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 and are similar, but aren’t cross-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 software only works on Windows computers, and some software only works 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 supposed to only be used as a “starting point”. Hardware manufacturers could use it to start to develop tools and equipment while a standard was finalized. It was never published, and it’s not publicly available.

SMPTE

Unfortunately, it took until 2009 to release the first published standard, much longer than anyone 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 most up-to-date technical requirements for modern Digital Cinema hardware and DCPs.

Because it is far more detailed and current, SMPTE DCPs support newer features and technology. SMPTE packages can support new audio formats and far more frame rates than Interop, including playback of HFR (High Frame Rate) material. SMPTE packages also better deal with subtitles and  encryption.

SMPTE is, without question, the “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 selling equipment. Because of the pressure to be “first to market” many shipped early projectors and cinema servers that only supported Interop.

No one is aware of the exact number of Interop-only systems still in use in the world. It’s likely the number is extremely small, and would decrease exponentially every year as equipment improves and prices drop. But, the fact that such systems might exist makes some people hesistant to move to the unquestionably better format.

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

It’s also only fair to note that the tools required to create Interop packages are also quite a bit more expensive and complicated. As such, major facilities have a vested interest in keeping the old format around as long as possible, as it helps to 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, needs to be in a non 24-fps frame rate, or has Dolby ATMOS sound – your only option is to use SMPTE.

If your film needs encryption or electronic subtitles, you should use SMPTE. There are security flaws with how Interop handles encrypted material, and problems with it’s support for electronic subtitling. 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 very unlikely, it’s possible that some future development  in the SMPTE standard could break compatibility with Interop packages.

For 100% compatibility, including equipment manufactured prior to 2009, 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 commercial 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.

Are you an independent filmmaker, distributor, or festival looking for professional, inexpensive, DCP services? Visit theDCPmaster.com to see what we can do for you!