Updated post. First published on November 21, 2018.
Although we have been working with DCP for a long time, I still encounter directors or producers who are not entirely clear on what a DCP is, and above all, many questions arise regarding distribution.
The DCP is the digital format that replaces 35mm. for cinema screenings. Although its implementation has been gradual, it is now fully standardized, and festivals are using it more and more.
Despite this, it is a format that continues to generate many questions. Every week I meet directors and producers who are unclear on certain concepts that are key to distributing their film.
In this post, I have compiled four of the topics I most frequently discuss about DCP. I have tried to make them clear and, above all, very practical concepts to help you communicate with your lab and avoid problems when you start promoting your film.
#1 A DCP is a package of files
The first thing you need to understand is that a DCP is not a video file; it is a package containing various types of files.
These include video and audio in separate files, within an .mxf container, programming files in .xml, and subtitle files, also in .xml.
Here is the structure of a DCP with subtitles:
This concept is important to understand that a DCP for distribution can contain many different versions and as many subtitle tracks as you need for festivals. Therefore, it makes no sense (except in very exceptional cases) to create a DCP for each language version you have.
The great advantage and fundamental change that DCP represents compared to previous formats is precisely this: the possibility of having all versions of the film in the same copy.
#2 CPLs: Composition Playlists
In relation to the above, you need to know what CPLs are. They are XML-programmed files that “order” the content within a DCP. Basically, they are playlists that are read by DCP projectors to screen the film and the necessary subtitles.
Therefore, there will be one CPL for each version you have in the DCP. For example, if you have a DCP with the original version and another in English, there will be two CPLs, one for the version without subtitles and one for the version with subtitles.
When the DCP is ingested into the projector, the projectionist will see both versions, and will be able to choose either of them for the screening. As you can see, each CPL functions as if they were different copies once loaded into the projector, with the advantage of always drawing from the same video and audio.
You can have a DCP with many CPLs, depending on the versions I mentioned at the beginning.
If you’re clear on this so far, let’s take another look at this topic.
Many times I encounter films that must always be viewed with subtitles, especially because they have an original version with multiple languages.
In these cases, it is very common for directors to be careful not to project the version without subtitles, by putting a note on the hard drive or trying to speak with the projectionist.
It’s much simpler: do not create a CPL with the original version without subtitles. You must make this very clear to the lab you are working with; by not creating that CPL, you are forcing the projectionist to use the subtitled versions, without having to explain anything.
Therefore, a film that can only be screened with Spanish and English subtitles will only have two CPLs, one for each language.
#3 Security Keys: The KDM
One of the advantages of DCP for commercial cinema is the ability to create different security levels; for example, you can create a code so that a copy is only screened in a specific theater, on a specific day, and at a specific time. There are multiple options.
These keys are the Key Delivery Messages, known as KDMs. They are usually sent by email to the projectionist once they have the copy, to ensure everything works correctly.
Do we really need KDMs for festival distribution?
No, it really doesn’t make sense to create KDMs for DCP copies of independent feature films and short films that will be distributed at festivals.
There are several reasons: on the one hand, it complicates copy management by requiring KDMs to be sent to all festivals where you screen your film. On the other hand, it is very unlikely that someone would make unauthorized copies of your DCP. This might occur with films from major studios or those that typically perform well at the box office, but not with independent cinema and short films.
So don’t worry, you don’t need to create KDMs.
#4 DCP: 24 or 25 fps?
This is another question you might ask yourself before generating the DCP copy for distribution. Is it worth converting from 25 to 24 fps (frames per second) to create a DCP?
Before considering this, you should be aware of the two standards used for DCP packaging.
Interop is the first and was the standard until a few years ago, created in 2001, and what we worked with until the arrival of SMPTE. Interop has several limitations, including that it only supports 24 and 48 fps. For a time, it was important to make DCPs in Interop, as most projectors only supported this format.
Currently, SMPTE has been standardized, which offers many more advantages; the most important for us is that it does support 25 fps. Although SMPTE’s implementation has been somewhat slow, in 2021, there are not many projectors left to update; it can be stated that practically all projectors worldwide are updated and support it.
Therefore, when creating your DCP copy, you can do so without issue at 25 fps; it is very rare to encounter problems.
You must have a DCP for distribution
I hope these four concepts help you prepare your DCP copy, which is something you must have for your film. Sometimes I encounter directors who hadn’t considered generating a DCP.
The price of making a DCP for a short film is between €50 and €150, a price point that makes it worthwhile to have, if only as an archive of your film and to be able to screen it at some point.
Also, keep in mind that it is not mandatory to send it to festivals on a hard drive; you can send a DCP online using systems like Filemail or Smash, which have very powerful free versions. More and more festivals are accepting it, with the resulting savings in time and money.