Question: FFTF entry not used if Frames unlimited inside P3d

[zwenna 1]

In another Forum info was given that FFTF entry in cfg is not used if inside P3d 4.3 Frames are set to unlimited. I am wondering because especially FFTF dynamic is given one Scenario where FPS are set to unlimited but application is working. Any Infos from yourside?

[Guest]

Good question! FFTF is ignored unless the frame rate is set to 60 or less in P3D. In other words if for example you have FFTF = 0.1 in your .cfg and you then set your frame rate in display settings to Unlimited you might as well have set FFTF = 0 because its turned off. Also, even if you have no FFTF entry in your .cfg and you set your Frame rate in Display to 60 or less FFTF =0.33 will be used by the sim by default.

I have heard that Dynamic FFTF can use an FFTF value with unlimited Frames but I am skeptical about that. The user interface may show that but in reality I think that probably defies logic Logic FFTF.

If you target frame rate is 30 and FFTF = 0.33 that means that 33% of the 1/30th of a second used to produce the frame is dedicated to FFTF. So the the fiber time fraction is 1/90th of a second. Unlimited Frame rate means that the it is mathematically impossible to determine the required fraction.

[zwenna 1]

This is confusing. May be in 4.3. there are some corrections compared to 4.2 and earlier. I am asking because my goal is following...

4k 30hz monitor

Vsync and TB on and unlimited frames

Fftf dynamic 0.15 to 0.33

Want to keep fps 30 as long as poss 

[newtie 533]

1 hour ago, Avidean said:

Good question! FFTF is ignored unless the frame rate is set to 60 or less in P3D. In other words if for example you have FFTF = 0.1 in your .cfg and you then set your frame rate in display settings to Unlimited you might as well have set FFTF = 0 because its turned off. Also, even if you have no FFTF entry in your .cfg and you set your Frame rate in Display to 60 or less FFTF =0.33 will be used by the sim by default.

I have heard that Dynamic FFTF can use an FFTF value with unlimited Frames but I am skeptical about that. The user interface may show that but in reality I think that probably defies logic Logic FFTF.

If you target frame rate is 30 and FFTF = 0.33 that means that 33% of the 1/30th of a second used to produce the frame is dedicated to FFTF. So the the fiber time fraction is 1/90th of a second. Unlimited Frame rate means that the it is mathematically impossible to determine the required fraction.

Not according to VGBaron...

 

[mpw8679 428]

From what I can tell u can set your FFTF within dynamic FFTF to any valid setting regardless of FPS settings.

[edpatino 1,960]

5 hours ago, zwenna said:

In another Forum info was given that FFTF entry in cfg is not used if inside P3d 4.3 Frames are set to unlimited. I am wondering because especially FFTF dynamic is given one Scenario where FPS are set to unlimited but application is working. Any Infos from yourside?

FFTF Dynamic works perfect for me. I don't have my FPS set to unlimited, since after several tests conducted on my system it was clear to me that I should locked them to 27 to reach my best ever fluid experience in P3D. Anyway I would recommend reading the FFTF Dynamic manual.

Cheers, Ed

 

[pgde 571]

14 minutes ago, edpatino said:

FFTF Dynamic works perfect for me. I don't have my FPS set to unlimited, since after several tests conducted on my system it was clear to me that I should locked them to 27 to reach my best ever fluid experience in P3D. Anyway I would recommend reading the FFTF Dynamic manual.

Cheers, Ed

 

Ed -- what upper limit do you use in FFTF Dynamic? I am using .4 as the top (the default I think).

Many thanks,

P.

[jabloomf1230 2,445]

31 minutes ago, pgde said:

Ed -- what upper limit do you use in FFTF Dynamic? I am using .4 as the top (the default I think).

Many thanks,

P.

Yout can try setting it higher, but scenery tiles and autogen will only load as needed, so using a higher value may have no discernible effect. That is, unless the sim has already gotten far behind in loading from having FFTF Dynamic using an FFTF that is too low to start the scenario. It's best to keep the parameter within a range around 0.33, which is the P3d4 default setting.

[Bob Scott 7,716]

Beau Hollis at LM says that FFTF does work with unlimited frame rates.  To paraphrase, when using the P3D internal frame rate limiter, the texture request jobs get whatever time is left after the main processing thread finishes the must-do core simulation processing that's done each frame.  With frame rate set in P3D to unlimited, the amount of time allocated for those texture request jobs is determined instead as a percentage of the time taken to process each frame (set with FFTF), or fixed between defined bounds using two lesser known parameters: MIN_FIBER_TIME_SEC and MAX_FIBER_TIME_SEC.

As I read his words, it seems to me that FFTF not only works with unlimited frame rates, but that P3D uses a completely different mechanism to allocate processing time for texture request threads when frame rate is not set to unlimited.  In other words, FFTF is only meaningful when frame rates are set to unlimited.

Now it could be that FFTF Dynamic sets the frame rate limiter to unlimited programatically inside P3D while it's running to enable the FFTF values it's setting to have effect.  But if you're setting the FFTF yourself in the Prepar3D.cfg file, I don't think it has any effect unless the frame rate is unlimited.

https://www.prepar3d.com/forum/viewtopic.php?f=6312&t=120133&p=139706&hilit=fiber_frame_time_fraction#p139706

Regards

 

[edpatino 1,960]

2 hours ago, pgde said:

Ed -- what upper limit do you use in FFTF Dynamic? I am using .4 as the top (the default I think).

Many thanks,

P.

Hi P:

I'm using the FFTF range from 0.01 to 0.33 (the default range I guess), and AGL range from 0.00 to 3,000 ft. Frames locked up to 27.

If I set my frames to unlimited, I get noticeable stuttering.

Very, very smooth experience.

Cheers, Ed

 

 

Edited November 13, 2018 by edpatino

[Guest]

4 hours ago, w6kd said:

But if you're setting the FFTF yourself in the Prepar3D.cfg file, I don't think it has any effect unless the frame rate is unlimited.

That exactly the opposite to my understanding of FFTF. If you enter an FFTF value in the .cfg it has no effect unless the Frame rate is limited.

I know from my own testing when I was using P3D that FFTF value has no effect on Frame Rate at all when the it was set to Unlimited. You could put FFTF = 0.99 in your .cfg and it would have no impact on Frame rate at all. On the other hand if you limit your Frame rate to say 30 and increase the FFTF value your Frame rate will drop accordingly.

That is my understanding of how dynamic FFTF works. It changes the target frame rate and the FFTF on the fly within set parameters. If I was still using P3D I would use dynamic FFTF. But I suspect that if you set your Frame rate in Display setting to Unlimited while using Dynamic FFTF, the app just changes that to a limited value behind the scenes.

[zwenna 1]

In my understanding it is opposite. In fftf dynamic Tutorial are 4 scenarios explained. One is unlimited fps together with vsync on and TB on. So that means to me that unlimited fps is Not a showstopper for fftf cfg entry. Where is the Information originally coming from? Or is it fake news....

Edited November 13, 2018 by zwenna

[Guest]

I've tested Unlimited and FFTF fairly extensively.  What this boils down to is actually pretty simple:

Set a Target Frame rate, set the FFTF value as low as possible so that you don't experience blurries or delayed/stopped rendering of Autogen.

Your hardware, graphics settings, flight location, speed of flight, altitude, and add-on suite will define how low you can go with FFTF (based on your target FPS) value before you start to get blurries and/or autogen issues.  I typically use 3 primary prepar3d.cfg used for light weight flights (GA in remote areas) moderate weight flights (turbo props in semi-dense areas), and commercial weight flights into large cities.  Overtime I make adjustments or will have a special case .cfg for a particular location (i.e. Orbx TrueEarth HD or SoCal/NorCal regions).

If you fly low and slow, then you can probably get away with higher graphics settings and lower FFTF values.

If you fly low and fast, then you'll either have to lower graphics settings and/or increase FFTF (which reduces FPS).

Cheers, Rob.

[newtie 533]

1 hour ago, Rob Ainscough said:

I've tested Unlimited and FFTF fairly extensively.

What were the results?

Mark

[Bob Scott 7,716]

Well, we have the software developer saying one thing, others saying the opposite based on experimentation, and a varied collection of user experiences that are all over the map.

I guess "fiddle with it until it works for you" is the answer...