Possible to gobally cap FPS?

[thegoonden]

Might seems like a strange question, but can you force all Dx games to limit themselves to a certain FPS? I know many games do it internally (Q4, Doom3, GPL, COD4 for example), so it must be technically possible.


I basically want to limit many games to 30FPS.

Some of my games, notably driving ones (and MSTS), can't QUITE manage 60FPS all the time. If you use vsync, a game running at 55FPS is horrible looking. It draws 50 frames each second which remain on screen for a single refresh, but 5 every second with hold on screen for twice as long. It almost makes a game at 55FPS look like one doing 5FPS, in terms of juddering (5 twitches a second). Turning vsync off stops this as no frames need to be "held", but then of course you get horrid tearing.

30FPS looks fabulous compared to 50 or 55, so how do I tell directX that "I want 30FPS, and once you've got 30 done, take the rest of the second off"


Any thoughts?

 

[thegoonden]

Which will always be 60+
Needs to be a value that even the trickiest games can exceed.

You'd think something like this would come in handy for developers, wouldn't you?

MSTS is the worst offended, doing 120MPH with the world doing 5 double length frames out the window gives me a headache after a while. But at least MSTS isn't TOO bad with vsync turned off, things like rfactor, there's just no happy solution, because one's camera view swings around so much that tearing's most distracting.

 

[thegoonden]

I think I feel better that the heregathered wise ones have come up with all the same answers I managed myself

It's ironic, FPS's have all the clever controls to set a framelimit, but don't need it as the effects of a few doubled frames don't show up when dashing around in random directions. Yet driving games tend not to even have a console, and are the worst affected owing to all the straightline motion.

Was worth a try askin you lot anyway.
Cheers

 

[thegoonden]

are you sure vsync can cause that? i always use vsync and have never seen anything like that happen, it just doesnt make sense.


try forcing triple buffering using rivatuner's tool as this negates the lost framerate of vsync

Vsync on:
there are 60 "ticks" to one second.
Frames may only be drawn on a tick.
You cannot draw 2 frames on any tick.
Therefor the only possible thing to happen when the machine can only generate 55 FPS is for 5 of those frame to be held for 2 ticks=60 ticks in total.

It's like playing 3 beats in a 4/4 bar.....vsync off allows "Triplet time",3 evenly spaced beats, but vsync on will result in two notes that last a beat, and one that lasts two.

I seem to be one of the few to notice it though. As I said, it's forward motion in TrainSim that REALLY makes it noticable.

Besides read any graphics tweaking guide for vsync and it will say that it eliminates tearing at the cost of potential ocassional stuttering.

 

[thegoonden]

The thing is, when the game settles at 30fps, it looks just as nice as 60 really, much nicer than 55, because it's even and regular.

Like I say, most folks don't seem to notice it.

Tripple buffering is of limited use in something like MS TrainSim because it will settle down at say 55 now and then for quite a while, tripple buffering seems to help much more during momentary dips.

It's a nightmare of a game. I had a 2800XP with a rad9800pro until I started playing it. Both boxes in my sig are almost entirely the result of a quest to get through clampham junction at 20+fps. Managed it at last, but still a LONG way from 60, who needs vantage when you have a cantankerous old MS bugfest that ignores all the best bits of your hardware, and is full of 2008 spec addons.

 

[thegoonden]

Well, all I can say is that 30 and 60FPS are smooth as glass, and 45,50, 55 and so on, look terrible, so we can assume from that that 55fps isn't actually just 30 as suggested, if it was it'd be smooth. Only in MSTS though, because of constant speed forward motion, without that you'd never notice the effect at all.

Guess I just have to deal with playing it with vsync off

I could make a video, but that would need to be at 60fps to show aht I'm talking about LOL

(and somehow, I think FRAPS might just upset MSTS a little, I'd have to record it off the hideous video in on my other machine)

 

[thegoonden]

Can't downspeed the card, because making it do 30fps in open country would make it do 10fps in cities.
Can't turn AA or Aif up any further, game absolutely requires them, so can't turn them off either.
I ran Doom3 with the vsync on and ludicrous settings and it behaved exactly as described above, either doing 60 OR 30 (or even 20) never an inbetween value. Other games don't, (this is using their internal FPS meter, I will try FRAPS).

I think this is a question of semantics, jumping between 30 and 60 in such a way as to give 55, as you describe, would cause the exact thing I've been talking about. This is somewhat backed up by the "stutter" having the exact same frequency as the difference between the displayed framerate and the nearest VBL locked speed. Ie, 55 FPS flicks at 5Hz, 58FPS at 2Hz, 45, looks OK because the flick is 15Hz.


I think vsync off is all I can do for TrainSim. The driving games are not ruined by this, and shooters are unaffected it seems. The only other game I MUST run without vsync is GPLegends, which wont work online if it cannot run at precisely 36fps.

 

[thegoonden]

Something not right about your doom3 results. I fired it up not so long ago just to see how it runs on todays modern platform and I was consistantly getting fps in excess of 60 fps so with vsync on you should never have dropped below 60 fps.

Ultra settings, 1680x1050, 16QxAA 16xAiF.

But I thought it was kinda low myself, and you should see the state of Quake4.

At the same time, the machine is pulling 45-50 on Crysis in the "dx9 hotlist" spec, 200K in aquamark and 7000 in Vantage, so it's no slouch. Must just be ID-phobic or something.

 

[thegoonden]

Oh no, you can't tell it at all in a game like Doom3. In fact it's all just set that way at the minute for the benefit of MSTS (all those parallell and near parrallell lines are aliasing city, and the track bed, being a constant texture running from under your nose to infinity is a prime candidate for AiF).
Also using what nhancer calls "32x" but I think it's really what NV calls 16Q.

Funny enough Aquamark still score really highly with all that guff on, until you engage the "supersampling transparency AA" thing, at which point the "large scale vegetation" test chokes down to about 12fps and ruins the whole score.

In general I get away with them being on in most games, it's only smoke/clouds/particles that lose the plot usually.
Starting to use nhancer to set the right levels for each game.

I do have a driving (I think) game that offers vsyn at half rate, which would be ideal....but it's only one game, and it goes up in a big ball of fail if you switch it on anyway