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Black frame insertion on Driver level

Posted: 26 Mar 2014, 15:35
by mdzapeer
Is it possible for nvidia or AMD to implement black frame insertion on the driver level?

Re: Black frame insertion on Driver level

Posted: 26 Mar 2014, 18:04
by Chief Blur Buster
Yes, it is technically possible. But I do not think they will do it...

It may even be technically possible at the third party or even application level. A third party utility application would go up in front of everything on the screen, and flash a black window every other VSYNC. It would work with windowed apps including full screen windowed mode. Providing a 72Hz half-persistence strobe mode for 144Hz, or 60Hz half-persistence strobe mode for 60Hz.

Re: Black frame insertion on Driver level

Posted: 28 Mar 2014, 14:15
by mdzapeer
I am not clear on "half-persistence strobe mode", do you mean it would half the refresh rate?

Re: Black frame insertion on Driver level

Posted: 28 Mar 2014, 14:33
by Chief Blur Buster
mdzapeer wrote:I am not clear on "half-persistence strobe mode", do you mean it would half the refresh rate?
No.
60fps with the equivalent amount of motion blur of 120fps.

Example: Compare http://www.testufo.com versus http://www.testufo.com/blackframes
A 50%:50% dark:bright duty cycle is half persistence, 50% less motion blur
A 75%:25% dark:bright duty cycle is quarter persistence, 75% less motion blur

Software based strobing is limited in persistence steps equalling a refresh cycle, so 120Hz can give you 60fps with 8.3ms persistence via software-based black frame insertion. (half the persistence of motion blur of 60fps@60Hz flickerfree, which has at least 16.7ms persistence regardless of the speed of pixel transitions). Hardware-based strobing, reduces far more motion blur because you can have persistence less than the length of a refresh cycle (e.g. 90% less motion blur).

Re: Black frame insertion on Driver level

Posted: 28 Mar 2014, 15:13
by mdzapeer
Ok, I think I understand. For 30 fps material at 60hz it will have 8.3ms persistence but I bet it will be flicker like crazy:P

Re: Black frame insertion on Driver level

Posted: 28 Mar 2014, 15:58
by DICKTracy
mdzapeer wrote:Ok, I think I understand. For 30 fps material at 60hz it will have 8.3ms persistence but I bet it will be flicker like crazy:P
No, I think 30fps at 60hz would have 16.6ms persistance

Re: Black frame insertion on Driver level

Posted: 28 Mar 2014, 19:48
by Chief Blur Buster
DICKTracy wrote:
mdzapeer wrote:Ok, I think I understand. For 30 fps material at 60hz it will have 8.3ms persistence but I bet it will be flicker like crazy:P
No, I think 30fps at 60hz would have 16.6ms persistance
Correct.

30fps full persistence = 1/30sec = 33.33ms
30fps half persistence = half of 1/30sec = 16.7ms

There is no visual difference between 30fps@30Hz versus 30fps@60Hz on flicker free displays (full persistence, sample and hold). A repeat refresh is just like a longer displayed refresh on standard LCDs.

Your minimum possible persistence with software based black frame insertion on a flickerfree display, would be one refresh cycle long. So no matter what you do with 60Hz on a strobefree display, your minimum possible persistence (without strobing, phosphor or other light modulation methods), will always be a minimum of 1/60 = 16.7ms.

To reduce motion blur at 60fps during software based black frame insertion, you need to begin with a higher native Hz, e.g. doing 120Hz and doing software based black frame insertion to reduce 60fps motion blur by half.

Re: Black frame insertion on Driver level

Posted: 28 Mar 2014, 21:38
by mdzapeer
Ah, Thanks for making it clear.