Why has 25fps exported as 23.81?

[Christie Allanson]

Thank you for getting back to me.
However, I think unfortunately it really is 23.81fps, not only because quicktime says so, but because the professionals at the edit house making my DCP told me so. I’ve just tried putting it back in FCP and it warned me that it was not optimised!
Any idea what’s going on?

Thank you

[Nick Meyers]

yeah, the question would be: how did you do your export?
as Dave says you should do a simple export as quicktime movie,
and leave the drop down menu set to the default “Current Settings”

nick

[Richard Van harderwijk]

Zombie software, assumed to be dead, but somehow alive…ish…

If all good advice above doesn’t work, and in the export there are no frames missing or repeated/blended or so, perhaps it has gotten the wrong metadata info (23.81 ??? is suggesting that, but how…).

Try to reconform the 23.81file to 25 with the also deadish cinema tools. (Takes 2 seconds, no rerendering in that tool, just rewriting the header info.) Probably you have to export the sound separately, or save it from the 23.81 file and later get them together. Check duration of the 2 video files (23.81; 25) and the sound file. Can be done with quicktime, but also with the free davinci resolve.

Or export an XML and do the final export in resolve. Resolve has FCP7 xml import, but if you have a very complicated timeline…

Good luck!

[Jeff Alldridge]

Nine years late, Christie, and your DCP went out long ago. So this is really for whoever types that number into Google and lands here next, which is exactly how I turned up.

Fair warning. This precise question sent me down a rabbit hole that ended with me writing an app. Not a proportionate response to a forum post. But once you see where 23.81 comes from you can’t unsee it.

23.81 is not a frame rate. Nobody shoots at it, no standard contains it, no camera offers it.

1000 divided by 42 is 23.8095.

That’s the whole number. Something in your chain wrote your frame duration as a whole number of milliseconds and landed on 42. Yes, 42.

So where does 42 come from? A 23.976 frame lasts 41.708 milliseconds. Round that to the nearest whole millisecond and you get 42. Divide back out and the file cheerfully announces 23.81.

Which answers what you actually asked, and it’s slightly annoying. A 25 fps frame is 40 milliseconds. Exactly forty. Nothing to round, no remainder, nothing to lose. You can’t reach 23.81 from 25 by this route however hard you push, and I did push before typing this.

So by the time that header got written your file wasn’t 25 anymore. Something conformed it to 23.98 on the way out and the rounding did the rest. Nick was pointing straight at it: export as QuickTime Movie and leave the dropdown on Current Settings. QuickTime Conversion is where a preset quietly conforms you and never mentions it.

Quick way to see how bad it is. Count the frames in the export and compare against your timeline. Same count means nothing got dropped and this is purely a label. Which is the good news and the bad news, because a label this wrong still costs you: 25 divided by 23.8095 is exactly 1.05, so the whole film is running five percent slow. Your 100 minute cut arrives as 105.

Fixable without re-rendering, though. Richard’s instinct about Cinema Tools was right even though the software was already a ghost by 2017. Rewrite the header, leave the pictures alone.

Holy crap. I haven’t thought about Cinema Tools in forever! I was telling a younger editor about edit decisions lists (EDL). I thought I was young. But when you’re old enough to know EDLs… 😑

And that’s the rabbit hole. I kept meeting files where every frame was present and correct and the header was lying about how fast to play them, and re-encoding a whole feature to correct a number is stupid. So I built something that rewrites the timing and leaves the pictures alone. Full disclosure that I make it, so I’m not neutral here. But it’s a header fix whatever you reach for, and that’s the bit worth knowing.

[Doug Metz]

At the risk of keeping this thing going, what happens with the timecode?

I ask, because this seems like a prime candidate for Bouke’s QTChange.app at VideoToolShed.