DCI released 11 new “errata” in December to its version 1.2 Digital Cinema System Specification, and 2 new “errata” in January. The bulk of these have more to do with housekeeping than with substantive change, either due to ripples caused by earlier errata, or the clean up of issues found when testing products.
One notable change in December’s errata is the refinements introduced for dual projection systems, now referred to as “Special Auditorium Situations.” Notably, an in-projector media block may now have a link-encrypted output for driving a second projector.
The notable change in January’s errata has to do with PNG-graphic subtitle images in 4K compositions. Fox’s “killer reel” in ISDCF Plugfests clearly uncovered a deficiency in the application of graphics in subtitles. The DCI specification has been clear that 4K subtitle graphic files must be employed with 4K image files. But when the projector extracts only a 2K image from the 4K, the 4K subtitle graphic was not always handled correctly. There was finger pointing as to where in the system the 4K subtitle graphic was to be converted to 2K. The DCI specification said that the “projection system” was to perform the downsizing. As simply stated as that may be, it was vague enough to cause no downsizing of the graphic to occur, with both server and projector companies pointing to the other as the problem. Similarly, 2K subtitle graphics must be upsized to 4K graphics for 4K projection, with more finger pointing taking place. To put an end to the finger pointing, DCI made a small change in wording, from “projection system” to “projector.”
DCI is now up to 89 errata for its version 1.2 specification. The joke going around is that the person who submits errata #100 will get a booby prize. But it could be that no one will have the opportunity to collect. DCI says it’s working on a clean version 1.3 of its specification, incorporating all errata to date. In conjunction, a revised Compliance Test Plan is being prepared, which no doubt will reflect the many changes that must have been necessary for GDC and Dolby servers to pass.
While v1.3 will contain at least 89 new revisions, it would be fair to say that the specification is, in general, becoming more precise, with less substantive changes being introduced over its predecessors. But when v1.3 comes out, it must be remembered that this only reflect the digital cinema concept of 10 years ago. It will not incorporate 3-D image, 3-D subtitling, higher frame rates, audio channel labeling, any of the newer sound formats coming out, extended metadata for the composition, and none of the security key management techniques being introduced. And it’s unlikely that DCI will ever will.