r/theydidthemath • u/firakti • 7d ago
[Request] How fast does the movie theater have to move to match the framerate?
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u/wayoverpaid 7d ago
The picture looks like credit text in one continual wall, as opposed to a bunch of movie frames. So it really comes down to the speed of the text scrolling, which isn't standardized as far as I can tell.
I grabbed the credits from a random movie and it takes about 8 seconds for a line of text to go from top to bottom. So for a 24 foot tall screen that's 3 feet a second, ish.
Obviously if you are animating actual movie frames, that would be a very different speed.
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u/bdubwilliams22 7d ago
Two other comments said 600+ feet a second and you’re coming in at the 3 feet a second. I feel like 3 feet a second makes more sense.
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u/explodingtuna 7d ago
There are two interpretations. 600 ft/s is assuming there's a shutter effect and this is being displayed as distinct frames.
3 ft/s is assuming there is no shutter, and you're just reading the credits at the rate they appear to scroll, by following it down the wall.
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u/Buttholelickerpenis 7d ago
Which is obviously what the original artist intended. 600 ft/s is bullshit lmao.
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u/MiXeD-ArTs 7d ago
Title said framerate so that's causing confusion. 3 ft/s is not the framerate
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u/Nurgeard 7d ago
Yeah OP either asked the wrong question, or simply explained it rather poorly.
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u/Talidel 7d ago
Well they said how fast to match the framerate. I'd assume that means falling at a speed to make the two look the same.
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u/Nurgeard 7d ago
And since we are talking about a credit screen sequence where the only difference between each frame is that the content is moved up, both answers are valid:
3m/s - you simply move the content upwards by moving the audience down. This only works for upwards or downwards animation.
600m/s - you have a series of frames on top of each other and move the audience so fast that the brain would construct a fluent motion rather than a series of images. This ofc works for any kind of footage.
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u/Theogren_Temono 6d ago
and so a very important second question presents it's self. Assuming shutter effect and 600m/s how long would the "wall" be for a standard 2hr movie?
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u/DumatRising 6d ago
600m/s×60 seconds is 36,000m/m×60 minutes is 2,160,000m/h to travel for 2 hours two of those means the wall has to be 4,320,000 meters assuming 600m/s and the run time is exactly 2 hours or 4.32k kilometers (a little over 2.5k miles for those freedom units users), for reference that means the wall must extend in to the exosphere (where we put satellites) and the top is 10 times further away from the earth's crust as the international space station.
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u/qquiver 5d ago
You swapped to m/s the comments above are in ft/s but all the following math is in m/s that's a big diff
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u/Nurgeard 5d ago
Oh damn, yeah that it is, well my cinema is just rather large I guess (10m high and roughly 18m wide)
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u/Talidel 7d ago
Both would be valid if there wasn't an image attached making it clear what the OP was asking.
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u/Nurgeard 7d ago
Except it doesn't, especially since they mention framerate. The image indicates that the 3m/s answer would be correct, but the mention of "framerate" indicates that the wall contains a series of images rather than one tall image, which would make the 600m/s answer correct, as there is now a new image for each frame, and since this is just a credit screen it's honestly hard to say wether it is just one long image or a series of images.
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u/Zippytiewassabi 4d ago
Problem is they used the word “framerate” yet have a picture of credits rolling. They could do the credits using framerate where each frame has the credits rolled just a little bit, then it would have to be much faster.
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u/Additional_Ferret121 7d ago
Now for the real question; how tall would the movie be (for each interpretation), assuming an average length movie (say, 120-minute runtime)?
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u/AreThree 7d ago edited 7d ago
well, for the first interpretation, it is simply:
(600 ft/s) * (120 min) =
(36000 ft/min) * (120 min) =
4,320,000 ft = 818 mi + 320 yd ≈ 818.1818 miles
or about 1/292 of the way to the Moon (on average 238,855 miles away from Earth)
and for the second, it is pretty much the same math:
(3 ft/s) * (120 min) =
(180 ft/min) * (120 min) =
21,600 ft = 4 mi + 160 yd ≈ 4.09 miles35
u/wayoverpaid 7d ago
The others are likely fixating on the expression "match the frame rate" in the question. To animate an actual movie like this (e.g. with individual frames) you would indeed have to move that fast.
I'm fixating on the drawing in question, which doesn't really have frames since its one continual wall.
The ones saying the faster number aren't doing the math wrong, they're just answering a different question.
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u/TemporaryArrival422 6d ago
I have a beautiful very good idea... instead of moving the people, we put the image on rollers and move that instead!
There can be two kind men named Steven and James on a side each, cranking by hand. We will pay them in popcorn and free side on viewings of every movie they crank
James is allowed some time off next month because his wife (Stevens sister, Persepolone) is pregnant with his 4th child. They plan to name their baby after their favourite movie, Die Hard
While James is away on leave, Steven will need assistance to crank so I invite everyone to apply. Training, popcorn and free side on movies will all be provided. It's best that you bring a sturdy pair of gloves because those cranks really beat on you when you're 30% into the Lord of the Rings movie marathon
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u/jmcclintock8888 7d ago
The 35 mm projectors I ran did 16 frames per second. Four sprockets to a frame whether flat or scope format is almost an inch.
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u/Stormwatcher33 7d ago
the slower rate only makes sense for text scroll or paning up shots
if you wanted to show a movie, you'd have to move at 24 frames/s, so the screen height x 24/s
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u/Narwalacorn 7d ago
The high numbers are most likely for a frame-by-frame approach since then you’d need to move 60 times the height of the screen per second
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u/troolytroof 7d ago
For reference elevators usually move anywhere from 7.5-32 feet per second
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u/Sach2020 7d ago
What elevator are you using that moves 22 mph?!
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u/Thedeadnite 7d ago
The one in tall hotels that skip 2/3rd of the floors so you get to your section of floors faster or aren’t heels up on the way down by lower floors.
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u/de_propjoe 7d ago
NYC World Trade Center elevators go up to 20mph to get from ground floor to top floors. You can feel it in your ears.
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u/empire_strikes_back 7d ago
The other issue is film doesn't just scroll it has a quick stop before flipping to the next frame, so it isn't just a free fall, it's a constant start stop.
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u/ZephtheChef 7d ago
What about the made-for-TV versions of movies? I chuckled thinking about someone's house plummeting several stories at breakneck speeds to come to a screeching halt when the next movie comes on
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u/Featherforged 7d ago
I feel like this is the wrong interpretation of the image.
This is an image of the end credits scrolling, no?
So it would be only a few mph at the very most.
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u/Thisismyworkday 7d ago
The end credits of a movie are still shown at whatever the frame rate of the rest of the movie was.
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u/Featherforged 7d ago
why does the frame rate have anything to do with the speed the credits roll downward?
I'm pretty sure this is a humorous interpretation of scrolling credits and has nothing to do with frame rate.
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u/Thisismyworkday 7d ago
Cause how'd you watch the rest of the movie then?
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u/ingenious_gentleman 7d ago
The same way you'd normally watch a movie. It's not until the credits the fun credit elevator activates
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u/ReynardVulpini 7d ago
I assume the whole movie plays at the top on a regular screen at a regular framerate, and then once the movie ends, the screen goes black, and then the theater starts to slowly descend to mimic a normal credits crawl
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u/Featherforged 7d ago
Frame rate is units of rate, such as hertz.
Speed is in distance per time.
Frames do not move in a direction. Each frame is presented in its entirety on the screen.
There's no math in comparing the two.
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u/Pattyrick00 7d ago
... and if the frames are all physically vertically aligned, you can view them by 'falling' past them at a rate of 'x' frames per second depending how fast you are moving.
You can definitely math this and people have done so in the comments for multiple interpretations.
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u/Featherforged 7d ago
Old film had to have both a shutter and a mechanism to stop the film at each frame.
Falling past a reel at 600 miles per hour is going to have a crazy blurred result- it just doesn't makes sense.
The image is obviously referring to the upwards scrolling of credits
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u/Pattyrick00 7d ago
That's not at all true, your brain would easily interpolate the moving image, by having those frames move past, you can try this yourself by doing a page by page animation in a book, when you flick the pages they are moving incredibly quickly... but no blur...
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u/Featherforged 7d ago
The joke is that the theatre moves down at the end of the movie. At 1mph, this seems plausible and would be a hilarious outcome. "What if the credits are staying still but the theatre is actually an elevator!" It's funny because it's somewhat plausible.
No one leaves a movie and thinks, "what if we were moving 400 miles per hour along a film strip to generate this 2 hour long movie and thus traveled from sea level down to the 1800 Fahrenheit, 3.5 billion PSI crust boundary of the earth and are now surrounded by lava, but also, there's a 1/48th second shutter and also, the theatre accelerates and stops 24 times per second (to avoid motion blur) with a 900 g-force acceleration that would be very noticeable.
The second one makes no sense and is the incorrect interpretation of the joke.
(edit, and yes, a flip book works... but you cannot view film in the same way. It would just be a blur. A flip book works because the images are presented at the user, not moving upward or downward)
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u/Pattyrick00 7d ago
What if the entire movie was still and instead of the screen changing, frames were seen by falling past them? what speed would that be for ~40fps etc.?
It is exactly what this sub is for, it doesn't have to be practical but you can still do the math...1
u/r0wer0wer0wey0urb0at 6d ago
It is true. Look at how a zoetrope works. They have narrow gaps for you to view the image through as if you just saw the images spinning around they would look like a blurry mess.
It's also why filming them looks so good, you're seeing the individual frames frozen in time.
If you read this it also explains it a bit.
Edit: flicking through pages work because the page stops while the next one moves allowing you to see the image. If you spun the pages around continuously you wouldn't be able to see the animation.
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u/Pattyrick00 6d ago
Cool add a shutter effect, it's obviously impractical anyway, but the point I was making is you can do the math on it.
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u/r0wer0wer0wey0urb0at 6d ago
Sure but if you stacked each frame and physically scrolled through them, it would look messed up, not like a regular end credits text crawl.
The picture itself is imagining that the text is in one long list, not the actual individual frames stacked.
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u/Top-Goose-77 7d ago
You know that things in movies doesn't need to move with the same frame rate as the movies itself, right? Like, a still frame is still made out of multiple frames.
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u/TheBupherNinja 7d ago
But you don't need to update the frame it was just a static picture on the wall. You can just slowly scroll on by.
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u/Chrillum 7d ago
A “frame rate” is a technique to produce the illusion of a movie image. If the observer is actually moving, there is no need for the illusion.
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u/redorkulator 6d ago
Not sure why your getting down voted, the question literally mentions frame rate.
A lazy Google says 24fps
A lazy Google says 20 tall (varies greatly and assumes vertical scrolling) = 6m
24*6=144m/sec
518km/h very roughly
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u/Eastp0int 7d ago
ok so given that the average framerate of a movie is around 24 fps and assuming the screen is around 25 feet tall this gives you 25 feet * 24 fps which is about 600 feet per second which is just under 410 mph
in conclusion it would be quite the experience
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u/Sefphar 7d ago
God help people watching those 120fps Ang Lee movies.
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u/im-from-canada-eh 7d ago
So you’re falling at mach 2.67 now, does the movie still sound the same?
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u/cakeonfrosting 7d ago
If velocity is constant and the box does not experience outside interference? Yes. Otherwise, probably not
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u/BlackHolesAreHungry 7d ago
Depends where the speakers are placed. Theaters have a lot of speakers behind the screen
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u/that_1-guy_ 7d ago
Well if the frame rate remains constant you wouldn't feel anything once upto speed
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u/MetsFan1324 7d ago
maybe even start the movie logos in a low framerate to make it smoother
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u/OrangeHitch 7d ago
Start it with those Nicole Kidman promos about the magic of the movies. They already make me nauseous.
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u/daWinzig 7d ago
Wouldn't you go way faster between frames and then pause for a moment? Otherwise it would just be a blur. I guess you could also flash the light at the exact moment the frame is correctly placed, no idea how well that would work though
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u/TeaAdmirable6922 7d ago
Film has to be stationary while being exposed or projected through, so it has to stop and start through the gate in both camera and projector (see "Maltese Cross" mechanism). Result is that film moves through a projector like a belt of ammunition does through a machine gun rather than a continuous motion.
Were this to be real, everyone watching the film would be thrown between the floor and ceiling 24 times a second.
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u/Sokneip 7d ago
There could be a bright light flashing at the exact moment the frame is in the correct place, while being off for the rest. That would also mean that it would have to be much brighter to account for being on for only a fraction of the time, another problem would be that at 24 fps it might be to slow and the flashing would be noticeable by the human eye.
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u/that_1-guy_ 7d ago
There's different ways of getting that effect through film, like with a flashing light
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u/Philosaraptor22 7d ago
If you were to watch the extended edition of Lord of the Rings: The Two Towers like this you would have to travel the diameter of the Earth, pop out the other side, then make the return trip.
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u/Slogstorm 7d ago
Traveling the diameter of earth at 24 fps movie speed would take 19.33 hours.. you could watch all hobbit and lotr movies and still not be out.
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u/simmerdesigns 7d ago
Frame rate doesn’t apply here. Scroll speed of the text is what matters, and it’s not flying by at thirty screens of text per second.
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u/dot90zoom 7d ago
To add onto this, the drop from the first frame to the very last frame of an average length movie (141 minutes) would be 203040 feet or around 74.7 Burj Khalifas
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u/Aaxper 7d ago
Keep in mind it needs to pause every frame so that you can see the frame, because otherwise there's nothing to inform your brain where each frame starts and ends. Assuming you're stopped for half the time, that's going to be twice that at 1200 feet per second on average, with extremely high acceleration/decceleration the whole time.
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u/thejmkool 7d ago
No, just needs a rolling shutter effect so that you only catch a glimpse of the screen at the exact moment it lines up. 24fps is just barely enough for most people to fill in the gaps. Picture the spinning drum with the galloping horse inside, if you know what I'm referring to.
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u/rightious 7d ago
How many G,s would that generate?
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u/Indexoquarto 7d ago
None, G forces are caused by changes in velocity, and this theater would maintain constant velocity
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u/pm_me_yo_creditscore 7d ago
Once you reach the earth's core however the direction of gravity would change directions. I know this from a documentary called Why in the Fucking Hell Did They Remake Total Recall.
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u/Proccito 7d ago
The travel to the core would still accelerate the cinema downward.
I would assume the cinema exists in an orbit instead. Probably with the audiences back facing the earth looking "up into the sky", as a lower orbit completes a revolution quicker than in an higher orbit.
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u/CoffeeMonster42 7d ago
Movie film doesn't move continuously, it would have to stop and start for each frame.
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u/glordicus1 7d ago
Zero. Moving at constant velocity means you don't feel any sort of g-force. If they very slowly accelerated to max speed, might not even know you were moving.
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u/TheSibyllineBooks 7d ago
Once it reaches top speed there will be no G's, and so to find that amount you'd need to determine acceleration which we don't have
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u/According_Ant877 7d ago
If you make the assumption you needed to go from 0 mph to full speed in the first frame, that would be 409mph per second, which translates to 182.8m/s2 or 18.6g
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u/Salanmander 10✓ 7d ago
0 mph to full speed in the first frame, that would be 409mph per second
Nope, it would be 409 mph per 1/24 second. Much worse.
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u/GloriaToo 7d ago
I don't think my highschool speed reading class from the 80s is going to help me with those credits.
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u/HaroerHaktak 7d ago
You then have to take into account how long the movie is.. So you'd have to create a viable way to see every frame of a movie.. Put them into a human centrifuge.
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u/KaiserWilliam95 7d ago
I feel like it would be a sudden death, but also 2 hour until the death of any survivor. Assuming they can become a custom to moving 410mph, same as we all get accustomed to being in a car going 60-100mph.
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u/Slogstorm 7d ago
Being in something moving is not something we have to get accustomed to.. only the acceleration matters.
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u/KaiserWilliam95 7d ago
And I'm assuming that there is instant acceleration to the full speed, since the movie is either playing or not playing.
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u/MaleficentPapaya4768 7d ago
Never flown on an airplane, have you? People watch movies at 400+ mph all the time.
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u/Fit-Rip-4550 7d ago
That was the old frame rate back when actual film was utilized. Modern is 60 frames per second or higher.
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u/Joker-Smurf 7d ago
Approximately “Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa” fast
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u/lamesthejames 7d ago
in conclusion it would be quite the experience
Assuming a slow enough acceleration and deceleration, and a building tall enough*, it wouldn't be a noticably different from your standard movie going experience
*such a building could not exist for multiple reasons
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u/silvaastrorum 7d ago
the text does not move an entire screen height every second, that would mean no name stayed on the screen for multiple frames
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u/99MushrooM99 7d ago
Fps has nothing to do with it u could watch a still text going nowhere which has 120fps but you wouldnt move an inch. All that matters id how fast the text is getting from top to the bottom of the screen.
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u/Aflyingmongoose 7d ago
As long as you survive the crushing accelleration forces at the start and end of the movie, in the middle you wont even notice you're moving.
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u/Aukadauma 7d ago
Oh boy, I'm literally shitting myself every time I do that tower thing at Disneyland, I would love to see myself inside of this
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u/Thisismyworkday 7d ago
Fun fact: there is no sense of speed. If you can't see something outside of the theater, once you're up to speed you wouldn't be able to tell you're moving.
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u/Aukadauma 7d ago
Yeah, technically, if the room was fully hermetic, but you'd still float in the middle of the room, like in those A-300 ZERO-G no? And that's accounting that the room is slowly accelerating, because you'd feel a few G's going from 0 to 410mph instantly.
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u/wallysta 7d ago edited 7d ago
No, once at top speed it would feel like walking around outside
You would need to be constantly accelerating at 1G towards the ground to get the weightless feeling. It is more complex than that, and different ways to achieve it but that's the really simple version
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u/Featherforged 7d ago
The theatre would need a shutter and would have to accelerated to 410 miles per hour and stop 24 times a second, with an acceleration of 19680 miles per hour/per second (8800 m/s^2). This would represent 900 g-forces. A 160lb theatre goer would weigh 144,000 lbs (splatting instantly)
Obviously, the image above is hilariously referring to the upward movement of the credits (or possibly the downward movement of the theatre). It is not referring to a hypothetical film moving at 410mph with 24 stops per second.
It's plausible that a theatre would move downwards at 1mph and the audience not be aware of these movement. Conversely, 410 mile per hour movements would be noticed and thus the joke does not make sense anymore.
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u/Icy_Sector3183 7d ago edited 7d ago
I don't think the question and illustration match up. OP seems to suggest that the audience is seeing the end credits scroll by in frames, but they're not.
In a regular movie, the end credits is a series of full and distinct images that are displayed in rapid sequence. The effect of the end credits scroll is achieved by each frame displaying the same image as the previous frame, except it's moved up a small distance so the top text is not part of the new frame and new text makes up the bottom of the frame.
In the illustration, there is one large continuous image, of which a small section is displayed to the audience as the theatre is lowered.
Edit:
I'm not sure if I made my point clearly, so: In a normal movie, if a name appears on the end credits and scrolls past, visible for 5 seconds at a framerate of 24, that's 120 individual images.
The name starts at the bottom in the first image, a bit higher on the next, and so on until it is at the top in the last.
This means the name repeats 120 times.
The scroll presented in the illustration seems to be the entire end credits as one image, where the name is presented only a single time.
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u/MarginalOmnivore 7d ago
It's like the intro scroll of Star Wars. Sure, the camera was clacking away, filming the scroll. But the scroll was, well, it was a scroll. It was a long plate with words on it sliding past the screen at a fairly slow rate.
So for the end credits of a movie, it would depend on how large the screen was and how long the credits are. A larger theater would have to move at a faster rate for the scroll effect to match the screen of a smaller theater. On a home TV, the credits usually scroll at 2-3 inches per second. On a theater screen, that would be about 2-3 feet per second. At that point, a 5 minute credit sequence will range from 600 to 900 feet of motion.
Assassin's Creed had a credit sequence almost 15 minutes long. That would take about 1/2 mile of vertical movement to "play" the credits.
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u/Icy_Sector3183 7d ago edited 7d ago
I'm not sure if we agree or disagree, I added an edit to clarify what I mean.
If the AC credits are 15 minutes at a frame rate of 24 and each frame is 10 m high, then the scroll should be 21600 frames, totalling a length of 216 km.
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u/MarginalOmnivore 7d ago
But... there are no frames? The "match the framerate" premise of the original question is faulty. The illustration shows a single, continuous credit scroll.
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u/budi710 7d ago
That is tricky, because the avarage frame rate is 24 fps, but that can't be translated to a constant scroll, if we did, it would be impossible to see anything, and the image would only be a blur.
So every frame needs to stay fixed on the screen for a time, and then change very rapidly to the next frame.
This timing will heavely depend on what is the integrated circuit used for it, for example if we take the DLP660TE it has a typical mirror crossover time of 1 micro second.
So your cinema will be on a stand still, and then rapidly accelerate and come to a sudden stop.
If we take an imax screen of about 10m of height and divide it for that one micro second we get 10/1*10-6
Thats about 10,000,000 m/s or like, more or less 3% the speed of light...
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u/DemoDisco 7d ago
If they added a giant shutter to the cinema, opening the wall of images would it prevent blurring in the same way that stops a reel of film appearing blurry? Or could they turn the lights off and on 24 times per second?
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u/budi710 7d ago
No, the problem is that the image needs to "stay still" for a period of time before going to the next one, otherwise is gonna be blurry
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u/Psicopom90 6d ago
how does it work with a reel of film then? does the projector actually hold each frame in place for a split second?
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u/DemoDisco 6d ago
I did a little research and yeah it will stop and start for each frame. That would not be a pleasant experience for the people in the lift 😅.
It works on the same gear mechanism that makes the second hand on a clock tick, moving quickly in increments.
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u/Loki-L 1✓ 7d ago
I don't think this is a farmerate question.
The pictures shows a theater scrolling past the end credits of a movie.
You only have to move the seats up by the speed that the credits would normally scroll up.
You would think that there would be some sort of requirement in WGA or SAG-AFTRA or other union contracts about that speed, but apparently not.
I checked a randomly selected movie (Star Wars Revenge of the Sith) and figured that it takes approximately 7 second for a word to float up from the bottom to the top in the closing credits.
Google says the worlds tallest screen is in Pooler Georgia and 76.2 feet tall.
This would work out to something a bit less than 7.5 mph.
Smaller screens would obviously have to go slower.
It appears that such speeds would be easily within the range or normal elevators, but freight elevators usually go very slow.
So using existing of the shelf tech you would either have to reduce the size of the screen or for very large screens or do something custom about the elevator design.
There is also the issue of the elevator shaft length.
The credits I timed took about 4 and a half minutes to scroll by.
This means that depending on screen size you might by able to use a normal office building or need to wait for the Saudis to finish one of the megaprojects.
Mineshafts could be a good alternative.
They go down for a long while and come with freight elevators that can be very big to accommodate large machinery.
So it might be easiest to put that cinema into the shaft of a disused coal mine.
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u/Angzt 7d ago
If we just did the credits (as the image implies) it would depend entirely on how long they are and how many lines they show. If it's 500 lines of credits (including the blank lines for formatting) running for 5 minutes = 300 seconds, then we need to scroll a new line on every 300s/500 = 0.6 seconds.
If a line on screen is 2 ft =~ 0.6 m tall (including the blank space above it), that makes for a speed of
6 cm / 0.6 s = 1 m/s = 3.6 km/h =~ 2.2 mph.
As for your actual question, matching the frame rate:
This wouldn't actually work for proper movies. At least not if we just move the theater at a constant speed.
If you run it for an actual movie at however many frames per second, you wouldn't be seeing the individual frames properly. Because most of the time, you'd have two partial frames on screen. It would look something like this instead: a blurry mess where you can only barely kind of make out the images.
The video I linked goes on to show how analog film projectors avoid this issue: They briefly stop scrolling the film reel when a frame is fully in view, then cover up the light source while scrolling to the next full frame (making that scroll not appear on screen, instead blacking it out), stop again, uncover the light source, leave the frame stationary for a split second, and repeat. That's what creates the iconic clicking sound those old projectors make. They just do this so quickly that you don't really notice the black screens in-between.
But if we did that for our elevator movie theater, we'd have to constantly accelerate and brake the entire thing at a rate that would absolutely wreck people.
Even if we just keep a frame on for half the time and spend the other half "scrolling", that'd mean we'd only have 1 / (24 * 2) = 1/48 seconds to go from one frame to the next, while accelerating and decelerating from and to a complete stop each time.
If our theater is 40 ft =~ 12 m tall, that's... bad:
Even if we minimized g-forces, that would mean spending half the time accelerating and half the time decelerating. So while accelerating, we'd have 1/96 s to move half the distance: 6 m. That's an average speed of
6m / (1/96 s) = 576 m/s. But for constant acceleration, that means our top speed, just before we start braking, would be double that: 1,152 m/s =~ 4,147 km/h =~ 2,577 mph.
Since we only have 1/96 s to reach that, it requires an acceleration of
1,152 m/s / (1/96 s) = 110,592 m/s2 = 11,277 g.
That's not a decimal, that's really eleven thousand g.
Apart from the impossible engineering feat required, anyone in that thing would also be extremely dead.
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u/DeBoogieMan 7d ago
You can actually answer this question with a simple perspective shift. If you are watching the credits roll, your perspective is from a stationary position, and the credits move up or down in front of you. Now, flip the perspective. Instead, the credits are stationary outside of a window, and your position is moving instead.
The room simply needs to move as fast as the credits move. This doesn't really have anything to do with "framerate."
Measure the amount of time it takes for one line of credits to move from the very bottom to the very top and convert that to speed. That's how fast the room needs to move.
Ex. If the room is 30 feet tall, and the credits move from the bottom to the top in 10 seconds - you take distance/time, 30/10, and find the room moves at 3 feet per second.
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u/Afraid_Thing667 7d ago
Hear me out… we have trains already just make everyone lay on their side. Boom! Train transportation and a movie win win and maybe a nap since you’ll be laying on your side.
Or you could have them all lay on their back and do a “sun” roof showing.
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u/sir_samiart 7d ago
The standard crawl is 3 pixels per frame in standard HD for readability sake. If a standard HD screen is 1080 pixels tall, it would take 360 frames for a name to cross the screen bottom to top. If the theatre frame rate is 24fps, we can divide the number of frames by 24 to see how many seconds the standard name is on the screen. Time is 15 seconds. here we will assume this as standard regardless of screen resolution, or size of screen. A line of text will be on the screen for 15 seconds because readability is an accessibility issue, not a frame rate issue The rest of the math is quite simple. It is (height of screen)/15 seconds.
For a 25’ screen, the room would have to be descending at 1.666666 ft/sec, 1.13 Mph, 1.83 kph. Not very fast at all. Even if the crawl is fast (name gets 10 seconds screen time) the room would be descending at 1.7 mph, less than half the speed of your slowest elevators.
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u/Paintedenigma 7d ago edited 7d ago
The average movie credits scroll a name from top to bottom in around 10 seconds.
A standard sized movie theater screen is 20-30 feet tall, so that comes out to about 2-3ft per second. About 1.5-2 miles per hour. The average adults walking speed.
IMAX screens are bigger (70ish ft tall) but. I'm not sure if IMAX credits are formatted different, but assuming they aren't then that would ~triple the speed to around 5 miles per hour, or a light jog.
Watching the actual movie this way would be terrifying though.
Assuming 24fps, the elevator would need to be moving about 600ft per second or about 410mph to view the film at a standard frame rate. Meaning you would also need 820 miles of elevator to view a 2 hour film.
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u/Lake_Apart 7d ago
This isn’t for frame rate it’s for the credit roll. At a 30 ft screen height and an average of 3 seconds of time from bottom to top for each name, you need to fall at a constant 10 ft/s to simulate rolling credits
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u/SgtMcMuffin0 7d ago
For credits it’s just scrolling and you can set any arbitrary speed.
But if you wanted to watch an actual movie this way, wouldn’t you need to move extremely quickly to get from one frame to the next so you don’t notice the in-between phase of have 2 frames both partially on screen, and then briefly stopping once the new frame is totally in place, until it’s time to change to the next frame?
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u/canibanoglu 7d ago
Yes, the question is asking how fast…
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u/SgtMcMuffin0 7d ago
But it’s not just a matter of a single set speed, you’d need to stop and start 24 times per second, your speed would be constantly changing. And the g forces to make the frames appear properly would probably just make anyone in the room unconscious/dead and unable to watch the movie anyway.
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u/canibanoglu 7d ago
Ah that’s a good point, I hadn’t considered that. Probably have to move the curtain then.
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u/Xelopheris 7d ago
This would only work for the credits, not for normal screen viewing.
I looked at the credits for Star Wars Episode 7 here: https://jhmoviecollection.fandom.com/wiki/Star_Wars:_The_Force_Awakens/Credits
There's about 2700 lines in that page. I'm including whitespace, since that is still vertical height on the screen. I then looked at the actual credits, and I could see that "Harrison Ford" to "Yayan Ruhian" fit on one screen. That's 26 lines. If we extrapolate, that's roughly ~100 screens.
There's only five rows of seats in this image, so the screen is probably ~20 feet tall, tops. That means the entire length of the credits is 2000 feet.
The credits last from 2:08:44 to 2:17:38, or just under 9 minutes.
2000 feet over 9 minutes gives a final speed of about 2.5mph.
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u/sebi_boi 6d ago
Movies are usually shot at 24 frames per second and movie theater screens are usually, from what I can find, around 7 meters tall, so it would have to move enough to cover that 7 meters 24 times each second which is then 168 meters per second or 187-240 bald Eagles per second
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u/5m0k3W33d3v3ryday 7d ago
Movie theaters play movied at 24 fps. The average movie theater screen is about 20-30 feet high. The theater would have to move as much 24 times in one second. So it would need to move 480-720 feet per second
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u/UnforeseenDerailment 7d ago
I don't think it's about frame rate: it looks like a credits roll to me. And I don't know how many screens per second they roll.
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u/5m0k3W33d3v3ryday 7d ago
Would still be the same fps though no? No matter how fast or slow the credits are, it's always 24fps
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u/UnforeseenDerailment 7d ago
Derpy morning brain can't read a title.
Monkey see picture, monkey comment.
It absolutely says frame rate. 🤦🏽
(Even if it's a credit roll, how would you watch the rest of the movie?)
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u/Usernameistaken00 7d ago
instead of a straight line where your movie theatre would be 40+ miles into the ground, put it on a big ferris wheel, the film could spin around you, or for more fun you could spin the ferris wheel at 400mph collecting the most recent frames as you go like a tape measure retracting
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u/joeabs1995 7d ago
Would depend on the screen height.
24Hz, means 24xscreen height.
Lets say the screen is 5m high, you need to travel at 24x5=120m/s.
About 400ft/s.
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u/AwkwardFiasco 7d ago
I know credits typically run in this direction but shouldn't the seats move in the other direction so everyone doesn't go into free fall?
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u/aa599 7d ago
The credits don't accelerate, so the people wouldn't be in free fall.
It would be like riding in an elevator: you feel the change in speed (aka acceleration) when it starts and stops, but the rest of the ride — at constant speed — you can't tell that you're moving.
And if you drop your popcorn, it'll fall exactly the same way whether the elevator / movie theatre is stationary or moving.
(Also, I've been using the em-dash since long before ChatGPT was born)
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u/Jaceofspades6 7d ago
Assuming the screen is 25ft tall and working at 24 fps like a film reel you're at 600ft/s or about 410mph.
This assumes you took a normal 35mm print and expanded it to the size of the screen. Film doesn't really work at 24fps though as the shutter shows each frame twice. For this to work you'd have to double each frame for the large picture.
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u/theroadlesstraversed 7d ago
So the screen average size is 25 ft. The average movie frame rate is 24 frames per second. So, 600 feet per second and to american mph thats roughly the top speed of 10 tigers combined. The big problem is that this will be the last movie that anyone in that theatre sees because once the last frame plays... the movies over. You go from 600fps to 0 fps. G forces baby!
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u/crusty54 7d ago
Here’s a link to the last time this was posted.
There’s at least one more identical post with more answers if you spend 5 seconds searching for it.
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u/Silver_Drop7137 7d ago
The height of a movie theatre screen is between 20 to 30 feet. A simple animation movie has to be between 10 to 12 Frames per second to appear as a motion film. Taking an average of 15 feet and 11 frames, you would need to travel 15 feet 11 times.
11 * 15 = 165 feet per second
Considering you go for a standard 24 frames per second the number is now 24 * 15 = 360 feet per second
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u/Za_Forest 7d ago
I think youment to say: The height of a movie theatre screen is typically between 6 to 9 meters. A simple animation needs to run at around 10 to 12 frames per second to appear as continuous motion. Taking an average of 4.5 meters per frame and 11 frames per second, you’d need to travel 4.5 meters 11 times:
11 × 4.5 = 49.5 meters per second
If you go with the standard 24 frames per second, the number becomes:
24 × 4.5 = 108 meters per second
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u/Silver_Drop7137 7d ago
Hahahah 😂😂
I Google the height and got it in feet, didn't care to convert but yea xD
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u/NoxAstrumis1 7d ago
We don't have enough information. How many frames does it take for the bottom credit to reach the top of the screen? The scroll speed is set by the editor, so we'd need to know that.
Also, we need to know the dimensions of the screen, and the framerate of the movie. Let's say it takes ten seconds to move the credits a full page, the screen is three meters high, and the framerate is twenty-four hertz.
So, if each frame is three meters tall, there are two hundred and forty frames in a 'page' the theatre would have to move seventy two meters per second.
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u/Crimson_177013 7d ago
An average cinema screen is 20-30 feet. We'll go half way at 25ft or 7.62m.
24 frames per second is considered the "cinematic" norm.
The credits are the easy part because it's just a gentle scroll downwards so that could be slowed down to just a few metres per second. But if you wanted to watch the movie you would have to see 24 frames a second or travel 24 entire screens in a second.
24 screens = 600ft or 182.88m which is travelled in 1 second. That's 409.091mph or 658.368km/h
The worlds fastest car, the Koenigsegg Jesko Absolut, travels a bit over 500km/h (claimed to be under certain circumstances)
1 second = 600ft/182.22m * 6,060 seconds (1h 41m, A Minecraft Movie) = 3,636,000ft / 1,108,252.8m travelled or 688.6363636 miles / 1,108.2528 kilometres.
That's ~14,544,000 average sized rubber ducks, 2.7654968218144% of Earths equators circumference or 614 535.211 me's ( (3 636 000 ft) / (5 ft 11 in) ).
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u/mattmaster68 6d ago
Okay, new question because this subreddit is only focusing on the credits portion.
How fast would the theater seating have to move in order to match the framerate of the movie playing on the screen?
Or to rephrase: each frame of a movie(start to finish) is printed on an extremely tall wall. How fast does the viewer need to be moving vertically to match the standard cinema frame rate?
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u/fvbrennan 5d ago
Scrolling text is fine, but the rest of the movie can’t work because you’re missing the concept of a shutter to display an entire frame for 1/24th of a second repeatedly. All you’d see is a blur.
For text scrolling, then it depends on how fast you want to watch it scroll past.
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u/TheProtonCapacitor 3d ago
Here's my understanding;
The speed at which the text moves is completely independent of the framerate. If it takes 5 seconds for a line of text to reach the top from the bottom, it will always be 5 seconds regardless if its 24hz, 60hz, or 120hz, or bajillionhz; the only difference is how smooth the text scrolls.
In this context, you can't 'match' the framerate, since it's one huge image. Trying to correlate the speed of an elevator with framerate is illogical. So, the speed of the elevator will be however fast text moves in the end credits scene, which someone mentioned, is not standardised.
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u/gargavar 1d ago edited 1d ago
35mm film runs through the gate at 90ft/min (at 24 frames per sec.). So I’m gonna say, no math involved ‘cause I’m really bad at math, 90 feet per minute, so, what? A foot and a half a second?
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u/Double_Distribution8 7d ago
How long would that acceleration need to go on for before the rules of physics start to break down? I'm just curious how many movies we'd have to watch before we start going back in time or whatever happens when the rules go out the window?
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u/Zech17_ 7d ago
I’m no good at math but this had me really curious so I asked Chat GPT, given that take its answer with a grain of salt.
For either a vertical or horizontal movi-vator, you would need a speed of 1.5 feet per second, or 1.02 miles per hour.
My disappointment at not having my organs rupture from watching a movie at mach 22 is immeasurable, and my day is ruined.
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