Digital Cinema Package

Digital Cinema Package

A Digital Cinema Package (DCP) is a collection of digital files used to store and convey Digital cinema (DC) audio, image, and data streams.

The term has been defined[1] by Digital Cinema Initiatives, LLC in their recommendations for packaging of DC contents. General practice adopts a file structure that is organized into a number of usually multi-gigabyte size Material eXchange Format (MXF) files, which are separately used to store audio and video streams, and auxiliary index files in XML format.

The MXF files contain streams that are compressed, encoded, and encrypted, in order to reduce the huge amount of required storage and to protect from unauthorized use. The image part is JPEG 2000 compressed, whereas the audio part is linear PCM. The adopted (optional) encryption standard is AES 128 bit in CBC mode.

The newer SMPTE standards are used to conform the recommendations among different tool vendors and producers. Interop, the legacy DCP standard, is still required to be supported by DCP players.[2][3]

Contents

Technical specifications

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.[4]

Picture MXF files

Picture contents may be stored in one or more reels corresponding to one or more MXF files. Each reel contains pictures as MPEG-2 or JPEG 2000 essence, depending on the adopted codec. MPEG-2 is no longer compliant with the DCI specification. JPEG 2000 is the only accepted compression format.

  • Supported frame rates are:
    • SMPTE (JPEG 2000)
      • 24, 25, 30, 48, 50, and 60 fps @ 2K
      • 24, 25, and 30 fps @ 4K
      • 24 and 48 fps @ 2K stereoscopic
    • MXF Interop (JPEG 2000) - Deprecated
      • 24 and 48 fps @ 2K (MXF Interop can be encoded at 25 frame/s but support is not guaranteed)
      • 24 fps @ 4K
      • 24 fps @ 2K stereoscopic
    • MXF Interop (MPEG-2) - Deprecated
      • 23.976 and 24 fps @ 1920x1080
  • Maximum frame sizes are 2048x1080 for 2K DC, and 4096x2160 for 4K DC. Common formats are:
    • SMPTE (JPEG 2000)
      • Flat (1998x1080 or 3996x2160), ~1.85:1 aspect ratio
      • Scope (2048x858 or 4096x1716), ~2.39:1 aspect ratio
      • HDTV (1920x1080 or 3840x2160), 16:9 aspect ratio (although not specifically defined in the DCI specification, this resolution is DCI compliant per section 3.2.1.2).
      • Full (2048x1080 or 4096x2160)
    • MXF Interop (MPEG-2) - Deprecated
      • Full Frame (1920x1080)
  • 12 bits per pixel precision (36 bits total)
  • XYZ colorspace
  • Maximum bit rate is 250 Mbit/s (1.3 MBytes per frame at 24 frame/s)

Sound MXF files

Sound contents are stored in reels, too, corresponding to picture reels in number and duration. In case of multilingual features, separate reels are required to convey different languages. Each file contains linear PCM essence.

  • Sampling rate is 48,000 or 96,000 samples per second
  • Sample precision of 24 bits
  • Linear mapping (no companding)
  • Up to 12 independent channels.
  • WAV container

Asset map file

List of all files included in the DCP, in XML format.

Composition playlist file

Defines the playback order during presentation. The order is saved in XML format in this file; each picture and sound reel is identified by its UUID. In the following example, a reel is composed by picture and sound:

<Reel>
 <Id>urn:uuid:632437bc-73f9-49ca-b687-fdb3f98f430c</Id>
 <AssetList>
  <MainPicture>
   <Id>urn:uuid:46afe8a3-50be-4986-b9c8-34f4ba69572f</Id>
   <EditRate>24 1</EditRate>
   <IntrinsicDuration>340</IntrinsicDuration>
   <EntryPoint>0</EntryPoint>
   <Duration>340</Duration>
   <FrameRate>24 1</FrameRate>
   <ScreenAspectRatio>2048 858</ScreenAspectRatio>
  </MainPicture>
  <MainSound>
   <Id>urn:uuid:1fce0915-f8c7-48a7-b023-36e204a66ed1</Id>
   <EditRate>24 1</EditRate>
   <IntrinsicDuration>340</IntrinsicDuration>
   <EntryPoint>0</EntryPoint>
   <Duration>340</Duration>
  </MainSound>
 </AssetList>
</Reel>

Packing list file

All files in the composition are hashed and their hash is stored here, in XML format. This file is generally used during ingestion in a digital cinema server to verify if data have been corrupted or tampered with in some way. For example, an MXF picture reel is identified by the following <asset> element:

<Asset>
 <Id>urn:uuid:46afe8a3-50be-4986-b9c8-34f4ba69572f</Id>
 <Hash>iqZ3X7TdAjAqniOxT2/hj66VCUU=</Hash>
 <Size>210598692</Size>
 <Type>application/x-smpte-mxf;asdcpKind=Picture</Type>
</Asset>

The hash value is the Base64 encoding of the SHA-1 checksum. It can be calculated with the command

openssl sha1 -binary "FILE_NAME" | openssl base64

Volume index file

A single DCP may be stored in more than one medium (e.g., multiple hard disks). This file is used to identify the volume order in the series.

3D DCP

The DCP format is also used to store stereoscopic (3D) contents. In this case, 48 frames per second are used, with frames alternating for left eye and right eye pictures. Since the maximum bit rate is always 250 Mbit/s, this results in a net 125 Mbit/s for single frame, but the visual quality decrease is generally unnoticeable.

DCP creation

Most film producers and distributors rely on digital cinema encoding facilities to produce and quality control check a digital cinema package before release. Facilities follow strict guidelines set out in the DCI recommendations to ensure compatibility with all digital cinema equipment. For bigger studio release films, the facility will usually create a DCDM (Digital Cinema Distribution Master).

A DCDM is the post-production step prior to a DCP. The frames are in XYZ TIFF format and both sound and picture are not yet wrapped into MXF files. A DCP can be encoded directly from a DCDM. A DCDM is useful for archiving purposes and also facilities can share them for international re-versioning purposes. They can easily be turned into alternative version DCPs for foreign territories. For smaller release films, the facility will usually skip the creation of a DCDM and instead encode directly from the DSM (Digital Source Master) the original film supplied to the encoding facility. A DSM can be supplied in a multitude of formats and colour spaces. For this reason, the encoding facility needs to have extensive knowledge in colour space handling including, on occasion, the use of 3D LUTs to carefully match the look of the finished DCP to a celluloid film print. This can be a highly involved process in which the DCP and the film print are "butterflied" (shown side by side) in a highly calibrated cinema.

Less demanding DCPs are encoded from tape formats such as HDCAM SR. Quality control checks are always performed in calibrated cinemas and carefully checked for errors. QC checks are often attended by colourists, directors, sound mixers and other personnel to check for correct picture and sound reproduction in the finished DCP.

DCP encryption

The AES encryption is applied to all MXF files. The encryption keys are generated and transmitted via a KDM (Key Delivery Message) to the projection site. KDMs are XML files that can be opened only by the destination device. A KDM is associated to each playlist and defines the start and stop times of validity for the projection of that particular feature.

DCP delivery methods

The most common method uses a specialist hard disk (most commonly the CRU DX115) designed specifically for digital cinema servers to ingest from. These hard drives were originally designed for military use but have since been adopted by digital cinema for their hard wearing and reliable characteristics. The hard drives are usually formatted in the Linux EXT2 or EXT3 format. Usually the iNode is set to 128 bits to avoid compatibility issues with some servers. Also, NTFS and FAT32 are occasionally used but they are generally not considered flexible enough since some Linux based digital cinema servers (such as those made by Dolby and Sony) are unable to read these formats. Hard drive units are normally hired from a digital cinema encoding company, sometimes in quantities of thousands. Drives are commonly shipped in protective hard cases. The drives are delivered via express courier to the exhibition site. Other, less common methods adopt a full digital delivery, using either dedicated satellite links or high speed Internet connections.

DCP creation tools

DCP creation tools
Name GUI CLI JPEG 2000 XYZ MXF XML Frame size 3D Frame rate (frame/s) Sampling rate (kHz) Multi-threaded Input formats Notes OS License
2DCP_GUI Yes Yes Yes Yes Yes Yes 2K, 4K Yes 24, 48 48, 96 Yes Multiple Picture scaling Windows Freeware
CineCert AS-DCP File Access Library No Yes No No Yes No 2K, 4K Yes 24, 25, 30, 48, 50, 60 48, 96 Yes[5] J2K, WAV, XML Needs separate codec Windows, Mac OS X, Linux BSD-like
Doremi CineAsset Yes No Yes Yes Yes Yes 2K, 4K Yes 24, 48 48 Multiple video formats,[6] TIFF, DPX, and others Windows, Mac OS X Commercial license
Cinemaslides No Yes Yes[7] Yes[8] Yes[9] Yes 2K, 4K No 24, 48 48, 96 No All known image[8] and audio[10] formats Encryption, KDM generation. Needs separate codec Linux GPLv3
DVS Clipster Yes No Yes Yes Yes Yes 2K, 4K 24, 48 48 Multiple formats Windows Commercial license
DCP Builder Yes Yes Yes[7] Yes Yes[9] Yes[11] 2K, 4K Yes 24, 48 48, 96 Yes Multiple video formats,[6] BMP, TIFF, JPEG, DPX, PNG, SGI, TGA No encryption, needs registration Windows, Mac OS X, Linux Freeware
DCPC - Digital Cinema Package Creator Yes No Yes[7] Yes[8] Yes[9] Yes 2K, 4K Yes 24, 25, 30, 48, 50, 60 48 Yes Multiple formats Needs separate codec Windows
Prism DCP Encoder Yes No Yes[7] Yes[8] Yes[9] Yes 2K, 4K Yes 24, 48 48 Yes DPX, CIN, TIFF, PNG, BMP, TGA, JPG Picture scaling presets Windows Commercial license
Inition DCP Pro Yes No Yes Yes Yes Yes 2K Yes 24 48 Multiple formats Network encoding of JPEG 2000 files Windows Commercial license
DCP Tool Yes No Yes[12] Yes Yes Yes 2K, 4K Yes 24, 48 48 Yes TIFF, DPX, WAV, AIFF Two separate tools Windows Commercial license
Dietrich No Yes Yes Yes Yes Yes 2K, 4K Yes 24, 25, 30, 48, 50, 60 48, 96 DCDM, DCP, MXF, XML Encryption, key management, KDM generation, package validation, subtitles Linux
Fraunhofer IIS easyDCP Creator Yes No Yes[12] Yes Yes[9] Yes 2K, 4K No 24, 25, 30, 48, 50, 60 48 Yes DPX, TIFF, J2K, JPEG, GIF, PNG, BMP Windows, Mac OS X Commercial license
Fraunhofer IIS easyDCP Creator+ Yes Yes Yes[12] Yes Yes[9] Yes 2K, 4K Yes 24, 25, 30, 48, 50, 60 48 Yes DPX, TIFF, J2K, JPEG, GIF, PNG, BMP Supports KDM and encryption with included easyDCP KDM Generator Windows, Mac OS X Commercial license
MagnaMana FinalDCP Yes No Yes Yes Yes Yes 2K, 4K Yes 24 48 AVI, QuickTime Windows, Mac OS X Commercial license
Extron J2KENC Yes No Yes Yes Yes No 2K Yes 24 48 No BMP, DPX, PNG, TGA, TIFF Windows Commercial license
opencinematools Yes Yes Yes[7] No Yes[9] Yes 2K, 4K Yes 24, 48 48 No TIFF Windows, Mac OS X, Linux BSD
OpenCubeDCP Yes No Yes Yes Yes Yes 2K, 4K Yes 24, 48 48 DPX, CIN, TIFF, TGA, BMP, SGI, RAW, RGB, YUV, WAV Rack mounted unit Linux Commercial license
OpenDCP Yes Yes Yes[7] Yes Yes[9] Yes 2K, 4K Yes 24, 25, 30, 48, 50, 60 48 , 96 Yes TIFF, DPX, CIN XML file generation with digital signatures Windows, Mac OSX, Linux GPL
QubeMaster Pro Yes No Yes Yes Yes Yes 2K, 4K Yes 24, 25, 30, 48, 50, 60 48, 96 Yes Multiple formats DPX, CIN, TIFF, TGA, BMP, AVI, QT, ASF, AUD, WAV, TXT Windows Commercial license
Dolby SCC2000 Yes No Yes Yes Yes Yes 2K, 4K Yes 24, 25, 30, 48, 50, 60 48, 96 All common D-Cinema master file formats Standalone unit, render farm Linux Commercial license
CineCert Wailua DCP Mastering System No Yes Yes Yes Yes Yes 2K, 4K Yes 24, 25, 30, 48, 50, 60 48, 96 Yes[13] TIF, DPX, J2K, MXF, WAV, XML DCP testing (individual assets and entire packages), Support for creating partial ("supplemental") DCPs, Encryption, KDM creation, Extensive Python API; Kii add-on module required for JP2K compression, colorspace conversion, and pixel array resizing Mac OS X, Linux Commercial License
QuVIS Wraptor Yes No Yes Yes Yes Yes 2K No 24 48 Multiple formats Plugin for Compressor in Final Cut Studio. Does not work with compressor 3.05 or higher. Mac OS X Commercial license
QubeMaster Xpress Yes No Yes Yes Yes Yes 2K No 24 48 Yes Multiple formats Windows Commercial license
QubeMaster Xport Yes No Yes Yes Yes Yes 2K, 4K Yes 24, 25, 30, 48, 50, 60 48 Yes Multiple formats Plugin for Compressor in Final Cut Studio. Mac OS X Commercial license

Notes

  1. ^ http://www.dcimovies.com/DCIDigitalCinemaSystemSpecv1_2.pdf
  2. ^ http://mkpe.com/digital_cinema/isdcf/transition/2011-3-2-SMPTE-Interop-DCP-Guidelines-with-Accessibility.pdf
  3. ^ http://isdcf.com/papers/ISDCF-Doc2-DCP-TransitionReview.pdf
  4. ^ http://www.digitalpreservation.gov/formats/fdd/fdd000200.shtml
  5. ^ Is thread safe.
  6. ^ a b Using FFmpeg
  7. ^ a b c d e f Using OpenJPEG
  8. ^ a b c d Using ImageMagick
  9. ^ a b c d e f g h Using CineCert AS-DCP File Access Library
  10. ^ Using SoX
  11. ^ Using opencinematools
  12. ^ a b c Using Kakadu
  13. ^ Concurrent operations use OS / Interpreter threading

External links


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