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I work with some clips, all taken from the same camera, which have the exact following characteristics (apart from the duration of course):

Video: 00:03:21.806, 47.952 fps progressive, 1920x1440x12, AVC
Audio: 00:03:21.835, 48,000 Hz, Stereo, AAC

The spec on the camera says "48 fps" but as seen above the software I load the clip shows 47.952.

My questions are:

  1. Is this a thing of the specific camera? Or is 47.952 some kind of standard number for the 48 fps?
  2. Should I render my final mix at 48 or 47.952 fps?
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2 Answers

Yeah! Welcome to the good ol' world of analog television. When they originally introduced color television and put a high frequency chroma signal on top of the black- and white luma signal, they had to introduce a freqeuncy shift to prevent the signal from bleeding over into the audio .... oh, you don't want to know. Srsly! Even in times of digital video this stuff will hunt us around for another hundred years.

To make it short: this is normal, and your computer handles it badly.

Those framerates are very common, for every plain frame rate there is the garbled version, because the framerate got shifted down by one thousands part:

24fps vs. 24000 / 1001 = 23.976...

25fps vs. 25000 / 1001 = 24.975...

30fps vs. 30000 / 1001 = 29.970...

Do the math - this is exactly what you experience too. Even worse: those numbers cannot be precisely represented in binary. Not even with long floating point numbers.

Video editing and player software is normally designed to somewhat compensate and prevent A/V desync anyway, either by dropping a frame every once in a while, or by doing ungodly things to the audio stream.

I would recommend you check the settings of your camera to find out if it really does not have a plain 48fps / 50fps setting. I do not think that in the digital age we are still supposed to keep up with this 1950s electron tube hack.

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There must be a setting on the camera that you're not describing which causes this shift. The difference is exactly the same as 24 vs 23.976 or 30 vs 29.97, which is the ratio 1000/1001 -- the 'color vs mono' ratio that originated with NTSC color and should have completely ended with digital standards. Maybe that will offer a clue to finding the setting.

In any case, I would treat these as 48 fps. There's no advantage (and plenty of downside) to still using these bastardized frame rates. Your editing system should allow you to import 47.952 cleanly to a 48fps timeline.

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