If there was a single endeavor that breathed life into ISDCF, it’s the content industry’s desire to rid itself of Interop DCP distributions in favor of SMPTE DCP distributions. The transition would bring political value in that it is SMPTE DCP that’s specified in the DCI Specification, and not Interop DCP. But there is functional value, as well, as only SMPTE DCP provides a mechanism for encrypting subtitles and captions, whose text can all too easily find its way to the Internet.
Some progress has been made. Hobbit: The Desolation of Smaug in HFR 3D was distributed in only the SMPTE DCP format, a step up from the prior year’s release of Hobbit in HFR 3D, which failed to play on all screens and was quickly replaced with an Interop version. Warner Bros’ success with its most recent release was the result of a lot of hard work, and they are not alone. Movies in the Dolby Atmos format (including Hobbit) are only released in SMPTE DCP. As Dolby is in control of the equipment on which Atmos releases play, success can be assured. But the industry has failed to achieve SMPTE DCP beyond these special case releases, giving ISDCF lots to chew on.
By focusing on points of failure, ISDCF has uncovered a lot. Problems isolate to backwards compatibility issues, incomplete implementations of standards, and bad mastering systems. Incomplete implementations of standards continue to exist, largely because SMPTE DCP has been a moving target. Not all manufacturers budget for an ongoing R&D expense to keep up with the latest noodling of a standards committee. Bad mastering systems are just one of those facts of life, stemming from a missed opportunity by DCI, who failed to consider mastering systems as worthy of a compliance program.
That leaves backwards compatibility issues to study. Subtitles are one area where backwards compatibility issues exist. ISDCF has determined that the application of certain constraints on SMPTE subtitles will allow them to play on Series 1 projectors, for example. Audio, however, is the major culprit of backwards compatibility issues. For reasons that are now arcane, SMPTE made no attempt to be backwards compatible with Interop audio, other than for 5.1 sound distributions. In fact, SMPTE did a crack job of messing even that up, giving mastering systems multiple, incompatible ways to package even a 5.1 audio track. (Incompatible to systems that haven’t fully implemented the very latest SMPTE DCP standards.) DCI is equally complicit, by completely ignoring SMPTE DCP audio in its compliance test plan. Mastering engineers, left to deal with this mess, simply don’t have time to get a PhD in SMPTE DCP audio. Their daily concern is getting DCPs out the door. ISDCF is just beginning to embrace this fact.
But that understanding only gelled this month. Attempting to solve the backwards compatibility problem for 7.1 audio, ISDCF in January took one last approach to making SMPTE DCP audio standards work. Taking the latest work in SMPTE DCP audio, called Multi-Channel Audio, or MCA, the proposal was floated that use of the channel labeling prescribed by the MCA standard would allow 7.1 channels in SMPTE distributions to line up with those in Interop distributions. It was a clever idea, finally giving MCA a problem to solve and a reason for existing. To test it, ISDCF actually ran such test files on real servers in this month’s Plugfest. But of course, the tests failed, as standards are not implemented uniformly across all products.
What could be the final proposal from ISDCF emerged this month, which is to incorporate the 16-channel Interop audio channel layout in the SMPTE 429-2 Audio Channel Assignment 4, affectionately known by insiders as the “WTF” label. (It is left as an exercise for the reader to reverse engineer the acronym.) The WTF channel assignment is simply a 16-channel scratch pad, prescribing no hard channel assignments, and intended for non-standard uses. Not too surprisingly, Dolby, whose older products have their share of SMPTE DCP audio compatibility issues, already does this with its Atmos distributions. To now make WTF the default channel assignment for SMPTE DCP is one of those steps that, once taken, will be hard to reverse. In effect, it is simply an admission that SMPTE DCP audio, a messy mix of ideas fatally ignored by DCI, are dead. Long live Interop Audio.