DCP-o-matic

Cinemas mostly play packages other people made. But not always. A festival receiving a submission as a video file, a venue running a local advertising reel, a community screening of something with no distributor, a Q&A intro that has to play before the feature — all of these need a compliant package and none of them justifies a post house invoice.

DCP-o-matic is the standard answer. It is free, open-source, actively maintained, and it produces packages that play. It handles both Interop and SMPTE, subtitles, and encryption with KDM generation if you need it.

It is not a shortcut past understanding the format. Feed it the wrong aspect ratio, the wrong frame rate or a mismatched audio layout and it will faithfully produce a package with exactly those problems, which you will discover in front of an audience.

Encoding is also slow — JPEG 2000 at cinema bitrates is genuinely heavy work, and a feature takes hours on ordinary hardware. Plan the timing, and always test the result on the actual screen it will play on rather than assuming.

For anything going into commercial distribution, use a post house. For everything else a venue actually needs, this is the tool.