30 fps Render animation video vs 24 fps render video then convert it into 30 fps

[Squirrel IT]

in keyshot i make animation for product because of render duration is high so i get an idea to reduce frame to 24 fps and then in after effect convert into 30 and 60 fps from 24 fps i cannot find any noticeable different so is it good idea to reduce fps in rendering and then increase in post production? i can't upload video due to size

[Levent]

51 minutes ago, Squirrel IT said:

it good idea to reduce fps in rendering and then increase in post production?

If source material is 24 fps, even if you make the output 400fps, it still will be 24fps. So no.

[LAwLz]

18 minutes ago, Levent said:

If source material is 24 fps, even if you make the output 400fps, it still will be 24fps. So no.

That's not true. 

I am not sure what processing OP is talking about, but it is possible to dynamically generate additional frames. It's called motion interpolation. It works pretty well, although I personally don't like it since I prefer my videos at 24 or 30 FPS. 

[wanderingfool2]

4 hours ago, Squirrel IT said:

in keyshot i make animation for product because of render duration is high so i get an idea to reduce frame to 24 fps and then in after effect convert into 30 and 60 fps from 24 fps i cannot find any noticeable different so is it good idea to reduce fps in rendering and then increase in post production? i can't upload video due to size

Well I mean 24 fps to 30 fps probably causes more issues than it's worth (with so little difference).  Now if you rendered at 30 fps and did 60 fps then maybe.

 

The reason I say this is at 24 fps to 30 fps the output will have 1 in every 5 frames "correct".  The other 4 frames would need to all be extracted and "guessed" from the other frames.  There would be a chance that it keeps the original frames and just tries interpolating between a couple frames...but then you get a temporal issue.

 

Could be wrong, but I would suspect rendering at 15 fps and converting to 30 fps might actually product better results (every 15 fps frame lands on the 30 fps frame...so you only have to guess on 50% of the frames).  vs the 24 fps you would have to guess on 80% of the frames (although each "frame" has a closer frame).

[LAwLz]

2 hours ago, wanderingfool2 said:

 

The reason I say this is at 24 fps to 30 fps the output will have 1 in every 5 frames "correct".  The other 4 frames would need to all be extracted and "guessed" from the other frames.  There would be a chance that it keeps the original frames and just tries interpolating between a couple frames...but then you get a temporal issue.

 

Could be wrong, but I would suspect rendering at 15 fps and converting to 30 fps might actually product better results (every 15 fps frame lands on the 30 fps frame...so you only have to guess on 50% of the frames).  vs the 24 fps you would have to guess on 80% of the frames (although each "frame" has a closer frame).

Can you explain the math you did here? 

15 FPS to 30 FPS means 50% of the frames are interpolated. 

24 to 30 FPS means 20% of the frames are interpolated. Not 80%.

[BabaGanuche]

1 hour ago, LAwLz said:

Can you explain the math you did here? 

15 FPS to 30 FPS means 50% of the frames are interpolated. 

24 to 30 FPS means 20% of the frames are interpolated. Not 80%.

30 FPS every other frame from the 15 FPS is an original frame.

 

30 FPS every 5th frame from 24 FPS is an original frame. It would when they are exact multiple of each other.

1/30, 1/15, 1/10, 2/15, 1/6. For 30 FPS

1/24, 1/12, 1/8, 1/6. For 24 FPS

[Blue4130]

3 hours ago, BabaGanuche said:

30 FPS every other frame from the 15 FPS is an original frame.

 

30 FPS every 5th frame from 24 FPS is an original frame. It would when they are exact multiple of each other.

1/30, 1/15, 1/10, 2/15, 1/6. For 30 FPS

1/24, 1/12, 1/8, 1/6. For 24 FPS

Yea, that isn't how it works...

[LAwLz]

3 hours ago, BabaGanuche said:

30 FPS every other frame from the 15 FPS is an original frame.

 

30 FPS every 5th frame from 24 FPS is an original frame. It would when they are exact multiple of each other.

1/30, 1/15, 1/10, 2/15, 1/6. For 30 FPS

1/24, 1/12, 1/8, 1/6. For 24 FPS

Still not following what you or wanderingfool are talking about.

 

Are you saying that if you got a 24 FPS source and want to "upscale" it to 30 FPS, the motion interpolation program will throw away frames until the source is 6 FPS, and then it will upscale it to 30 FPS from there?

I guess that some programs might do that, but that seems like a really dumb way of doing things so I doubt it is done.

SVP for example allows you to tweak how many frames you want to use as the source for your interpolated frames. It does not have to double the FPS.

 

Even if you use some primitive motion interpolation, it makes no sense to drop frames from the source and then create new frames.

If you got a 24 FPS source and want it at 30 FPS, but don't know how to do motion interpolation from a non-common-multiplier (or whatever it's called in English), just double the frame rate to 48, and then do some kind of 3:2 pulldown (except you delete the frames). That way you keep all the original frames, and get some newly generated frames inserted so that the frame rate becomes 30 FPS.

[BabaGanuche]

13 hours ago, LAwLz said:

Still not following what you or wanderingfool are talking about.

 

Are you saying that if you got a 24 FPS source and want to "upscale" it to 30 FPS, the motion interpolation program will throw away frames until the source is 6 FPS, and then it will upscale it to 30 FPS from there?

I guess that some programs might do that, but that seems like a really dumb way of doing things so I doubt it is done.

SVP for example allows you to tweak how many frames you want to use as the source for your interpolated frames. It does not have to double the FPS.

 

Even if you use some primitive motion interpolation, it makes no sense to drop frames from the source and then create new frames.

If you got a 24 FPS source and want it at 30 FPS, but don't know how to do motion interpolation from a non-common-multiplier (or whatever it's called in English), just double the frame rate to 48, and then do some kind of 3:2 pulldown (except you delete the frames). That way you keep all the original frames, and get some newly generated frames inserted so that the frame rate becomes 30 FPS.

See the graph below that better describes what I am talking about.The vertical axis of the graph is 24 FPS frame number and the horizontal axis is 30 FPS frame number. You can only directly use the original 24 FPS frame when it would occur at the same time as 30 FPS frame. This means that 4 of 5 frames are interpolated of the 30 FPS version.

 

[LAwLz]

52 minutes ago, BabaGanuche said:

You can only directly use the original 24 FPS frame when it would occur at the same time as 30 FPS frame. 

Why do you believe this is true? It isn't. 

[wanderingfool2]

23 hours ago, LAwLz said:

Can you explain the math you did here? 

15 FPS to 30 FPS means 50% of the frames are interpolated. 

24 to 30 FPS means 20% of the frames are interpolated. Not 80%.

That assumes you would use 24 of the original frames as frames in the 30 fps.  That creates a visual temporal anomaly because you are now needing to insert 6 new frames at different intervals.

 

19 hours ago, LAwLz said:

If you got a 24 FPS source and want it at 30 FPS, but don't know how to do motion interpolation from a non-common-multiplier (or whatever it's called in English), just double the frame rate to 48, and then do some kind of 3:2 pulldown (except you delete the frames). That way you keep all the original frames, and get some newly generated frames inserted so that the frame rate becomes 30 FPS.

That still creates temporal issues if you just use all 48 of the frames generated and convert to 30 fps.

 

For the sake of not having to do all 30 frames of math, I've but it down to first cycle

24 fps You have frames to display at

0, 1/24, 2/24, 3/24, 4/24 (1/6)

 

30 fps

0, 1/30, 2/30, 3/30, 4/30, 5/30 (1/6)

 

Now the naive way (the way -some- programs do it, it just grabs the closest frames), that would mean 24 to 30 fps would look like this

0, 1/24, 2/24, 2/24, 3/24, 4/24 (exact match)

The glaring issue is the 2/24 one being doubled up, so lets say we create an interpolated frame just for that one

0, 1/24, [interpolated], 2/24, 3/24, 4/24

 

The reason the first 2/24 was interpolated is because it was the one that was "off" by the most.  This still creates a temporal issue though, because each frame is shown slightly off of where it would be at 24 fps.  Here is the "off by" numbers (negative results means it was shown early)

Frame 0: 0

Frame 1: 1/30 - 1/24 = -0.01666 [early]

Frame 2: [Interpolated]

Frame 3: 3/30 - 2/24 = 0.01666 [late]

Frame 4: 4/30 - 3/24 = 0.008333 [late]

Frame 5: 0

 

So that is sort of where the issue lies, if you decide to use original frames in the 30 fps feed, you now are displaying it in the worst case (without any interpolations) at 0.0333 seconds difference in time..or if you somehow had a perfect interpolation on frame 2, the difference of 0.01666 seconds from the actual display time.

 

Generally people won't notice it, depending on the scene, but it could very well become noticeable during certain kinds of motion events (lets say you have a fence in the background and are panning the camera...you get the effect of the camera slowing down then speeding up).  It's enough to make it look slightly unnatural (even if most people wouldn't be able to pinpoint what feels wrong about it).

 

The "solution" would be then to interpolate frames 1, 2, 3, 4...where you use the 2 closest frames and have an intelligent system to know to put a heavier bias on the closer number.  Which is why I was saying only 20% of the frames are correct...because realistically they are.  The other frames either are interpolated but if you choose the original frame approach you get a temporal issue from above.  Either way that's why I suspect 15 fps would work better, because you effectively have every original frame used in exactly the correct position (and the other half of the 30 fps frames are interpolated)

 

 

[Avocado Diaboli]

@LAwLz I think the issue the others are raising would probably best be illustrated visually. Let's say I have an animation that's 4 frames long. Here's a mock up with a circle moving from left to right over the course of 4 frames (the grey lines are just guides to show relative placement within each frame)

 

 

 

Now I want to interpolate that so that the same animation with the same duration takes place in the span of 5 frames. That would look like this:

 

In order to animate that circle from the left side of the frame to the right side of the frame in 5 instead of 4 frames within the same time limit, I can only really reuse frame 1 and 4 of the original animation and have to create 3 new frames from scratch, because the frames in-between don't exist in the original animation.

 

 

[LAwLz]

1 hour ago, wanderingfool2 said:

-snip-

1 hour ago, Avocado Diaboli said:

-snip-

Both of these posts assumes each frame has to be displayed for the same amount of time, which is simply not true.

In fact, video is rarely displayed with the same frame time for each frame. It create some judder, but we are used to that because we experience it all the time. A bit of judder is most likely way better than throwing away 80% of the frames just to recreate them as well.

 

I'll play around with some tools and report back how it goes, because right now I am not entirely sure how they handle it. It feels very stupid if the program would throw away all the frames so that it's 6 FPS, and then interpolate from there.

[wanderingfool2]

19 minutes ago, LAwLz said:

In fact, video is rarely displayed with the same frame time for each frame. It create some judder, but we are used to that because we experience it all the time. A bit of judder is most likely way better than throwing away 80% of the frames just to recreate them as well.

Realistically the variation of displaying from 30fps isn't really as big compared to what happens if you double up frames and such.  I think one of the corridor crew videos talked about it once upon a time and showed examples of the film being changed as such.

 

The whole https://en.wikipedia.org/wiki/Three-two_pull_down  also explains it pretty decently as well.  The best example would be a quick strobe; or like what Avocado said with a moving object.

[LAwLz]

2 minutes ago, wanderingfool2 said:

Realistically the variation of displaying from 30fps isn't really as big compared to what happens if you double up frames and such.  I think one of the corridor crew videos talked about it once upon a time and showed examples of the film being changed as such.

 

The whole https://en.wikipedia.org/wiki/Three-two_pull_down  also explains it pretty decently as well.  The best example would be a quick strobe; or like what Avocado said with a moving object.

I know... I even referenced exactly what you're talking about here:

21 hours ago, LAwLz said:

If you got a 24 FPS source and want it at 30 FPS, but don't know how to do motion interpolation from a non-common-multiplier (or whatever it's called in English), just double the frame rate to 48, and then do some kind of 3:2 pulldown (except you delete the frames). That way you keep all the original frames, and get some newly generated frames inserted so that the frame rate becomes 30 FPS.

 

[wanderingfool2]

20 minutes ago, LAwLz said:

I know... I even referenced exactly what you're talking about here:

I know that you referenced it, but thought I would show the wiki article because it does a good job showing it...especially given that you still were mentioning that you keep all the original frames...which 3:2 pull down definitely doesn't...and even doing 48 to 30 wouldn't.

[LAwLz]

22 minutes ago, wanderingfool2 said:

I know that you referenced it, but thought I would show the wiki article because it does a good job showing it...especially given that you still were mentioning that you keep all the original frames...which 3:2 pull down definitely doesn't...and even doing 48 to 30 wouldn't.

It does...

 

3:2 pull down from 24 FPS to 30 FPS keeps all the original frames.

 

Going from 24 FPS to 48 FPS keeps all the original frames, then you could strip out a bunch of frames in an uneven pattern (similar to how 3:2 pull down displays frames in an uneven pattern) to get to 30 FPS. That's what I was trying to say.

[LAwLz]

Okay, I just tested SVP.

 

I created a 24 frame long video that looked like this:

 

Then the red square moves 1.25 blocks each frame.

 

 

This is what happens when playing it back through SVP, converting it to 60 FPS:

Frame 01 - Original frame 1

Frame 02 - new

Frame 03 - new

Frame 04 - new

Frame 05 - new

Frame 06 - new

Frame 07 - Original frame 3

Frame 08 - new

Frame 09 - new

Frame 10 - Original frame 4

Frame 11 - new

Frame 12 - new

Frame 13 - Original frame 5

Frame 14 - new

Frame 15 - new

Frame 16 - new

Frame 17 - new

Frame 18 - new

Frame 19 - Original frame 7

Frame 20 - new

Frame 21 - new

Frame 22 - new

Frame 23 - new

Frame 24 - Original frame 9

Frame 25 - new

Frame 26 - new

Frame 27 - new

Frame 28 - new

Frame 29 - Original frame 11

Frame 30 - new

Frame 31 - new

Frame 32 - new

Frame 33 - new

Frame 34 - Original frame 13

Frame 35 - new

Frame 36 - new

Frame 37 - new

Frame 38 - new

Frame 39 - Original frame 15

Frame 40 - new

Frame 41 - new

Frame 42 - new

Frame 43 - new

Frame 44 - Original frame 17

Frame 45 - new

Frame 46 - new

Frame 47 - new

Frame 48 - new

Frame 49 - Original frame 19

Frame 50 - new

Frame 51 - new

Frame 52 - new

Frame 53 - new

Frame 54 - Original frame 21

 

After frame 54 the video glitches out.

 

 

 

Not sure what SVP was doing in the beginning, but after a while it seems like it will skip every 1 frame of the original, and create 4 new frames between them.

Sadly it seems like you can't manually set SVP to output 30 FPS so I can't check what the pattern is for that. 

 

Seems like I was wrong. At least when it comes to SVP using default settings, it will drop the frame rate and then convert from there.

[wanderingfool2]

1 hour ago, LAwLz said:

3:2 pull down from 24 FPS to 30 FPS keeps all the original frames.

That's why I posted the wiki page.  It does a good job explaining, and the visual bit showing that it doesn't keep the original frames.  In the example they show they effectively use an interlace technique to generate the new frames.

 

1 hour ago, LAwLz said:

Going from 24 FPS to 48 FPS keeps all the original frames, then you could strip out a bunch of frames in an uneven pattern (similar to how 3:2 pull down displays frames in an uneven pattern) to get to 30 FPS. That's what I was trying to say.

The fact is doubling it up and creating a 48 fps that means every other frame is now a generated frame (not an original frame).  So if you use the closer frames you effectively then hit the same situation I was talking about (where you effectively are using an interpolated frame).

 

38 minutes ago, LAwLz said:

Seems like I was wrong. At least when it comes to SVP using default settings, it will drop the frame rate and then convert from there.

It all really boils down to the math.  There is only so much you can do when you have uneven frames, which is why having perfect multiples is important.

[Mark Kaine]

p sure you can "uprender" frames … same as resolution… you can always be like "its just fake" but actually the "fake" higher res will look sharper, and the "fake" framerate smoother…

 

I do this all the time with handbrake , obs, etc…

 

 

 

[wanderingfool2]

19 hours ago, Mark Kaine said:

p sure you can "uprender" frames … same as resolution… you can always be like "its just fake" but actually the "fake" higher res will look sharper, and the "fake" framerate smoother…

 

I do this all the time with handbrake , obs, etc…

 

 

 

Not necessarily.  People are a lot more adept at detecting temporal differences than fine detail.  Uprendering resolution can work, especially on video, because you can actually garner a lot of information based on how the pixels are changing.

 

The ball example is the best case where interpolating can really get messed up.  In the perfect scenario you isolate the ball, detect the movement it did and place it...but in reality it's not the case.  You will either get artifacting (like the 3:2 as described on wiki would create interlacing artifacts, and also slight temporal issues).

[Mark Kaine]

On 4/19/2022 at 7:59 PM, wanderingfool2 said:

Not necessarily.  People are a lot more adept at detecting temporal differences than fine detail.  Uprendering resolution can work, especially on video, because you can actually garner a lot of information based on how the pixels are changing.

 

The ball example is the best case where interpolating can really get messed up.  In the perfect scenario you isolate the ball, detect the movement it did and place it...but in reality it's not the case.  You will either get artifacting (like the 3:2 as described on wiki would create interlacing artifacts, and also slight temporal issues).

Thing is tbf, most of the time i see no diff between 30 and 60 fps "upscaled" , but sometimes I do - and sometimes it goes wrong and is really jittery… but if it works my friend will immediately stop complaining that its only "30fps" lol…

 

but yeah, sometimes it does look smoother… idk 25fps video will look more smooth when recorded at 60fps - even if this maybe doesnt  make sense - its especially noticable on my phone (definetley depends on screen / motion blur / etc imo) 

[wanderingfool2]

57 minutes ago, Mark Kaine said:

Thing is tbf, most of the time i see no diff between 30 and 60 fps "upscaled" , but sometimes I do - and sometimes it goes wrong and is really jittery… but if it works my friend will immediately stop complaining that its only "30fps" lol…

 

but yeah, sometimes it does look smoother… idk 25fps video will look more smooth when recorded at 60fps - even if this maybe doesnt  make sense - its especially noticable on my phone (definetley depends on screen / motion blur / etc imo) 

Well I mean doing 24 fps to 60 fps would produce a better result than 24fps to 30 fps.  The sheer fact that the frames are now closer to the original.

 

Like instead of having a 0.01666 variance you now have 0.0083333 variance...which is why you will have less perceived jitter.  You still will get issues, but the issue becomes less pronounced.

 

It will greatly depend on the person, some people are more adept at spotting changes in speed like that (like myself).  Other people are more sensitive to color changes (I'm terrible at spotting color issues) and other people are good at picking out HDR.

[Mark Kaine]

52 minutes ago, wanderingfool2 said:

Well I mean doing 24 fps to 60 fps would produce a better result than 24fps to 30 fps.  The sheer fact that the frames are now closer to the original.

 

Like instead of having a 0.01666 variance you now have 0.0083333 variance...which is why you will have less perceived jitter.  You still will get issues, but the issue becomes less pronounced.

 

It will greatly depend on the person, some people are more adept at spotting changes in speed like that (like myself).  Other people are more sensitive to color changes (I'm terrible at spotting color issues) and other people are good at picking out HDR.

yeah i guess that makes sense, 60fps/60hz should look smoother than 25fps/60hz to begin with…

 

its just when i watch on my monitor it looks ok, when i watch on my phone it looks almost like in slowmotion… so it depends on many things.

 

i also generally like movies and such at 60fps… it just feels less jittery, and normal movies often have this "soap opera" effect to me. But some people seem to prefer 24/25fps for that "movie feeling".