Author Topic: IMAX going to digital media?  (Read 1679 times)

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Offline Technowraith

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IMAX going to digital media?
« on: May 10, 2010, 07:13:35 am »
This is more or less a discussion technology relating to viewing Avatar, not how it is made or a behind the scenes feature. I didn't know where else to put this, but it can be moved if needed. :)

In other threads, there has been mention that IMAX 3D has some limitations. The most obvious is feature length. This is due to the physical capacity of the film reels on the IMAX projector. You can only fit so much film on the platters! It's been discovered that Avatar has pushed the IMAX projector to it's limits due to length. So as it stands as of this moment, an extended edition of Avatar may not be available for IMAX viewing.

A possible solution to this (if hollywood isn't already on it) would be to convert the media to digital. Instead of a reel-to-reel film, why not a digital disc, essentially a mega-dvd? or a couple mega-dvd's? Obviously DVD's have a capacity limitation, but with blu-ray and enhanced encoding and processing, IMAX films could possibly migrate to digital media. It would solve the problem of length (as inherently, length becomes a non-issue with digital media, so long as you have enough capacity). This obviously requires a bit re-work to the IMAX projector, both internally and software wise. Another option would be a direct stream to an on-site high capacity server located in the projector room. Store the film on the server hard disk and stream it directly to the projector. 

This seems like a viable solution if hollywood wants to have extended full length features playing in IMAX.

Thoughts and concerns?
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Offline Kerame Pxel Nume

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Re: IMAX going to digital media?
« Reply #1 on: May 10, 2010, 07:26:21 am »
As Avatar has been shot and produced entirely digital, there's not much need for conversion. In fact the IMAX 3D version is a computer to film converted version. The next important thing to know is, that Avatar has been produced in 2K digital cinema, which is 2048x1152 resolution, which is only slightly more than what you got on the BluRay.

Now the BluRay has the full picture. IMAX has a smaller aspect ratio, so the image got cropped on the sides, whereas the cinemascope version was 2.31:1, thus a wider aspect ration, and thus cropping the full frame on the top and bottom.

Or in other words: The image quality you have on the BluRay is more or less the one you got to see in the cinema. And converting the digital image to IMAX 3D won't increase the picture quality, as there's just so much information. You could as well put a bunch of Christie high luminance digital projectors into an IMAX auditorium and will get about the same quality in digital, which is what Digital IMAX is. To really take leverage of the IMAX projection system you'd have to shoot with IMAX cameras and render in IMAX resolution - which hasn't been done with Avatar.

Offline Ilisaqpuq

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Re: IMAX going to digital media?
« Reply #2 on: May 10, 2010, 08:40:58 am »
The above post pretty much covers it, but digital projectors with the ability to illuminate as full IMAX screen would be horrendously expensive to install just for Avatar (most other IMAX features would still be shot in true IMAX film format, not converted from digital).
« Last Edit: May 10, 2010, 08:45:25 am by Ilisaqpuq »

Offline Roiki

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Re: IMAX going to digital media?
« Reply #3 on: May 10, 2010, 08:30:57 pm »
As Avatar has been shot and produced entirely digital, there's not much need for conversion. In fact the IMAX 3D version is a computer to film converted version. The next important thing to know is, that Avatar has been produced in 2K digital cinema, which is 2048x1152 resolution, which is only slightly more than what you got on the BluRay.

Actually avatar was filmed with two Sony CineAlta HDC-F950 cameras that have a resolution of 1920x1080, in other words full HD. IMAX is around 6120 × 4500 actually discernible pixels.

Many theaters are increasingly converting themselves to digital(mostly with 2K projectors) which decreases digital->film conversion, here the movies and their soundtracks are delivered in separate encrypted hard drives and then sync'd with a time-code. Right now only certain bits of big-budget movies are shot in IMAX, the special film stock being about 10-20 times more expensive than regular 35mm, or about 200 times more expensive than digital storage. They are developing a digital IMAX camera, which should make the production easier. However since even IMAX digital uses 2 2K projectors, i don't see this to be of any benefit.

And the real problem about the length of a movie in IMAX format isn't so much of the length, but the weight it brings with it, since platters with a 2.5 hour feature film will weigh 250kg. Talk about a logistical nightmare.
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Offline Technowraith

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Re: IMAX going to digital media?
« Reply #4 on: May 10, 2010, 11:08:25 pm »
Guessing an IMAX feature film must take up terabytes of disk space. There are 1-2 Terabyte hard disks out there. I'm sure heavy duty industrial drives exist, and their capacities must be near the 5-10TB range. Gigabyte hard disks were made available to industries like data centers and corporate servers before they were offered to the public. So i'm guessing the same may be true for Terabyte drives. Where i'm going with this is IMAX feature films are encoded onto the encrypted hard disks and fed to the projectors from the hard disks. If the film can not fit onto a single hard disk, then multiple hard disks can be used i'm guessing?
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Offline Ilisaqpuq

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Re: IMAX going to digital media?
« Reply #5 on: May 11, 2010, 12:18:14 am »
Storage space for digital would not be a problem, the movie would be split up into harddrive-sized files, put onto said hard drives, put into a transport-ready assembly, and once at the theatre, read by a custom bit of software that pulls them together as they're being decoded for display (probably with some RAID thrown in for bonus access speed). After digital high-resolution films become popular some company will probably come out with a de facto standard method for secure and reliable delivery of films to theatres.

Offline Kerame Pxel Nume

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Re: IMAX going to digital media?
« Reply #6 on: May 11, 2010, 01:50:52 am »
Guessing an IMAX feature film must take up terabytes of disk space. There are 1-2 Terabyte hard disks out there. I'm sure heavy duty industrial drives exist, and their capacities must be near the 5-10TB range.
Industrial "heavy duty" drives aren't so much about big capacity, but high durability under high loads.

Digital cinema is stored in form of a flat series of JPEG2K image files, one image for each frame, and Broadcast WAV files (Broadcast WAV are ordinary WAV files with a specific set of settings, i.e. channel assignment, 48kHz or 96kHz sampling rate, 24 bits per sample). For 3D cinema a special stereoscopic flag is set in the metadata, which tells the projector to send all even numbered frames to the left eye and all odd numbered to the right eye. The movie itself is then stored at the double framerate and left and right frames full frame interlaced (it's not that annoying line interlacing you know from DVD and old TV)

A typical feature film takes about 1TiB of space, Avatar 3D takes 3TiB. No problem here: Disks are cheap, for 1k€ you can have 20TiB storage.

EDIT: Fixed a typo
« Last Edit: May 27, 2010, 03:02:30 pm by Kerame Pxel Nume »

Offline Roiki

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Re: IMAX going to digital media?
« Reply #7 on: May 11, 2010, 04:39:05 am »
After digital high-resolution films become popular some company will probably come out with a de facto standard method for secure and reliable delivery of films to theatres.

There already exists an industrial standard, Digital Cinema Initiatives, that's a common digital theatrical distribution method for motion pictures from every major publisher.

I doubt it has changed much since 2007, but back then a normal feature film could fit in a 300gig hard drive.(hard to imagine those were the biggest you could get in 2005).
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Offline txe'lan tírol

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Re: IMAX going to digital media?
« Reply #8 on: May 27, 2010, 02:19:46 pm »
There is a company called Red Digital Cinema that makes a modular camera system that is capable of shooting RAW 4K Video at 30 FPS and lower resolutions at much higher frame rates. (like 2K video at 120fps).

 

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