DCP-o-matic

For more than a year now I have been using DCP-o-Matic to my content (1000 thanks to Carl & Co.) Only recently I noticed a problem: flickering images. The projection of the DCP looks almost as projected by an not quite correctly adjusted 35mm-projector. Why is that?

When I check the digital "master" there is no flickering.

I convert DCPs from 23.97fps "master" to 24, interop. I tried signed and not-signed. No difference.
I have not yet tested other frame rates, e.g.. 25 to 25 SMPTE etc.
I use the Mac OS X version, mostly with additional rendering nodes.

Is this a problem of converting the frame rates?

When I do all the different steps myself - like in the old pre-dcp-o-magic-days - there is no flickering.

Also, in my memory, this is a relatively new problem. I cannot recall having that issue when I started using DCP-o-matic.

Any advise and help is appreciated.

Hi, what version of DCP-o-matic are you using? Do you know at what version you started having problems? Does it happen with all DCPs? If so, could you make a faulty DCP and upload it somewhere so we can take a look?
Thanks, Carl

Wondering if this could be an issue with different versions on the master and the rendering clients? So every other frame or so might have traveled through a slightly different processing pipeline, causing brightness/contrast/color variations?

The question is - is it 'flicker', or 'stutter'?

- Carsten

Carsten,

You suspected right –
Sorry, for the late reply, but it took me quite some time to follow your lead and make some tests. So, to cut it short:

Yes, there were different version of DCP-o-matic installed on the various render nodes. And, when I finally finished a DCP on just the "master machine" with no help of any node, the flickering was gone. (no stutter by the way, but really the various brightness in succeeding pictures, some were even black).

So, problem solved. You just need to keep being up to date on all your DCP-o-matic-stations.

Thanks a lot!
Primo

Hi Primo,
Thanks for the reply. I'm glad it's working ok. Newer versions of DCP-o-matic are (or should be) more robust in checking for different versions on render nodes.
Regards, Carl.

That may sound too much work - but would it be possible to update the render nodes through the main/master gui (automatically)? Would be a neat option - inquire version, if mismatch, push updated render node/cli version to remote machine. Would this interfere with OS software installation/authentification requests, or could this be possible transparently?
Hmm, sounds like a virus distribution scheme

Maybe it would be better to simply report render node version numbers in the GUI encoding server overview, or in the hints window? And then show them in red or so, for 'version mismatch - not used'. The issue is, how to qualify outdated encoding servers for 'not usable'? Simply by version number? Or some internal code that is updated with an actually changed processing pipeline?

I remember the CLI versions did some reporting towards a version mismatch (had that when trying the CLI on a Mac) - however, this can only be seen when actually sitting in front of that remote machine while encoding. It would be better to have these hints in the GUI, I guess? Also report version number in the GUI encode server?

What happens currently with v1.x vs. v2. GUI/encode servers? Ah, I see, v2 GUI-Master vs. 1.79.3 encode server reports 'ERROR: Mismatched server/client versions' - and is ignoring these servers for work.

- Carsten