Pulldown VS Pulldown Removal

[Tom Shortridge]

Is it just me, or do a lot of people use these terms (pulldown and pulldown removal) interchangeably?

It's been kinda confusing to me, but I think I got the hang of it now - "pulldown" is how frames are repeated to fill out the 60i nature of tape, while "pulldown removal" plucks out those repeated frames so you can just work with your 24 progressive frames per second.

Is this right, or am I an idiot?

 

[andy_starbuck]

You are correct.

Also, there are two methods for "topping up" the 24 frames to 30 frames per second so that it can be divided into 60 interlaced fields for storage and transmission over 60i standards (ie, 60i magnetic tape, broadcast video, firewire).

One method is to take one field from an original frame, the opposite field from the subsequent original frame, and combine them to make a new "created" in-between frame. This is called "24p".

Another method is called "frame repeating", or in Panasonic terms "24pA" or "Advanced" pulldown. Some frames are simply duplicated.

24p results in video that can be immediately used in 60i and the motion will appear smooth. The repeated frames in 24pA make video that cannot be directly used in 60i because the motion will look choppy or jittery.

Because 24p uses "created" frames it is somewhat harder for a program to remove the extra frames and return to the original 24 frames, because it must first identify the created frames from the original so that it knows which ones to drop.

24pA is easier to get back to the original 24 frames, because the program only needs to recognize duplicates and remove them.

The latest editing software is able to deal with both 24p and 24pA. The ability of earlier versions of editing software to correctly remove pulldown when required and to leave it in when appropriate varies with the age and maker of the software.