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

Question

Same curiosity applies for 24 and 23.976.

My primary concern is loss of quality. I want to work exclusively in 30.000 frames per second; if I understand correctly, some software defaults to 29.97, and some recording devices use 30 implying 29.97, and some screen capture software use exactly 30 as it should be.

I'm just concerned with recording 30.000 1080p RGB video with my Canon 60D and editing it at 30.000 1080p RGB (not YCK or whatever) in Premiere Pro, so I'd like to understand how these standards work with each other, how they convert, and how they play back.

Are there dropped frames or interpolated frames? If I convert a video from 30 to 29.97 and back and forth many many many times, will video quality degrade? What codecs and file formats should I work in to ensure 1080p or UHD support at exactly 30fps or 60fps RGB?

Answer 1

First off, you are correct in your assumption that 23.98 and 24 are indeed different. They are not effectively the same, and they are not "rounded up". Sometimes 24p means 23.98, and sometimes it means 24. They are both separate and it can be quite problematic to treat them the same.

But in practicality, you don't need to worry about the quality, especially if you are using something like Premiere, which is very good about matching your sequence settings with those of your footage (and warning you if they aren't the same).

Your 60D does indeed shoot in 23.98, and modern editing software will know the difference. You can make a 23.98 sequence yourself if you wish; your footage will suffer no quality loss, as no conversion is actually occurring.

Thankfully, the reason we have to distinguish between 23.98 and 24 is that we are moving on from the standards and hurdles that lead to drop-frame frame rates. Plenty of new cameras (such as the RED) can shoot 24fps, and they actually mean 24. And doing exactly that can be quite nice.

So yeah, don't worry about it. Just always match settings with your footage, but newer versions of Premiere do this without fail, faster and accurately.

Answer 2

From a software point of view, 30 are 29.97 are effectively the same frame rate, rounded for simplification. The same is true of 24fps and 23.976 where 23.976 is simply the precise video compatible version of 24fps.

In pure software environments the distinction should be ignored by the software and the more precise references are often omitted to avoid confusion. I always specify the precise rate when possible, but it should be unnecessary.

All video electronics run at 29.97 precisely so the distinction can be important in field production and playback when synchronization of electronic devices is critical.