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Topic: J2C frames workflow advice

Rayjohn Tagayon
Film Handler

Posts: 25
From: Taytay, Rizal, Philippines
Registered: Sep 2016

posted 11-01-2018 08:16 AM

Hi, recently we had a client that required us to make multiple versions of DCPs to be aired locally and abroad, there's a different version for every mall circuit (3 versions in total), and for every region where the film was shown internationally (7 to be exact)

So in total I processed 10 DCPs, all rendered from the same master timeline on Davinci Resolve, generated via easyDCP plugin. Each had a "hidden watermark", a hint where we can know what region or mall circuit leaked the file in case a copy comes up online.

Each took about 2hrs and 30mins to process, it took a lot of time for us to submit each and every DCP they required.

So i'm thinking -

standalone easydcp has the option to NOT re-encode .j2c frames and instead just wrap them in MXF together with the pcm into a new dcp, and these takes only about 30 mins. Which is a lot faster.

Do you think It would have been smarter for me to just generate (next time) a Jpeg2000 master of the entire film, and only replace the frames where the watermark should appear everytime I make a new version? Is this workflow possible?

Thank you very much.

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Carsten Kurz
Film God

Posts: 4340
From: Cologne, NRW, Germany
Registered: Aug 2009

posted 11-01-2018 02:58 PM

In how far do these DCPs differ from each other? Is it just your custom watermarking? And where/when does that watermark occur? How long is every DCP? Depending on your Davinci project complexity, the actual J2C encoding may not be the most time consuming part, so, rendering the same project over and over may indeed be a considerable waste of time.

You should try DCP-o-matic - it will do repackaging of existing J2C/MXF without re-encoding, and you can still add new content (hard cut wise). So, it may be possible to create the main part of these DCPs only once, plus all the watermarked parts, and add them in DCP-o-matic, which is a fast copy/wrap process. I guess you could even add some sort of watermarking by using TimedText/Subtitling, which would speed the process up even more. Depends on your watermarking requirements.

DCP-o-matic also offers a commandline interface, so you could even automate that versioning workflow with a script.

DCI servers create their own watermarking when encrypted content is played. However, I guess encryption may be too hard to accomplish for you under the given conditions. Also, it could become costly to actually access the watermark detection tools for evaluations, the systems used by DCI servers are proprietary and not documented for obvious reasons.

- Carsten

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