FrankB said:
Bringing everything to 120 (119.88)fps is not good, too. Ok, you can take the smooth, ready IVTCed 23.976 and “enlarge” it with a ratio 4:1, that is, repeat each frame 5 times. For the 29.97 portions, also smooth, repeat each frame 4 times. Everything 100% smooth, ok, BUT: The speed ratio of both won’t be correct, the latter ones (29.97) will play 4/5 slower than the others.
Just did it again… myself a victim of the mentioned fallacies… 😉
After combining the different portions to 120fps as mentioned above, everything will of course play in exactly the same and correct speed. So 120 would really be an option, if done right.