ISDCF is preparing for its fourth Plugfest on June 6 and 7. The milestone two-day event will be held at Cinecert’s new facility in Burbank, California. Details are available on the ISDCF website.
The Plugfest has become the industry’s means for testing interoperability of SMPTE DCP content. While manufacturers have demonstrated an ability to play picture and sound from SMPTE DCP packages, problems have been found with open subtitles and closed captions. Further testing is also needed to insure that all devices respond properly to SMPTE 429-2 Annex A audio configurations. The configuration codes for the 7.1DS format, introduced in the most recent revision of S429-2 (still in progress), will be tested with 7.1DS content prepared by Disney.
Altogether, 10 different sets of SMPTE DCP test material, packaged by different houses, are expected to be tested during the event. Some of the materials are designed to test the most extreme parameters possible for open subtitles to learn if the server under test will break. (In this, Fox has developed a reputation for its “killer reel.”) Five different servers will be tested, supplied by Dolby, Doremi, GDC, Qube, and Sony. Notably, XDC will not be participating in this event, following its acquisition by Barco.
While some test material will be new to the Plugfest, there is substantial hope that few surprises will be found. In prior tests, the presentation of subtitle material on screen left much to be desired in terms of uniformity among products. In earlier days of digital cinema, all on-screen subtitles were rendered by the projector electronics. As the rendering software came from TI, uniform presentation of subtitles among different makes of projector was assured. But those days are no longer. Sony’s projector and the newer in-projector media blocks for TI Series-2 projectors, in addition to TI’s own Series 2 software, each introduce a different subtitle rendering engine to the marketplace. A significant part of this test is expected to focus on the uniformity of their performance.
Closed captions will also be evaluated, with a focus on start-up conditions for the closed caption text. Start-up conditions are important as the caption text file must be announced to the closed caption server/transmitter when using the CSP/RPL protocol. The server/transmitter device responds by pulling a chunk of the file and playing its contents at the appropriate time. The time taken to accomplish these tasks will vary, sometimes leading to the late start of closed captions. Some servers designs took care to initiate the sequence in advance of start time to minimize start up issues. It is hoped that all devices have made similar improvements for this test.
If all goes well, this will be the last Plugfest, and will signal to studios that the latest server and projector software is ready for the rollout of SMPTE DCP content. The next hurdle, of course, will be the updating of software in the field, a messy process at best, as manufacturers rarely have control over their products once sold.
SMPTE 21DC is gearing up for its next set of ad hoc group meetings on June 16. The followup Technology Committee meeting will be held in Sydney, Australia, on July 16 (Sydney time). In the June meetings, it is expected that any remaining issues with S429-2 DCP Constraints will be resolved. Assuming this is so, the document will be voice-voted in the July meeting to move forward. The next step is administrative review and approval, followed by an informal check of the final draft by the authors, and then publication.
The significance of S429-2 is it’s role as the parent document for the suite of standards that define SMPTE DCP. It was first published in 2009. Revision work began in 2010 once implementation errors began to appear, and we hope to see the revision published by this Fall. Your author has chaired this revision committee, entailing a process that has taken much longer than warranted, due to issues beyond control. A key improvement is more detailed instruction for the packaging of subtitle and closed caption files, in an attempt to correct anomalies found in both packaging software and servers. In addition, this version introduces the 7.1DS audio format as a new “configuration.” As this standard is also the parent document for SMPTE DCP audio, it will undergo revision at least one more time, by plan, once the standards for channel labeling of audio are ready move to ballot.
In other work in SMPTE, one can only hope that the committee will finally forward for publication the cleanup work for the “backwards slash” aka “ugly slash” issues found in the XML code contained in or associated with several security-related documents. New work will also be introduced. The work for 3-D subtitles should be set to begin, and new auxiliary work may be proposed to amend a companion document that constrains subtitles files for use in the closed caption application. Most importantly, new work will be proposed to introduce changes to S430-3 Extra Theatre Message, the parent document for the Key Delivery Message (KDM). Revisions are needed to introduce the changes agreed to that will allow the use of dual certificates in media blocks, now required by NIST FIPS 140-2 and 140-3.