DCI Specs - Digital Cinema Initiatives

2.1.1. Major System Concepts2.1.1.1. Digital Source Master (DSM)The Digital Source Master (DSM) is created in post-production and can be used toconvert into a Digital Cinema Distribution Master (DCDM). The DSM can also be used toconvert to a film duplication master, a home video master, and/or a master for archivalpurposes. It is not the intention of this document to, in any way, specify the DSM. This isleft to the discretion of the content provider. The content could come from a wide rangeof sources with a wide range of technical levels.2.1.1.2. CompositionWhen discussing Digital Cinema content, it was realized that other content besidesfeature films would make use of the same digital system. Therefore, a new term wascreated to refer to any content that would have similar requirements to feature filmcontent. The term “Composition” refers to all of the essence and metadata required for asingle presentation of a feature, or a trailer, or an advertisement, or a logo to create apresentation using a digital system. This term will be used throughout this document andis intended to refer to a single element such as one and only one feature, trailer,advertisement or logo.2.1.1.3. Digital Cinema Distribution Master (DCDM)This document specifies a DCDM for the purpose of exchanging the image, audio andsubtitles to encoding systems and to the Digital Cinema playback system. The DCDM isthe output of the Digital Cinema post-production process (not to be confused with thefeature post-production process, which creates the DSM) and is the image structure,audio structure, subtitle structure. These structures are mapped into data file formatsthat make up the DCDM. This master set of files can then be given a quality controlcheck to verify items like synchronization and that the composition is complete. Thisrequires the DCDM files to be played back directly to the final devices (e.g., projectorand sound system) in their native decrypted, uncompressed, unpackaged form.2.1.1.4. Digital Cinema Package (DCP)Once the DCDM is compressed, encrypted and packaged for distribution, it isconsidered to be the Digital Cinema Package or DCP. This term is used to distinguishthe package from the raw collection of files known as the DCDM. Shown below is atypical flow for Digital Cinema. When the DCP arrives at the theater, it is eventuallyunpackaged, decrypted and decompressed to create the DCDM*, where DCDM* imageis visually indistinguishable from the original DCDM image.DSM → DCDM → DCP → DCDM* → Image and SoundNote: Integrated projector and Media Blocks are strongly recommended. However in theexclusive case to accommodate a 2K, 48 FPS, 12 bit DCDM to use [SMPTE 372M DualLink HD-SDI] as an interface, it is acceptable, but not recommended, to allow 10 bit colorsub-sampling to create the DCDM* at the output of the Image Media Block decoder. Thisbit depth reduction and color subsampling is only allowed in the single combination of aDCDM at 2K, 48 FPS being transported over a link encrypted SMPTE 372M connection.DCI Digital Cinema System Specification v.1.2 Page 22