144hz G-Sync monitor, how do I properly set/use Black Frame Insertion?

RetroArch General
#1

I just found out about BFI by chance and it seems to look amazing but I can’t seem to get it to work properly.

First of all my system and settings:

OS: Windows 10 2009

GPU: GTX 1070

Screen: MSI Optix MAG241CR 144hz 1080p FreeSync running in G-Sync mode over DisplayPort

RA Version: 1.9.0

API: Vulkan

V-Sync in RetroArch: Off

Sync to content Refresh Rate: On

Fullscreen: On

Windowed Fullscreen: Off

Menu Refresh Rate: 143.whatever decimal RA was detecting

V-Sync in Nvidia Drivers: On globally

RTSS FPS Cap: 140 globally

So if I launch a game now and turn on BFI it first just resulted in a black screen when going back to the game. I quickly figured out this can be solved by turning V-Sync back on in RA itself and then, while the game is of course darker, the motion-fluidity is unbelievable.

It doesn’t seem to work 100% properly though, every 5-6 seconds or so it feels like the screen cuts out for a few milliseconds or so, it almost feels like a inverse flash to black so I wondered if I perhaps have any settings set wrongly?

Also is there any downside to use it for all games? So far I only tried it with the bSNES core but I assume it will work fine for PSX and N64 games too even if they run at 25/30fps? If there’s none, what’s the best way to counter the brightness loss aside from setting my monitor itself brighter?

Oh and I use the default CRT Royale shader-preset along with a custom border if it makes any difference.

Thanks for any help in advance!

#2

Like @Awakened said on reddit, I think your best bet is to run at 120 Hz, turn off sync to exact content framerate, turn ON vsync in RetroArch, set it to “let application decide” or whatever in the Nvidia control panel, set RetroArch’s refresh rate to your monitor’s native refresh (144 Hz in this case). I think with those settings you should have smooth scrolling and no uneven BFI flicker.

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#3

Enable vsync in RA and quit RTSS as you don’t need it in RA and it will probably interfere (external FPS capping should never be used with emulators.)

If you still get flicker, switch to 120Hz.

If that still doesn’t fix it, then I’m afraid you’ll need to disable gsync and run 120Hz with plain vsync. Which is not that bad mind you, because emulators usually run at 60FPS so you don’t get full vsync lag.

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#4

Thanks for the suggestions both of you! As I think I posted on Reddit if I didn’t forget, setting my monitor to 120hz in Windows somewhat mitigates the issues although it still happens every 15-20 seconds then. I’ll try the other suggestions and see where this gets me :slight_smile:

What I found interesting, I found out that my monitor has a native, global Black Frame Insertion mode. I can activate it by disabling G-Sync and setting the response-time to Fastest. Then I can enable Anti Motion Blur which darkens the image similarly to RA’s BFI mode although curiously enough this doesn’t result in the same motion-clarity as enabling BFI in RA does.

Also a somewhat related question, is there any way I can have RA switch my monitor to 120hz automatically when it launches?

#5

I figured it out, after setting my Windows refresh-rate to 120hz I had to set the refresh-rate in RA to exactly 119.982002, now BFI works properly with G-Sync enabled even! :smiley:

If I now find a way how I can automate the switch to 120hz I’m happy.

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#6

This is normal. With backlight strobing (which is what blur reduction in monitors does) you get 120Hz BFI. The backlight is switched on and off every frame (meaning it is toggled 240 times per second.) That means for 60FPS content, you will get a double-image effect which increases blur somewhat. See the “Double-Images Effects From Low Frame Rates” section in:

https://blurbusters.com/faq/advanced-strobe-crosstalk-faq

So this is really intended for running 120FPS games, not 60FPS.

When you use a software-based BFI (like what RA does), you get 60Hz BFI because what it does is simply show a black after every normal one. That means there is no double-image effect that would increase blur.

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#7

Ah okay I get it, thanks for the explanation! It’s a shame monitors can’t do 60hz BFI as it feels less error-prone when the monitor itself does it but with these results I’ll still happily use RA’s implementation.

#8

Some can do 60Hz strobe. Mine can for example with a tweaked mode. However, the severe flicker makes it pretty unusable. This is the reason why monitors usually do not allow you to use blur reduction at lower than 85Hz. The backlight flicker is very harsh.

#9

A lot of people can’t stand to use CRT monitors at 60 Hz, either :stuck_out_tongue:

Personally, 60 Hz flicker on a CRT doesn’t bother me, but 50 Hz PAL flicker is excruciating.

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#10

60Hz LCD strobing is much, much worse than 60Hz CRT. It’s really bad. Some people are still fine with it, weirdly…

The reason 60Hz on a CRT is not as bad is because some part of the screen is always lit. The scanning happens line by line. On an LCD, the whole backlight switches on and off, all at once. At 60Hz, this feels like foam is about to come out of my mouth :stuck_out_tongue:

#11

lol yeah, very true. I splurged on a high-refresh monitor years ago when I first learned about BFI and was horrified when I actually tried it.

#12

Interesting, well RA’s implementation is a clear improvement to me now that it works so I suppose I shouldn’t complain :stuck_out_tongue: I also managed to get automatic refresh-rate switching when launching and exiting RA going via AutoHotKey. I just wish it also would be easy to have a 100/120hz switch for 50/60fps games but at this point I’m complaining on a very high level of laziness :stuck_out_tongue:

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#13

Could someone explain the advantages of using BFI instead of “Sync to exact content framerate” on a Gsync monitor ? The idea of Gsync is to get perfect sync between the monitor refresh rate and the game… I don’t understand why not use that with a Gsync monitor.

#14

BFI eliminates “sample and hold” motionblur. It’s a different issue than what GSync addresses, which is sync/stuttering/scrolling.