Confirmation in regard to adding Closed Captioning to an existing DCP.

[Carsten]

There is no way (or at least none that I know of) to switch subtitles on or off for DCI players during playout. Software players of course can do it, but the DCI players in cinemas do not have that option. Once you start to play an OV or VF that has subtitles, they will show to the end with them being visible. Some players allow to disable subtitles, but then it's a global setting.

All cinemas today get DCPs with a version that has no subtitles, and another version that does have subtitles. The way to switch between the two is to stop playout of one, and start playout of the other.


OCAPs can be done in two ways: One is burning the text into the image. They will always be visible. The other version is to create them as timed-text or PNG, in that case, they will be rendered at playout time. Unless the burn-in uses very sophisticated methods to create the image, an audience can't tell the difference between burn-in and timed-text.


Some players (Doremi/Dolby) allow to play CCAPs as OCAPs (on screen). If configured to do so, the player will direct CCAPs to the screen, if no OCAPs are present. This is possible because the captions are timed text and not burn in, so the player is able to decide where to direct the text for playout - CCAP glasses/CCAP display, or screen.

[clownshoe]

Thanks for this rundown, Carsten.

Really helpful for me, moving forward.

All the best.

[clownshoe]

Hey again, Carsten...

So, circling back around because now I'm messing with Captiview delivery.

Am I understanding this right?
- Captiview requires a specific XML file built it it's own standards.
- This XML isn't something that ever gets packaged into the DCP itself, but rather is delivered separately.

I'd love to be able to feel confident about producing an XML that works with these Captiview-like devices.

Open to any help you can offer. Thanks as always.

[Carsten]

The captiview devices use the standard DCI ClosedCaption mechanism, when installed properly in an auditorium. In order to create a DCP using them, you need to add any supported subtitle/captioning file (e.g. SRT, XML), with specific limitations for ClosedCaptioning devices, to your DCP-o-matic project.

https://files.isdcf.com/papers/ISDCF-Do ... ctices.pdf

Create a ClosedCaptioning track in DCP-o-matic, add the necessary language tags, and then create the DCP (usually, but not necessarily, in the form of a VF). The ClosedCaptioning track is added and transported with the DCP, either as an XML file/folder for Interop, or as an additional MXF file for SMPTE DCPs. Basically, it's the same as timed-text for open subtitles, just that the server is instructed to not send it to the screen, but the Captiview devices.

DCP-o-matic player has a test function, you can test basic compliance of your CC DCP, as well as formatting.

It is surprisingly easy to quick start this - just create a new DCP-o-matic project, add any SRT or XML file, set it to 'Use as closed captions', hit 'make DCP'. The result is a formally correct DCP with black image, no sound, just a CC track, that you can view in DCP-o-matic player or on any DCI projection system.

[clownshoe]

Morning Carsten!

Thanks so much for the in depth info.

So the part that throws me a bit is this:
"The ClosedCaptioning track is added and transported with the DCP, either as an XML file/folder for Interop, or as an additional MXF file for SMPTE DCPs. Basically, it's the same as timed-text for open subtitles, just that the server is instructed to not send it to the screen, but the Captiview devices."

But last we spoke, I was under the assumption that if the CCAP was made as an MXF (when making SMPTE DCPs, which is how I do it) devices like Captiview couldn't utilize them.

Because of captiview can indeed utilize MXF closed caption from DCP then that's great news for me.

[Carsten]

It's the server that reads the CCAP file and sends it to Captiview device. If the server is fully SMPTE compliant, it will make no difference wether the CCAPs are bundled in an Interop or SMPTE DCP.

[clownshoe]

Hey Carsten,

Ok, great. That's good to hear. Sounds like, then, in the world of SMPTE DCP my .MXF subtitle file will be compatibile with Captiview-type devices.

Thanks for the confirmation.