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My live action footage is Frame Rate 29.97 FPS. When exporting frame by frame animation from Photoshop that I intend to composite on top of the live footage. Since I have the ability in Photoshop to specify should I enter 30 FPS or the exact 29.97 FPS?

You can see Jumper and ISO BG.mov is 30 fps

Lines for Jumper and ISO Switch

I read this question:

What is the proper workflow for slightly different framerates, i.e. 30, 29.97, 29.976?

But it has conflicting answers and neither one has many upvotes or marked correct. Will there be any difference if I export it with the precise 29.97 and 30 or does it make no difference?

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  • What is your target? There is no "one right rate", only what you need it to be. If the majority of your inputs are 29.97, then sticking with that as the project rate, and for PS export, makes sense.
    – Jim Mack
    Nov 3, 2015 at 1:48
  • @JimMack Not sure what you mean by target?
    – Ryan
    Nov 3, 2015 at 1:54
  • The frame rate of the final output i.e. edited movie
    – Gyan
    Nov 3, 2015 at 9:39

1 Answer 1

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29.97 is the NTSC compromise for 30 fps. 23.976 is the NTSC compromise for 24 fps. 29.976 is a framerate that results from confusing these two numbers into a single bit of nonsense.

The bottom line is that if you have a mix of 29.97fps and 30fps, then every 1000 frames (about every 33 seconds) there's going to be a glitch. Either you have to double up a frame of the 29.97fps stream to keep up with the 30fps stream, or you have to skip a frame of the 30fps stream so as not to overrun the 29.97fps stream.

If you never have to composite 1000 differently-timed frames in a row, then you can fudge the two as being equal. But unless you can read the source code of your video editor, you don't really know at what point the program is going to try to "correct" the glitch. It might be uppity and try to do it half-way through the 1000 sequence to minimize the average divergence, rather than waiting until the divergence is indisputable. In that case, best to output your generated frames to match the frame rate of the rest of your content.

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  • None of those decimals are exact. The real values are 30/1.001 and 24/1.001. (or with integer ratios, 30000/1001). They're good enough for almost everything, though: 29.97 is extremely close to 29.97002997 (with infinite repeating blocks of ...002997), and 23.976 is also very close to 23.976023976
    – Peter Cordes
    Nov 7, 2015 at 21:56
  • Where does the 1001 divisor come from?
    – xiota
    Sep 13, 2018 at 9:09

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