What is 3-2 pulldown?

This is a term that refers to the technical process of transferring film-based material to DVD and then the reverse process (usually referred to as reverse 3-2 pulldown) whereby a progressive scan DVD player correctly reads this information and transmits a signal to a display.

3-2 pulldown is needed because of the difference in frame rates between film and video. Film consists of 24 frames per second, while NTSC video consists of approximately 30 frames per second (or, more accurately 60 half-frames woven together). The problem is, then, how do you translate 24 film-based frames to 60 video frames? The answer is 3-2 pulldown. Each film frame is matched to the corresponding video frame in a cadence in a sequence of 3-2 as represented below.

As you can see from this diagram, 3-2 pulldown allows us to successfully convert 4 film-based frames into 10 video frames. Repeat this 6 times, and we have produced 1 second of interlaced video. Without reverse 3-2 pulldown, a progressive scan DVD player or display device will render film-based DVDs with serious motion artifacts that most people find very annoying. The subject of 3-2 pulldown can become very technical. If you want to know more, see this source.