High FPS (160+) Slows Creep Footstep Timing

[sullium]

Hi, I tried playing TDM on a 170 hz monitor but there seems to be a problem with the footstep noise rate and camera sway speed when creeping at very high framerates. I tried a few searches in this forum and couldn't find any posts about it so here goes.

With the Max FPS setting at 150, creeping footstep noise and camera sway seem similar to capped 60 fps behavior, possibly a tiny bit faster.

With Max FPS at 160 and then 166, the footsteps slow down such that creeping feels noticeably floaty.

With Max FPS at 170, I've recorded a whopping 1 minute and 20 seconds between starting to creep and hearing the first footstep noise. The camera sway is slow and smooth enough that it is hard to notice at all.

My specs: Windows 10 64 bit, Nvidia RTX 3060 Ti, Intel Core i7-13700KF.

I'm playing on TDM 2.11 and have experienced this issue while testing both the Training Mission and Tears of St. Lucia.

On a possibly related note, the "Max FPS" setting in found in the game's menu seems highly inaccurate. According to the game's own fps counter as well as my external counter, "Max FPS 180" actually caps the fps to 166, "Max FPS 200" actually caps fps to about 180, and so on. For this post I used the numbers shown in the game's menu, not the ones reported by the counter.

Edited December 31, 2023 by sullium
Added specs, TDM version, missions. Clarified title.

[chakkman]

6 minutes ago, sullium said:

Hi, I tried playing TDM on a 170 hz monitor but there seems to be a big problem with the footstep noise rate and camera sway speed when creeping at high framerates. I tried a few searches in this forum and couldn't find any posts about it so here goes.

With the Max FPS setting at 150, creeping footstep noise and camera sway seem similar to capped 60 fps behavior, possibly a tiny bit faster.

I definitely haven't noticed any difference on 144 Hz here...

You should add your hardware details here though. Operating system, and computer specs. Also, the used The Dark Mod version, and fan mission you noticed the issues.

Edited December 30, 2023 by chakkman

[sullium]

44 minutes ago, chakkman said:

I definitely haven't noticed any difference on 144 Hz here...

You should add your hardware details here though. Operating system, and computer specs. Also, the used The Dark Mod version, and fan mission you noticed the issues.

It works like normal for me when I cap to 144 fps. Seems like there's a cutoff somewhere between 150-170 fps where it suddenly starts to become a problem.

Also thanks for reminding me, I just edited to add those details.

[chakkman]

Definitely sounds like something the devs should look into. Or, maybe there is an actual framerate limit to what the engine is capable of. I know that some other engines have these limits, where the physics freak out when you exceed them. 

Edited December 30, 2023 by chakkman

[Xolvix]

I can confirm your issue. My monitor can run at 165 Hz so I set the in-game FPS cap to 166. When capped at 166 FPS I can't hear any faint footsteps while creeping either, but when set to a cap of 144 FPS the creeping footsteps played as expected. I've only played a handful of missions since I got this monitor so I likely just didn't notice this and if there were any other oddities like the camera and other movement, I didn't notice them either. Still, there's clearly something subtle happening at higher frame rates. I'd be curious if the problem happens on say a 60 Hz monitor but still capped at 166 FPS. Guessing it would.

As for the other thing you noticed where the actual frame rate cap doesn't seem to match the one selected in the menus, I think this is more of an issue with the Doom 3 (id Tech 4) engine the game uses as its base. My understanding is it took some work to actually get higher frame rates than 60 working in the game in the first place. Even the dhewm3 source port of Doom 3 doesn't have it working correctly. Even if you uncap the FPS the timing of the game goes to warp speed and it's completely unplayable. https://github.com/dhewm/dhewm3/pull/297. Amusingly there's at least one TDM dev who posted there, since people talk about how TDM implemented their own solution (not without its own bugs).

[stgatilov]

I believe the issue with footsteps not playing is fixed on 2.12 beta.

As for how max FPS settings works, I noticed that it takes effect on integer number of milliseconds per frame.
So if you set 180 Hz, you'll get 166 because it's 6 ms. And if you set 220, then you'll get 200, since it is 5 ms.

The actual code which establishes FPS cap uses microsecond precision, it is not obvious why this millisecond effect happens.

[stgatilov]

Maybe we should adjust menu setting to only include these "integer ms" values (while secretly settings com_maxfps between two consecutive ms values for reliability).

[chakkman]

At least that explains why I only ever got 139-140 FPS, when I set the max FPS in-game to 144.

Edited December 31, 2023 by chakkman