I remember an old thread over at nogripracing where people discussed how to achieve smooth gameplay with minimal input lag in rFactor and what gave the best results was Vsync ON and cap the framerate to your monitors frequency -1. But this would give you a skipped frame once every second so it turned most people off.
Now with new technology we can cap the framerate at a much higher precision (down to 3 decimal points) which in theory will eliminate this problem.
I came across a thread browsing the guru3d forums last night and a guy named RealNC made a great guide on the subject.
Credit goes to RealNC over at guru3d.com
Here is the actual thread https://forums.guru3d.com/threads/the-truth-about-pre-rendering-0.365860/page-12#post-5380262
I highly recommend reading the entire thread for more insight.
You want to use RTSS (Riva Tuner Statistics Server) to cap your framerate as it's the only tool (that I know of) that have sub ms accuracy.
Ok here we go!
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Vsync does not actually cap the frame rate. This is a popular misconception about vsync. What it does is syncing the output of new frames to the monitor's "vblank" signal (the point between the monitor having finished scanning out the current frame and is preparing to scan out the next.) The frame rate not exceeding the refresh rate is just a side effect of that. There's no actual frame capping involved.
Because there is no frame cap, the game is preparing new frames as fast as it can. Once all possible frame buffers and all pre-render queues have been filled, only then will the game stop queuing more frames to be displayed. That means when all these buffered and queued frames are displayed later on, they're based on old input. Meaning input lag.
Setting pre-rendered frames to 1 means less queued work is waiting to be processed. The game stops trying to output more frames sooner. Meaning you get less input lag. However, this doesn't help with queued frames that have already been rendered but have accumulated in the output buffers. You still get more input lag that needed.
You can fix this issue by using a frame cap that's set at almost the exact same value as your refresh rate. Something like 0.01FPS below refresh rate works fine (RTSS is accurate enough to allow for this kind of frame limiter accuracy.) Note that "0.01" is just a ballpark number. Anything between 0.007 and 0.015 or so should work fine. Too low and the trick doesn't work anymore, too high and you get repeated frames that result in "hiccups".
Please note that all this is for vsync. You don't need to do any of this when using G-Sync or FreeSync. For those two sync methods, just cap to 3FPS below your refresh rate and you're done! Also note that all this also doesn't apply to vsync off. This guide really, really is just for non-gsync, non-freesync monitors with vsync enabled. (Or if you for some reason disabled gsync/freesync on your monitor and want to use plain vsync.)
Step 1: Find out your real refresh rate
Nope, your real refresh rate is in the majority of cases not 60 nor 59. It's usually fractional. Most monitors use 59.94Hz for "60Hz" and 119.982Hz for "120Hz". You can detect your real refresh rate on these sites:
http://www.testufo.com/#test=refreshrate
https://www.vsynctester.com
Let the test run for a while (around 2 or 3 minutes should be enough.) Do not run both tests at the same time. Do not have any background tasks running.
If both sites give you results very close to each other, then you can be confident that the number you got is pretty accurate and very close to your real refresh rate.
It's important to use a browser that works (Chrome and Firefox should be OK), and that if you're using Windows 7, Aero must be enabled (the test needs Aero's vsync in order to detect your refresh rate.) You also need to make sure that GPU acceleration is enabled in your browser, otherwise you'll get wrong results.
You only need the first three decimals of the detected number. If the result is something like "59.940875" for example, you can consider "59.940" as the important part for simplicity.
Step 2: Use RTSS's new fractional frame cap feature
Unless you're using a very old RTSS version (so please make sure you have a recent version) you can set a denominator for the frame cap. For a 59.940Hz monitor, you'd cap to 59.930FPS (59.940 - 0.01 = 59.930). For a 119.982Hz monitor, you'd cap to 119.972FPS (119.982 - 0.01 = 119.972).
Do do this, you need to edit the profile file of RTSS (to set this globally, you need to edit the "Global" file inside the "Profiles" folder of your RTSS installation directory.) There's no GUI for this. For a 119.972FPS cap, you would need this in the profile file:
For a 59.930FPS cap, you'd use:
Step 2 different method: Using CRU
Instead of using a fractional RTSS frame rate limit, you can instead continue using the default frame cap, but instead modify your monitor's refresh rate slightly. You can do that using CRU:
https://www.monitortests.com/forum/Thread-Custom-Resolution-Utility-CRU
For example, if you want to cap to 60FPS, modify your 60Hz mode to 60.01Hz. For 120FPS, modify your refresh rate to 120.01Hz. Please note that it's usually not possible to get exactly that number! Again: 0.01 is just a ballpark number. If 60.01Hz or 120.01Hz are rounded off by CRU to 60.008 or 60.012 for example, or 120.009 or 120.013 in the 120Hz case, that's fine! Just use a number between 0.007 and 0.015 and it will be fine.
The downside to using CRU for this is that you need to re-apply your edits every time you upgrade your GPU drivers. Fortunately that's easy since CRU has an "export" button where you can save your custom resolutions to a file and then use "import" after driver updates.
After you've edited and activated your tweaked refresh rate, you should now go to the refresh rate testing sites mentioned previously and verify that your new refresh rate actually works.
If all went well, you can now just cap normally with RTSS. For 60.01Hz cap to 60FPS, for 120.01Hz cap to 120FPS. Obviously you can do this for any refresh rate you want. Cap to 75FPS if you've added a 75.01Hz mode, 90FPS for 90.01Hz, etc. The only important part is that "0.01" difference.
Result
This will keep the pre-render and other frame buffers empty by stopping the game from rendering frames faster than your refresh rate. And empty frame buffers means no added latency due to buffering.
If you don't do the above, then setting pre-rendered frames higher than 1 will result in more input lag, and can result in bad frame pacing in some games.
And even if you do the above, setting this value to 1 still helps as a guard against temporary framerate fluctuations (no frame capper is perfect), giving a more consistent input lag value.
Keep in mind that all this requires a PC that's able to render frames fast enough. Since the above keeps render/frame buffers empty, it means there's no guard against frame rendering time spikes. If your PC can't maintain a solid 60FPS (or whatever your refresh is), then you might be better off not doing any of this.
If your PC is fast enough though, then this is an excellent way of minimizing vsync input lag and maximizing smoothness by having good frame pacing (meaning frame times that match your refresh rate.)
Now with new technology we can cap the framerate at a much higher precision (down to 3 decimal points) which in theory will eliminate this problem.
I came across a thread browsing the guru3d forums last night and a guy named RealNC made a great guide on the subject.
Credit goes to RealNC over at guru3d.com
Here is the actual thread https://forums.guru3d.com/threads/the-truth-about-pre-rendering-0.365860/page-12#post-5380262
I highly recommend reading the entire thread for more insight.
You want to use RTSS (Riva Tuner Statistics Server) to cap your framerate as it's the only tool (that I know of) that have sub ms accuracy.
Ok here we go!
---------------------------------------------------------------------------------------------------------------------------------
Vsync does not actually cap the frame rate. This is a popular misconception about vsync. What it does is syncing the output of new frames to the monitor's "vblank" signal (the point between the monitor having finished scanning out the current frame and is preparing to scan out the next.) The frame rate not exceeding the refresh rate is just a side effect of that. There's no actual frame capping involved.
Because there is no frame cap, the game is preparing new frames as fast as it can. Once all possible frame buffers and all pre-render queues have been filled, only then will the game stop queuing more frames to be displayed. That means when all these buffered and queued frames are displayed later on, they're based on old input. Meaning input lag.
Setting pre-rendered frames to 1 means less queued work is waiting to be processed. The game stops trying to output more frames sooner. Meaning you get less input lag. However, this doesn't help with queued frames that have already been rendered but have accumulated in the output buffers. You still get more input lag that needed.
You can fix this issue by using a frame cap that's set at almost the exact same value as your refresh rate. Something like 0.01FPS below refresh rate works fine (RTSS is accurate enough to allow for this kind of frame limiter accuracy.) Note that "0.01" is just a ballpark number. Anything between 0.007 and 0.015 or so should work fine. Too low and the trick doesn't work anymore, too high and you get repeated frames that result in "hiccups".
Please note that all this is for vsync. You don't need to do any of this when using G-Sync or FreeSync. For those two sync methods, just cap to 3FPS below your refresh rate and you're done! Also note that all this also doesn't apply to vsync off. This guide really, really is just for non-gsync, non-freesync monitors with vsync enabled. (Or if you for some reason disabled gsync/freesync on your monitor and want to use plain vsync.)
Step 1: Find out your real refresh rate
Nope, your real refresh rate is in the majority of cases not 60 nor 59. It's usually fractional. Most monitors use 59.94Hz for "60Hz" and 119.982Hz for "120Hz". You can detect your real refresh rate on these sites:
http://www.testufo.com/#test=refreshrate
https://www.vsynctester.com
Let the test run for a while (around 2 or 3 minutes should be enough.) Do not run both tests at the same time. Do not have any background tasks running.
If both sites give you results very close to each other, then you can be confident that the number you got is pretty accurate and very close to your real refresh rate.
It's important to use a browser that works (Chrome and Firefox should be OK), and that if you're using Windows 7, Aero must be enabled (the test needs Aero's vsync in order to detect your refresh rate.) You also need to make sure that GPU acceleration is enabled in your browser, otherwise you'll get wrong results.
You only need the first three decimals of the detected number. If the result is something like "59.940875" for example, you can consider "59.940" as the important part for simplicity.
Step 2: Use RTSS's new fractional frame cap feature
Unless you're using a very old RTSS version (so please make sure you have a recent version) you can set a denominator for the frame cap. For a 59.940Hz monitor, you'd cap to 59.930FPS (59.940 - 0.01 = 59.930). For a 119.982Hz monitor, you'd cap to 119.972FPS (119.982 - 0.01 = 119.972).
Do do this, you need to edit the profile file of RTSS (to set this globally, you need to edit the "Global" file inside the "Profiles" folder of your RTSS installation directory.) There's no GUI for this. For a 119.972FPS cap, you would need this in the profile file:
Code:
[Framerate]
Limit=119972
LimitDenominator=1000For a 59.930FPS cap, you'd use:
Code:
[Framerate]
Limit=59930
LimitDenominator=1000Step 2 different method: Using CRU
Instead of using a fractional RTSS frame rate limit, you can instead continue using the default frame cap, but instead modify your monitor's refresh rate slightly. You can do that using CRU:
https://www.monitortests.com/forum/Thread-Custom-Resolution-Utility-CRU
For example, if you want to cap to 60FPS, modify your 60Hz mode to 60.01Hz. For 120FPS, modify your refresh rate to 120.01Hz. Please note that it's usually not possible to get exactly that number! Again: 0.01 is just a ballpark number. If 60.01Hz or 120.01Hz are rounded off by CRU to 60.008 or 60.012 for example, or 120.009 or 120.013 in the 120Hz case, that's fine! Just use a number between 0.007 and 0.015 and it will be fine.
The downside to using CRU for this is that you need to re-apply your edits every time you upgrade your GPU drivers. Fortunately that's easy since CRU has an "export" button where you can save your custom resolutions to a file and then use "import" after driver updates.
After you've edited and activated your tweaked refresh rate, you should now go to the refresh rate testing sites mentioned previously and verify that your new refresh rate actually works.
If all went well, you can now just cap normally with RTSS. For 60.01Hz cap to 60FPS, for 120.01Hz cap to 120FPS. Obviously you can do this for any refresh rate you want. Cap to 75FPS if you've added a 75.01Hz mode, 90FPS for 90.01Hz, etc. The only important part is that "0.01" difference.
Result
This will keep the pre-render and other frame buffers empty by stopping the game from rendering frames faster than your refresh rate. And empty frame buffers means no added latency due to buffering.
If you don't do the above, then setting pre-rendered frames higher than 1 will result in more input lag, and can result in bad frame pacing in some games.
And even if you do the above, setting this value to 1 still helps as a guard against temporary framerate fluctuations (no frame capper is perfect), giving a more consistent input lag value.
Keep in mind that all this requires a PC that's able to render frames fast enough. Since the above keeps render/frame buffers empty, it means there's no guard against frame rendering time spikes. If your PC can't maintain a solid 60FPS (or whatever your refresh is), then you might be better off not doing any of this.
If your PC is fast enough though, then this is an excellent way of minimizing vsync input lag and maximizing smoothness by having good frame pacing (meaning frame times that match your refresh rate.)
