JPEG 2000 is the only accepted compression format. MPEG-2 is no longer compliant with the DCI specification. Each reel contains pictures as MPEG-2 or JPEG 2000 essence, depending on the adopted codec. Picture contents may be stored in one or more reels corresponding to one or more MXF files. The DCP root folder (in the storage medium) contains a number of files, some used to store the image and audio contents, and some other used to organize and manage the whole playlist.
The composition consists of a Composition Playlist (in XML format) that defines the playback sequence of a set of Track Files. not a complete set of files), a single complete composition, or multiple and complete compositions. The DCP may carry a partial composition (e.g. ) A DCP is a “packing crate” for compositions, a hierarchical file structure that represents a title version. ("You PLAY a composition, You do NOT play a Digital Cinema Package". However, the industry tends to apply the term to the structure more formally known as the composition. The term was popularized by Digital Cinema Initiatives, LLC in its original recommendation for packaging DC contents.
A Digital Cinema Package ( DCP) is a collection of digital files used to store and convey digital cinema (DC) audio, image, and data streams.