About Video Frame Rates

@Mizamook
> ...Also, duplicating frames. As I found out the hard way...dumped 24fps clips on a 30p timeline in Resolve...

If you have Resolve Studio, it has optical flow time warp.

Depending on the kind of motion in the clip you can do a change from 24 to 30 with optical flow interpolated frames... whether not you'll have good results is quite variable, when it works well it works really well, when it doesn't work it breaks in very interesting and spectacular ways.

Frame duplication with 24-to-30fps is a common practice. It happens all the time. Those Hollywood movies on DVD all have frames 3 and 4 duplicated since they were shot in 24 and your TV (NTSC) is 30. (At least, your old tube TV...)

That said, yes, of course you shouldn't submit stock with frames 3 and 4 duplicated, but the end-result of frame duplication in a final project is completely acceptable. The frame duplication is virtually unnoticeable unless you pixel peep or watch one frame at a time. I'd rather see a 24 clip edited in a 30 timeline with frame duplication than a 30 clip in a 24 timeline where frames need to be chucked or slowed to fit. (Unless you do some voodoo frame optical flow warp conversion, which is a whole other conversation.)

With interlaced video, video "tapes", and CRT TVs basically a thing of the past, it really doesn't matter anymore. Every frame rate has it's own use. One isn't necessarily better than the other. 30, 60, or higher is great for sports, gaming and VR because it handles motion better, but 24 is still considered "cinematic."

We're shooting stock. And stock can't cover all scenarios or situations. So, pick a frame rate you like and don't fret about it. For me, that's mostly 24.

Plus, my file sizes are smaller ... :)

Resolve's optical flow, I find, is not always satisfactory. Much easier to simply create a new timeline with the appropriate settings and work with the footage the way it was shot. Unless speed ramping/changing, etc, I don't use Optical Flow especially on more detailed movement shots.

In VR higher frame rates matter. A lot. Even if it's not action-packed, it can be literally sickening to have lower than 90fps. On that note I wonder if elements intended for VR be created for a higher frame rate.

I suspect, I say "suspect" as I haven't seen real cinema in almost 2 decades ... that home "cinema" and internet/smaller screens have highly reduced the aesthetic reasons for 24p. And in wildlife shooting, or nature scenics, taking 30p and slowing to 24 can indeed make everything majestic. Slowing native 24p can just be ... well, not great. I'll stick with 30 for stock. Can't say that changing now after 12 years is going to affect anything sales-wise.

Ironically, because I'm a lazy sod, I'm working at 16p in some cases for my stop motion, 1:1 on a 24p timeline. Don't ask. Not sure how it is working, but it is. Not much to do with stock, which was of course the query made by the OP.

@Desgns said:
"Frame duplication with 24-to-30fps is a common practice. It happens all the time. Those Hollywood movies on DVD all have frames 3 and 4 duplicated since they were shot in 24 and your TV (NTSC) is 30. (At least, your old tube TV...)"

No that's not what I was talking about. I was talking about taking 30p and going down to 24p — This is a problem because skipping progressive frames with a 1:1:1:2 cadence will be jumpy.

But just to mention, your description of telecine "of Hollywood movies" is a little off. NTSC is 60 individual fields per second, each field is temporally displaced so it is essentially a 60fps system, except that each field is half resolution of a complete "frame" and interlaced. Nevertheless each field is temporally discrete.

24 fps film to NTSC telecine does not "duplicate frames three and four". Transfer of 24fps (24p) to 30i (60 Interlaced fields per second) uses a 3:2 field pulldown cadence, and it goes like this like this: (frames are lettered A-E fields are F1/F2)

Film frame A Goes to NTSC frame A - F1 & F2 and frame B - F1
Film frame B Goes to NTSC frame B - F2 and frame C - F1
Film frame C Goes to NTSC frame C - F2 and frame D - F1 & F2
Film frame D Goes to NTSC frame E - F1 & F2

Here, the cadence is 3:2:3:2

This is sometimes called a 3:2 interleave, But more often 3:2 pulldown. Another cadence sometimes used with digital video is the 2:3 pulldown, Where the cadence is 2:3:3:2 (and is less desirable, no thanks Panasonic)....

The reason it's interleaved over 60 fields instead of duplicating full frames, is to alleviate the jumping as that happens when you try to duplicate (Or cut) full frames.

Not that it matters, but I actually work on "Those Hollywood movies" 😎

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@Mizamook
"optical flow, I find, is not always satisfactory."

Oh for sure, like I was saying optical flow can work really well with certain kind of material, but when it breaks, it breaks pretty spectacularly. I haven't tried out specifically the one in Resolve myself, but most of them are just using the same algorithm that Kodak developed back in the 90s (I think it was the 90s LOL).

The tuning settings do make a difference depending on material.

"Slowing native 24p can just be ... well, not great"

I've had decent luck taking 24fps straight to 48fps, but not so much for anything between. Good for clouds, water, smooth motion, sometimes OK for people walking..... but very terrible for people running.

Taking 24fps to 96fps is.... I can only describe it as "psychedelic".

cheers

So, given what BBC and Netflix wants it is not a waste of time to record at 24p 422 prores and upload 24p 422 prores ..... and buy more storage. Right? I will give it a try.

👍👍👍👍👍👍 Great information !!!

Agreed. All good information. Thanks.

Basic question here lol
If I've shot 29.97 and my timeline and render frame rate is 23.976 do I:

Modify/interpret the clip to 23.976 before putting it on the timeline or do I simply throw the 29 clip onto the 23 timeline?

PS I'm using Premiere Pro if that makes any difference.
Thanks for any help on the difference.

@Videostock50 said
> "Modify/interpret the clip to 23.976 before putting it on the timeline or do I simply throw the 29 clip onto the 23 timeline?"

Well, theoretically you can just throw it on a 23.976 timeline, and hope Premier does an OK job Interpolating it. In this case it's really more how you like the results.

I usually recommend that all clips on the timeline are prepared and at the frame rate of the timeline, doing any speed changes as a separate effect. But keep in mind that I am old school and that was the traditional way of always doing this.

For instance, if you shot 29.97, but it was something like interlaced NTSC which is 60 fields per second (59.94), then you would want to do a combination of de-interlacing that would preserve vertical resolution and remove the interlacing motion artifacts. Systems that do this use Motion detection techniques to convert the 60 field on the 24 progressive frames, by removing the small amounts of interfield motion.

If you are at 29.97 but progressive, and want to maintain speed when going to 24fps you need to either skip frames, use frame blending, or do an optical flow/time warp.

Skip frames is fast but often objectionably jumpy, frame blending kind of sucks with its own jittery smear nastiness, optical flow is time and processor intensive and results can be "weird". In other words none of these options are really great.

Best practice is, if you shot at 29.97, then cut at 29.97. Or vice versa.

As I mentioned above, if I have some 30p footage that needs to be at 24, I'm more than likely just going to slow it down to 24 on a frame to frame basis. Obviously this does not work well for dialogue scenes, but often is great in a montage, as I think about it that's probably one of the more common places to use stock footage.

That said, I always shoot at 24 unless I specifically think something would be good in slow-mo in which case I shoot at 60, which can also go to 30 or 24 without much problem.

Thank you for your detailed reply.
I should have been more specific. It is shot in progressive. There is no dialogue.
I simply want to slow it down a little to make it smoother, which is the reason for shooting at 30 and rendering at 24.
From what you've said it sounds as though interpreting the clip before adding to the timeline is the best practice.