It’s often been said (by this author) that the primary achievement of the DCI specification was the agreement by the major studios on a common distribution format utilizing shared methods to secure the content. One hears some studios wax about single-inventory content. A more real achievement was uniformity in systems, at least at the playback level. All of this deserves examination, as the industry is about to plunge into yet another leap in technology: high frame 3D.
It goes without saying that all media is reliant on current-day technology, going as far back as stone tablets, to modern day electronic tablets. For generations, the rate of technology change has been slow enough to allow users to believe that the current technology was stable. We talk about 100 years of film being replaced by digital technology, led by the DCI specification. Six years after publication of that specification, things are about to change again. There is somewhat reasonable concern that this extraordinary rate of change will continue for the foreseeable future. This deserves examination, too.
Uniformity of playback system capability was a worthy achievement of the DCI specification. A director knew the limits of technology, and could create a movie that could play on all compliant systems. A 4K movie can play on a 2K system, for example. Differences in system capability are limited to audio playback. Even while sound format differences such as 5.1 audio and 7.1DS exist, the playback system can still play the distribution, even though the sound system may not reproduce the sound correctly. 3-D poses a similar problem, where all playback systems — 2-D, 3-D, 2K, 4K — can fundamentally play the 3-D movie, regardless of whether one has the 3-D add-on technology to view it properly. Regardless, while mistakes may occur, no one really wants to play a movie improperly. Differences in formats may not always force dark screens, but the impact has the same effect.
The introduction of frame rates beyond the DCI spec poses a new technology hurdle. Those with TI Series 1 projectors and outboard servers will be out of luck. The dual HD-SDI link between server and projector can barely handle 48 fps 3-D, compressing the color representation from 4:4:4 to 4:2:2 to squeeze the bits over the HD-SDI links. (It may be possible to also support 60 fps 2-D in this manner, but that remains to be seen.) The only way in which higher frame rates can be supported is with in-projector media blocks (IMBs), which are only supported by the TI Series 2 projectors, and by Sony. This limitation alone will divide the installed base of digital cinemas into at least two camps: those that can support higher frame rates, and those that don’t.
An artifact of the DCI specification further divides system capability into camps that do not necessarily overlap with the IMB limitation. The DCI spec sets the minimum decompression decoder bit rate at 250 Mb/s. Effectively, in doing so, DCI establishes this number as the maximum compression encoding rate. But high frame rate 3-D will undoubtedly require higher encode rates. If so, the DCI spec can no longer be relied upon to establish the maximum bit rate for encoding. This poses other problems for DCI, which are discussed elsewhere in this report.
For equipment owners, owning an IMB does not necessarily absolve one of obsolescence. Decoder bit rate is directly associated with image quality. All it takes is for one manufacturer with a higher bit rate IMB to convince a director that their movie will look better on their device. Such limitations may sound foolish and unlikely, but one only needs to look at recent history to appreciate that such things actually occur. The introduction of 7.1DS sound with Disney’s Toy Story 3, which Dolby (unsuccessfully) attempted to get an exclusive on. The introduction in 1999 EX Surround with Lucasfilm’s Star Wars Episode I: The Phantom Menace, which Dolby and THX attempted to limit exclusively to Dolby audio equipment. And, of course, the use of proprietary noise reduction on analog film tracks, which attempted to limit playback to one brand of equipment. Prior to the introduction of digital cinema, cinema sound was the area where technology ruled, and where attempts to introduce exclusive technology were played out. After all, no technology leader is content to be a me-too.
The concern that the pace of development in cinema will soon obsolete available IMBs has some merit. The IMBs currently on the market are limited to 500 or 600 Mb/s decoder bit rates. That they are this high is due to certain economies offered by current-day silicon, not because of market requirements. If these bit rates happen to be deliver the quality required of the higher frame rates envisioned by movie directors, then further disruption is unlikely. But if bit rates above 500 Mb/s do produce strikingly better images, as some expect, then all bets are off.
If there is a mountain in technology that’s unlikely to move, it’s the projector. DLP powers the majority of the world’s screens, due to its stability and robustness. Digital cinema would likely have been delayed a decade without it. It is expected that TI will produce lighter weight light engines to address the smaller screens of the world, which comprise the majority of remaining screens to be converted. These newer projectors may impact the resale value of current models, but they will not obsolete them. As it is, the projectors available today sell for lower prices than the projectors purchased only a few years ago. Given the propensity of technology to change, if there is a turning point where it appears to be a good time to buy, that time is now. Lower cost projectors, combined with the flexibility of the replaceable IMB, make this so.
Those familiar with the past few decades of cinema sound know how multifarious cinema technology can be. In truth, cinema owners hoped to avoid similar issues of non-compatibility with digital projection, and had 6 years of dodging that bullet thanks to DCI. Then Mr. Cameron demonstrated 60 fps 3-D, and unleashed the possibility of moving into an area where limits have yet to be set. The roller coaster ride of cinema technology is about to begin.