A local theater recently switched to digital projectors and it’s my understanding that they download the movies rather than get them shipped on a drive.
I’m curious what size a typical movie might be (for instance, I recently saw Dredd). The girl at the counter couldn’t tell me.
A related question necessary to know how big the file would be:
If the starting file is 225GB for a 2hr film, what is the range of compression which can be expected in most cases?
I know that it depends on the content and the acceptable loss of quality but for most content, how much does compression actually compress?
I’ve seen 720p, 22 minutes episodes of Modern Family which were anywhere from 550MGs to 750MGs. Extrapolating from that, it seems a 2hr 4K would be in the 15GB to 25GB range.
A cartoon like MLP in 1080p for 22 minutes is usually in the 450MGs to 550MGs range. Extrapolating that gives us about 9GBs to 11GBs for a 2hr 4K.
Is someone more knowledgeable about video compression capable of telling me if my extrapolation is off?
Why would a cinema compress it?
Your math is fine but as already noted, there’s no reason for a cinema to use compression and lots of reasons not too. I’m no video expert but even I notice artifacts introduced by compression, most noticeably slow pans and zooms tend to get jerky and I’m sure that there are others that I simply don’t notice.
Is 4k standard for digital films, or is it higher/lower than normal?
It seems from beowulff’s link that they do compress it:
In its currently uncompressed format, a two-hour film would take somewhere between 1-2 terabytes
The figure of 225GB is for the current maximum of “250 Mbits/sec for a JPEG2000 compressed 4K image”. You’re probably not going to see many artefacts at bit rates like that.
The RED ONE digital cinema camera shoots at 4K, and RED is currently one of the film industry favourites.
Depends upon the compression. The compression we see in home settings is quite severe, and it is little surprise we see artifacts. Digital cinema uses JPEG2000, which is a much more advanced compression system than the block based compression you are used to with DVD or Blu Ray. Most importantly, jpeg2000 does not use motion based compression, it has a separate full frame for every movie frame - so motion compression artefacts don’t occur. You can get a compressed video stream that is indistinguishable from the original. Jpeg2000 also include encryption and ownership, something the studios are going to want.
And it allows for lossless compression, if desired.
Which, at 300 baud rates of 30 years ago, would take almost 200 years to download. :):eek:
Is all digital cinema being done by download now? I just messed around with a download calculator, and unless the theaters have T3 service, it will take the better part of a day to move those files. If you wanted to leave them uncompressed, Andrew Tanenbaum’s commentary* on bandwidth once again comes true, and FedEx becomes the faster way to move the bits.
If the movies are being shipped to theaters on hard drives, why would they use *any *compression at all? It doesn’t take any longer to transport uncompressed files as long as they’re all in the same box, and one terabyte drives are cheap.
** Never underestimate the bandwidth of a station wagon full of tapes hurtling down the highway.*
Today, it’s more likely to be a box of DVD-Rs in a 747, but the point is it’s often far faster to move data physically rather than electronically.
Why wouldn’t they have a T3? It’s not THAT expensive. $200/monthly isn’t that much for a business.
Also, a large 20-screen cineplex might show 30 or 40 different movies a month, at the very, very most. That basically works out to one download a day or less. That’s not going to cause a bandwidth problem, even with only a fairly fast residential-type internet connection. Granted, they are going to destroy any download limits, but some ISPs don’t have those, especially for business-class connections.
Also, if they show 30 movies a month, that’s about $15 EACH to have them shipped. You’d need a full size 250 GB hard drive for each of those, and shipping those very far is at least $15 or so. The internet connection is already slightly cheaper, at that point.