Bits at the Bijou

To the acclaim of filmmaking luminaries like George Lucas and James Cameron, the Digital Cinema Initiatives (DCI) group has released Version 1.0 of its Digital Cinema System Specification, which details how a filmless, fully digital movie theater will work. Because the Hollywood studios formed DCI, the standard has their full blessing and stands a good chance of revolutionizing moviegoing.

The standard (available online through couldn't come at a better time, since theaters are under intense competition not only from other forms of entertainment but also from home theaters, many of which are already fully digital. Your neighborhood multiplex must go all-digital if it's going to keep up.

Accordingly, the new specs call for a movie's "image-structure container" to have a resolution of either "4k" (4,096 x 2,160 pixels) or "2k" (2,048 x 1,080) - the latter being approximately the resolution of a 1,080-line HDTV signal and the former four times as detailed. Every pixel is described by 36 bits of color information, for an impressive 68.72 billion possible colors. All of the picture data is organized into a series of independent still frames that undergo compression via the JPEG 2000 encoding standard - no MPEG-encoding artifacts here.

Audio will be uncompressed 24-bit PCM at either 48- or 96-kHz sampling rates. That's the same as the DVD-Audio format, except digital cinema will have 16 channels of sound. For the moment, the standard assigns positions to only eight of the channels: five front channels, one subwoofer channel, and two surround channels. A sample speaker diagram also shows two vertical front channels at the top of the screen and a top center surround on the ceiling.

While the specs for sound and image have pride of position at the front of the standard, the entire second half of the document's 162 pages covers the elaborate security measures that will be used to protect movies from "content theft," unauthorized exhibition (at the wrong facility, for example), manipulation of content (editing), unlogged usage, and the type of digital attacks that crash Web sites. Just imagine some hacker taking one of the notorious hidden scenes from the Grand Theft Auto videogame and inserting it into the screening of a Disney movie.

Having a standard to work with, manufacturers of digital theater components will benefit since they can now design gear that will work correctly with equipment made by others. But while we home theater enthusiasts might be drawn to new projectors or sound systems, the behind-the-scenes equipment is probably even more important - and it's further behind in development. While there are theaters with digital projectors, none yet receive their data by secure satellite transmission or high-speed network, and there are no all-digital multiplexes with centralized distribution of movies to every room - all as envisioned by the DCI standard. Until this digital "backbone" is put in place, the visual, sonic, and financial benefits of fully digital cinema will remain a promise.

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