• About INTERPOLATION and why you should use multiples of your project-fps setting
If you use e.g. only 30, 60, 120fps files in a 30fps project and you want to
slow down e.g. the 60fps clip by setting it to 1/2 speed, then the algorithm
just has to pull out every second frame to get the 30 frames for a 30fps timeline.
A 120fps file at 1/4 speed would only use every 4th frame.
However, if you want to extract frames from a 50fps file to match the frame
boundaries of a 30fps timeline it is not that easy anymore. Because you are
referencing a position between frames and the software has to interpolate a
Just imagine splitting 10 into five steps -> 2, 4, 6, 8, 10...
So just pull out these frames!
Now split 10 into 3 steps -> 3.33 6.66 9.99...
Now you’d have to round for frames: 3.33 goes 3 - 6.66 goes 7 - 9.99 goes 10
These numbers 3, 7, 10 would not lead to a smooth result but you can’t just use
‘in between’ frames or half frames, so you have to go odd.
That’s why you should stick to either recording with 30, 60, 120 for a 30fps timeline
or 25, 50, 100 for a 25fps timeline etc. because there is no interpolation involved that
makes you depend on the quality of the software algorithms your application provides.
The same counts of course for the speed factor you choose to slow down your footage.
Last edited by mramosch on Sun Oct 14, 2018 10:50 am, edited 1 time in total.