The Digital Cinema Package is the digital projection format that has replaced 35mm film projection in movie theaters (since 2012 in Switzerland). It consists of a set of digital files, including an image track (stream), one or more audio streams, and possibly one or more subtitle streams, using “Version Files.” It should be noted that some DCPs are created by burning in the subtitles, see below. DCP copies are much cheaper to produce than 35mm copies and, above all, can be transported on small discs or sent over the internet, unlike bulky and fragile 35mm copies. All films (with a few exceptions, particularly in film libraries) are distributed in digital format.
DCPs are generally compiled and stored on physical media: hard drives, SSDs, or USB drives. The file format can only be read using a DCP player. The disk (or drive) formats that can be read by DCP projectors/servers are: NTFS, ex2, and ex3. Films are most often sent to theaters via the internet. It should be noted that, on average, a feature film weighs around 100 GB, which requires good internet connections, or even dedicated servers. Several specialized services exist for the secure transfer of DCPs.
IMAGE FORMAT
DCPs are either in 2K or 4K, with maximum aspect ratios of 1080 x 2048 and 2160 x 4096 pixels, respectively. To create a DCP, your file must have a height OR width that corresponds to one of these dimensions. The standard formats are:
– “FLAT” 1:1.85, i.e. 1080 x 1998 or 2160 x 3996
– “SCOPE” 1:2.39, i.e. 858 x 2048 or 1716 x 4096
– “FULL CONTAINER” 1:1.89, i.e. 1080 x 2048 or 2160 x 4096
For other formats, apart from 16×9 (1920 x 1080 or 3840 x 2160), which is accepted as a “flat” format, black must be added to achieve one of the above formats.
FRAME RATE
The frame rates generally used are 24 and 25 frames per second (fps), but other frame rates are possible, although only whole numbers and whole frames (no interlacing). The possible frame rates are: 30 and, in HFR (high frame rate): 48, 50, and 60.
SUBTITLING & FILES VERSION
When digital projection (DCP) first began, standards had not yet been finalized. To avoid incompatibilities and playback issues, it was recommended that subtitles be embedded in the image, which required creating a separate DCP for each language version. Today, these teething problems have been resolved and it is easy to create “Version Files,” which are supplements to a DCP and contain only subtitles. They can be created after the original DCP version (OV) has been created. It is also possible to create VFs containing alternative audio tracks.
AUDIO
The standard DCP format is 5.1 (surround sound), but some theaters are equipped to play other specific formats, notably 7.1. Stereo is accepted, but since theaters are not equipped for stereo playback, the sound quality may suffer. If possible, it is preferable to ask a sound engineer to prepare a 3.0 or 3.1 file, i.e., with a center channel and left and right tracks, as well as a possible bass channel (LFE).
ENCRYPTION & KDM
Your DCP files may be encrypted (or not) with a “KDM.” To play them, digital keys (codes) specific to the server and projector must be sent to the cinema and installed in order to authorize playback of the file. This is intended to prevent piracy, but is mainly used by large distributors to keep track of screenings and prevent playback outside the periods for which rights have been granted.
