DCP or Digital Cinema Package is the video file format used in cinemas.
Support for the DCP format in software
You can export and view a film in the DCP format in software like DaVinci Resolve Studio that costs €249. I wrote a post about it here.
You can make and view more advanced DCPs in Easydcp Creator plus. I wrote a post it here.
Interop and SMPTE DCPs
There are two kinds of DCPs:
-The early version called Interop from around 2005
-The newer SMPTE version from around 2010 with support for additional frame rates and encrypted subtitles.
The equipment used in cinemas and film festivals were mostly upgraded around 2015 to play both types of DCPs.
Encrypted and unencrypted DCPs
Some general guidelines for delivering in the DCP format
- Make the DCP in 4K or 2K. 4K DCPs will usually be larger than 2K DCPs because 4K will max out the 250 mbit bitrate of DCPs. The 2K portion of a 4K DCP will use max 200 mbit per color component.
- The normal frame rate for a DCP is 24 FPS. If the film is 25 FPS, it is best to avoid converting to 24 FPS. Most cinemas can play 25 FPS SMPTE DCPs.
- If you need to deliver a 25 FPS film as a 24 FPS Interop DCP, avoid frame dropping and phase problems with the sound. I wrote a post about it here.
- Make the DCP in DCI Flat 1.85:1 or DCI Scope 2.39:1. Do not use DCI Full Container, it is not in use.
- Use a DCI resolution:
4K Scope 2.39:1 4096 1716
4K Flat 1.85:1 3996 2160
2K Scope 2.39:1 2048 858
2K Flat 1.85:1 1998 1080
- Make the DCP from a uncompressed or high bit rate source that supports the DCI resolutions:
-16 bit TIFF image sequence
-Prores 422/4444 HQ
-DnXHR HQ 10 bit
- DCPs can be made from films in rec.709 or P3 color space. Not Rec.2020 or other wide gamuts, a film in Rec.2020 have to be converted to Rec.709 or P3 before making the DCP.
- Deliver the film with a 5.1 soundtrack. 2 channel stereo is not used in cinemas. I wrote a post about converting stereo to 5.1 here.
- If you want to deliver a DCP with a 7.1 soundtrack, deliver a 5.1 DCP with a supplemental pack/Version File that adds a 7.1 soundtrack. I wrote a post about it here.
- When the aspect ratio is less than 2.39:1 (Scope) like 2.2:1, the DCPs have been delivered letterboxed in Flat with subtitles above the letterboxing. I wrote a post about it here.
- Soft subtitles usually are Arial or similar font, around 38-42 in size, and around 7 percent from the edge of the picture. I wrote a post about subtitles here
- You can often deliver the DCP as a download link, which I wrote about here. Or on a Linux MBR ext 2 formatted hard drive, which I wrote about here.
DCP Format specifications
-Max P3 Color space
-250 Mbit JPEG2000
The DCP format was chosen after many tests on what digital format could match 35 mm prints in quality:
-P3 color space was already in use in post-production, color grading was done on DLP 3 chip Xenon projectors. The P3 color space has more saturated colors than Rec.709, especially red.
-250 Mbit intra-frame JPEG2000 encoding was chosen because it could retain film grain and details in detail-rich scenes like forest and ocean scenes.
-12-bit encoding was chosen because it lets you retain more shadow detail and avoid banding in grey areas and skies.
-2.6 gamma is similar to the LOG encoding used in film scans and digital cinema cameras. The steep 2.6 gamma slope together with 12-bit encoding lets you encode more shadow detail.
-24 bit 48 kHz uncompressed 5.1 sound was used in post-production. Later 7.1 audio and Dolby Atmos were added.
A DCI DCP means that the DCP is made with the current DCI specification. The DCI specification was agreed upon by the big Hollywood studios in 2005 and has been updated regularly.
The current DCI specification tells us to follow these SMPTE standards when making a DCP:
The archived DCI specification 1.2 has parts of earlier versions of these standards. The standards have changed since then as errors have been corrected and equipment has improved.
Some current DCI DCP/cinema specifications:
- DCI DCPs uses these ST 428-1:2019 example aspect ratios:
Scope 2.39:1 4096 1716
Flat 1.85:1 3996 2160
Scope 2.39:1 2048 858
Flat 1.85:1 1998 1080
- ST 431-1:2006 tells us to use 14 fL/48 cd/m2 screen brightness. If the screen brightness is much lower or higher when screening the DCP, the colors, contrast and details will look different.
- RP 431-2:2011 calibration white was changed to virtual white (50.34832, 0.3190, 0.3338). The old RP- 431-2:2007 DCI White (48.00, 0.314, 0.351.) is also in use.
- The minimum pixel count in RP 431-2:2011 is at least 2048×1080, so a DCI cinema uses a zoom lens to switch between Flat and Scope.
- RP 431-2:2011 says to use side masking for both Flat and Scope.
Version File/ Supplemental package DCP
The original version (OV) of the DCP is often the film with original language and no subtitles. This OV DCP is often sent ahead of the versioning DCP to the cinemas.
The versioning DCP is called a Version File (VF) DCP or a supplemental package DCP. The VF DCP reference the MXF files in the OV DCP. The VF DCP typically adds dubbed language tracks, subtitle tracks, and 7.1 sound.
The content of a Digital Cinema Package (DCP)
The XML files in a DCP consist of:
-the video MXF files,
-the audio MXF files,
-the subtitle MXF (SMPTE) files
-XML + TTF font(Interop),
and the metadata files: Volindex, Assetmap, The Packing List (PKL), and the Composition Playlist (CPL).
The PKL XML file lists all the MXF files in the DCP and has a hash checksum of the files for verification. If the files are corrupted in a transfer they will not ingest on the server if they do not pass the hash checksum test.
You can run a Hash checksum test on DCPs in the trial Easydcp plus
The CPL XML file specifies the MXF files in each reel, the order of the reels, and the offset on the video and audio MXF files.