Film-Tech Forum ARCHIVE: Accessing subtitles track on DCP server?

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Posted by Tony Tse (Member # 10075) on 07-07-2017, 05:00 AM:

Hello,

I am working on a personalized device to improve closed caption technology. I have talked to local cinemas here (they have Doremi DCP server) and they are willing to help me do some testing.

Is it possible to accessing the subtitles if they are available? For example, call the server to return the line at current video time.

I am an engineer (and hard of hearing!) but I don't work specifically in DCP so any info would be appreciated [Smile]

Posted by Marcel Birgelen (Member # 6801) on 07-07-2017, 06:30 AM:

You should check SMPTE ST430-10 and SMPTE ST430-11, both describe a protocol to receive closed captions from DCI servers compatible with the protocol (which covers most of them).

Both specifications are available on-line, though not necessarily for free. The protocol itself is royalty free though.

Other routes, like reading it directly from the DCP are problematic, as most DCPs for commercial distribution are encrypted and your equipment would need to become part of the "secure chain", which would require DCI certification. Furthermore, you would still need to implement SMPTE ST430-10 in order to synchronize with the playback.

Posted by Tony Tse (Member # 10075) on 07-07-2017, 07:07 AM:

Thanks, Marcel! That's the kind of information I needed.

Posted by Harold Hallikainen (Member # 5405) on 07-07-2017, 09:45 AM:

The SMPTE standards used in closed captioning are described at http://ftp.uslinc.com/ftp/Products/IRC-28/Documents/Manual/IRC-28C_Manual.pdf#page=6 . A streaming log out of a QSC/USL IRC-28C is shown at http://ftp.uslinc.com/ftp/Products/IRC-28/Documents/Manual/IRC-28C_Manual.pdf#page=14 . This gives some idea of the communications that goes on to deal with closed captions.

Finally, many servers also support Rear Window closed captioning. These servers send captions out an RS232 port at the time the caption is supposed to run. The text is ASCII with the text of each line in reverse order (right to left). There are also control codes to clear the display and select which line the text is to appear on. The RS232 port was pretty common on external servers, but I don't think it was brought over to systems where the server and IMB are combined and are in the projector.

Good luck!

Harold

Posted by Stephan Shelley (Member # 8587) on 07-07-2017, 07:45 PM:

Should point out that Doremi servers require a license to enable the closed captions. Without the license in place it will not work. Depending on the age of the server you might be able to download the license from Dolby/Doremi. If they are not there they have to be purchased from Dolby.

Posted by Steve Guttag (Member # 268) on 07-07-2017, 10:12 PM:

Dolby has made the CC license available to all servers now at no charge.

Posted by Stephan Shelley (Member # 8587) on 07-07-2017, 10:21 PM:

Steve you sure it is all. Last I heard it was those under software warranty original 3 years or extended. Those not one had to purchase.

Posted by Harold Hallikainen (Member # 5405) on 07-07-2017, 11:26 PM:

Steve is correct. See http://ftp.uslinc.com/ftp/Products/IRC-28/Documents/Technical/DolbyDoremiLicense170213.html .

Harold

Posted by Stephan Shelley (Member # 8587) on 07-08-2017, 12:02 AM:

well a 9 plex that I help out with that has very old Doremi servers only 3 can be found in that list. the other six are not there. I will contact Dolby support and see what they say.

This is what Dolby said in Feb. 2017 "Effective immediately, we will be including the ACC-DCP license as part of our standard software release. This license is required to allow accessibility equipment to communicate with Dolby and Doremi servers. This also means that all units under software maintenance or extended warranty will have the entitlement available to them."

Posted by Stephan Shelley (Member # 8587) on 07-08-2017, 03:37 PM:

I stand corrected but not all can be found on the FTP site the ones missing I had to go through:

http://www.dolbycustomer.com/cinema/FeatureDlms

and have it search for them.

Stephan

Posted by Tony Tse (Member # 10075) on 07-13-2017, 03:27 AM:

Thanks for replies! Just another quick question, is it possible to test the SMPTE protocol on an emulator? It would help ironing out the bugs in my software.

Posted by Marcel Birgelen (Member # 6801) on 07-13-2017, 03:48 AM:

I'm afraid nobody has built an emulator to simulate ST430-10 and ST430-11 interactions and made it publicly available. The industry is really pretty small, so the amount of third-party tools is somewhat limited. Obviously, if you do not have constant access to a DCI server, it will be hard to test this part of your interface.

But since you're developing an accessibility implementation as an add-on to their offer, you might try to contact someone at e.g. Dolby, Barco, Christie, GDC, etc. Maybe one of them can help you with some kind of emulator or can provide other means to test your interface.