Frame rates for FSX explained

:confused: Hello everyone I'm new here and also to the flight simming world. I always hear of flight simmers talking about frame rates. Can someone please explain to me what this is? Between what numbers are ideal to run FSX/add-on's and such? I always see people saying stuff like "I get 25 FPS with this curtain airport add-on" or "it runs at 35 FPS" that's what confuses me. is there some kind of a chart that tells you that you're PC is running smoothly according to your specs or something? or what are idea numbers for your frame rates or FPS? AND how can I check my FPS while running FSX (I use Fraps) Thanks guys. :confused:

Think of watching a movie at home on an "old fashioned" movie projector. You know the old reel to reel model. They usually go at 24 frames per second so that the movie flows nicely for your eyes. Some newer movies are filmed at higher rates and some people have complained about motion sickness while watching them.

 

Disregard frame rates and look for smoothness in your Sim. That's what counts.

..how can I check my FPS while running FSX (I use Fraps) Thanks guys[/b]. :confused:

 

You don't need Fraps, just hit Shift Z to get a small red datastrip at the top left of the screen when you're playing FSX which gives the FPS and other things like grid coordinates, height, speed, heading etc.

Hit Shift Z a few times to cycle through the readouts to the FPS.

 

PS- I've had FSX for 9 years and have never been able to understand the framerate settings thing, so I just leave it set at 'Unlimited' and FSX runs as smooth as silk..:)

I've had FSX for 9 years and have never been able to understand the framerate settings thing, so I just leave it set at 'Unlimited' and FSX runs as smooth as silk..:)

The best attitude to the "frameratemania"!

Thanks for your replies guys. Today I was landing at KPHX but almost landed way way before the runway. It saw 3,500 on the PFD, but I heard the callout "1,000" and the plane kept sinking lower and lower to the ground. I wonder why? if on the PFD it said 3,500 feet :confused::confused::confused:

I'm guessing that you don't have your altimeter set to the correct setting. I never use it, but i think it's the B key, press that and it will automatically set your altimeter to the correct setting. When i say i never use it, i mean the B key not the altimeter.

Oh ok, gotcha. Thanks, ntai. I thought it had to do with the certain altitude the airport is above sea level and you would have to add or subtract numbers.

The "B" key does, indeed, set your altimeter to the current barometer reading, thus giving you your altitude above sea level. Brits like to set their altimeter to indicate zero when on the airport, but in the U..S. That would cause difficulty, especially in mountain areas.

 

It saw 3,500 on the PFD, but I heard the callout "1,000" and the plane kept sinking lower and lower to the ground.

 

The 3500 feet would be above sea level (MSL, or Mean Sea Level), while the callout of 1000 apparently was AGL, or Above Ground Level.

To come back to the initial question "what are frames".

 

With this simulator there are two types of frames: "sim frames" and "visual frames"

 

Sim frames:

the simulator calculates "snapshots of reality" - called "frames". Every frame contains all information how the simulated world presents itself at a single point in time. How many of these frames your CPU can calculate in each second determines the accuracy of your simulation. For example, if you only have one frame each second, everything that happened in between is lost - all moving objects jump from where they were a second ago to where they are now.

Sim frames basically only depend on how capable your CPU is.

 

Visual frames:

The calculated sim frames are passed on to the GPU to render them into an image to be displayed on your screen (this is very simplified, actually quite a bit of rendering is done by the CPU too). So the time needed by the CPU to calculate the sim frame plus the time that the rendering pipeline takes to produce the image determine how many "FPS" you will see as a result.

 

As the human eye is very sensitive to movement, you will notice when objects in your sim world are beginning to "jump" = the frame rate is so slow that moving from one spot to the next becomes jerky.

 

Obviously, the more there is to calculate (more addons, more objects, more weather, higher resolution, more eye candy), the longer the CPU will take to calculate a sim frame, and the GPU to render the visual frame. Put enough of "stuff" into your sim, push the settings high enough, and your frame rate will slow down to a crawl. The relation is really that simple. On cruise altitude, there is not much to see = not much to calculate - so FPS are high. On approach to a complex airport there are AI aircraft, complex buildings, large amounts of ground objects, textures, lighting effects etc. = more to do for the CPU and GPU = FPS are low.

 

A bit of confusion creeps in when people start to throw the monitor refresh rate or human percepion limits into the mix. They state that you don't need more than 60/30/whatever frames, because that is the maximum value "your monitor can display / your eye can see / ...". While this is of course true, it neglects the issue of accuracy. If your system is barely generating those 30/60/... frames, then you will notice every internal slow down immediately - resulting in stutters or jerks. If on the other hand your system is capable of rendering 100 FPS, then there always is enough data to render all 30/60/... frames at exactly the right moment in time.

There is actually a limit to how many frames/second the human eye can perceive. This has been covered in several earlier threads, but to sum it up, why is the frame rate on a TV set half of the AC line frequency? In most countries, this frequency is 50 Hz, so the TV frame rate is then 25 frames/sec., if the AC frequency is 60 Hz, then the TV frame rate is 30 frames/sec. And yet, the movies on TV are reasonably smooth, right?

 

The thing we need to chase is smoothness, not astronomical frame rates. The frame rate IS important, don't get me wrong, but the point is that the frame rate only has to be high ENOUGH.

 

Jorgen

Jorgen is correct. So many of us get hooked into 'analysis paralysis', & end up spending more time tweaking than flying!

 

Frame rates are also dependant on scenery & aircraft complexity, as well as different views.

There is actually a limit to how many frames/second the human eye can perceive. This has been covered in several earlier threads, but to sum it up, why is the frame rate on a TV set half of the AC line frequency? In most countries, this frequency is 50 Hz, so the TV frame rate is then 25 frames/sec., if the AC frequency is 60 Hz, then the TV frame rate is 30 frames/sec. And yet, the movies on TV are reasonably smooth, right?

 

The thing we need to chase is smoothness, not astronomical frame rates. The frame rate IS important, don't get me wrong, but the point is that the frame rate only has to be high ENOUGH.

 

Jorgen

 

Right. But what I wrote is not meant to imply you have to chase astronomical values at all.

The point IMHO is not the highest absolute total value of frames per second but their consistency. TV worked so well, because the 25/30 Hz are guaranteed. They are not with the simulator. If you have a computer that struggles to achieve 25 FPS, then you will notice stutters when you set your expected limit there. And every computer will struggle, when you cram enough "stuff" into the sim.

 

I guess my point is, to only set your settings so high and use only so many addons that your sim can comfortably hold the FPS value that you perceive as fluent.

I agree with evm. I have a fairly high-end processor and video card. And as we know FSX is basically a processor-intensive single-thread application hungry for processor frequency. I have recently progressed into the multiple monitor fray. I brought two monitors home from work and experimented with my current 28" High-def main monitor coupled with two low-end monitors for side view. Before the additional monitors I had sliders about maxed and was getting about 40fps average (as reported by FSUIPC). I would say each additional monitor killed 10-15 fps, so a notable reduction. The two additional monitors could not run near the resolution I run on the main screen and the Simsamari manual says one can pay an additional penalty for not running monitors all at the same resolution. Well I fly twin-engine jets and I really only have opportunity to look out side windows when there is little view. I am too busy on approach and landing. So only on replay did it have any value. So I have decided to splurge for an additional hi-res. 28" monitor and will have two "front" screens. One will be full outside view, the other will use about 7" worth of its 15" height for EFIS screens. I shall report on the frame rate hit. But I definitely found what evm said to be true, reducing my slider settings with even the three screens allowed me to achieve a smooth viewing experience. One of the key settings was not setting the one slider to unlimited frame rate. Setting the slider closer to the average reported by FSUIPC calmed things down and left more processor resources to other things (I believe). The key is compromise on your settings based on your hardware and configuration until you achieve a smooth viewing experience. If this is not possible, you would need to reduce your number of open windows or possibly network additional machines (I have not done networking or Wide FS for FSX, I am hoping to avoid this complexity, but we shall see).

Shall be interested in your final configuration. Good luck!

My 2 cents. Reduce auto gen slider to 'Normal'. Get rid of cumulus clouds (cirrus at 30K to 40K only). Set desired frame rate in FSX to 25. Enjoy the sim.

Chuck B

Napamule

You don't NEED 60 FPS in FSX. It's not a shoot-em-up.

Thank you all for your replies :) but could someone please tell me why Saitek's Pro Flight hardware has gone up so ridiculously high in price? for example the throttle is $175 on amazon, the multi panel $215, rudder pedals $275. why have they gone up so high? they use to be at a reasonable price

Thank you all for your replies :) but could someone please tell me why Saitek's Pro Flight hardware has gone up so ridiculously high in price? for example the throttle is $175 on amazon, the multi panel $215, rudder pedals $275. why have they gone up so high? they use to be at a reasonable price

 

Supply and demand. Following trouble at their production facility in China, Saitek stopped making those articles about a year ago. So prices for the remaining stock skyrocketed.

A few weeks ago, what was left of Saitek was acquired by Logitech. If and when production of the flight simming gear will be resumed remains to be seen.

Frame rates DO have an impact. For example, if I'm flying a very sophisticated aircraft (like the VRS F/A-18E Superbug) over very dense scenery (like New York City), pretty soon I'm going to get a message that says I've run out of memory and to restart FSX. The trade offs are these: high frame rates = smooth response but degraded scenery and vice versa. If I want to go sightseeing, I choose a simple aircraft and decrease the frame rate. For flying 400 knots and doing complex missions in my F-18, I increase the frame rate which kind of washes out the scenery. You can't have high performance and dense scenery at the same time. "FSX Booster Live" is a simple app to install that gives you quick and easy in-flight control over frame rates without having to go to FSX Display Settings.

#1: The thread has been dead for just about 2 years.

 

#2: Frame rate and OOM errors have nothing to do with each other.

 

#3: More than 30 FPS is baloney, the eye cannot grasp more than 30 or so.

 

#4: "Frame rate boosters" are more baloney and a waste of money.

 

#5: Set your frame rate to 30, then forget it and work on smoothness.

 

Jorgen

 

PS: Have I started a flame war here?

PS: Have I started a flame war here?

 

Nope -- you're correct, though for some it may be beneficial to set fps to 20 or 25, since less powerful systems need a bit more time (thus lower fps) to put each frame together, thus the lower rates will help smoothness on those systems. The unlimited advocates just trade high fps for detail, and you can control it better by setting a max rate.

 

I DO wonder why a 2 year old thread was revived instead of starting a new one, but that seems to happen often, even an 8 or 10 year old thread on occasion.

#1: The thread has been dead for just about 2 years.

 

#2: Frame rate and OOM errors have nothing to do with each other.

 

#3: More than 30 FPS is baloney, the eye cannot grasp more than 30 or so.

 

#4: "Frame rate boosters" are more baloney and a waste of money.

 

#5: Set your frame rate to 30, then forget it and work on smoothness.

 

Jorgen

 

PS: Have I started a flame war here?

 

Nope

 

#1: The thread has been dead for just about 2 years.

Yes, and FSX a lot longer. But we're still talking about THAT...

 

#2: Frame rate and OOM errors have nothing to do with each other.

Correct. And I don't know anyone with an ounce of common sense who has suggested it does...

 

#3: More than 30 FPS is baloney, the eye cannot grasp more than 30 or so.

Baloney. You've now confused TV and Computer methodology. Unless that was the intention?

 

#4: "Frame rate boosters" are more baloney and a waste of money.

Ah! Something we most certainly DO agree on... No-one has EVER explained to my satisfaction why having an EXTRA application intervening between simmer and his/her sim actually improves frame rates. Nor why that is a Good Thing? Surely it is better for the simmer to take control of the gaming machine to the betterment of the Sim?

 

#5: Set your frame rate to 30, then forget it and work on smoothness.

No. Set the frame rate to a persistently sustainable level, and the smoothness is the consequence. It could be 60, 59, 30, 25, 20 FPS but it really doesn't matter IF it's the right limit.

+1, Larry!

 

Jorgen

 

PS: From 2001 to 2009 I also lived in CO, first in the Springs and then in Castle Rock, and in Castle Rock I installed FSX for the first time....