What is a Digital Cinema System and How do you get there (Part One)?

What is cinema?

No, it’s not a question in the same vein ala La Nouvelle Vague. More like: What do you get with cinema? Assuming you buy a ticket for the sole purpose of watching a movie, this is what you get:

Movie Theater
Image Courtesy: Fernando de Sousa from Melbourne, Australia

What is Digital Cinema?

Digital cinema tries to replicate the same experience you had with 35mm film (assuming you ever saw a movie that way); but with digital technology.

You still get all of the above, but for some reason you’re having to pay more.

Digital cinema works exactly like how you play a movie on your computer. You open a player of your choice, load the movie and hit ‘play’. No more film loading, scratches, misaligned frames, reel numbers and the soothing ‘whir’ of film. It’s that simple.

The challenges that plague digital cinema are surprisingly similar to what plagued 35mm film viewing. You still have to throw a tremendous amount of consistent light on to a silver screen, and projectors are still esoteric monsters that demand reverence (and a lot of expensive service).

The extra features a cinema playback software provides are:

  • Ability to insert advertisement
  • Ability to censor scenes
  • Encryption
  • Ability to change sub-titles or audio on the fly

In many ways, it is the amalgamation of the free VLC player with the free distribution service called Youtube – but without the ‘free’.

What are the parts of a Digital Cinema System?

A digital cinema system is a group of hardware and software within a movie theater that makes the whole shebang run. Its job is to store, sync, playback and secure the data for continuous use.

The parts of a digital cinema system are:

  • Server – a computer whose job is to ‘serve’ files. To know more about servers, read Storage and Servers, from AFRAID: A RAID Primer
  • Storage – Hard drives that store the movies, usually encrypted; and in RAID or other redundancy.
  • Projector – typically a DLP projector from Sony, Barco, Christie Digital or NEC.
  • Projection Screen – silver or similar material which reflects as much light as possible for maximum efficiency.
  • Audio speakers – for surround sound.
  • Audio and video interfaces – for specific audio and video support – like Dolby, THX, etc.
  • Software – the glue and lubricant that holds everything together and ensures smooth operation.

For the sake of simplicity I’m avoiding stereoscopic projection, though it’s not very different.

What is Digital Cinema Distribution?

Digital Cinema Distribution is the network of movie theater chains (single theaters are getting eaten alive) that are ‘connected’ to receive a movie for playback.

Depending on how paranoid the distribution service is, the playback might be live (streaming), or off an encrypted hard drive. There is always a ‘key’ exchanged, for validation, between a specific movie theater and the distribution mother-center. This is similar to signing-in to your favorite service.

Many digital cinema systems connected together is nothing but many computers connected together over a wide area (Wide Area Network, or WAN). If the distances are too great, movies can be transmitted via satellite. The widespread belief is that anything that costs more money is proportionately more secure. As the piracy industry shows, this is baloney.

All the servers are connected to a central server that dishes out movies, ensures no uninvited server is connected (even the legal ones who have forgotten to pay their dues), and keeps a log of every activity. In comparison to Youtube, the worldwide digital cinema distribution network is child’s play.

What is Digital Cinema Initiatives (DCI)?

Depending on which country you’re in, you’ll find many digital cinema ‘standards’. The most famous is the DCI (Digital Cinema Initiatives) joint venture. Why is it famous? Simply because it represents all the major Hollywood studios.

It is neither the ‘best’ standard (in terms of quality) or the easiest or cheapest (in terms of logistics and economy). It’s just the ones the big guns use. In their own words:

Digital Cinema Initiatives, LLC (DCI) was created in March, 2002, and is a joint venture of Disney, Fox, Paramount, Sony Pictures Entertainment, Universal and Warner Bros. Studios. DCI’s primary purpose is to establish and document voluntary specifications for an open architecture for digital cinema that ensures a uniform and high level of technical performance, reliability and quality control.

The current version of the specification (v1.2 at the time of this writing) is available here. Here are the important details (Click to enlarge):

DCI Specs v1.2

*With HFR, the bit rate is set to max out at 500 Mbps (as reference, the BMCC CinemaDNG file is 5MB/frame, or 2.5 Gbps for 60 fps and 5 Gbps for 120 fps). This compression is similar to Prores.

**High Frame rates (HFR) is a recent addition (not recent anymore), with The Hobbit being the first movie projected at 48 fps worldwide. The initial spec only had 24 and 48 fps.

As you can see, there is nothing phenomenally unique or great about watching a movie in DCI. It is similar to playback of a Prores file. A typical consumer grade hard drive can easily transfer 500 Mbps. The audio can be replaced by a well-planned home theater environment or stereo headphones.

Just for fun, take a look at this (Warning: it has nothing to do with the topic we’re discussing):

Is it better to watch a movie in a movie theater or at home?

Let’s assume you are family of four. If the typical screen is 30 feet long, according to THX the ideal distance to the screen is somewhere at 20 feet.

The general formula is d (distance to screen in feet) = L (length of screen in feet) / 1.45

If you want the same experience at home from a distance of 6 feet, you’ll need a screen that is 9 feet long. At 10 feet, you’ll need a screen that is 15 feet long horizontally. In comparison, a 55″ HDTV is only 4 feet horizontally. Nearly not the same experience, is it?

But, with a home theater projection system, you can get a similar feel. How much does it cost?

Let’s say your family goes to the movies twice a month, and each ticket costs you about $10. The average spend on one trip to the multiplex is about $100. That’s $200 per month, or about $5,000 over a two year period.

What if you watched these movies at home on a projector with Blu-ray (same as 2K)?

  • Cost of 50 Blu-ray titles (bought, $20 per title) – $1,000
  • Cost of 50 Blu-ray titles (rented) – $10/month – $250

Total: about $4,500 if you’re buying, and about $3,750 if you’re renting.

Of course, depending on your budget, you can buy even better systems, and more people can watch. You own everything, and if you take care of your systems, they should last for at least five years before a total overhaul.

The challenges to home viewing is getting the design of the room right, which includes audio. Light is also an issue. A projector like the Optoma HD33 is great when the ambient light is minimum (read: totally dark).

Finally, regarding the community experience. Which is better: sitting with 10 or 15 of your friends or family watching a movie in your living room; or sitting with strangers in a theater?

You decide.

In Part Two we’ll look at the various stages of the DCI specification, and how to prepare your video for theatrical release.