Edit Rate vs Frame Rate in CPL Reel list

[oblomova]

Hello,

We work with NeoDCP in a small arthouse type venue (no means to have dci compliant system). I have a question about the CPL xml specs (which I couldn't find online, looks like it's the only one that isn't freely available?)

I instructed the volunteers doing the screenings to inspect an ingested DCP and check for the EditRate in NeoDCP, to see at which refresh rate NeoDCP should set the projector for a given screening. NeoDCP only shows the EditRate field. However, after re-creating a DCP with DCP-o-matic for a movie that had the wrong subtitles, I checked the CPL XML file and saw that there is also a field called FrameRate. Both fields had the same value.

My question: are the EditRate and FrameRate essentially the same thing or do they represent different concepts? Is there a risk I might once receive a DCP with different EditRate and FrameRate and thus configure the screening at the wrong refresh rate?

I wish NeoDCP would have an option to just detect and adjust the refresh rate automatically, like non-DCP players can...

thanks for your help!

[Carsten]

The frame rate and edit rate relation is usually 2 for 3D DCPs, as stereographic 3D video assets are frame-sequential, so 2 frames=1 edit rate unit.

I haven't looked at NEODCP for a while, but as it reads out frame rate, shouldn't it be able to set the proper output frame rate automatically then?
I assume you don't show 3D DCPs, so, you should safely assume frame rate and edit rate to be the same. Strictly spoken, if only used to set the proper refresh rate for the graphics card, then frame rate is the proper value (as it would e.g. be 48fps for a 24fps 3D CPL).

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[oblomova]

aaah, excellent stuff, thanks for your help, that makes sense! Indeed, we don't screen in 3D, so we can rely on the Edit Rate.

I have already sent requests to NeoDCP regarding this issue, but never received a reply. Guess we're not a big enough client... I wonder how they do it in festivals where they also use this software. It really is a mess to use when you screen shorts programs with different framerates... oh well, I will try my luck again writing to them. Actually, come to think of it, I don't think they ever replied to a single email after the lifetime license was purchased... heh.

Anyway, this is not the place for this talk. Thanks again for your help with the xml definition!

[Carsten]

Certainly a problem on festivals where you will usually receive content with a huge range of frame rates. For most cinematic DCPs, 24fps is the dominant frame rate. Rarely we do see 25 in germany.

[oblomova]

Well I recently had to do a screening of short experimental movies originally shot on super-8 and 16mm and transferred to DCP... had a good mix of 24fps and 30fps DCPs. Had to stop the screening between the movies, change the refresh rate and load the next one... Audience didn't notice anything apparently, but that was stressful

I also had a couple 25fps movies, mainly independent european ones. Why they don't convert to 24 when they master it I don't know.

But yes, roughly 90-95% of what we receive is 24fps. But you can't just leave NeoDCP at 24Hz as it's a catastrophe the day you have a 25fps or 30fps movie and forget to check it.

If DCP-o-matic aims at developping an audience-screening player in the long term, I'll be down to help and pay for that!

[carl]

There have been some efforts towards an audience-screening player - there are some prefs in the player which allow two-screen mode (controls on one, picture on the other) and some simple playlist-type features. It probably needs GPU-acceleration of the J2K decoding to be reliably fast enough, but that should come sooner rather than later (though not for free).