One flash or two flashes per frame [Yes on Z-Series w/V2 fw]

[fhunleth]

It seems that some monitors flash the backlight once per frame and others flash twice per flame. On my firmware V1 BenQ XL2420Z, 60 and 75 Hz flash twice per frame and >=100 Hz frame rates flash once per frame. Has anyone looked at this between monitors (or between the V1 and V2 firmware)? I'd like to experiment with a single, possibly longer, flash at 75 Hz. Is this possible?

[ophidon]

Ugh, and I was -extremely- close to pulling the trigger on this, for the 60hz strobing.

I'm extraordinarily tired of the hand-holding on this issue of 'protecting' us from lower hz strobing. I can see that square-wave patterned led's at 60hz might be somewhat worse than CRT's were at equal strobe length due to phosphor persistence. But this can be compensated just by increasing the strobe length enough to get it equal to a CRT in flickering (if a small bit blurrier). And surprise, surprise, the new util was going to let us do just that, fine tune the strobe length.

I need an answer on this too, as forced double strobe at 60/75hz is a total deal breaker.

[Chief Blur Buster]

I need an answer on this too, as forced double strobe at 60/75hz is a total deal breaker.

It seems that some monitors flash the backlight once per frame and others flash twice per flame. On my firmware V1 BenQ XL2420Z, 60 and 75 Hz flash twice per frame and >=100 Hz frame rates flash once per frame. Has anyone looked at this between monitors (or between the V1 and V2 firmware)? I'd like to experiment with a single, possibly longer, flash at 75 Hz. Is this possible?

V2 firmwares of BENQ XL Z-series can do single-strobe with longer flashes at 60Hz and 75Hz, when combined with Blur Busters Strobe Utility.



You can do 60Hz and 75Hz single-strobe with longer flashes. But make sure you get V2 Firmware -- such as a BENQ Z-Series with V2 Firmware Preinstalled or manually install the V2 firmware upgrade (requires additional equipment).

"Persistence" controls flash length.

Please note, though, there is substantial flicker at 60Hz single-strobe, while 75Hz single-strobe is reasonably tolerable. Also, keep in mind that there is a lot of strobe crosstalk unless you use larger blanking intervals (e.g. Vertical Total 1350 trick). The Vertical Total 1350 trick will create long blanking intervals (pauses between refresh cycles) approximately 4ms long, which will be able to hide most of the strobe crosstalk between refreshes, eliminating most of the ghosting during 60Hz and 75Hz single-strobe, after you adjust the Crosstalk to adjust the strobe timing flash phase relative to VSYNC, to move the flash to the correct time between refresh cycles.

[ophidon]

For this Vertical Total 1350 trick.. does it work in fullscreen mode in games that don't let you select your custom resolution? Ie if I create a 1080p resolution with the custom timing, but in the game I can only pick 1080p as a choice, will the custom timing for my 'own' 1080p overwrite the default 1080p the game will assume I meant to choose?

Also, I'm confused why crosstalk would be -worse- in general at 60/75hz when there is so much more time between refreshes than at 120+hz.

[Chief Blur Buster]

For this Vertical Total 1350 trick.. does it work in fullscreen mode in games that don't let you select your custom resolution? Ie if I create a 1080p resolution with the custom timing, but in the game I can only pick 1080p as a choice, will the custom timing for my 'own' 1080p overwrite the default 1080p the game will assume I meant to choose?

Yes, it can, if you remove the original mode. e.g. If you replace the 120Hz mode with this, it works.

Also, it also works with the 1079p Trick too (e.g. creating a 1920x1079 resolution that only has 120Hz as the only refresh rate and no other refresh rates -- this can be combined with the Vertical Total 1350 trick). This works in games that let you select a resolution more easily than a refresh rate for forcing 120Hz operation.

Also, I'm confused why crosstalk would be -worse- in general at 60/75hz when there is so much more time between refreshes than at 120+hz.

Yes, it is easier to fix strobe crosstalk at 60Hz than at 120Hz. So you are right on that.

It's that the default BENQ Blur Reduction (from factory) has lots of crosstalk at all refresh rates (BENQ calibrated to strobe a little too early, in an attempt to reduce input lag, at the cost of much worse motion quality), making it absolutely necessary to recalibrate the crosstalk to fix this. However, the time between refreshes even at 1080p 60Hz is still less than 1ms by default because the LCD pixels gradually scans from top to bottom without much pause between refreshes. This is what the panel does by default. So there is still visible crosstalk even after adjusting strobe timing. So you need the Vertical Total 1350 trick to make the time between refreshes much longer than they would otherwise be (VT1350 trick allows a pause between refreshes of ~3.4ms at 60Hz, ~1.7ms at 120Hz). The BENQ Z-Series panel is a real-time-refreshing (refreshes pixels essentially on the fly as they comes in from the monitor's input) so it responds very well to the VT1350 trick. The VT1350 trick speeds up the scanout while creating a longer pause between refreshes, at the same refresh rate. VT1350 trick makes your graphics card output 1350 scan lines per refresh, including 1080 visible scan lines (rows of pixels seen by eye) plus 270 blanking interval scan lines (longer dummy pause between refreshes). High speed video of LCD refresh scanout shows each scanline refreshing one by one, top to bottom, gradually, starting at the top again almost immediately after finishing scanning to the bottom. The VT1350 speeds up that scanout and then idles longer between refreshes. The longer pauses between refreshes more fully fits the ~1ms GtG pixel transitions (often >1ms in real world). This is still helpful at 60Hz. Hope this makes better sense now!

[masterotaku]

I could even do it with a vertical total of 1500 pixels. I guess it should be better than 1350, once I update my monitor.

[Chief Blur Buster]

I could even do it with a vertical total of 1500 pixels. I guess it should be better than 1350, once I update my monitor.

Vertical Total 1500 is even better, but it goes out of sync at high refresh rates, since 120Hz Vertical Total 1500 exceeds the bandwidth of regular 144Hz. Which refresh rate did you try Vertical Total 1500 at, and on which monitor? Also, which utility did you use - ToastyX or NVIDIA? - and did you edit any specific numbers (e.g. Back Porch, Sync, Front Porch, Vertical Total) to achieve the larger Total?

[masterotaku]

Vertical Total 1500 is even better, but it goes out of sync at high refresh rates, since 120Hz Vertical Total 1500 exceeds the bandwidth of regular 144Hz. Which refresh rate did you try Vertical Total 1500 at, and on which monitor? Also, which utility did you use - ToastyX or NVIDIA? - and did you edit any specific numbers (e.g. Back Porch, Sync, Front Porch, Vertical Total) to achieve the larger Total?

I did it in Nvidia CP, the monitor is a BenQ XL2411Z. The other numbers are the same as with the 1350VT, the default ones. In order to check these parameters after creating that custom resolution, I have to be using another frequency, like 100Hz. Keep in mind that I used before the Nvidia clock patcher by ToastyX (http://www.monitortests.com/forum/Threa ... ck-Patcher), so I don't know if it would work without that. Bandwidth is 374.4MHz, pretty high.
Another bonus info is that the monitor says it's running at 60Hz, but it isn't. Motion tests show that it's running at 120Hz.

[fhunleth]

Thanks all for the responses. Now I can't wait until I get my monitor upgraded to V2. Best forum ever.

[Chief Blur Buster]

Another advantage of the VT1350 and VT1500 trick is you get slightly lower input lag during VSYNC ON situations, especially in non-strobed mode. This is because the top-to-bottom scanout is finished more quickly. So VSYNC ON lovers can combine the fps_max 119 trick (in Source Engine games) combined with the VT1350/VT1500 trick to get a much lower-latency VSYNC ON.

It won't be as fast as VSYNC OFF, but it eliminates more than half of the latency difference (between VSYNC ON and VSYNC OFF) in my experience when you combine the fps_max 119 trick with the VT1350 trick. This is good for tearing-sensitive people who don't have GSYNC monitors.