Beamrace Lagless Stability

[Octopus66]

Hi Toni,

The most exciting development for WinUAE in recent years must be the beam racing lagless latency which has been implemented from version 4 onwards. I love this feature however I am struggling to get a solid picture with no tearing 100% of the time. It seems that it will work 95% and then tear randomly.

I think I have a fairly good PC set-up (i5-6500 3.2Ghz) with cheap but ok GFX card (GV-N1030D5-2GL) and I am only trying slices of 4 or 2 to make this fully stable. I am using HDMI out to get 50Hz.

Are there any tips on how to make this rock solid?
Does this work in full screen and full window with same stability?
Do the CPU settings have an impact? Is only exact recommended?
What other factors play a part in getting this working perfectly?
Would old config files mess anything up?

Thanks!

[Octopus66]

I have been using the latest beta too - which appears to change the behavior somewhat but I still cannot get it rock solid.

[Toni Wilen]

Start with A500 quickstart config, use some game that works fine without cycle-exact (so that there is not much CPU usage), full screen mode (native resolution).

Try different slice numbers, press END+F9 to enable debug colors.

EDIT: also check nvidia control panel and test if setting power management mode = optimal power helps.

[Octopus66]

Thanks - I have been playing with the power management settings for the graphics card which did seem to help (I found this is an old beta thread, forgot to say), but not still not perfect.

When I press END+F9 what is supposed to happen exactly? I see a black horizontal line on screen sometimes. Should I hold END+F9? I don't see any colours...?

[Toni Wilen]

END+F9 toggles debug colors that shows slice change positions in real time. The less vertical jittery, the more stable it is.

[Octopus66]

When I press END+F9 I see a black horizontal line (maybe 1 pixel) on the screen at various heights for a split second. I cannot make an assessment of how "jittery" the line is because it vanishes almost immediately.

Not sure how to interpret this...?

[Toni Wilen]

There should be large colors bars at both edges of horizontal border. Make sure your filter mode does not hide them.

[Octopus66]

Ah! Yes, I see it now. Yes the bars are quite jittery. At 10 slice or 2 slice the bars seem to be quite jittery, but similar jitter levels - is this normal? Any ideas on techniques to reduce the jitter?

[Retro-Nerd]

I noticed it too. But before i start to test more. It's began with the update to Windows 10 v1809 a few days ago. Did they screw something in the last two years? Happens to some other emulators (mostly D3D renderer) too. W10 v1607 was rock solid in that department.

[Toni Wilen]

It is a hack (or abuse of common side-effect of immediate buffer swap) that wants line accurate tearing that is "hidden" by having both previous and next frame identical around the buffer swap point.

Which unfortunately means any driver or Windows update may change lagless vsync behavior without breaking any documented driver behavior rules..

[Retro-Nerd]

Ah, ok. Didn't know that.

Edit: Ok, did some testing (also a few days ago). The good thing: Via standard quickstart settings and loading games (OCS and AGA) from disk everthing's smooth, no tearing. Loading WHDLoad via 68020/30 WB setup (most compatible settings of course) causes a moderate tearing, mostly horizontal. But if i disable cycle exact settings it's 99,9% tearing-free. I know, WHDLoad isn't a good test case. But as i said it worked flawlessly with the same PC running W10 v1607. Maybe it only needs a tiny bit of tweeking.

[Octopus66]

Just for clarity, I have never had this working perfectly with any version of Windows 10. Is there anything I can try to improve the stability of the coloured bars?

[Octopus66]

Anyone? Does anyone have a setup with rock solid bars? I am wondering what I can do here to improve my setup. What confuses me most is that it is just as unstable with 2 slices as 8 slices... Merry Christmas all!

[Toni Wilen]

It is very PC hardware/driver specific and uses not really supported method so there is no guarantee. Logs and config required, even if it is Christmas

Jitter isn't that important as long as it is about half than total F9 bar size.

Try also without sound to confirm if it is sound related or something else. (Note that sound mode must be WASAPI)

[Retro-Nerd]

Just noticed that (on my hardware) only shader or software Filter (PAL etc). causes horizontal tearing in games/demos in combination with beam racing. With "Null Filter" everthing is smooth, even wither faster CPUs and WHDLoad games. Any clue how to fix this? And it's not a too high CPU usage, with beam racing+shader it uses app 50-55%.

[Toni Wilen]

"my hardware" does not tell much but biggest problem with shaders and lagless vsync is that each slice needs full screen re-render which can get very GPU heavy.

Check GPU usage. Perhaps it is getting too large.

[Retro-Nerd]

It's indeed very high. With internal resolution for shader 1x, 4x it shows 100% sometimes. But it also happens with 1x, 2x were it mostly shows 65-90%, never 100% GPU usage. And it doesn't happen on all games. Pretty good example for getting a tearing in Beamracing+shader combination is Brian the Lion (right when level 1 begins). In vertical scroller (with 1x,4x and 100% usage too) there is no tearing visible, like Hybris, Battle Squadron or Slam Tilt. Strange. Thought a Radeon RX 560 would be good enough for 4 slices+shader. But it seems it doesn't.

edit: Also happens with 2 slices and a GPU usage of app. 45%.

[lordofchaos]

Originally Posted by Retro-Nerd

It's indeed very high. With internal resolution for shader 1x, 4x it shows 100% sometimes. But it also happens with 1x, 2x were it mostly shows 65-90%, never 100% GPU usage. And it doesn't happen on all games. Pretty good example for getting a tearing in Beamracing+shader combination is Brian the Lion (right when level 1 begins). In vertical scroller (with 1x,4x and 100% usage too) there is no tearing visible, like Hybris, Battle Squadron or Slam Tilt. Strange. Thought a Radeon RX 560 would be good enough for 4 slices+shader. But it seems it doesn't.

edit: Also happens with 2 slices and a GPU usage of app. 45%.

For what it's worth, I had a similar issue with Beamracing, everything seemed to run well with 4 slices, then some weeks later tearing started to happen, and reducing the slices didn't have any effect. Strangely when updating my NVIDIA drivers the issue vanished, perhaps a video driver change was responsible.?

[Retro-Nerd]

For me it was the update from W10 v1607 to V1809. Since then i have the tearing in some games. I can't update the AMD driver anyway. They have some ugly bugs left related to dual display setups. Sometimes it kills the whole system with a black screen when i switch the Hz or bit depth on my connected 4K TV. And as is said. Only in combination with shaders or software filters. Without them beam racing is currently rock solid on my PC.

[buckrogers]

I get a horizontal shimmer that is most noticeable with top-down games (eg., chaos engine and warzone). The waterfalls in stage 1 of turrican 2 also reveal some tearing. This all goes away when I do not select beam racing or one of the vsync options OR when the number of slices is set to 2 (slight tearing seen on 3 depending on the game and level/stage).

When I switch the refresh rate to 100Hz in both W10 and winUAE none of the tearing is visible - problem solved when using my CRT that supports 100Hz but not a solution for CRTs that do not support 100Hz

Perhaps a roll-back to win 8.1 is in order or better yet swap out the 750ti for a newer card. I was briefly using a 1070ti with a digital to analogue transcoder (HD Fury 3) but on another machine with perhaps a different W10 update and do not recall seeing the same tearing.