Best frame rate for a 29.97fps file

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sean2212
Posts: 2
Joined: Wed Nov 02, 2016 1:30 pm

Best frame rate for a 29.97fps file

Post by sean2212 »

Hi folks,

I need to make a DCP from a .mov file that is at 29.97 fps. DCP-o-matic automatically selected 30 fps when I added the file.

Would there be any noticeable difference if I selected 25 fps instead? (The film was originally shot at 25 fps, was given to an NYC-based mastering company who sent back a 29.97 version, hence my slight confusion...)

Or should I just stick with 30 fps?

Thanks in advance.
Carsten
Posts: 1779
Joined: Tue Apr 15, 2014 9:11 pm
Location: Germany

Re: Best frame rate for a 29.97fps file

Post by Carsten »

In general, 30fps is the best choice for 29,97 - if the projector is able to display 30fps properly (should be SMPTE, but some few systems may also allow this in Interop-DCPs).


However, if this 29.97 file has been converted from 25fps- it is impossible to give a good suggestion, as we don't know how this conversion has been done. Was it an interlaced 25fps source, did it go through a telecine process, whas it simply sped up to 29.97?

I suppose you need to test both methods and see what comes out. Why did they convert from 25fps to 29.97? This would only be necessary for specific broadcast or distribution use cases.
IoannisSyrogiannis
Posts: 53
Joined: Mon Nov 13, 2017 8:40 pm

Re: Best frame rate for a 29.97fps file

Post by IoannisSyrogiannis »

My vote is to not try to correct things with DCP-o-matic.
Get your best first material and work with that.

If you want to have a 25fps movie out of your 25fps shots, make it so.
Don't compromise with changing the framerate twice. You can't make such changes twice and get the quality you had at first.
If it was a 23.976fps to 29.97fps and then back, you may have had a chance to not loose quality.
25fps doesn't work the same.
carl
Site Admin
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Joined: Thu Nov 14, 2013 2:53 pm

Re: Best frame rate for a 29.97fps file

Post by carl »

It would be interesting to see what the "test" version of DCP-o-matic thinks of the file

https://dcpomatic.com/test-download

since it has some code to detect the pulldown (telecine) that the mastering company might have done.
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