Falkentyne wrote:Benq claimed that this was due to a "bug" when I asked them about this in email. I suspected long ago it had to do with how they reverse engineered Lightboost on the old V1 firmwares and then added custom adjustments to V2 firmware. I know Chief still doesn't believe me, but me and Masterotaku did a lot of work with this (I love you Chief). But basically, when the Vertical Total exceeds the default for a certain refresh rate, by more than a small margain, the firmware 'reverts' to the 60hz strobe timings (based on .167ms). This is the "simple" version of why using a Vertical total "Tweak" makes the monitor brighter.
I never said I didn't believe you
BenQ is correct, but both (A) and (B) are both simultaneously true
(A) VT1350 activated a beneficial (but risky) bug. It boosted brightness, as you say.
This is what BenQ answered to Falkentyne & me about. No disagreement.
(B) VT1350 has a genuine non-bug purpose; of creating more time for LCD GtG, as explained in reducing strobe crosstalk.
BenQ originally was unaware of this, did not confirm this, but I have confirmed via high speed video
There are still benefits (B) even when (A) was fixed.
And (B) is generic. Large Vertical totals also reduced strobe crosstalk on certain other brands than BenQ/Zowie (e.g. Zisworks 4K120).
Large Vertical Total also mathematically creates more time between refresh cycles on other monitors than BenQ/Zowie too -- large vertical totals was successfully also done in the new Zisworks 4K120 display, to reduce strobe crosstalk of its open-source strobe backlight. This is just simple generic math, and the law of physics of a Large Vertical Total, combined with synchronous scanout (Instant Mode type LCD refreshing techniques).
Even many monitor engineers are unaware of the beneficial accidental effects of user-initiated Large Vertical Totals -- basically the trick of using a CRU to create a non-standard extra-large blanking interval, to create more time for LCD GtG pixel response to settle between refresh cycles, for cleaner strobe backlight operation. Some monitor manufacturers have generally been completely unaware that end users have had control over this on certain monitors. When monitor manufacturers began adding instant modes (real time scanouts, GPU cable scanout becoming synchronous to panel scanout), and was CRU-compatible, it automatically meant Large Vertical Totals was a successful mathematical user-controllable solution to creating a longer blanking interval to create cleaner strobing. By working hard to reduce lag in a CRU-flexible computer monitor by adding instant modes (and also, thanks to FreeSync using variable blanking intervals) -- modern LCD panels have become more and more compatible with large vertical totals -- and unwittingly, that is a feature that improves strobing, unbeknownst to many manufacturers at the time when they built their first-ever strobe backlight.
Large Vertical Totals are a
generic mathematical trick that works successfully to reduce strobe crosstalk on any generic instant-scanout panels that has a strobing mode -- it is not a BenQ/Zowie specific phenomenon.
For example, ~VT2200 successfully works at 1080p120Hz (basically, a 1080p mode with 240Hz timings) on the Zisworks 4K120 panel. That's not a BenQ/Zowie panel, and it mathematically worked to reduce strobe crosstalk in exactly the same way. Basically, load the 1080p240 mode, get its VT, switch to 1080p120, modify its VT to exactly double what you saw during 240Hz, and then apply the new custom resolution. Done. Worked. Strobe crosstalk greatly reduced. This was because it mathematically created a fast 4.1ms scanout + 4.1ms pause between refresh cycles. This produces much cleaner strobing, as the 1ms GtG more easily fits in the 4.1ms blanking interval (longer VSYNC pause) between refresh cycles. Also quite important, since the Zisworks panel does not have overdrive.
Falkentyne, can you tell me where I didn't believe you? I believe it boils down to a misunderstanding of (A) versus (B) which are completely independent of each other, and simultaneous independent advantages.