MSI AB / RTSS development news thread

New hybrid scanline sync mode, new scanline sync calibration related performance counters and indicator are demonstrated in this short video:

 

I'm not that optimistic on automating it. Actual tearline position is close to present return time for old games where frame complexity and GPU rendering time are low. For GPU heavy rendering cases it can jitter a lot.

 

Forgot to mention one thing about upcoming RTSS 7.3.0 beta 7. Some time ago I've already informed you that it will have updated digital signature for hooks library. I'll bump it one more time in case you missed it. That's not a functional change, we just move to new signature after the previous one expired. Major anticheats like EAC and BattleEye already whitelist it, but some smaller anticheats may need some time to adopt their whitelists to it. So keep it in mind.

 

It should be as close to your real hardware refresh rate as it is possible (ideally match it), othwerwise the tearline position will showly drift up/down.

 

RTSS 7.3.0 beta 7 build 23717 is online:

https://download-eu2.guru3d.com/rtss/RTSSSetup730Beta7Build23717.rar

Changes list was published a few posts above.

 

The following 3 conditions must be met to engage new hybrid mode:

- Framerate limiter must be enabled
- Scanline sync must be enabled
- One of two alternate synchronous framerate limiting modes must be selected. Front edge sync is recommended as it gives closest result to classic scanline sync

Setting up the framerate limit is the most tricky part, ideally it must exactly match your hardware refresh rate or at least it must be as close to it as it is possible. Clock frequency generation is based on the principle of deriving target clock from fixed crystal (reference) clock with a few multipliers/dividers. So target clock is rarely an exact integer value, for example for my 60Hz 1440p display mode hardware refresh rate is 59.952Hz. That’s what I specify as a framerate limit on my system to get it working.

New performance counters displayed in scanline sync info panel help you to see if you set up everything properly. For classic scanline sync mode you’ll see constantly changing sync start counter and sync end counter jittering close to the target scanline. That’s normal because synchronization is performed on every frame. That’s also a sign of inactive hybrid mode.
For properly configured and active hybrid mode scanline syncronization is performed just once, so sync start and sync end counters should never update in realtime. Present counter (and tearline position) should jitter close to target scanline and may slowly drift up or down depending on delta between hardware refresh rate and specified framerate limit. If it drifts too far after a few minutes, you may return it back by toggling the framerate limiter off/on (updated sync start/end counters will reflect new synchronization event).

 

Yes, it can be calibrated this way. But there is no any strict “it should be done this way”.

It is framerate limiters sync mode selectable via GUI. Do not edit it directly.

???? External tools? There are a lot of ways to find out detailed timings of your videomode including dot/pixel clock, htotal and vtotal. Knowing those values allows you to calculate refresh rate.

 

You’ll easily see if framerate limit is specified correctly by monitoring “Present” counter in the info panel (actual scanline index where Present was called). It will move up/down fast enough if framerate limit is far below/above your actual refresh rate. If it is close to the target (and for some fractional refresh rates there will be no exact match) then it will remain relatively static and keep moving up or down really slow (1 scanline per a few seconds).

No need to confuse display mode timing variables (back and front porch) with framerate limiting modes. Those are completely unrelated things.

 

And one more time: It will move up/down fast enough if framerate limit is far below/above your actual refresh rate.

 

To understand it better try to enable FCAT indicator and set it to new "moving bar" mode then ty to set framerate limit explicitly above (e.g. 60.5Hz) and explicitly below (e.g. 59.5Hz) your refresh rate (60Hz). Then see what is happening with tearline position visible on moving FCAT bar indicator and what is happening with "Present" performance counter in scanline sync info panel. Tearline will always drift up with fixed speed and "Present" counter will monotonically decrease in first case (60.5Hz). For the second case (59.5Hz) tearline will drift down and "Present" counter will monotonicaly increase.
So applying it to your case (sync going slowly upwards) you can conclude that your specified framerate limit is stll slightly higher than your actual hardware refresh rate. So try to decrease it till the point when tearline drift direction change and it will start drifting down. That will mean that you crossed the limit.
Matching hardware refreshr rate preciesly can be impossible for some display modes and refresh rates, because RTSS allows you to specify limit with 0.001Hz precision for <100Hz refresh rates (and with 0.01Hz precision for >100Hz), but I can extend framerate limit field with a few additional decimal digits to deal with such cases in future versions.