Comment Telecine transform (Score 1) 599
This is done by way of a process which duplicates every 6th frame.
Not exactly. The telecine 2:3 pulldown conversion is from 24 full frames per second to ~60 interlaced fields (half-frames) per second, which means 4 input frames get converted to 10 output fields. In a straight 2:3 pulldown, film frames ABCD are output as interlaced fields AABBBCCDDD. This transform interacts badly with naïve deinterlacing though: if you just pair off the fields, you get AA BB BC CD DD, leaving you with two mixed-up frames and no intact C frame. Some other pulldown patterns are better behaved when naïvely deinterlaced, such as 2:3:3:2 which produces AA BB BC CC DD.
Many nonlinear editing toolkits, and maybe even a few viewing sets, can recognize when pulldown has been applied and remove it, reconstructing video at the original frame rate.