How Digital Cinema Works

Distribution Packaging

Distribution packaging is the means for enabling a common interchange format for content. While this can be thought of as the "DVD" of the cinema world, it is far more complex in nature. The basic requirements of a packaging method are:

• Allow any make of system to read the packaged content,
• Allow defective files to be replaced by segment, without replacing the entire movie,
• Provide a flexible means for including additional language sound tracks, subtitles, etc.,
• Provide a means to communicate the synchronization of files.
• Provide the means for content management tools to efficiently operate.

Through early work in the SMPTE DC28 Packaging ad hoc group, the schematic of a packaging scheme was outlined and circulated among industry particpants. To learn more on how digital cinema packaging will operate, you are invited to read a tutorial on digital cinema packaging, presented by the ad hoc group chairman, Michael Karagosian, at the NAB (National Association of Broadcasters) convention in 2002.

In early 2003, it was the recommendation of the DC28 ad hoc group that MXF (Material Exchange Format) be employed as the packaging technology for digital cinema. MXF is a technology originally proposed by the Pro-MPEG group, and standardized through the work of the SMPTE W25 Technology Committee. In digital cinema, MXF will be used as the "wrapping" technology for track files. For example, an MXF-wrapped image track file will contain JPEG2000-compressed, AES-encrypted image data, stored frame-by-frame. XML will be used as the "playlist" to dictate how the various track files are to be played. This playlist is called the Composition Playlist, and the entire collection of track files is called the Composition. For lack of a better name, we use the term MXF/XML Packaging Method to describe the technique.

Our System-Level Interoperability diagram is taking shape, as shown below.

Next: Putting It All Together