October 13, 2016

This Video Explains Why Cameras Shoot 29.97fps

Have you ever wondered why cameras shoot 29.97fps? Why not just 30?

If you've ever picked up a camera, looked at the frame rate settings, and wondered why you had the option to shoot 29.97fps and 30fps, well there's a reason for that. It's pretty much the same reason why there's an option to shoot in 23.98fps, too, and it has to do with math—and the introduction of color—and TV—and interlaced video—and the NTSC system—and—well, just let stand-up comedian/mathematician Matt Parker explain it to you:

Okay, to simplify (that's a joke), here is Parker's explanation of the calculations that led technicians to coming up with 29.97fps:

North American television has a frame rate of 29.97fps because if you multiply that by the number of horizontal rows in each frame and then you multiply that by an integer, happens to be 286, you get out a whole number which matches exactly the frequency window this data is sent over.

This is a pretty nifty piece of trivia for video nerds, but it can also save you from some major confusion and aggravation, namely if a client asks for a project to be shot/delivered in 30fps or 24fps when what they really need is 29.97fps or 23.98fps. If you know the distinction and the instances in which one must be used over the other (interlaced video vs. progressive scan, for example), then you'll save yourself a lot of time, money, and heartache from angry clientele.      

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6 Comments

60Hz powergrid resulted in 60i 30fps black and white TV, but adding color to the signal posed a problem as it would add some kind of interferance. They did a little frequency shift to make it possible.

October 13, 2016 at 7:02AM

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WalterBrokx
Director, DOP, Writer, Editor, Producer
8975

lol, a downvote for adding some context to the NFS simplification?

BTW, this video is great: not only very clear, but the concept is pretty creative and on topic :-)

October 15, 2016 at 10:24AM

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WalterBrokx
Director, DOP, Writer, Editor, Producer
8975

Regardless of whether it's interlaced or progressive, the American frame rate for TV is the oddball frame range: 29.97 or 23.976. If your project ever sees a TV at any stage (even for monitoring), you need to use these frame rates.

The ONLY time you would operate in whole numbers is if you're going to straight film out. Even if you do use the oddball frame rates, every film printing company can cope with it. DCP also do whole frame FPS.

But the conversion these days between 23.976 and 24 is pretty easy and you'll never see the difference. Stick to 23.976 for the most compatibility here in North America.

October 13, 2016 at 11:39AM

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This is happening as we speak... The codec develped by Cinegy (Cinegy Daniel2) is a game changer to the post-prod workflow. It is a open source codec, ultra eficient, based on GPU image processing witch bring a whole another level in terms of image processing... Current GPUs deal, with ease, 8k footage!! This is a massive improvement to all the small production companies, this is a solution that gives the best! for no buck...

Just want to spread the word about this! it might get the "big players" to integrate this codec in their NLEs!

I ask the community to embrace the idea of new. If it wasnt for these leaps in technology 99.7% of the people who want to make movies, wouldnt be able to express themselves.

Choose your information. Be wise about the information you choose. Don't take for granted anything that is put out there without experienced it!

October 13, 2016 at 9:30PM

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What does this have to do with frame rates?

October 20, 2016 at 2:50PM

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David Gurney
DP
1401

The analog system was deactivated years ago, and thus we should not be saddled with these asinine non-integer frame rates anymore. Integer frame rates are supported, so why not use them: https://en.wikipedia.org/wiki/ATSC_standards#H.264.2FMPEG-4_AVC

We shouldn't have interlacing either, but the gutless ATSC caved to ignorant, lazy, FUD-spreading broadcasters who whined that progressive footage would "break their pipelines." Never mind the fact that progressive images can be split into interlaced fields, therefore not breaking anything.

October 20, 2016 at 2:56PM, Edited October 20, 2:59PM

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David Gurney
DP
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