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Comment by greenknight | Hacker News Reader

Fun fact, whenever you go to the movies, films (that are projected digitally) are encoding in JPEG2000 (wrapped in a MXF in XYZ Colourspace).

We also use it for our 3D renders for archviz, and is supported in our editing applications aswell... lower filesize compared to PNG, and better quality compared to JPG, and also supports alphas.

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JPEG2000 is big in medical imaging as well.

I'll mention libraries and museums as well. Instead of having a tiff available of high quality record images, some institutions use jpeg2000 and a zoomable js library like openseadragon.

In this case, the jpeg 2000 is probably considered a derivative and thus not a big issue for preservation.

In other words, motion JPEG2000, and it's decoded by (no doubt extremely expensive) hardware. There's no way a general-purpose CPU can decode in realtime otherwise.

This benchmark is showing 4k decoding on commodity hardware from 2018 fast enough for movie theaters. https://www.fastcompression.com/benchmarks/decoder-benchmark...

So, presumably they could have swapped to commodity hardware a while ago.

With a Windows Update banner and forced reboot right at the climax of the movie.

Commodity hardware doesn't require Windows...

Though lets be honest, they'd probably use Windows anyways and that probably would happen.

A couple months ago, I've been to a 2020 anime feature film in a cinema here in Estonia. To my amusement, after the credits I was greeted with the VLC interface for a brief moment (though they've turned off the projector very quickly after that).

Edit: obviously, that's not how most movies are shown here :D

I wonder if that was because that film's distributor is relaxed about DRM, or if the cinema just decided not to care about licensing it assuming that an Asian (I guess) IP holder would be unlikely to find out or take legal action against a small cinema in Estonia?

It’s almost worse than that - the common commercial playback servers I’m familiar with run Linux 2.6.x and fail in all kinds of weird and wonderful ways!

The fastest decoder there uses the GPU, not the CPU.

The fastest one that runs on a CPU, Kakadu (proprietary), is far behind.

CPU or GPU it’s still commodity hardware.

> The fastest decoder there uses the GPU, not the CPU.

How does that matter? It was a reply to your incorrect claim:

> it's decoded by (no doubt extremely expensive) hardware

See here: https://news.ycombinator.com/item?id=32136471

The issue for commercial cinemas is not necessarily handling storage and playback of DCinema packages - it’s the DRM that the studios insist upon playing nice with the projectors. Most cinemas converted their screens at least a decade ago, financed partly by distributors, and the industry is sort of stuck in time as a result.

The digital cinema projectors have hardware JPEG 2000 decoders. This IP is licensed from companies like IntoPIX:

https://www.intopix.com/JPEG2000

Most post-production software that reads/writes DCPs will be using a GPU JPEG2000 encoder & decoder, like this from Comprimato:

https://comprimato.com/products/comprimato-jpeg2000/

we use comprimato which can use the GPU. It's very performant

Do they really use straight up XYZ? Where can I read more about this format?

Appears to be this https://en.wikipedia.org/wiki/Digital_Cinema_Package

I think people mis-estimate file sizes these days - two hours of completely uncompressed 4K video is under 5 TB. Fits on a basic consumer external hard drive no problem. Send it by mail.

https://toolstud.io/video/filesize.php?width=3840&height=216...

Well, two hard drives in RAID-0 if you want to play it back in real-time without copying it first to faster storage, because a single SATA drive cannot sustain 597.2MB/sec. Unless your definition of "basic consumer external hard drive" is an NVMe SSD over 10Gbps USB 3.2 or better.

As the thread says - it’s compressed. I’m giving uncompressed sizes as an upper bound.

The GP is pointing out that storing an uncompressed film isn't useful if it can't be played back. Playing back an uncompressed 4K film is nearly 600MBps. That's a data rate you're not going to get out of any consumer HDDs.

But they're not uncompressed. They're compressed. You don't need to play them back uncompressed. You can even compress them losslessly.

I probably wouldn't call it "basic", but aside from that, https://www.amazon.com/Sabrent-Rocket-Thunderbolt-External-S... seems to fit the bill fine.

How common is 4K at 24fps though? I'd expect 4K to usually use higher framerates than that.

24fps is still standard for movies, in part because people have associated higher framerate video with amateur home video recordings so it looks cheap. :)

To elaborate on this, higher frame rate video registers the same way to people who aren’t aware that’s what they’re noticing. I was discussing this with my dad just a little over a week ago, where he noted some portion of a movie looked lower production than the rest of the movie. I had noticed it too, because it was visibly higher frame rate. Lower frame rates more closely match the visuals of film, and higher frame rates more closely match the production of daytime TV like judge shows and “soap operas”, and that’s what they visually evoke.

Thankfully this changes with latest generation brought up on 60fps YT and Twitch.

> I'd expect 4K to usually use higher framerates than that.

They tried higher frame rates with for example the Hobbit, remember, and lots of people didn't like it for some silly reason.

Sadly, I was going to reply with "daily" because of this

In what way is it interesting to note that the format is used by someone, somewhere, for something?

That much is a given, and addresses none of the article's points.

It was interesting to me.

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