r/Damnthatsinteresting • u/NoWork215 • Jul 16 '26

Video The Odyssey IMAX 70mm Setup

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u/thomasthedude Jul 16 '26

some cinemas do that, when I went to the latest avatar movie, the audio was out of sync and when they were fixing it you could see they used VLC

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u/justjanne Jul 16 '26

While that can happen (sometimes cinemas can actually get a license to show a movie off a bluray disc), typically there's dedicated playback servers showing a much higher quality version of the movie (think about 600GB for a movie).

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u/Away-Way5656 Jul 16 '26

what are they doing storing every single frame as a uncompressed image?

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u/justjanne Jul 16 '26

Pretty much! Every frame is a separate JPEG2000 at almost lossless quality.

That's 10× more data than a typical 4K UHD Blu-ray, with 64 times more color depth than Dolby Vision.

And the sound is for trailers typically uncompressed 5.1 surround, for most movies 1024 channels of lossless Dolby Atmos, or with IMAX lossless 12.1 surround.

e.g. here's a 3 minute trailer in 2048×1080p, aka DCI 2K or 1080p HD, at 3.4 GB filesize: https://archive.org/download/avatar-2009-official-trailer-2k-prores/AVATAR_TLR-B-2D_S_EN-XX_51_2K_20091108_SMPTE_OV.zip

That should give you a feeling for why movies in cinemas look so much better than at home.

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u/retiredalavalathi Jul 16 '26

That should give you a feeling for why movies in cinemas look so much better than at home.

I've never felt that. Picture quality is always crisper on a TV screen than a cinema screen.

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u/justjanne Jul 16 '26

Interesting!

For me, even Blu Rays will look slightly softer on my OLED at home than in the local IMAX cinemas.

I'm only able to match the crisp cinema look where every piece of film grain is perfectly sharp if I actually play DCP packages at home.

It's possible your cinema is just not up to spec, which is sadly common (and part of why cinema has been dying for almost a century now)

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u/yamoth Jul 16 '26

That is because the theater screen on average measured 800 inches diagonally whereas most people home TV screen average 65 inches. Same reason why a 1080P youtube video look better on your phone screen vs your 4k 27" monitor.

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u/mrminutehand Jul 17 '26

Mostly feel the same, though for IMAX in particular. The Manchester Printworks Vue (UK)'s 70mm IMAX presentations usually have film noise or slight blurriness in general, though that's probably more to do with the film itself as opposed to projection quality.

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u/BeersTeddy Jul 17 '26

Not a rocket science when 85" TV which already shows poor compression in 4k is probably 2m while imax is 22m.

Also the distance from 85" is still labour 3-6m

Whike in cinema you don't really sit 50m aways from the screen

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u/SagittaryX Jul 16 '26

Compared to streaming yes, that's a noticeable difference to quite a few people. But I doubt that if you played that quality vs a 4K BluRay on the same screen that there is that huge of a difference that people would notice.

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u/VexingRaven Jul 16 '26

Of course, but that's the point right? They're not playing it on an 85 inch screen. They're playing it on an 85 foot screen. It needs to be perfect.

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u/Zac3d Jul 16 '26 edited Jul 17 '26

It needs to be perfect.

Last time I went to the movies the projector screen was dirty. Which meant the brighter the image, the more apparent any flaws in the screen were. And also the black levels for projection just sucks compared to a modern OLED. Flaws of a theater are more apparent than what Blu-ray compression would be.

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u/ZooAreYou Jul 17 '26

Theres one cinema we go to where some prick clearly threw a milkshake at the screen and apparently the cost to clean it is somehow too much for the cinema to bother with. As you say its noticable in bright scenes. Its like an infuriating dead pixel once you know about it.

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u/SandpaperTeddyBear Jul 16 '26

It truly doesn’t matter, because you’re sitting so much further from the 85 foot screen.

My understanding of the development “HD” format is that it was more or less designed to be similar to sitting in the middle of a movie theater watching a normal screening print. My experience of having watched movies off of a 35 mm projector for many years, followed by some years of watching standard blu rays get sometimes played in movie theaters, is that they got it about right.

The one exception is well-shot black and white movies, which have much more dynamic range than the HD blu ray format allowed for, but 4K UHD discs are basically reference quality even for those.

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u/FrozenLogger Jul 16 '26

Or just good enough. I haven't been able to find a theatre that gave a shit in years. Even IMAX.

Looks better at home.

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u/ExultantSandwich Jul 16 '26

Have you actually been to an IMAX theater? The US has 14 screens, NYC has exactly one. California has two for the entire state

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u/42nu Jul 16 '26

Wait, are we talking the IMAXs that are a giant dome and more likely to be part of a science museum?

I could see there only being 14 of those in the US.

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u/justjanne Jul 16 '26

IMAX is a weird, overloaded term.

There are only 41 IMAX film cinemas in the world (which are also the ones showing the Odyssey on film).

There are hundreds of IMAX Laser cinemas, which often also have the same aspect ratio, same size screens, and just slightly less sharp image.

And then there's all the shitty cheap regular cinemas that have an IMAX label attached but did nothing to earn it.

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u/LeedsFan2442 Jul 16 '26

There are very few cinemas that are truly IMAX and actually use 70mm film projectors

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u/FrozenLogger Jul 16 '26 edited Jul 16 '26

Yep, many times actually. The angle of the seating and size of the screen is the amazing part. But it seems like the quality of those isnt what they used to be.

Funny thing about IMAX, is they are not all the same. They really should be if they are marketed as IMAX.

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u/dragonbud20 Jul 16 '26

You're either partially deaf, partially blind, or you've never been to a real IMAX theatre with an actual 70mm projector.

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u/FrozenLogger Jul 16 '26

OR enshitification is everywhere, i have a great home system, my viewing angle is perfect, the screen is kept clean and my proximity matters.

Again, been to many IMAX theatres they are not all the same, but even the best ones just dont impress me that much.

But speaking of 70mm, that used to not be an uncommon format. Approx 150 theatres in the US in the 60's and 70's. Nowdays it is mostly IMAX.

There was a LOT lost by creating all these dinky little movie boxes that are everywhere today. IMAX at least makes up for that.

Well at least the ones that actually are 70mm. A lot of IMAX are not. Scammy little company.

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u/Redthemagnificent Jul 16 '26

I agree with 90% of movies. But a properly mastered IMAX movie is legitimately a different experience. Every once and a while I think it's worth it

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u/[deleted] Jul 16 '26

[deleted]

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u/skepticalbob Jul 16 '26

That's a big movie theater.

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u/slonkulocuswily182 Jul 16 '26

Streaming’s data rate is incredibly low quality.

The picture relies on your tv/phone to sharpen the image.

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u/InvidiousPlay Jul 17 '26

That's not correct at all. Most devices do very little on the fly "sharpening"; it's not an effective strategy anyway, you can't magic away compression artifacts.

Compression algorithms are just extremely efficient at keeping half-decent images even at awful bitrates.

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u/Comprehensive-Mud373 Jul 16 '26

Yeah, why like have different quality on video at all? What's the reason of having 2160p 4K when 480p is more than good enough on my phone? /s

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u/Fooly_411 Jul 17 '26

I bet you would easily notice the difference on a large theater screen in the dark. There is a vast gulf of what is noticable to the eye with that set up vs even high quality TV panels.

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u/orthogonius Jul 16 '26

1024 channels of lossless Dolby Atmos

How many speakers does your local theater have‽

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u/justjanne Jul 16 '26

Most cinemas have usually something like 64 actual speaker channels, but that's the point of Atmos (or DTS:X), object-based surround sound automatically mixed for whatever speaker configuration the local cinema has.

(In contrast to the old times, when cinemas had 5.1 channels with 5-10 speakers per channel)

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u/LightShadow Jul 16 '26

cinemas look so much better than at home

Only if the projector is in focus...which is a real problem around here.

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u/LikeALincolnLog42 Jul 16 '26

The movies at my local AMC look like total shit unless you’re in one of the only two big auditoriums. The other 14 screens are complete and utter crap. They’re unbelievably dim, and no amount of polite complaints to the local staff or via their website has resolved it. Thanks, AMC! /s

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u/WantonKerfuffle Jul 16 '26

So that's what it takes to squeeze the maximum amount of quality out of our current technology.

...only for me to go "wow that is uncomfortably loud" as my main takeaway comparing the cinema experience to a BD at home.

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u/rIceCream_King Jul 16 '26

That’s fascinating, thank you for sharing.

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u/LickingSmegma Jul 16 '26

The hell are you gonna do with 1024 audio channels? Are you mixing them with 1024 sliders, with near-analog precision?

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u/Redthemagnificent Jul 16 '26 edited Jul 16 '26

Its done with software using object-oriented sounds in 3D space. "dolby atmos" is one example of such software.

The idea is you want the your explosion sound or whatever to sound like it's coming from the same direction with the same volume in every theater no matter what the speaker configuration is. So instead of a fixed master track tuned to a specific speaker layout, the audio system gets a command saying "make this sound come from XYZ coordinate in your theater" and it does some processing in realtime to figure out the exact volume and timing (phase) each speaker needs to use to fullfil that command.

To come back to your question on the number of channels, that defines your maximum resolution. More channels = more precise beam forming. Idk about the 1024 number. That does seem to high to me. But idk, it's possible. Audio processing is cheap these days

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u/LickingSmegma Jul 17 '26

Interesting, thanks!

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u/justjanne Jul 16 '26

Basically, once you go beyond 12.1, each cinema will have a different speaker configuration.

So instead you have each individual object as a separate track, in the scene positioned in 3D space, and typically a Dolby Atmos processor that then mixes that automatically for the specific speaker configuration of each cinema.

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u/LickingSmegma Jul 16 '26

So indeed pretty much close to what I was imagining. Except hopefully you just specify how your speakers are positioned in some kinda virtual room, and the thing calculates the mix itself.

This must be a nightmare for the studio's audio engineers too. I'm gonna guess most films don't use anywhere near the whole 1024 channels.

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u/Specialist_Bad3391 Jul 16 '26

All that and then you have an uncalibrated projector with chromatic aberration all over the picture. Totally skewed and flickering luminosity.

That's where I saw backroom. At least half the time there was a vhs look over the image so the poor image quality wasn't so important. But come on, if I'm paying 15 for a 2h screening theater better up their rig

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u/justjanne Jul 16 '26

And if you're in a non-english country, the sound is often also dubbed.

There's a reason why I only watch movies either in IMAX with Laser 4K in the original language, or at home (with an OLED and proper Dolby Atmos 5.1.4 system, not a soundbar).

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u/piss_puncher227 Jul 16 '26

Too bad the movie is shit then.

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u/AllEncompassingThey Jul 16 '26

I feel like when you bought a ticket to The Emoji Movie you knew what you were getting into

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u/GloriousNewt Jul 16 '26

Awww did all those positive reviews hurt you?

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u/Nolis Jul 16 '26

Usually the contrarians who just sort by top to find a bunch of movies they've pretended they've seen and pretend they don't like at least try to copy and paste points they've seen from negative reviews online, it's funny that you guys just literally can't find any for this movie lol