fps - issue to understand this topic

Question Animation

Hallo everyone

I see a lot of videos about fps. should it be 24 or 25 (for easier calculation... maybe) or even 50. What is even the difference between 23.98 vs 24? really?

What I do not understand is that when an character is animated and you render it in 24 frames and then in 50 frames does that mean it moves faster?

I made two animations with a cube moving from left to right with once 25 fps and once 50 fps and one is (obviously) clearly moving faster. Now what I don't understand is the process of animating something for example a character in 24 fps, and when it gets rendered in 50 fps doesn't it move too fast and it would look silly?

can anyone explain this to me... I thought I know this but found out I was wrong.


Thank you and have a nice Weekend

  • Martin Bergwerf replied

    Hi Martin,

    Have you watched this already:

    https://www.youtube.com/watch?v=DyqjTZHRdRs

    ?

    • The good Captain
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  • Omar Domenech replied

    Hello Mastart. I don't work with animation much, @waylow will probably give you a better answer, but I'll try it anyways.

    I think the frame rate is all about perception of movement. The 24fps, 30fps or 60 fps are just standards that have been set throughout the years, I think. At 60 frames, or 60 consecutive pictures in one second, there is a lot more information in there to perceive the movements better. You've probably seen gifs like this one FPS GIF, where you see the difference on how your eye can tell there is more spacing in between the movement in the 24fps one and in the 60fps it looks much more smooth.

    I remember when Peter Jackson wanted to do movies at 60fps but people hated how it felt, movement feels very strange because 24fps is how our eyes see, that's what I've heard anyways. YouTube for some reason sets the standard at 30fps, they want 30 pictures for each second. What I know is that animating at 60fps instead of 24fps is doing a lot more work, since for one second of animation you have to go through 60 frames instead of 24, and also you have to render 60 frames for one second of animation instead of rendering 24 frames.

    There must be some weird reason why 23.98fps exists, maybe one of those weird choices people developing tech did back then. Stories like that exists all over, like when choosing the time length a CD had to play music, PAL or NTSC, electrical currents, cargo shipping containers, file compression, etc.

    When playing a game or moving the camera around and you have speed involved, you can always tell how there aren't enough frames when you see that side stepping in the image, because there aren't enough frames in between to fill the spaces.

    30fpsvs60fps2small.jpg

    When you animate the cube moving from left to right, one in 25fps and one in 50fps, you perceive one moving faster, but it's a perception, they will arrive at the same time, only that the 50fps one has more frames in between so you don't notice the side stepping, the 24fps one will feel jagged in the motion if it goes fast enough, because there aren't enough frames in there to mask the movement in space. The cube has to reach it's destination and get from point A to point B, and while it travels to point B in a given time, if it doesn't have enough frames to fill that journey, it will look that it jumps and skips from one moment to the other.

    And for your other scenario, if you animate a character in 24fps, so for one second of animation you will have 24 consecutive images, but then if you render it at 50fps, now that second of animation, instead of having 24 pictures inside it, now it's requiring 50 pictures inside of it, but you only have 24 pictures on there, so what does the software do? well there isn't enough info there, so it looks like it is skipping, like that image above.

    On the other hand, if you animate at 50fps and then you turn it down to 24fps, well now you have lots of info, you have 50 cramped inside the 24 spaces, so it looks fast. Now to get from point A to point B you have 24 frames, but worked with 50 frames worth of info, and it has to goes through 50 fast, because it only has 24 frames to get there. So instead of having 24 images to show in 24 frames, it has 50 images to show in 24 frames, so it rushes through them.

    I hope that long winded explanation help you out a bit.


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  • mastart replied

    Thank you for this verbose explanation Omar, thank you for the video Martin. Maybe I did something wrong at the render settings but they don't arrive at the same time . This it what confuses me. I made 200 frames (201) rendered them out and one video goes 4 sec the other 8 sec... Actually back in the days I thought that If I make 24 fps in 200 I would have 4800 pics until I realised that it just plays 24 frames in a second so in that case 50 fps are faster played then 24... that is why I don't see that an Object should arrive at the same time...

    It seems the more research I make about this the more I know and the more I know the less I understand.... (I know... Paul Weller)

    Thank you so far for your help

    martin

  • Omar Domenech replied

    Ok, check this out... if you set Blender to run at 30fps and you put the scrubber at frame 30, it should be one second, right?

    1.png

    So you change the setting for the timeline to show not frames but time...

    2.png

    Then at the 30 frame mark it'll show 1 second, being at 30fps...

    3.png

    If you leave the scrubber there and you change the Frame Rate to 60, remember the scrubber is resting at frame 30... now Blender set at 60 frames, the time should read half a second, and it does as you can see here....

    4.png

    Now if you want to go to 1 second, you're going to have to go to frame 60 for it to show 1 second, and it does...

    6.png

    Changing back to show frames now, it is at frame 60...

    5.png

    So both in 30 frames and 60 frames, you have 1 second of animation. For 60 frames you had to go double as far in the time line, but it was still one second. If you hit play at 30fps, the scrubber will reach frame 30 in one second, if you hit play at 60fps, the scrubber will reach frame 60 in one second, but it'll just have to get there faster, because now it has 30 extra frames it has to travel.

    So probably what you have been experiencing is that you are rendering at 30 frames and when opening your 30fps render export, Blender is set  to 60fps and it has to re-interpret, or maybe vice verse, you have been rendering at 60 frames but then when importing back into Blender, is set to 30fps and it has to re-interpret your 60fps render. That's mostly when that out of wack time happens. In other words, if you exported in 30fps you have to open it with your software set to 30fps and of course, if you exported in 60fps you have to open it with your software set to 60fps.

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  • mastart replied

    Thank you Omar for your time, really cool what effort you put in here to explain "fps" to me. Thank you very much. I will go through this as you did and hopefully I get this right.

    blessings

    Martin

  • mastart replied

    btw... that GIF already explains a lot

  • Omar Domenech replied

    Cool man. We ACEs take to the sky to demonstrate and demystify. Glad to be of service.  

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