SMPTE vs. Interop, and the name on the folder.
Updated: 1 day ago
Make a SMPTE DCP. That’s the whole answer for a first film in 2026, and the rest of this post explains why, then teaches you to read the long name on the outside of the folder.
Last week we went inside the DCP folder and met the ASSETMAP, PKL, CPL and MXF files. Both standards use that same structure. They differ in the details, and details are where screenings fail.
Two standards, one history.
When digital cinema rolled out in the mid-2000s, the formal standards weren’t finished. The industry needed something that worked right away, so it agreed on a provisional format built on the draft work. That format is Interop, short for interoperable. It was deployed in 2004 and was never formally standardized.
The finished standard, SMPTE DCP, was completed in 2009. It’s defined by SMPTE’s ST 429 family of standards, and today it’s pinned down further by an application profile called Bv2.1, published as SMPTE RDD 52:2020. That profile is what DCP-o-matic’s verifier checks against when it reports “Bv2.1 errors.”
In 2011 the industry group ISDCF put it in one sentence: “The Digital Cinema industry is moving from Interop-DCP to SMPTE-DCP.” That move has taken years, and it isn’t finished everywhere. As late as 2020 SMPTE described parts of Eastern Europe and the Balkans as having minimal SMPTE adoption. In the US, SMPTE is the default.
What actually differs.
From the outside, the two look almost identical. Inside, the differences are small and specific:
Subtitles. Interop carries subtitles as plain XML files in a format called CineCanvas. SMPTE wraps them as timed text inside MXF track files, which can be encrypted. This is the difference most likely to bite you. It’s also why week ten exists.
Audio labeling. SMPTE lets a package label exactly which channel is which speaker. Interop relies on convention.
Encryption keys. SMPTE is stricter about how keys are built and checked.
File names. SMPTE’s map file is ASSETMAP.xml. Interop’s is ASSETMAP, no extension.
Mixing the two is fatal. A package with an Interop subtitle file inside a SMPTE composition won’t pass verification, and may not play.
Which one to make.
SMPTE, for four reasons:
The Academy requires it. The 99th Oscars rules specify DCPs “in conformance with the most recent revision of SMPTE ST 429-2.”
Your tools default to it. DCP-o-matic’s manual: “If in doubt, use SMPTE (the more modern of the two).” Penguin DCP’s FAQ says its packages are SMPTE by default too.
Modern servers play it. Dolby’s IMS3000 and GDC’s SR-1000 play both, and SMPTE is what the industry profile tests against.
It’s where things are going. Interop maintenance stopped years ago.
When would you make Interop? When a specific venue asks for it, usually because of older equipment. Some early DLP projectors can’t render SMPTE subtitle files, for example. If a venue asks, make them a separate Interop version. Don’t make Interop your master.
The name on the folder.
Every professional DCP carries a long, ugly name. It follows the Digital Cinema Naming Convention, maintained by ISDCF. It looks like a password, and it’s actually a label. A projectionist can read what’s inside without opening anything.
Here’s a real example from ISDCF’s own registry:
ThankYouService_FTR-4_S_EN-XX-CCAP_US-R-INT-TD_51-HI-VI_2K_UP_20170928_DTB_SMPTE_OV
Underscores separate the fields. Hyphens split a field into parts. Read it left to right:
ThankYouService. The title, words run together with capital letters. ISDCF says to separate words “with initial caps” and warns that hyphens or underscores in a title “can cause problems with some software.”
FTR-4. Content type: feature, version 4. A short is SHR. A trailer is TLR.
S. Aspect ratio: scope. Flat is F.
EN-XX-CCAP. Language: English audio, no subtitles (XX), with closed captions.
US-R-INT-TD. Territory and rating: the US, rated R, plus additional codes.
51-HI-VI. Audio: 5.1, plus a hearing-impaired track and a visually-impaired narration track.
2K. Resolution.
UP. The studio code.
20170928. The date, year first.
DTB. The facility that made it.
SMPTE. The standard. An Interop package says IOP.
OV. Original version. A version file that borrows assets from an OV says VF.
Naming your own.
Let the software do it. In DCP-o-matic, tick “Use ISDCF name” and fill in the metadata: content type, language, territory, rating, audio. It builds the name from your settings. If your film isn’t rated, there’s a code for that. Use it rather than making up a rating.
The manual is honest about stakes. The name “should not affect how the DCP ingests or plays,” but “projectionists will appreciate it if you use the standard naming scheme.” Picture a booth during a festival with forty packages on the server and five minutes to build a show. A correct name is a kindness to that person. It’s also how you avoid your film playing with the wrong CPL.
Three rules for first-timers:
Keep the title short and readable. Someone has to find it in a list of forty.
Name versions honestly. If you make a captioned version and an uncaptioned one, the names should differ where the captions differ.
Name it before you encode. The name lives inside the CPL, so renaming the folder afterward changes nothing the server reads.
Next week we go inside the picture itself: JPEG 2000, XYZ color, and why cinema images are encoded the way they are. If you want the standard and the naming handled for you, our DCP service builds SMPTE packages named to the ISDCF convention. You can compare it against the DIY route in week three.
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