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Ever-Emerging Digital Theater Technology

May 3rd, 2006 by Multimedia Mike

IMDb Studio Briefing has another in a long line of articles detailing how all movie theaters are about to go digital anytime now. Paramount Going Digital with ‘M:I 3’. I remember about the time that Star Wars Episode 1 was coming out in 1999, George Lucas was promising that by Episode 2’s release in 2002, everything would be digital.

Has anyone thought about what this means to unauthorized distribution (colloquially referred to as piracy)? If the studios think it’s bad with the current 0-day distribution, wow…

Seriously, does anyone give any thought to how this would work, the technologies driving it all, and weaknesses in the chain? I just want to think out loud here for a moment.

A lot of the intelligence I have gathered on this subject over the years has come from news snippets. Naturally, that’s not very solid source information. Invariably, they describe a system where a number of theaters are refitted with revolutionary, state of the art, digital projection systems. The resolution of these systems is somewhat in flux but let’s use the figure of 4096×2160 pixels which comes from an IMDb Studio Briefing from over a year ago: Landmark Theaters To Go Digital. Where does the movie content come from? Forget the reels. The content is usually reported to be delivered over satellite somehow. That still sounds high-tech, though I have not seen any figures lately on how satellite transmissions compare with land-based communications methods in terms of bandwidth. Because, let’s face it, there is going to be a lot of data to move. I heard from someone that he had heard somewhere that they were actually planning to distribute the video uncompressed! Not an especially reliable piece of information, but let’s run with it for the sake of argument. Let’s assume that astounding video resolution mentioned above, with YUV 4:2:0 video (average 12 bits/pixel) and 24 frames/second, for a 100-minute movie:

(4096 * 2160) pixels/frame * 12 bits/pixel * 1/8 byte/bits * 24 frames/second * 60 seconds/minute * 100 minutes/movie = 1,911,029,760,000 bytes/movie

So, nearly 2 terabytes just for the video requirements. See, this is why people have invested so much effort in this thing called “compression technology”. Let’s not discount the fact that some people insist that this is the perfect opportunity to make movies 60 frames/second and the requirement goes up to around 4.7 TB. And why stop at subsampled chroma planes? Send across full color information which means 24 bits/pixel and double the requirement again. And don’t forget 8 or 16 or however many channels of uncompressed, 24-bit, 192 kHz audio. You get the idea. Oh, and then there’s the opportunity to make various subtitles available separate from the actual video. This would need to be its own alpha channel capable video stream needed for curious effects as demonstrated by certain recent Russian supernatural horror movies.

So we can assume that there is a whole bunch of data that somehow needs to get from the studio to the theater when release time arrives. The details here are a little sketchy. As mentioned earlier, the articles usually claim that they would prefer to broadcast encrypted content via satellite. News snippets seem to imply that the theater never stores any data related to the movie, that all showings are coordinated via a central studio authority and broadcast in realtime for projection. At least, that’s the impression I gained from the earliest articles on the matter. It makes more sense for the studio to transmit the movie to the theaters just before release so they can verify they all have it ready to run. If the studios employ some modest compression scheme they might even be able to use some BitTorrent-like method for theater distribution.

I’m certain the system will use some kind of encryption, probably AES to protect the actual content. For efficiency, there will be one master encrypted copy of the data and each theater will have its own public/private key pair with the studio which will allow the theater to unlock the the AES key to decrypt the data for presentation.

What will this projection system look like? I don’t know the exact hardware requirements (maybe a mirrored RAID to make sure no movie pieces drop out) but it’s a reasonable wager that the machine will be Windows-based. Everything is. It will probably be a Windows machine with custom software that knows how to talk to the studio mothership, download the content, decrypt it, play some pre-programming commercials, trailers, and anti-copying propaganda, and then play the movie. Don’t laugh about the Windows hypothesis. You all know its stability has vastly improved over the years. That said, if it’s a stock Windows installation it will only be a matter of time before we read stories of the infuriated movie crowds thanks to the movie crashing which can be traced directly back to theater employees installing random spyware-infested software from the internet on the machine.

When first-run movies first started appearing on the internet they were captured by handheld video camera. For best recording, people gained access to the projection booths. Ultimately, I predict that those poor, maligned theater employees are going to be the weakest link in this chain. If someone with the right kind of knowledge can gain access to one of these machines, and most importantly the software on board, it shouldn’t be too far-fetched that the encrypted data can be copied away, the encryption key can be recovered, and the data can be recoded into a more internet-friendly format at a more convenient time. How would such an individual gain access to these machines? People always seem to blame such breaches on the lowest-paid employees.

What do you think of the future of theater technology?

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