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Author Topic: Get sync information from digital server  (Read 5970 times)

liloneum

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Get sync information from digital server
« on: June 18, 2014, 05:20:14 PM »
Hi all,

I developed this tool with friends a few time ago for captioning with 35mm projections: http://subtivals.org/
Some users are asking now for very precise sync with digital projection.
Does any one know a way to get the informations from the server about reel playing / current frame playing etc.
Any documentation is welcome to improve this subtitle tool.

Thanks,

Lilian

joop!

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Re: Get sync information from digital server
« Reply #1 on: June 19, 2014, 04:07:25 AM »
Doremi is supporting smpte LTC out. For their DCP2000/DCP2K4 servers an additional card, called synDCP or dolphinlock, is available for $450. Their IMB's are supporting embedded LTC out from the SDI outputs on the IMB.

liloneum

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Re: Get sync information from digital server
« Reply #2 on: June 19, 2014, 04:29:03 AM »
OK thanks!

So it means that only the current time code is provided? What happens in case of multiple reel? Did you already experience that?

And for other servers? Any idea?

joop!

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Re: Get sync information from digital server
« Reply #3 on: June 20, 2014, 05:19:51 AM »
Not 100% sure, but I think it is output per CPL, and not per reel. No ideas for other servers.

liloneum

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Re: Get sync information from digital server
« Reply #4 on: June 21, 2014, 04:08:16 PM »
OK thanks! I'll try to get more information from doremi...

joop!

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Re: Get sync information from digital server
« Reply #5 on: June 26, 2014, 12:50:10 PM »
Was able to test and check this today. It is as I thougt: LTC output is by CPL, not by reel and not by playlist.

Was in the meantime looking at your software, and very impressed. I have seen different applications in different festivals, but yours is very well done. And LTC imput would expand the application nicely.

Carsten

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Re: Get sync information from digital server
« Reply #6 on: October 17, 2014, 09:43:26 AM »
Maybe there is an easier way, although I don't know wether that support access to the reel level.

You can get playback/transport information from any Doremi through the API over the network. That is a lot easier to accomplish than to set up LTC output and reader in hardware between server and subtitle player during festival conditions.

I know a guy who programmed it's own show monitor that way. The Doremi API is not free for download, but there should be ways to get this information.

The good thing is that in contrast to LTC only, this interface will give you actual indication about the current clip that is played. With LTC alone, you can never be sure to which part of the main feature this is referenced to. The API may not be able to give you such a fine grained sync as LTC would allow I guess, but I don't think such a high degree of sync precision is needed for subtitling. The dominant aspect in my opinion is easy application of the system under festival conditions. Network/IP based access is probably the easiest way to do this.


- Carsten

liloneum

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Re: Get sync information from digital server
« Reply #7 on: October 21, 2014, 12:14:09 PM »
Thanks Carsten,

Indeed, I found that the LTC output is not the best way: the TC does not start with the CPL but with the whole show list!
Subtitle sync needs a frame precision. If the Network/IP does not provide such a precision, I will not follow this way neither.
Is there a way to get the show monitor you're talking about?
Our project is all open source and this improvement could be shared with a lot of festivals that have this tool.

Lilian

Carsten

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Re: Get sync information from digital server
« Reply #8 on: October 24, 2014, 06:34:51 PM »
Hmm, why would you need access to the individual frame for subtitling? When you read absolute time from the Doremi in regular intervals, you can create your own local fps time source anyway. Only occasional resync should be necessary then. At least I wouldn't understand why subtitles would need to be played with single fps accuracy?

I can make a contact to the programmer if you want. Send me an email to caku1 <at>t-online.de

Another option would be fingerprinting the audio track. This already works quite good with some applications. You would need access to a simple recording of the audio beforehand. There is already a subtitling app for iOS devices using that scheme, however, currently this is not open for free projects, the fingerprinting and title generation is done offline. Would be great to have an App on an iPad that listens to the screen sound, and plays the titles in sync through an iPad-HDMI cable to a projector. Also, this would be completely independent of cinema server type. Would even work for BluRays or computer files being projected.

- Carsten
« Last Edit: October 24, 2014, 06:36:44 PM by Carsten »

liloneum

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Re: Get sync information from digital server
« Reply #9 on: October 25, 2014, 05:36:43 AM »
The aim would be to have a very precise sync in case of double subtitling.
E.g. English subtitles in the image and French subtitles on a second screen.
Users want to have both subtitles displaying exactly at the same time.
In case of 'electronic' subtitling only, Subtivals already gives precise sync. No resync is needed if the sync of the subtitle is correct.
The idea is to give the same TC in Subtivals than the one present in the DCP. The information of TC I'm looking for would automatize the process.
I already had the idea of the audio track in case of 35mm projection, to automatize the sync, as frame rate is not exactly 24 fps. But this kind of projection is very rare now, and the frame rate of actual digital content is regular.
The idea of the App on iPad would be great to control the computer plugged to the projector and therefore the subtitle sync, seated in the theater! It is submitted!
If you want to try this tool (useful for film festival), feel free to give your feedback on github!

dcinemaforum.com

Re: Get sync information from digital server
« Reply #9 on: October 25, 2014, 05:36:43 AM »