What's inside a DCP?

You received a DCP expecting a video file, but what you got is a folder with a bunch of files… and none of them will play. Don't worry—it's completely normal.

This happens because a DCP is, just as its name says, a Digital Cinema Package. And inside that package are several files, each with its own job.

The files that organize the package

The VOLINDEX (volume index) simply indicates the volume number. In the past, you sometimes had to send two or three disks for a single film, and this file was used to keep them in order; that hardly ever happens today, but it's still there. The ASSETMAP is, as the name says, the map of the assets: it lists every element in the package. And the PKL (Packing List) is like an ASSETMAP but a bit more detailed, with serial numbers and other data, used to verify the integrity of the files inside.

The files that really matter

Here are the MXF files: one for video and one for audio, which carry the actual image and sound of your film (subtitles may come in an XML file or a separate MXF). And, above all, the CPL (Composition Playlist), the file that tells the cinema which video and which audio to play.

A single DCP can have multiple video and audio tracks, and it's the CPL that defines which to use. It can even have several CPLs—different sections of a film, or even different films—though most commonly the different CPLs are used for different languages or subtitles. It's not customary to package several different contents in one DCP.