# Twixtor, Slow Motion



## CheeseForSteeze (May 11, 2011)

I'm sure most of you have seen this video, but the point is it was shot on HD Hero 2's which are only capable of 120fps @ 800x480 or full HD (1080p?) at 60fps. 

I was curious as to how this works if anyone knows. So you can get this kind of slow mo with post processing but the source only being shot at 120fps or even 60fps? I'm guessing it uses some sort of interpolation method to smooth it out. Is there some sort of rule of thumb to how slow you could make stuff? Like, I'm sure there are advantages to shooting at 120fps in that the post processing could slow your media to a greater degree before interpolation artifacts started appearing.

Theoretically a very high quality camera like the Phantom Flex or VariCam systems Brainfarm used in Art of Flight/TiTA are capable of achieving incredible slow mo as seen in those films (copter blades spinning, big pow slashes almost stationary etc.) since those cameras can shoot full HD at thousands of frames per second ... is post processing still needed or can these cameras achieve ultra-slow mo naturally? Their site says the Phantom system can shoot at 2570 @ 1080p which on 22fps playback on a television would be something like 0.85% real time.

Any information from you multimedia gurus would be appreciated.


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## CaP17A (Sep 23, 2011)

CheeseForSteeze said:


> I'm sure most of you have seen this video, but the point is it was shot on HD Hero 2's which are only capable of 120fps @ 800x480 or full HD (1080p?) at 60fps.
> 
> I was curious as to how this works if anyone knows. So you can get this kind of slow mo with post processing but the source only being shot at 120fps or even 60fps? I'm guessing it uses some sort of interpolation method to smooth it out. Is there some sort of rule of thumb to how slow you could make stuff? Like, I'm sure there are advantages to shooting at 120fps in that the post processing could slow your media to a greater degree before interpolation artifacts started appearing.
> 
> ...


I don't know very much on it but basically Twixtor and Optical Flow in FCPX guesses at the frame rate and how to smooth it out. Theoretically you can go as slow as you want but there would be more warp or ghosting around the edges of the subject. From my limited experience with it it works a huge amount better if the background is one color or not too exciting...I have gotten it as slow as 25% speed I believe with only a small amount of ghosting and the camera I was shooting at was 60i @ 1080i.


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