Forgot to mention: The game speed is not slowed down alongside the timer. We looked at other runs from the “world record holder” mentioned in this video and some of them are actually faster than humanly possible. It is possible that some of the game physics are running faster than intended, giving him an even bigger advantage, but we are not 100% sure about this one and there are no reliable ways to test it. This is another thing for to investigate Correction At 4:28: That's 56 clean runs for 30fps

"he has a better gamong chair" is now officially working in fh5.

"The players, with less tools, doing developer's jobs for free." That hit hard

Interesting to have the physics refresh rate tied to your FPS. Major sim racing titles figured out ages ago that it was a bad idea to do so. Now they have physics updates detween 300 and 900 Hz for increased fidelity.

At one point I know Forza (Motorsport, at least) ran a fixed 180hz physics refresh rate, and also most major racing sim titles run fixed physics refresh rates as well. I suspect this is caused here because at some point, Forza switched to tying the physics refresh to your framerate - or may do this in specifically Horizon titles. It still doesn’t explain the game timer issues, but it would at least explain the physics issues between 30 and 60 fps locks.

Rivals mode's biggest sin is the inability to sort times by cars driven. That way you could pick whatever you want and tally your time with others who used the same car. Otherwise it's 1-2 META cars per track or GTFO. Apart from well known issues plaguing this mode, looks like there's even more, quite significant to anyone that cares or cared at this point...

Undeterministic physics in competitive games is a crime.

Im glad to see this about the physics and the timing. I honestly felt I was going insane and the only one thinking the physics were off. I’d enter a turn with all the same variables and it was almost always different everytime. Like my car will grip the earth like a champ, slide a little, or act like it was on ice. Frustrating to say the least.

"you might have tried dozens of tuning setups with little to no improvements" (shows ugrundy's tunes) this is kinda genius way to explain why there's no impovements lol

People won't believe this is happening in CoD, but you literally just proved it's going on in Forza. Lol

Lego island physics.

Reminds me of these good old DOS games that run their timers by the CPU fequency and therefore spazzed out on faster systems

I know you mention that it doesn't affect online races, but I can't even count the number of times I've clearly beaten someone to the finish line, only for the game to register them as finishing ahead of me. It was a big issue in FH4 as well. I have a sneaking suspicion that these issues are related.

Have you ever noticed that sometimes when you downgrade the tire compound, the lateral g stat and acceleration stats improve? I'd love to have an explanation for this besides "don't trust the in game stats"

I actually really appreciate your effort in researching this. It’s weird because I had a gut feeling some things were off, like no matter how good I was or how perfect my timing when breaking on upcoming corners was the ghosts always were ahead of me. Seeing this kind of relaxes me and hopes this will eventually be fixed or acknowledged. I like how some one mentioned the ability to filter would be helpful.

In "Beetle Adventure Racing" Physics also change with different frame rates. PAL N64 runs in 50 fps where american version N64 runs in 60 fps. The console calculates the cars position every frame. Means that if the car experiences any changes in (the track) directions, it calculates whether it gets closer to the ground or further away. Resulting in a change of the cars direction, or not. For example if your going up a ramp, your car wants go into the ground. The cars velocity and direction is always the result of the calculation from the last frame and the players input ofc. So going up a ramp means that the cars calculated direction and the direction of the street do not match, resulting in compression of the springs and a change in direction and velocitiy for the next frame. Long story short. In 60 fps it does that progress more smoothly than in the 50 fps version, resulting in the cars physics and behaviour beeing more volatile. It is more likely that strange things happen with lower fps. Maybe thats whats going on here

I remember something similar happened to me in The Crew 1: Back then I had pretty old and slow hardware which limited my fps. This lead to the problem that I couldn't drive with/against my friends in multiplayer because there was some sort of correlation betweem FPS and the speed/distance a car drove. I could drive top speed with my LaFerrari and my friends with high fps could just drive past me with some default offroad car lol...

Having worked with lots of physics simulation programming I think i could provide some insight into possible causes. Things like suspension, tire friction modelling, aerodynamics simulation are bound to be error prone when handled incorrectly. Time interval between the frames of simulation can change the outcome. In the case of the suspension - for example slower simulation rate may cause springs to get more compressed under changes of load on the car (like seen in the video with the cliiping on the loop) because there is more time between the cause (compression of the spring) and effect (spring force and damping acting on the car). Same can happen with tire friction but the time precision errors are usually more pronounced because the response in non-linear. You can search for tire friction curves if you want to see how they look. This can cause a tire to spin further before the forces are applied, therefore making it possible to spin faster than it should and getting less friction as a result. If the simulation results are dependent on the simulation framerate, an unstable simulation framerate will make them more random/non deterministic. Possible solutions to these problems are: running the simulation at a (edit: stable) rate independent of the graphics fps (commonly used, not idea why it's not used in fh5) and numerical integration or running critical parts of the simulation multiple times per frame internally to minimize the errors. It would be interesting to see you test the friction with different fps. Maybe some powerful cars with a lot with wheelspin? No idea about the possible cause of the timer thing, but someone definitely did a shitty job with that.

I have something to add about the suspension clipping in the loop. Two of my friends playing at uncapped FPS always wondered how I get less clipping when playing in the Hot Wheels world. I play at capped 72 fps. When my friends also tried capping their fps to 72 they stated getting significantly less clipping than before. So it seems like at high enough fps you start getting disadvantages again.

I think this is because the delta time is a float of 32 bits and when it multiplies to get the values of the timer and physics it just loses a little bit of precision every time

FH5 was the last game I expected where dropping graphic settings gave you an edge. well I guess it's time to drop them ultra/extreme settings and make the frame counter go brr

I really like how this channel evolved 😊 from memes to technical analysis. I literally use only use your car settings for online racing. Btw nice work as always 😊

My conclusion from the suspension graphs; the physics updates are fully tied to the framerate. Reducing the framerate reduces the amount of updates the suspension model recieves. The lack of updates means that the suspension will behave less consistently due to important details of the track not being reflected in it. At the same time, while higher framerates seem to help with consistency, I'm sure there is a point in the hundreds of frames per second, where the suspension will update so quickly that it may begin to behave erratically. And because the update rate improves consistency, the erratic behavior may also be consistent.

The F1 game had a problem this year where certain frame rates would allow you to go over curbs like they were nothing

I've thought something like this was happening, especially with the random nature regarding physics. I've also noticed that when racing against AI in a single player race, the AIs performance is often drastically impacted by my settings, especially if my PC is a bit laggy and the AI are close to me

See: Quake 3 Arena Rocket Jumping and FPS. This is what happens when in engine timing, that also controls things like physics polling rates, and the in game clock, are intrinsically locked to frame rates. You end up bending the rules of how the math is done by cheating the frame rate. This has been an issue on Q3A for physics, as previously mentioned, and also for leaderboards on Sega Rally 2, where higher uncapped frame rate would also cheat the clock to run slower, and make the "wall tap" braking technique for hairpins much easier, as it also cheated the physics engine, and made the collision and accompanying speed drop less severe, the higher the FPS was. Which eventually led to all PC Sega Rally 2 times being rejected.

Lots of games have mechanics that are based on your FPS. Personally I think the best part of this game is how your stats and movement are all local, meaning you can speed-hack, fly-hack, get cars and money, and also even save-swap with accounts all local to your computer, kind of like Grand Theft Auto 5. (I think save-swapping was patched not too long ago, but it was a thing.)

something about game physics is that normally you move in the direction of your velocity and THEN the game looks at if you've collided with stuff and adjusts accordingly. If your on 30fps instead of 60, the game has to move you twice as far between timesteps, meaning the suspension system wont be able to keep up and apply force between those frames. making the suspension more unstable at lower framerates. Maybe the team tried to counter this, but as someone starting out in gamedev, thats my guess for the loop problem, and it needs some very smart work-arounds to fix, possibly engine-level changes

Pay2win physics has been a problem not only in forza but in entire gaming history. Like for example in cod4 league, everyone is hitting 200+ fps and the rule no 300+ fps is enforced on some matches In gta fivem racing communities, moderators and admin has server grade gaming pc running 400+ fps to assert their ego on us and going even a second faster on 40 seconds straight with the same car/build

Tested your track out. My specs are 1080Ti, 3900XT. With my settings I get an average of 110 FPS if I had to guess (like 130 in bumper cam because the game doesnt need to render my car). Game timer was 506.6ms faster than the event lab timer. I was using the S209 with an A class road tune with the body kit. That's pretty dumb lol. Now I feel like a cheater now :( I did some more testing for science, trying different camera views (bumper cam gives a slight FPS improvement). My fastest lap in this car was a 1:39.828 with a 502.6ms difference. Seems like the slower you go, the bigger the gap grows which makes sense.

I read a while back about this issue in GTA Online, frames and physics were tied closely, somewhat rigging races to your hardware. Surprisingly, this was fixed with Expanded and Enhanced.

I kinda wondered why I always did so well in the game. Running at 144fps would give an advantage over the NPCs as well.

do a drag race with identical cars and one player on xbox one another on xbox series and another on pc with 120 fps+, you will see how crazy this game is.

The physics difference is because the physics engine works on a 2x multiple of your framerate, so I believe what you are seeing is half the data points hence the smoother graph at 30fps.

That made quite a bit of sense as to why things like my suspension bottoming out and losing control of a vehicle whilst drag racing on the highway happens WAYY more often to me on my Xbox one than all my friends on next gen

awesome research you clearly did a lot of editing and researching. Glad there are good youtubers out there

Your study of this situation in the game is very important!

That loop scenario is why i tend to run Rally Suspension on almost every car, sure i'm not getting most handling possible but avoiding bottoming out is perferable imo

If I had to guess, it seems like it’s in-part a problem with interpolation, and the frequency of physics updates. It seems from the video like collision + physics updates are only applied when a frame is rendered. If you had a mod to prevent the rendering of the game without triggering some sort of lag compensation system (if one exists), I have a feeling the cars may start “driving” through walls. Video games these days are meant to work at varying framerates in a roughly consistent manner. However, it can be difficult to handle collision updates in these non-deterministic situations - almost as if the collision detection somehow relies on the frame that was previously rendered to determine if a collision happened rather than calculating the physical interpolation based on a frame or two ahead. As such, it makes sense in the loop example that the car clips into the floor more at lower frame rates because the game has to “catch up” more slightly more to visually reflect the velocity applied from the previously-rendered frame. As easy as it can be to put our conspiracy hats on, as a developer of other games and systems I believe this “pay2win” aspect that appears here is very much not an intentional design element, but rather just an unfortunate side-effect of the way physics updates are handled. I think that one of the few ways to level the playing field more in ‘competitive’ environment would be to limit physics to a time-based system. Ex - when the in-game timer passes certain thresholds, one or more physics updates are applied, but not so much that it causes the game to lag on older hardware. This would, however, cause a VERY SMALL visual desync in the moment to moment gameplay that can cause things to feel _extremely_ different on newer hardware. It’s a biiig balancing act. If ya wanna truly fix things, fix the real-world economy lol

another idea for testing this: make an autohotkey script (or similar recorded inputs) with set steering and throttle/brake inputs, then let that run on 2 different machines. When overlaying the two videos, it should show one of them with synchronous inputs, but different positions on the course, leading to inputs that are desychronized from the track leading to a wipeout.

Incase you weren't mad enough already at the game, here's some more crap to work you up. You do such incredible work man, respect

Does this advantage extend to 120, 144, and even 300 frames per second or is the internal clock rate(unsure of exact terminology) limited to 60 per second?

I've seen something of the same nature happen to some graphical adventure puzzles. The game update the timer every some amount of prosessor cycles instead of real time, while online timers depend on the servers' cycles.

Gravity is often tied to fps in first-person shooters. I think a simple way to make it make sense is that a faster device doesn't have to skip any calculations to meet a performance target. Hence why with more fps the suspension values have time to go through more position checks, returning more values, smoothing out the transitions.

I have noticed the frame affects something very early. when playing 10 skill points blueprint, such as 139 710 733, the lower frame makes you run faster. Using X seseto fe, 41 fps → about 25.4s，83 fps → about26.3s. And sometimes, the speed just ignores obstacles. You have the skill points but just like going through the obstacles, so it will be under 23s. But when you go faster, you will get less exp. using 165fps, about 3733 3961 4000 exp per round, 30 fps would be 32xx exp. It seems like because one frame cannot handle more than 2 times collisions. For example, if the speed is enough to hit 61 obstacles in 60s, but you only have 60fps, there will be at least one frame that has 2 or more than 2 collisions. It may only cause one slowdown. So lower fps let you ignore more slowdown by collisions. And I think I played afk more than all players in fh5, my id : nmcleo, I even go afk for online racing. And now I am on the top 25 of the exp board. I spent a lot of time on tuning for afk, so I have tried what is the best fps for afk. Higher fps have advantages in most maps. But the game is more likely to crash with the unlocked frame, so I am using 83fps. With NV gpu + over 5ghz cpu, using nvidia profile inspector, you can run fh5 over 200 fps. Just like how some people play pubg.

I would say the physics vary based on the cpu load but that's is something that hasn't been a problem for years where if you manage to boot up some really antique games on modern hardware, the physics would be overclocked because it was designed around a much slower processor.

It is the physics tick speed which has numerous different names. Almost every modern game with any sort of collision has separate tick speeds, it's usually locked to a lower number like 40-60fps which has very little deviation in consistency and they use something called DeltaTime which is an approximation of the time between two frames to do t mathematics which is everything from the timer to the rate of force dispersion in suspension. However the larger the difference tick consistency the more deviation. Im not sure exactly why but I suspect Forza's default tick rate (for menu logic and what not) is somewhat tied into the physics system so unstable normal tickrate has an impact on the physics tickrate. I beleive it might have something to do with performance in that regard or it could be a legacy issue with their engine being built for 30fps on older consoles. That's why many games still have a fps cap on consoles so that the gameplay is consistent especially in physics based games. The non determinism you spoke about is true, it can be caused by another computer science term called "floating point errors" where a number is too large or small for the computers 32bit floats to encapsule so numbers get trimmed. If the framerate is higher or lower it can change what values are in certain equations and sometimes they can get chopped off, only causes minor mis-calculations in equations but when the equations go from like millimetres surface are to newton meters of force created by downforce you could be a whole int value out, have that happen a bunch of times and you get some silly physics or silly timers. en.wikipedia.org/wiki/Delta_timing en.wikipedia.org/wiki/Floating-point_error_mitigation en.wikipedia.org/wiki/Speedrunning

new forza game is locked to 60fps online most likely due to this problem lol

Ok, I got some questions. So, I play on 4k, and can get 90FPS if my FPS is unlocked. If I have locked my FPS to 60, does that mean I'm giving up that unfair advantage? If I were to play 1080p or even 720p & unlocked FPS, would that make me impossibly fast? How does the loop thing actually work? I have noticed before that every now & then my certain cars does clip on the loop. (With 60fps lock)

I’ve always told myself that I swear I’m not playing the same game as everyone else. Turns out I was on to something.

This can effect a lot of games and is down to time delta not being accurate enough. In multiplayer the *tick* for physics takes place on the server and so it should be more consistent in terms of timing. In singleplayer the "tick" is on the players CPU. If there are 60 ticks in 1 second and the time between each tick is some number, e.g. 0.000230 but the CPU depending on architecture and also lots of other factors can reduce the accuracy of this number (in other words, the computer isn't fast/good enough to know the smallest amount of times possible in reality, i.e. picoseconds) After the 5 ticks are added up discrepancies can appear, for example: Tick 1. 0ms Tick 2. 0.0020000032ms Tick 2. 0.0010000032ms Tick 2. 0.0030000032ms Tick 2. 0.020000032ms If this were handled by a a computer, it may not have this degree of accuracy so lets round it up. Tick 1. 0ms Tick 2. 0.00200000ms Tick 2. 0.00100000ms Tick 2. 0.00300000ms Tick 2. 0.0200000ms As we can see now, we missed all those 0.000000032ms at the end of the number... And that really matters. All of this adds up over many ticks. A good way to think about Ticks is FPS, its not always the case, but you could say for every frame, there is one tick. 30 FPS means much less numbers, also rounded innacurately, therefore producing worse results 60 FPS means trying to do 60 ticks inside 1 second, rather than 30. Well if we imagine if the CPU can handle 60 ticks, it probably has less of a time delta between each ticks. Because its a better CPU. 30 FPS means trying to do 30 ticks inside 1 second, which means if the CPU is running fast, or the tick is running faster than 1 per frame, the maths get's even more out of whack. For example your game may be 30 fps, but your tick is 60 ticks per second. Now the maths to calculate the time between frames is much more different, we're now factoring the fact 2 ticks occur per frame, and so we once again destroy the original "1 tick per frame" ideal, and end up with some bodge maths. As game devs we use a simple math trick to resolve the issue, which when we're talking on the "seconds" time scale is fine. But anything sub 1 second, we all accept we lose the accuracy. Here is the math: 1 Second is equal to Desired FPS/TicksPerFrame - Time since last frame Example: Desired FPS / Ticks per frame - Time since last trick (or frame) 60 / 60 - 0.0002ms

What about playing in less than 10 FPS?

amazing job, good work m8!

I can confirm this… the physics does really change with hardware…some things do behave a lot differently When I play on my pc, 12th Gen i3 and 3060ti, I am always racing as perfect as I want….but when I switch to my laptop which is like 4+ years old (7th Gen i5 and GTX 1050 4GB), so it runs on 1080p 30fps, it has a significant impact on my driving…and it becomes irritating as my driving becomes bad and turning and braking become mess… Whereas on pc I can easily play 60/90/120 fps (I play with 1080p60 EXTREME) and its just perfect…no shenanigans…..and there’s slightly more things you can get away with And no I’m not a bad driver…its like above above average….

is there any advantage above 60 fps?

you have to love games where physics and whatnot are still tied framerates

4:29 44 + 66 = 100!

Thank you for confirming. I am using XSX before I get a 3070 w/AMD 3600. I found my lap time to be faster on the PC. I thought it’s the fps that make a huge difference. My friend commented maybe I am sitting closer to the mon compare to the tv. Now I know it’s the money I paid that the difference.

You will always encounter these accuracies unless you use deterministic code, I don't know any game that uses a deterministic physics system, apart from games that have very basic movement that doesn't require a physics engine, such as among us (probably). The reason why it doesn't happen in online races is likely because the multiplayer system is server biased (i don't remember the actual word) which means that what you see in your screen is just a local simulation, your inputs are sent to the server which then runs its own simulation and decides the actual results. If there is a difference in your local simulation and the server simulation, the game will gently apply the corrections to your local sim. If the difference between what the server calculated and what your game calculated is too large, that is when the game might teleport you to the server's calculated position. Besides that, even if the game ignores a small amount of difference, the timer will be based on the server's simulation. So it doesn't matter if you're running on 10 fps or 100 in your local sim, what would matter is the server's performance. Even that won't matter much in a race since everyone will face the same affects caused by the server's performance

Nice. Looks like physics are tied to frametimes in some way. Seems that in the loop test suspension is reacting slower in 30 than 60 fps, which in some situation will cause clipping. Possibly frame frequency was not enough for game to perform bounce back of the suspension, causing it to clip eventually. I do wonder if this glitched times were however done with limited fps or not. If not maybe physics engine couldn't keep up and caused game to go out of sync between physics and frames?

i knew it wasnt because im a rammer who spams meta!

With the difference in physics between 30 and 60fps it makes me wonder how something like 24, 75, 90 and 120+ will fair for those on lower end hardware and those with high refresh rate monitors.

In Redout 2 there’s a similar issue, the ships tend to bottom out or not activate boosts at top speeds where they shouldn’t. I also encountered an issue where I approached a jump at a steep angle and clipped straight theough because of a similar frame rate limitation.

The thing with fps: the physics engine might have in it's calculations the number of frames. Lower frames means bigger difference in position between 2 frames, meaning that clipping will me much more frequent since it would not have enough subsequent frames to correct the clipping.

this should be brought to Playground's attention so it could be fixed... and maybe reset leaderboards

i always felt like my high fps gave an advantage more than just better reaction time. thanks for the intel!

I've seen at least one case where using rewind in an online race also effected the timer, like it does in single player mode. It resulted in a win.

This is true for all games. In sim racing titles like Raceroom, AM2, I racing, etc., you can have a screen that only does 60fps but the game does 90 or 120 fps with a frame viewer. With each fps all of the inputs and physics is updated and calculated. So, 120 fps is going to be more fluid and accurate in it's handling even though the screen is updating at 60 fps. There was a mod that allowed one of the Transformers games to run at 60fps. The catch was the physics were a little off because the engine was built around 30 updates a second.

59.94p vs 60p would be my go-to probably moment when you show that time difference. Time conforming broadcast vs computer framerates can cause things like this to happen.

This situation rememberem me the things with 3d fallout engines and why an internal clock is so important Basically, in 3d fallout the physics engine does the calculation on movement, time and so on based on your frame rate, given the game was made to run @30fps anything bigger than this will cause problems, we see faster movement, objects behaving weirdly and many clippings happening To solve this problem many developers started implementing an internal clock, it limits the ammounts of inputs the game engine recieves so you don't get weird bugs while maintaining a high fps count, see any multiplayer game for instance, the vast majority of servers only register stuff @30fps so to maintain low performance cost and a somewhat smooth physics simulation I believe the same things is happening to FH5, either the engine lack an internal clock that limits the game inputs to a set ammount or the game does feature an internal clock but the same is set to capture >=60 inputs per second, resulting in weird behavior from a lack of inputs

How do you enable this specified lap time interface? I only get the dumbed down version. Nothing with [ms] or the sort...

I recently doing a real time rendering job for an earthquake simulation in UE. The only way to get a precise calculation is by NOT going real time. Dividing and calculating 1 frame 20 times will get you more accurate physics. But it will slow down your rendering by 20 times. that's what basically what's substeps does. So if you're using a slow PC, the calculation of 1 frame could cut short, and it goes "fuck it, just move to the next frame" and you get a very bad incomplete calculation. This could lead to understeering a lot. In other kinds of games, say fps for example, where you sometimes see boxes or ragdoll goes crazy, is because it had 1 bad frame, and it intersects with the floor or other rigid bodies, and the next frame goes "that's not supposed to be in here" and tries to push it back out, which leads to the boxes launches at high speed.

I am so happy you made this video. This happens across games as well

Finally, a reality that 66 + 44 equals to 100

I tried getting better in fh4. Watched your video about how to drive better, messed with my own, and other tunes, and ended posting a few top 1 thousand and 2 thousand times. For me who has never tried to be competitive ever I’m pretty happy about that. It was only on road racing and I want to try rally next.

I have a powerful pc and I dont see an improvement on lap times weather Im locked at 60fps or 240fps. I have been testing this. Maybe it happens on specific tracks ??

IIRC, someone posted a couple of months ago on r/F1Game a video on how taking the same corner with a big sausage kerb on 30 FPS had almost no effect, whereas at over 60 FPS he was almost flying. That's a game made by Codemasters ( now part of EA but that's another story ) so this makes it even more strange that 2 completely different racing games have this behaviour

Shit like this, and how brutally stupid a lot of the meta builds are is what made me lose interest in FH5 after putting quite a bit of time into it. FH tries to be this weird middle ground in terms of realism and arcade hilariousness and that just breaks it IMO. I've had a lot of fun TBF, and really enjoyed building and tuning cars to a high level and taking on online races. This just gets shit on by stupid meta builds, glitches and half assed development though. It really is a bummer when one has built up their favorite car, spent ages tuning it to be a winner in its class, but then has to resign their mindset to "winning the non-meta class" in online races. Drifting was fun, I got involved in some online communities that did great, realistic driving and it was the most fun I'd had in FH5. It's a real letdown how half assed the competitive component of drifting is. If a dozen cheap mobile games can implement more realistic drift scoring (zones, clipping points and proximity), why cant PG? It's kind of interest specific I know, but really highlights how much of a lazy, child market cash grab FH has become. Mobile games do most of it's elements better. Just this morning I uninstalled FH5 after playing it since launch and change my racing game library to two polar opposites that don't try to split the genre and come out half assed. I'm happily playing Unbound for fun and really enjoying the style and story, and getting into Assetto drifting now that people have figured out controller support while I save for a wheel.

Wait so what happens if you are running at even higher frame rates such as 360 fps?

More updates per second makes physics more accurate. It all comes down to collision detection\acceleration with better accuracy, which means that every interaction between game objects happens slightly earlier.

this game's physics became very forgiving

So what i would like to know is what happens when you set the graphics on potato mode on a mid spec pc? Can you gain an advantage by that?

I have an educated guess on why cars are faster at higher frame rates. It's jerk, or the change in acceleration. The jerk for each car will be a fixed value (lets say J=1 for now). That means that the acceleration for each car will be a a function that approaches the controller value depending on the jerk. In a perfect world, the velocity at each moment would represent the area under the curve, but since the physics engine measured the jerk and acceleration each frame, it looks like those Riemann sums you did in highschool. The more rectangles you add, the closer the area approaches the true value, so if you double the sampling rate you will get a closer answer to the true velocity of your car. One way to fix this is for the PC to do all its physics calculations every other frame to match 30 fps.

Now forza fans will use this as a excuse to why they are still slow

This explains why in multiplayer finishing first yet somehow still getting 2nd despite the guy in 2nd being behind you is a thing. ALSO, I'm probably one of the few people that has over 2000 hours in FH4 (and now soon in FH5) most of which spent tuning and racing online (hell I still have "NEW" tags on races on the map because I hate racing against bots so I don't even touch those lol). And I noticed something VERY strange when I once played on a friend's PC who has the game capped at 30 FPS because his PC is slower. Now, being a top 100 ranked player in FH4 and playing the game for this amount of time, I could win online races against meta cars even in meme machines, so I know EXACTLY how a car SHOULD react to my inputs and the road ahead. Yet I've noticed something very weird when playing at 30 FPS, especially visible on rally races, the car would regularly over-react to any road inconsistencies, steering would over-correct, tiny bumps that would mean close to nothing at 60 FPS now required micro taps of 25-50ms on the keyboard to correct, minor stuff like this that I'd have no realistic issues in correcting but I KNEW something felt ever so slightly off, now thanks to this video it all makes sense. It appears the game's physics simulation runs at the same refresh rate as the game's refresh rate, HOWEVER there might be a hard cap to this, or highly diminishing returns. You see something very weird happening when driving a car with slicks + high front aero, like the Viper AE or the new Lynk & CO race car on varying refresh rates. Play the game at 10, 20 and 40 FPS, make a simple test in which you take a corner at high speed on flat ground, same speed, same everything in all runs, just hold forward + left/right at 10, 20 and 40 FPS, look where the car ends up and what happens to the car's grip + suspension in the telemetry, you'll be amazed.

It's crazy how much effort y'all put into working out that someone is devouring your time and giving you literally nothing in exchange

back in forza horizon 3 when it first came to pc. my raptor was nearly undrivable on console or at 30 fps. but with a uncapped framerate it changed how physics handled the truck and it became extreamly stable to drive at high speeds

At this point, after 610 hours of playtime on FH5, the game is just awful, might as well just play Asetto Corsa. >proceeds to play FH5 after writing this comment anyway

Best forza content

Have you test this with water? Maybe it placebo and people consistently take bad lines to cross water but I seem to gain ground more often then not when I cross.

On my first watch here, the bit about 30fps vs 60fps and its effect on lap times seems to rest on some flimsy logic. If you just got done running 100 laps on the same track in the same car, you’ve gotten more and more familiar with both the track and how to maneuver around it with that particular setup. It’s not at all unreasonable to imagine that you’re genuinely just doing better and are able to meet the time much more quickly and consistently with all that practice - especially if you’re now receiving visual updates twice as often as on your first 100 attempts. Those are both pretty huge advantages.

This happens in every game with a time and therefore physics altering mechanic....like rewind in driving games or V.A.T.S. in Fallout 4. Once the system was ported to Fallout 76, players found those with unlimited frame rates could run faster than people who didn't as physics was tied to framerate. Add to that Horizon was the fun-park-not-seriuz-candy-racer compared to the straight-faces-stopwatch of Forza Motorsport 7 (despite it having a rewind mechanic too).

Knew it wasn’t because we spent five nights at Gumi’s 🦜

One of the best breakdowns I have ever seen. Amazing. Subbed

It's a very common bug in videogame engines. Basically it is a rounding error. The numbers in your PC re represented by a finite number of bits, usually 32. When you divide something unevenly, on paper you often generate an imfinite decimal nimber. Think of Pi for example - it never ends. But your PC can't do that - it can only calculate numbers up to a certain measure of precision, after which it will discard everything else. That precision is usually more than enough for any error to be absolutely negligable and unnoticeable. But sometimes, like here, you may notice it. Imagine if a timer is calculated every frame. If you run at 60 FPS, you add 1/60th of a second every frame. If you are at 120 fps - 1/120th. But those fractions only look neat if they are represented as a fraction. If you show them as a decimal, the story is different. 1/60 = 0.01666666(6) 1/120 = 0.0083333(3) They stretch on infinitely to the right. Now let's cut them! The PC is a bit smarter than what I'm gonna show here, and much more precise, but the gist of the problem is the same. I will just drop everything after 5th decimal place,and then round the remainder: 0.01666666... = 0.0167 0.00833333... = 0.0083 And... Uh-oh, we were forced to round up on the first number, but we are rounding down on the second. So at 60 fps we are adding slightly more to the timer than necessary, and on 120 fps we are adding slightly less. I should note that depending on calculations and exact fps you can see the reverse as well, so it is never a clearcut "more fps = better timer". Unfortunately, I should note that the only way to get rid of this error is to run your timer in a frame-locked thread or to compare it with system time or something. And even then you will get discrepancies on 2 different machines. This is impossible to fix completely simply due to how computer maths works.

Interesting video. I have an xbox and a pretty good pc (framerate is normally in 100s). I run lots of rivals mainly on pc, but sometimes on xbox. I've set pb laps on both. I can't say I've noticed this bug myself and I usually race my own ghost. It seems like a massive oversight for a racing game if it is correct.

I don't think there is really a complete solution for this problem, because a better pc will just go through the code in the loops faster. I had the same problem (but far worse) in a small racing game I had to programm for university and the professor said there isn't really a solution to fully eliminate that problem. On my slow Laptop it would take about double the amount of time to finish the course compared to a gaming pc.

Really interesting ! I immediatly think of "simulation" : Physics in a car game is always simulated. While in the real world, the compression of the spring is continuous, in a simulation, it is discrete. In mathematics, something continuous is when all values of times (in this example) are available. Something discrete is only "step-by-step". For example, y=x^2 is a continuous function, but Fibonacci sequence is discrete (1, 1, 2, 3, 5 etc, but nothing between 3 and 5). For a 30fps rate, values are calculated every 0.0333.. seconds and for 60fps, it's every 0.0166... seconds. It seems a detail, but for a simulation it highly important. Due to the interaction between all values (with derivatives, primitives etc), calculations for continuous in live are quite impossible, because there far too massive. So physicists and developers use simplified discrete calculations. Far more simple, far faster, but more or less approximative. So approximate that for the same starting value, the t=0.003 value at 30 fps and at 60 fps will not longer be exactly the same, simply because at 60 fps there was an intermediate value. On the contrary, for a rendering scene in 3d, you can use longer and more precise calculations. That's why rendering in a 3d software takes so long.

If I were to hazard a spurious, unresearched guess, I'd say the engine is brushing up against processors that are too effective for it. Sometimes, on high-end gear, outsourced calculations like physics (which are often offloaded to a high-end GPU) might get back before they're actually needed for the next frame, possibly causing a sliding desync until the engine notices and then dumps a frame of execution to bring everything back into balance... the problem being that it absentmindedly stops the clock for a frame as well, since when the engine was made this otherwise sensible error-correction could safely assume that if it needed everyone to shut up for a second to gets its ducks in a row, it would be rendering a lag frame where everything's stopped - but here, it can't remotely tell the GPU to stop in time, so it just takes and processes the next set of input to empty the queue. The means that physics execute for this "lag frame", allowing some movement, but the clock does not, giving the player a frame of free time. This adds up over a race to the point precise external timing can pick up on it, and the replay function reconciles the error (which passed muster under local verification, since everything on the user's end was functioning as intended) as a faster-than-normal ghost. Disclaimer: Not a software engineer, just someone who's seen too many youtube videos explaining obscure execution/memory exploit glitches. (Also see the pinned comment, since skullduggery could be the simple answer.)

This feels like the type of thing that Microsoft would just never bother to fix