minimizing temporal aliasing


Slowing down or speeding up videos can introduce visible temporal artifacts, even with interpolation, especially if the input and output rates differ.
I made myself this table to define the best trade-offs to approach desired fps while avoiding aliasing.
I also took arbitrary constraints (such as fps target or slow motion rates) from well-known softwares into account and favored interpolating first rather than adjusting speed first.

frameRates.ods

desired speed original fps output fps Interpolated fps slow motion x speed on timeline duration of
1 original second
number of final
available frames in 1s
will use every
n frames
(should be integer)
final speed %
(should match
desired speed)

25.00% 25 25 25 4 100.00% 4.00 25 1 25.00%
33.33% 25 25 25 3 100.00% 3.00 25 1 33.33%
50.00% 25 25 50 1 50.00% 2.00 25 1 50.00%
50.00% 25 25 25 2 100.00% 2.00 25 1 50.00%
55.56% 25 25 90 1 55.56% 1.80 50.0004 2.000016 55.56%
62.50% 25 25 120 1 62.50% 1.60 75 3 62.50%
66.66% 25 25 25 3 200.00% 1.50 50 2 66.67%
83.00% 25 25 30 1 83.33% 1.20 25.0002 1.000008 83.33%
100.00% 25 25 25 1 100.00% 1.00 25 1 100.00%
104.17% 25 25 120 1 104.17% 0.96 125.0004 5.000016 104.17%
111.11% 25 25 90 1 111.11% 0.90 99.999 3.99996 111.11%
125.00% 25 25 60 1 125.00% 0.80 75 3 125.00%
145.83% 25 25 120 1 145.83% 0.69 174.996 6.99984 145.83%
150.00% 25 25 50 1 150.00% 0.67 75 3 150.00%
166.67% 25 25 30 1 166.67% 0.60 50.001 2.00004 166.67%
200.00% 25 25 25 1 200.00% 0.50 50 2 200.00%