What is the DCP format?

What is a DCP or a Digital Cinema Package?

It is the video file format used in cinemas.

Software used for exporting DCPs

You can export and view Interop/SMPTE DCPs in DaVinci Resolve. Which cost €249. It can be used to convert Prores to DCP

CPU JPEG2000 DCP encoding can be slow. It can be as slow as 5 FPS on 4K and grainy sources even on moderately fast computers.

You can make and view more advanced DCPs in Easydcp plus.

It supports faster NVIDIA CUDA GPU JPEG2000 DCP encoding (Windows), which can reach 24 FPS even on 4K and grainy sources.

A free alternative to making and testing DCPs is
DCP-o-matic/DCP-o-matic player.
It can be used to convert an mp4 video file to a DCP

INTEROP and SMPTE

The first DCPs were made in the Interop format which supported 24/48 FPS.

Today many big Hollywood films are delivered in the SMPTE format. SMPTE DCPs have support for Atmos sound and additional frame rates like 25.

Some general guidelines for delivering in the DCP format

1. 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 a maximum of 200 Mbits/sec per color component.
2. The normal frame rate for an Interop 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. To be safer you can make a 25 FPS 2K DCP instead of 25 FPS 4K DCP even if most systems support them.
3. 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.
4. 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
5. Make the DCP from an uncompressed or high bit rate source that supports the DCI resolutions:
   -16 bit TIFF image sequence
   -Prores 422 HQ/4444
   -DnXHR HQ 10 bit
6. Read more guidelines in my e-book

DCP Format specifications

-Max P3 Color space
-2K/4K resolution
-2.6 gamma
-12 bit
-250 Mbit JPEG2000
-Uncompressed sound

250 Mbit intra-frame JPEG2000 encoding was chosen because:
-It supports both 2K and 4K.
-Each frame is encoded separately so film grain is retained.
-The high bitrate helps detail-rich scenes like forest and ocean scenes to look good.

-12-bit and 2.6 gamma encoding were chosen because they let you retain more shadow detail and avoid banding in grey areas and skies.

-24 bit 48 kHz uncompressed 5.1 sound was used in post-production. Later 7.1 audio and Dolby Atmos were added.

Version File/ Supplemental package DCP

The original version (OV) of the DCP is usually the film with the original language and no subtitles. This OV DCP is often delivered to the cinemas first. Then, the version file (VF) DCPs or supplemental package DCPs with the dubbed language or subtitles are delivered later. The VF DCPs use the MXF files from the OV DCP and add new tracks or files. The VF DCPs typically add dubbed language tracks, subtitle tracks, and 7.1 sound. I wrote about making 7.1 VF DCP in this post.

Encrypted and unencrypted DCPs

Feature films are often encrypted and you need a decryption key (KDM) to play the movie. I wrote a post about making encrypted DCPs here.

Short films, advertisements, and trailers are usually unencrypted.

SMPTE DCP Bv2.1 RDD-52

“SMPTE RDD-52 – “D-Cinema Packaging — SMPTE DCP Bv2.1 Application Profile” is a document that describes the SMPTE DCP format endorsed and used by some of the largest DCP labs in 2020.

They restrain SMPTE Bv2.1 RDD-52 DCPs to these formats:
2K Scope 2048×858 24/25/48 FPS 2D/3D
2K Flat 1998×1080 24/25/48 FPS 2D/3D

4K Scope 4096×1716 24 FPS 2D
4K Flat 3996×2160 24 FPS 2D

Note:

• All cinemas have settings for 2K/4K flat and scope. On 2K projectors, the 4K resolution layers are discarded.
• 2.39 fills the screen in common-height cinemas, where Flat and Scope share the same height, and the screen is 2.39:1. This is the most common type of cinema.
• 1.85 fills the screen in common-width cinemas where Scope and Flat have the same width. And the screen is 1.85:1.
• Aspect ratios smaller than close to 1.85, like 1.37 and 2.0 are used inside Flat 1.85.
• Larger aspect ratios than 2.39, like 2.66, are used inside Scope 2.39.
• 2.2 has been delivered in 1.85, but Oppenheimer is delivered in both flat and scope. The flat version is for common-width cinemas and the scope version is for common-height cinemas. If a common-width cinema shows the scope version, the picture will be both letterboxed and pillarboxed.

Old “A” SMPTE DCP

The old “A” SMPTE DCP has these restrictions:

• Only Wild track format on sound MXF files.
• No offset on subtitles
• Max 640 KB font.

The content of a Digital Cinema Package (DCP)

The 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 XML files: Volindex, Assetmap, The Packing List (PKL), and the Composition Playlist (CPL).

The CPL XML file is a playlist that lists the MXF files in each reel, the order of the reels, and the offset on the video and audio MXF files.

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 do not pass the hash checksum test they will not ingest on the server.

DCI Specifications

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 SMPTE standards like 431-2:2011 when making a DCP.

The archived DCI specification 1.2  had early versions of these standards as part of the specification. The standards have changed a little since then as errors have been corrected and equipment has improved.

Some important DCI DCP/cinema specifications: