Interop and SMPTE

Comparing SMPTE and Interop is like comparing apples and some clearly worse apples
Creative Commons photo courtesy of NaJina McEnany

Interop and SMPTE are different standards for DCP. They both specify how Digital Cinema Print packages should work, but aren’t compatible. SMPTE DCPs aren’t valid Interop DCPs, and Interop DCPs aren’t valid SMPTE DCPs. If it helps, you can think of them like how some hard drives only work on Windows computers, and some hard drives only work on Mac computers.

Interop

Interop (short for “Interoperable”) was the original “draft” specification for Digital Cinema Packages. Created around 2001 as a de-facto standard, it was a “starting point”. Hardware manufacturers could use it to start to develop tools and equipment. It was never published, and it’s not publicly available.

SMPTE

Unfortunately, it took until 2009 to release the first published standard, longer than expected. The Society of Motion Picture & Television Engineers now maintains nearly 50 DCP papers. Each one is part of the “SMPTE” standard. Together they detail the latest technical requirements for modern Digital Cinema hardware and DCPs.

Because it is more detailed and current, SMPTE DCPs support newer features and technology. SMPTE packages can better handle subtitles, encryption, and new audio formats. They also have richer support for additional frame rates, including HFR (High Frame Rate) material.

There is no debate that SMPTE is a “better” format between the two.

Why are Most DCPs Still Interop

In the eight years between 2001 and 2009, Hardware manufacturers were eager to get a jump on releasing equipment. Because of the pressure to be “first to market” many shipped projectors and servers that only supported the Interop format.

No one is aware of the exact number of Interop-only systems still in use in the world. It’s likely the number is quite small, and decreasing every year. But, the fact that they might exist makes moving to the better format tricky.

All systems are backward compatible – so Interop will currently play everywhere. Since there is a non-zero chance Interop-only machines may still be in use, the majority of DCPs coming out of the major labs remain Interop.

It’s only fair to note that the tools required to create Interop packages are also quite a bit more expensive and complicated. Arguably, facilities have an interest in keeping the format, as it helps limit competition.

So which format should I make my DCP in?

We generally suggest the following rough guidelines to our clients:

If your film is HFR or not in 24 fps, has Dolby ATMOS sound, or electronic subtitles – you need to use SMPTE

Interop does not support these features (or does so with significant issues).

If your film needs encryption, you should use SMPTE. There are security flaws with how Interop handles encrypted material. These issues have been corrected in SMPTE.

If accessibility is important to you (subtitles or described video), you should consider SMPTE. The newer format has much richer implementation of accessibility features. The more SMPTE is in use, the more the pressure there can be on the industry to widely support these features.

If a filmmaker’s concern is long-term compatibility, you should consider SMPTE. As Interop isn’t an official standard there is no assurance of future support. While unlikely, it’s possible that some future development could break compatibility with Interop packages.

For 100% compatability, including extreme edge cases, you should stick with Interop.

Looking to the Future

We believe that the SMPTE format is a superior standard for DCPs. We encourage filmmakers whenever possible to move to the more modern format. Since 2011 we have yet to find an Interop-only machine still in use. We believe most “early adopter” theatres, would likely have upgraded their equipment since 2009. However, we do understand, that for certain projects, 100% compatibility is an important concern.

 
Do you have questions about the confusing world of Digital Cinema? Don’t worry Ask The DCP Master is here to help. Check out our most common questions, or ask your own.

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