Forensic Marking - KDM

Anything and everything to do with DCP-o-matic.
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Guddu
Posts: 117
Joined: Wed Oct 04, 2017 4:49 am

Forensic Marking - KDM

Post by Guddu »

What exactly is the effect of the forensic marking option if enabled when generating a KDM?

It is enabled by default at the moment.
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Carsten
Posts: 2658
Joined: Tue Apr 15, 2014 9:11 pm
Location: Germany

Re: Forensic Marking - KDM

Post by Carsten »

When forensic marking is active - and it is the norm for encrypted content - then the DCI playout server adds invisible and inaudible watermarks to the content while it is being played out in the cinema. These watermarks contain the serial number of the server used for the playout, as well as date and time. The idea is to track unauthorized recording of the content down to the location where and when it has been played.

However, as the content owner/author, you can freely decide to disable this when creating the KDM. This is not a general decision you make for your content, but for every individual KDM (or set of KDMs).

Certain audio tracks can be excluded from watermark creation - that makes sense, e.g. for ATMOS timecode or dbox control tracks. The added signals for watermarking could destroy these digital signals, so it's better to disable watermarking for all tracks above 12 (as 11/12 will usually be the highest audio only tracks - the back surrounds). Hence the defaults set in DCP-o-matic.

- Carsten
Guddu
Posts: 117
Joined: Wed Oct 04, 2017 4:49 am

Re: Forensic Marking - KDM

Post by Guddu »

Dear Carsten, Thanks for your kind reply. If the watermarks are "invisible (and inaudible)" then how exactly do we figure out what is the serial number of the server used for the playout?

For example, if we have a video file that was recorded using a camera in some cinema (that we don't know which one yet) then how do we go about trying to figure out which cinema exactly was involved in this illegal practice? What part of video file will contain the watermark?
Carsten
Posts: 2658
Joined: Tue Apr 15, 2014 9:11 pm
Location: Germany

Re: Forensic Marking - KDM

Post by Carsten »

That's a bit of a secret. The watermarks are repeated all over the run length of the DCP. As far as I know, these methods have been licensed from some companies like Thomson or Philips. These companies supply tools that can be used to analyse a video recording of the content. Usually these tools are used by agencies like MPAA. I have never seen them in the wild. As a small individual rights owner, your chances to get hands on them are probably limited.

https://dtv.nagra.com/what-is-watermarking

https://dtv.nagra.com/early-release-and-digital-cinema

- Carsten
Last edited by Carsten on Tue Feb 27, 2024 11:17 am, edited 1 time in total.
Guddu
Posts: 117
Joined: Wed Oct 04, 2017 4:49 am

Re: Forensic Marking - KDM

Post by Guddu »

Thanks Carsten. I have contacted the folks at Nagra to see if they can help with the investigation of the cam video file.
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