that frame, again, 8 < 16. Of course you could introduce tearing (only) in that case (similar to the swap_control_tear OpenGL extension).
So, we want a 120Hz display with G-Sync, but also more than FullHD, right? 2560*1440 pixel smartphone screens are available... Sadly, I'm not aware of a display connector with the required bandwidth for both (10.6 GBit/s) that is already widely available (HDMI 2 could be an option in the near future).
Will we see 1440p or 4K G-Sync 120Hz HMDs? Sure, but most likely not in 2014...
G-Sync will not work with any panel, ideally you want a 120Hz panel to get the lowest possible latency: The frame redraw takes only 8ms instead of 16ms. You also have a minimal refresh-rate with G-Sync: You can't drive the display a 1 FPS, instead the lower limit might be 40. This means when you are running between the minimal and maximal frame-rate you won't have tearing and a latency of the screen update rate (8 vs 16 ms). If you drop below, the screen has to refresh and will refresh the last frame. If you are just below that limit (e.g. 39 FPS) that means you have to wait one refresh before you can display that frame, again, 8 < 16. Of course you could introduce tearing (only) in that case (similar to the swap_control_tear OpenGL extension).
So, we want a 120Hz display with G-Sync, but also more than FullHD, right? 2560*1440 pixel smartphone screens are available... Sadly, I'm not aware of a display connector with the required bandwidth for both (10.6 GBit/s) that is already widely available (HDMI 2 could be an option in the near future).
Will we see 1440p or 4K G-Sync 120Hz HMDs? Sure, but most likely not in 2014...