Anyone have problems with Timed Text (aka subtitles) because of longplay audio?

[Larry Blake]

Hi all:

As some of you know me know, my day job is in post-production film sound, as a sound editor and re-recording mixer.

For the past 20 years, I haven't work in film reels. First (from 2001-2010) working in three-reel "parts," and since 2010 I've only worked longplay, with the whole movie tied together together. A few disadvantages and even more advantages to working "home video" longplay vs. ye olde film reels. Until 2016—the last movie I did that was filmed out, Magic Mike XXL—we would easily carve the longplay stems into reels to make by-reel printmasters to shoot the optical track negatives.

But that's not why I'm writing. Just background.

Now that I'm only releasing (theatrically, that is) on DCPs, I have been making longplay printmasters to wrap into DCPs. (Again, this is since 2016, as before that I would turn in by-reel printmasters for the DI facility to wrap with the picture and subtitles)

The first movie I did this on was Logan Lucky, in 2017. I also did the final mixes of all dubbed versions (numbering around 18), and can say with certainty that all printmasters worldwide were longplay.

We heard no problems from distributors anywhere, in showing the movie both simply (English track, no subtitles) and in the multitude of options ( dubbed and/or subtitled).

However, I have heard from some studio folk that longplay audio can cause problems with Timed Text (the formal name of subtitles in DCI-speak), especially in ideographic languages, where symbols (in the form of .png files) are needed to create the "text."

The issue relates to the amount of subtitles that can be loaded into the server at any one time. (There might be a more elegant and accurate way of expressing this, and anyone should correct me as necessary.)

I've also heard that there are very easy get-arounds for this potential problem, and that is to create mythical "reels" (and not necessarily in 21-minutes or less old-school lengths; longer is okay) from the original longplay subtitle file, and that doing this alone will solve the problem.

Sorry for the mouthful here . . . has anyone come across any problems in situations such as these? I know that most F-T members are from the U.S., so would especially appreciate any feedback from those elsewhere, especially in Asia, which to my knowledge, has ideographic languages exclusively. (Again, please correct me as necessary.)

Sorry for the length of this post. Your real-world experiences will be appreciated.

best,

Larry Blake

[Harold Hallikainen]

Not subtitles, but closed captions, many systems do have a file size limit, so breaking the timed text file into reels is recommended. See https://isdcf.com/papers/ISDCF-Doc9-...-Practices.pdf . The closed caption system I designed could handle timed text files up to 400 kB. The most recent revision allows it to handle files of unlimited size (it fetches about 400 kB at a time and parses as it goes). For ultimate compatibility, breaking timed text into reels is best.

Harold

[Carsten Kurz]

Yup. DCP/DCI servers/projetors all have different size capabilities for subtitle/fonts/PNG packs, and they are not well documented. What to do and what not to do is usually secret knowledge of mastering companies that they learned the hard way.

I do see quite a few commercial single reel DCPs over here, mostly european arthouse titles. But in general, reel segmenting is recommended.

Btw - it is very easy to segment even a completed subtitled single reel DCP into a 'reel'd' version.
With the pure mathematical addressing of frame numbers/audio blocks in DCPs, this can be done automatically without much thinking. You could try this e.g. with the free DCP-o-matic, but I am sure the usual commercial mastering packages will support this as well.

- Carsten

[Leo Enticknap]

As Carsten points out, different server, media block, FIB (Series 1) and ICP (Series 2) and projector combinations have different levels of resilience when it comes to subtitles and CCAPs; and even within the same hardware combination, different software versions. As a general rule, any Series 1 projectors and old school server/media block (i.e. connected to the projector by encrypted, dual SMPTE 292 HD-SDI) must be updated to the final versions of the software and firmware published for all components, to ensure maximum reliability, especially for playing SMPTE DCPs. Even modern equipment is still being updated to accommodate all the possible issues with subtitles. For example, an update for the Barco ICMP and ICP-D published as recently as June this year fixed bugs that prevented subtitles in older Interop DCPs from playing correctly:

ICMP_notes.PNG
Obviously this is not something that can be fixed in content mastering, beyond ensuring that technical standards as published are adhered to. There was a Japanese anime film released just before the pandemic (can't remember the title, sorry) that broke out from arthouse to semi-mainstream, resulting in no subtitles on between dozens and hundreds of screens nationwide, because it was played on older Series 1 equipment that hadn't been updated in years and normally never played subtitled movies. In the aftermath of that, the distributor involved announced that in the future, they would issue all DCPs with burned-in subtitles (e.g. JP-en instead of JP-EN), in order to make them immune to bugs in the firmware in older projection systems.

[Harold Hallikainen]

Also see SMPTE RDD52 ( https://www.d-cine.net/wp-content/up...rdd52-2020.pdf ) which is based on ISDCF recommendations derived through very extensive testing.

I did a lot of work to ensure closed captioning equipment would work with any content that complied with the standards. Now and then I would hear of some content that did not work properly. I would get a log from the captioning equipment and try to determine if the problem was mine or the content (or the server). If the problem was in the captioning equipment, I'd do an update (again, the most recent was very large timed text file size. Prior to that was a change in how languages were handled so a trailer that was en-us followed by a feature that was en would end up on the same captioning stream).

ST 428-7 specifies the default value for StartTime is 01:00:00:00. I got a call from a theater once about captions not working. The timed text did not have a StartTime element, and the TimeIn and TimeOut assumed a StartTime of 00:00:00:00. So, none of the captions ran. After a discussion with the distributor, they sent out a new set of timed text files. RDD52 specifies that StartTime shall be present, and has a value of 00:00:00:00.

Anyway, it would be good for content to follow RDD52. I really appreciate the cooperation I found in the industry. I was able to work with exhibitors, distributors, and manufacturers to get problems resolved.

Harold