Sustainability of Digital Formats: Planning for Library of Congress Collections
Sustainability of Digital Formats: Planning for Library of Congress Collections |
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| Introduction | Sustainability Factors | Content Categories | Format Descriptions | Contact | |
| Full name | Digital Cinema Initiative Package (DCP), Digital Cinema System Specification v1.0, July 20, 2005 |
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| Description |
The Digital Cinema Initiative Package (DCP) is the compressed and encrypted version of the DCDM files representing digital moving image content and associated files packaged for distribution. According to the Digital Cinema Initiative (DCI) system specification, when the DCP arrives at the theater or other playback venue, it is "unpackaged, decrypted and decompressed to create the DCDM*, where DCDM* image is visually indistinguishable from the original DCDM image." See DCDM for more information about the structure of Digital Cinema Initiative Distribution Master (DCDM) files. Only the image track is compressed in the DCP; see Notes below. The DCP consists of the package itself (with all of the track files) and a separate XML Packing List that identifies and includes file-integrity checks ("hash") for each file, as well as a public key and digital signature that is part of the overall security system. The overall Digital Cinema Initiative (DCI) system specification defines a life cycle in which content exists in a succession of states:
The overall system specification devotes considerable space to the required capabilities for playback and projection systems in theaters, and regarding security and content protection. |
| Production phase | Final-state for use in a distribution chain; may also serve as a middle-state format for archiving. |
| Relationship to other formats | |
| May contain | MXF_OP1a_JP2_LSY, MXF File, OP1a, Lossy JPEG 2000 in Generic Container |
| Contains | DCDM_1_0, Digital Cinema Initiative Distribution Master, Version 1.0 |
| Has earlier version | Draft versions of overall specification: Digital Cinema System Specification v4.2 (August 2004), v4.3 (December 2004), v5.0 (March 2005), v5.1 (April 2005), and v5.2 (June 2005), not documented at this time |
| Affinity to | IMF, Interoperable Master Format. Not described at this time |
| LC experience or existing holdings | None |
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| LC preference |
The Library of Congress Recommended Formats Statement (RFS) lists unencrypted DCP as a Preferred format for Motion Pictures - Digital And Physical Media.Users should first contact the Library for guidance |
| Disclosure | Fully disclosed. Developed by the Digital Cinema Initiatives. [See Notes below for information on the relationship of the DCI to the SMPTE DC28 standards-development process.] |
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| Documentation | The DCP is one element defined in the Digital Cinema System Specification, V1.0. July 20, 2005. Errata and later versions are also at the Digital Cinema Initiatives Web site as Current specification and Archives. |
| Adoption | The digital distribution of movies has been adopted rapidly in the United States following the SMPTE standardization of DCP. See for example, "The ABCs of DCPs: Unwrapping the Digital Cinema Package" an article from the theater operator's point of view and states "the studios will cease 35mm distribution by 2015; the buzz is that 90% of U.S. theaters will be digital by 2013; and back in January there were more digital than 35mm theatre screens." |
| Licensing and patents | None identified. The specification includes a disclaimer: "Compliance with this document may require use of one or more features covered by proprietary rights . . . no position is taken by DCI with respect to the validity of any patent of other proprietary right." (p. vii) |
| Transparency | The Packing List will be transparent. The package itself will be compressed and encrypted and not transparent; like a ZIP file, the DCP exists to support the movement of data. The encryption method for non-interleaved MXF frame-wrapped tracks is defined in SMPTE 429-6:2006. The algorithm and mode for the KLV encrypted triplets is defined in the Cipher Algorithm metadata item within the Cryptographic Context Set. The default is Advanced Encryption Standard (AES) cipher as defined by NIST SP 800-38a. |
| Self-documentation |
The Packing List identifies each file, includes file-integrity checks ("hash") for each file, as well as a public key and digital signature that is part of the overall security system. Optional "MIC" (media content integrity) hash values can be created at the KLV triplet level using a structure which parallels that for encryption defined in SMPTE 429-6:2006. The MIC value within the KLV triplet is calculated only on the V portion of triplet - not the K and L. The hash algorithm type is defined in the "MIC Algorithm" metadata item within the Cryptographic Context Set. The default algorithm is SHA-1. The actual hash value is stored on the "MIC" metadata item within the Encrypted Triplet Variable Length Pack. Accessibility Features The DCDM_1_0 Digital Cinema format offers good accessibility support. This format supports subtitling, titling and captioning. Sections 3.4.2.and 3.4.3 of the DCI specification define the text rendering requirements and parameters for subpicture (typically for subtitles) and timed text (for subtitles or captions, or both), respectively. In all cases, subpicture and timed text data are required to be encoded as a standardized XML-based document. See W3C's Making Audio and Video Media Accessible for more general information about accessible sound and moving image media. |
| External dependencies | See DCDM_1_0 |
| Technical protection considerations | Employs a public-private key, signature based system. |
| Moving Image | |
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| Normal rendering | Not relevant; see DCDM_1_0 |
| Clarity (high image resolution) | Not relevant; see DCDM_1_0 |
| Functionality beyond normal rendering | Not relevant; see DCDM_1_0 |
| Sound | |
| Normal rendering | Not relevant; see DCDM_1_0 |
| Fidelity (high audio resolution) | Not relevant; see DCDM_1_0 |
| Multiple channels | Not relevant; see DCDM_1_0 |
| Functionality beyond normal rendering | Not investigated at this time. |
| Tag | Value | Note |
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| Filename extension | Not applicable. | |
| Internet Media Type | Not applicable. | |
| Magic numbers | Not applicable. | |
| Other | NF00462 |
See NARA File Format Preservation Plan ID https://www.archives.gov/files/lod/dpframework/id/NF00462.ttl for DCP_1_0. |
| Pronom PUID | Not applicable. | |
| Wikidata Title ID | Q2581328 |
See https://www.wikidata.org/wiki/Q2581328. |
| General | In the DCDM_1_0, the image track consists of uncompressed data mapped to the MXF Generic Container in accord with SMPTE standard 384M, using the frame wrapping method. In the DCP, the image track consists of lossy JPEG 2000 data mapped to the MXF Generic Container in accord with SMPTE standard 422M, and using JPEG 2000 codestreams conforming to J2K_C_Profile_3 (for 2K) and J2K_C_Profile_4 (for 4K). |
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| History |
From the Digital Cinema Initiatives Web site: "Digital Cinema Initiatives, LLC (DCI) was created in March 2002, as a joint venture of Disney, Fox, MGM, Paramount, Sony Pictures Entertainment, Universal and Warner Bros. Studios. DCI's primary purpose is to establish and document voluntary specifications for an open architecture for digital cinema that ensures a uniform and high level of technical performance, reliability and quality control. DCI will also facilitate the development of business plans and strategies to help spur deployment of digital cinema systems in movie theaters." The first version of the Digital Cinema System Specification (v1.0) was published on July 20, 2005 with many erratas (1-148) to v1.0 published afterwards. Subsequent versions followed:
Archived version of the specifications and erratas are available on the Digital Cinema Initiatives Archives site. Digital Cinema Initiatives published Version 1.4.1 of its Digital Cinema System Specification (DCSS) as of 13 October 2021. DCSS Version 1.4.1 incorporates the 23 errata issued to DCSS, Version 1.4. The specification includes addenda as supplements which are integral to the DCSS (links available from the main specification page:
According to the SMPTE DCP Migration Project, "The DCP, its assets and their corresponding video/audio/text based data sources are governed by a suite of SMPTE standards which regulate the constrained application specific implementation of said assets which compose the package. In simpler terms, the SMPTE DCP is built upon the Interop DCP but with further enhancements and explicitly defined constraints. The specification is published as a formal suite of standards by SMPTE under the 21DC Technology Committee. The SMPTE DCP can be categorised based on the level of features used that are offered within the standard. This categorisation is denoted by an increasing letter. A, B, C etc. Given the nature of Industry adoption, the current baseline for when someone infers SMPTE DCP is 'SMPTE DCP Bv2.1 Application Profile' or Bv2.1 for short. The feature set of this profile is summarised in RDD 52 SMPTE DCP Bv2.1 Application Profile", which can be obtained from IEEE (no cost to access). A bit of history about SMPTE DCP and InterOP DCP both of which are separate from the DCI DCP discussed in this document. According to Jim Whittlesey in a SMPTE Connect video from 2017, SMPTE started the Digital Cinema work in 2000 with seven study groups. The DCI specification (covered in this document) completed its first draft of the DCP specification in 2005 with the rollout of the first DCI DCP packages in 2006. The first DCP movie may be the 2006 family comedy Aquamarine. However SMPTE DCP standards were still in process at this time so the "industry" used a point-in-time snapshot of the DCI specification and called it InterOP (sometimes seen as Interop) for use in distributing DCPs. SMPTE continued to develop the SMPTE Digital Cinema standards with the first specifications completed circa 2009. The DCPMaster.com details the difference between InterOP and SMPTE DCPs: "Interop and SMPTE are different standards for DCP. They both specify how Digital Cinema Print packages should work and are similar, but aren’t cross-compatible. SMPTE DCPs aren’t valid Interop DCPs, and Interop DCPs aren’t valid SMPTE DCPs. If it helps, you can think of them like how some software only works on Windows computers, and some software only works on Mac computers." |
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