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30p footage imports as 29.97?

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Robert Koiter
30p footage imports as 29.97?
on Jul 29, 2015 at 2:45:28 pm

Hi there!

I'm running into an issue where my software (CC Ae 2015, FCPX) believes my 30p footage is actually 29.97. My project settings/comps are all set to 30p.

We're recording on a Canon xf305 (1920x1080, 30p, 50Mb/s) as MXF to a CF card. We copy everything on the card to our RAID and import from there.

I was wondering why the 30p footage is interpolated as 29.97p instead, when imported. I know I can change the interpolation in Ae and force FCPX to 30p, but the Canon 305 should record 30p natively. (I've tried opening the footage in VLC, the only program that will play it, but it does not display any info about fps or resolution size in the inspector).

I've read some stuff about Progressive Segmented Frames (PsF), but I am unsure if it applies to the camera we're using or if it results in the problem I'm having.

Any feedback is welcome! Thanks in advance!

- Rob


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Dave LaRonde
Re: 30p footage imports as 29.97?
on Jul 29, 2015 at 5:15:33 pm
Last Edited By Dave LaRonde on Jul 29, 2015 at 6:13:14 pm

Learn your frame rates, bud.

30p IS 29.97 fps. There is no such thing as 30 fps in video... and I presume you used a video camera to shoot this. It's 29.97 fps.

The only people who ever made progressive-scan cameras that did NOT shoot at 29.97 fps were companies that assumed that 30 actually meant 30. In other words, they didn't do their homework well-enough to know that their little cheapo DSLR's intended to substitute for real video cameras would be the ONLY cameras on the planet that would shoot 30 actual frames every second... while the rest of the world shot at 29.97.

The DSLR's came out with a firmware fix to correct the maker's incomprehensible oversight, and they now shoot 29.97.

The roots of this very-odd frame rate go back more than 60 years to the birth of the NTSC color system, so people have had a long time to learn how to deal with it. Lately, I understand that some cameras will actually shoot at 30 fps because some indiviuals actually insist on shooting at that rate.

Never mind that 30 fps never sees the light of day for anything that goes out over the air waves. It's only used on web video, which has absolutely no problem accommodating 29.97 in the first place. And nver mind that broadcast monitors also work best at 29.97 or at double the frame rate, 59.94. And never mind that DVD and Blu-Ray work at 29.97 / 59.94. And never mind that the vast majority of pro playback devices work at 29.97 / 59.94.

Don't get me wrong: I wish it was 30 fps too, because it's just tidier, y'know? But it isn't. It's 29.97.

And if it comes to you as a shocker that 30p is 29.97, here's one that'll send you off the deep end -- 24p is actually 23.976.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


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Robert Koiter
Re: 30p footage imports as 29.97?
on Jul 29, 2015 at 6:36:28 pm

Thanks so much for the clarification Dave. I had a feeling there was a simple explanation, and I feel stupid as I know I've heard of this before and completely forgot.

So if there are 29.97 and 30p settings, say in After Effects, I would obviously use 29.97 if doing a digital workflow and delivery. For the 30p option, even in FCP, is that meant to be used if you intend to be outputting and using telecine back to film?Just curious.

And thanks again, I always look for your responses on other threads as they're always informative and helpful.

- Rob


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Dave LaRonde
Re: 30p footage imports as 29.97?
on Jul 29, 2015 at 10:57:07 pm
Last Edited By Dave LaRonde on Jul 29, 2015 at 10:57:56 pm

Nope -- for film you'd use 24p (actually 23.976). If it would be for an actual theatrical delivery, or for the now-oh-so-rare film out,you would most certainly want to check on the frame rate to be delivered.

Yeah, the difference is just 24-thousandths of a frame per second, but it can come back to bite you big time if you get the frame rate wrong right out of the blocks.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


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