Knut Erik Evensen - DCP FORMAT

In Easydcp Creator plus you can make supplemental package/Version File (VF) DCPs that add subtitles or audio to an Original Version (OV) DCP. Instead of making a DCP for every version of the film, VF DCPs are generated for each version and sent with the OV DCP.

To make a 7.1 DCP you first make a 5.1 DCP and then add a 7.1 VF DCP with the 7.1 sound. The 7.1 VF DCP references the 5.1 OV DCP picture track(s) and will be around 7 GB for a feature film. This way both 5.1 and 7.1 cinemas can play the film correctly.

In this post, I show how you can make 7.1 VF and 7.1 + Atmos VF DCPs and how to merge them with the OV DCP.

Make the 5.1 OV DCP

Add the picture track and the 5.1 sound

Choose a DCP name with 51 and OV

Easydcp is linked with the ISDCF database.
Use the Easydcp ISDCF name generator to make a DCP name

Example:
Test_FTR_F_EN-XX_INT-TL_51_2K_NULL_20210713_NUL_SMPTE_OV

Generate Package

Make the 7.1 VF DCP

Open the 5.1 OV DCP in Easydcp Creator plus

Change the picture track to a supplemental track

Right-click on the picture track and choose “Supplemental” – “This Track”

This 7.1 DCP will now reference the 5.1 OV DCP picture track.

Remove the 5.1 audio

Add the 7.1 sound track

Easydcp Creator will add silence on the four empty tracks. The left rear surround channel will be on track 11 and the right rear surround channel will be on track 12. The resulting sound track will be a 12 Wild Track Format audio track.

Add the 7.1 track to the reel and give the DCP a new name

Drag the 7.1 sound track to the reel.

Change the ISDCF name so it includes 71 and VF:

Test_FTR_F_EN-XX_INT-TL_71_2K_NULL_20210713_NUL_SMPTE_VF

Generate Package

Check the DCPs (optional)

Drag both DCPs to Easydcp player to check them.

When playing the DCP the 7.1 DCP should have sound on channels 11 and 12.

Both folders can be included on a hard drive or sent via a download link.

More info

Merging the OV and VF DCP to a multiple CPL DCP

Sometimes it can be easier to use a multiple CPL DCP instead of OV+VF DCPs. A trailer DCP with multiple CPLs can have all the languages for a trailer in one DCP. Ordinarily, you would just add a composition using the plus icon.

but you can also merge OV+VF DCPs using Package – Merge CPLs

The PKL name will then match the first composition. On a Doremi server, you have to click on the PKL name to see the two CPL names in the ingest manager.

7.1 + Atmos VF DCP

Making a 7.1 + Atmos VF DCP is similar to making a 7.1 VF DCP.

Add a 7.1 + Atmos sound track

You will get a 14 wild track format track where track 14 will be a silent track, but when the DCP is played it will be an automatically generated sync track from the Dolby Atmos MXF track.

The Dolby Atmos MXF track is added to the reel with “Track” – “Add Aux Data / Dolby Atmos / DTS:X Track”

The 7.1 + Atmos VF DCP can be merged with the 5.1 + Atmos DCP OV DCP if the logistics of having two separate DCPs is difficult.

DCP or Digital Cinema Package is the video file format used in cinemas. The first DCPs was made in the interop format which only supported 24 FPS and unencrypted subtitles. . Today most Hollywood films are delivered in the new SMPTE format. It has support for Atmos sound, additional frame rates and encrypted subtitles. The equipment used in cinemas and film festivals have been upgraded to play most kinds of SMPTE DCPs. Some big DCP labs made a document in 2020 called “SMPTE RDD-52 – “D-Cinema Packaging — SMPTE DCP Bv2.1 Application Profile” which describes the SMPTE DCP format they use on Hollywood films.

Support for the DCP format in software

You can export and view a film in Interop/SMPTE 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.

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 it here.
Short films, advertisements, and trailers are usually unencrypted.

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 of each color component.
2. 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.
3. 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.
4. 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.
5. 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
6. 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
7. DCPs can be made from films in rec.709 or P3 color space. Not Rec.2020 or similar color spaces, a film in Rec.2020 have to be converted to Rec.709 or P3 before making the DCP.
8. 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.
9. 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.
10. When the aspect ratio is less than 2.39:1 (Scope) like 2.2:1, the Hollywood DCPs have been delivered letterboxed in Flat with subtitles above the letterboxing. I wrote a post about it here.
11. Soft subtitles usually are Arial or a similar font, around 38-42 in size, and around 8 percent from the edge of the picture. I wrote a post about subtitles here
12. 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
-2K/4K resolution
-2.6 gamma
-12 bit
-250 Mbit JPEG2000
-Uncompressed sound

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.

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 these SMPTE standards when making a DCP:

ST 428-1:2019 – SMPTE Standard – D-Cinema Distribution Master — Image Characteristics

RP 431-2:2011 – SMPTE Recommended Practice – D-Cinema Quality — Reference Projector and Environment

RP 431-2:2011 references:
ST 431-1:2006 – SMPTE Standard – D-Cinema Quality — Screen Luminance Level, Chromaticity and Uniformity

The archived DCI specification 1.2 has parts of earlier versions of these standards in the document. The standards have changed since then as errors have been corrected and equipment has improved.

Some current DCI DCP/cinema specifications:

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 sometimes 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. I wrote a post about it here.

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 version of 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.

When you export a video file from a Rec.709 2.4 gamma project in DaVinci Resolve 17.2, the film may look darker than the original in QuickTime player on macs and some other video players/web services.

The video file will look the same as the original in Resolve, but QuickTime player does not recognize the 2.4 gamma tag and the video will look darker. The fix is to use the same gamma tag as the original: Rec. 709-A when exporting from Resolve.

If you have Project setting – Color management with Rec.709-A Timeline Color space you will get the same gamma tag as the original video file.

If you have Project setting – Color management with Rec.709 Gamma 2.4 Timeline Color space you will get the unrecognized gamma tag. Sometimes it is important to have the Timeline Color space as REC.709 Gamma 2.4. One example is when you drop a DCP in the timeline and the DCP is converted from DCI X’Y’Z’ to the timeline color space. Then the solution is to change the tag when exporting.

How to fix the gamma tag when exporting

The default in Advanced Settings when exporting is:
Color Space Tag: Same as Project
Gamma Tag: Same as Project

The original QuickTime from Final Cut X had these tags:
Color Primaries: ITU-R BT.709
Transfer Function: ITU-R BT.709
YCBCr Matrix: ITU-R BT.709
Code Points: (1-1-1)

The Quicktime with the Rec 709, 2.4 gamma tag was recognized in QuickTime player as:
Color Primaries: ITU-R BT.709
Transfer Function: Unspecified
YCBCr Matrix: ITU-R BT.709
Code Points: (1-2-1)

Choose Rec-709-A as the gamma tag

If you want to avoid gamma shift in QuickTime player you have to choose Rec.709-A as the Gamma tag when exporting.

When exporting choose

In Advanced Settings:

Color Space Tag Rec.709
Gamma Tag Rec.709-A

Now the Quicktime has the same tags as the original and does not have a gamma shift in Quicktime player.
Color Primaries: ITU-R BT.709
Transfer Function: ITU-R BT.709
YCBCr Matrix: ITU-R BT.709
Code Points: (1-1-1)