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Digital Cinema Initiative Distribution Master (DCDM), Version 1.0

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Format Description Properties Explanation of format description terms

Identification and description Explanation of format description terms

Full name Digital Cinema Initiative Distribution Master (DCDM). Described in the Digital Cinema System Specification v1.0, July 20, 2005

The Digital Cinema Initiative Distribution Master (DCDM) is a set of uncompressed and unencrypted files that represent moving image content optimized for the electronic playback in theaters. The specification defined by the Digital Cinema Initiatives embraces not only theatrical feature films but is also intended for content like trailers and advertisements; the full range of works are called compositions in the specification. The DCDM's files or tracks contain images (high resolution representations of motion picture frames, often produced by scanning film), audio, subpictures and/or timed text (mainly subtitles and/or captions), and auxiliary data (which includes such things as data to control room lights and curtains in a theater). A Composition Playlist synchronizes the playback of these files.

The overall Digital Cinema Initiative (DCI) system specification defines a life cycle in which content exists in a succession of states:

  • DSM. Content originates as a Digital Source Master; format selected by producer, not specified.
  • DCDM_1_0. Content is shaped into a Digital Cinema Distribution Master, covered by the specification
  • DCP. Content is compressed and encrypted for transport to the theater as a Digital Cinema Package, covered by the specification
  • DCDM (again). Content is unpackaged, decrypted, and decompressed at the theater for exhibition.

As detailed in the specification, DCDM has three fundamental requirements:

  • "DCDM is required to use a common standardized file format for each element (image, audio, subtitles, etc.). The DCDM image file format is required to be an uncompressed MXF-conformant file, based on existing SMPTE standards. The DCDM audio file format is required to be based on Broadcast Wave version 1 (PCM WAVE coding).
  • The DCDM image structure is required to support a frame rate of 24.000 Hz. The DCDM image structure can also support a frame rate of 48.000 Hz for 2K image content only. The frame rate of any individual DCDM master is required to remain constant. Metadata is carried in the image data file format to indicate the frame rate.
  • Files within the DCDM set are required to carry information to provide for frame-based synchronization between each file. At a minimum, they are required to include a 'start of file' and a continuous frame count."

Content is divided into reels, segments of picture and sound analogous to the film reels (typically 22 minutes in duration) that are distributed to theaters.

DCDM employs a hierarchical structure that provides imagery at both 2K (2048x1080 pixels) and 4K (4096x2160 pixels) resolution, in order to serve projectors with different capabilities.

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_UNC, MXF File with Uncompressed Images in Generic Container
    May contain WAVE_BWF_LPCM_1, Broadcast WAVE Audio File Format, Version 1
    May contain WAVE_BWF_LPCM_2, Broadcast WAVE Audio File Format, Version 2
    May contain PNG, Portable Network Graphics Format (PNG). DCDM's subpicture track(s)
    May contain XML, XML (eXtensible Markup Language). DCDM's subpicture navigation file(s) and timed text track(s)
    May contain Auxiliary data file(s) conforming to SMPTE specification 12M, not documented at this time
    Used by DCP_1_0, Digital Cinema Initiative Package (DCP), Version 1.0
    Has earlier version Draft versions of overall specification; see Format specifications below; not documented at this Web site.

Local use Explanation of format description terms

LC experience or existing holdings None
LC preference

The Library of Congress Recommended Formats Statement (RFS) lists a Preferred format for master materials for Motion Pictures - Digital And Physical Media but that users should first contact the Library for guidance.

Sustainability factors Explanation of format description terms

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.]
    Documentation The DCDM is one element defined in the Digital Cinema System Specification v1.0, June 2005. The specification is accessible at the Digital Cinema Initiatives Web site. As of April 2022, the most recent version is 1.4.1.
Adoption This format and the overall system was introduced in July 2005, and adoption will begin during the following years.
    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 bundling structure and some other elements will be encoded in XML, which is very transparent. The essence wrappers, e.g., MXF, are generally transparent. The DCDM essences will be as transparent as their underlying encodings.
Self-documentation Metadata to describe the content and to manage the playback process and security protections is a part of the specification.
External dependencies Depends upon specialized projectors and other playback systems in theaters, including the use of a surround sound infrastructure and systems for curtains and lighting that respond to data in the DCDM, etc.
Technical protection considerations Not fully investigated at this time. In the 161-page draft specification, 78 pages are devoted to security. A public-private key, signature based system is specified.

Quality and functionality factors Explanation of format description terms

Moving Image
Normal rendering DCDM files will play in special authoring or theater systems.
Clarity (high image resolution) Although the DCDM is uncompressed by definition, image files are compressed for movement to theaters in the DCP, using lossy JPEG 2000 with a maximum data rate of 250 Mb/s, which will yield excellent quality when decompressed.  Quality when projected will vary depending upon picture size (2K vs. 4K; see Description above).
Functionality beyond normal rendering Extensive; not documented at this time.
Normal rendering DCDM files will play in special authoring or theater systems.
Fidelity (high audio resolution) Excellent; sound track files can have sampling rates as high as 96 kHz; bit depth is specified as 24 bits per sample.
Multiple channels Intended for use in surround-type environments; 16 channels are possible and specified mappings for 8- and 6-channel systems are specified. Each channel will be represented by a separate sound file or track.
Support for user-defined sounds, samples, and patches Not investigated at this time.
Functionality beyond normal rendering Not investigated at this time.

File type signifiers and format identifiers Explanation of format description terms

Tag Value Note
Filename extension Not applicable.   
Internet Media Type Not applicable.   
Magic numbers Not applicable.   
Pronom PUID Not applicable.   
Wikidata Title ID See note.  Wikidata has no corresponding entry as of April 2022.

Notes Explanation of format description terms

General In the DCDM, 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_1_0, 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).

From the Digital Cinema Initiatives Web site: "Digital Cinema Initiatives, LLC (DCI) was created in March, 2002, and is a joint venture of Disney, 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." During 2004, DCI and others applied considerable effort to image quality testing, examining image-creation methodology, encoding, and projection systems. The testing used Standardised Evaluation Material (StEM) created through a collaborative effort of the American Society of Cinematographers (ASC) and DCI.

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 Specification 1.1 (Approved April 12, 2007) plus errata 1-100 from April 2007 to March 8 2008
  • Archived Specification 1.2 (Approved March 7 2008 ) plus errata 1-45 from March 8 2008 through August 30 2012
  • Archived Specification 1.2 (Approved March 7 2008) with errata as of 30 August 2012 Incorporated
  • Archived DCI Specification, Version 1.3 (Approved 27 June 2018) plus errata 1-29
  • Archived DCI Specification, Version 1.4 (Approved 20 July 2020) plus errata 1-23

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:

  • DCI Direct View Display D-Cinema Addendum, Version 1.0, dated 30 March 2022
  • Digital Cinema Object-Based Audio Addendum, dated October 1, 2018
  • DCI Stereoscopic Digital Cinema Addendum, Version 1.0, dated July 11, 2007

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 obtatined from IEEE (no cost to access).

Format specifications Explanation of format description terms

Useful references


Books, articles, etc.

Last Updated: 04/25/2022