"Pulldown"

[lilhobo]

i have seen this term used every now and then for video editing and encoding.

what does it mean? Guessing would be something to do with video aspect?


edit:

http://www.zerocut.com/tech/pulldown.html

But what does it mean for home video directors?? :D

[Guest]

It means the same thing for everyone.

If you mean what is the relevance of pulldown for "home video directors", you'll have to tell us what you mean by the latter term.

Pulldown is generally used to display film content at NTSC frame rates.

[lilhobo]

well what do u mean by film content?

Even Lucas is shooting with digital cameras now not the 35 mm

[Guest]

I mean video at traditional film frame rates.

Pulldown is used to increase the native frame rate of the source material to match a higher frame rate of a display device. Is it clear now?

[DewAsmara]

PullDown is to matching 24p frame rate into NTSC 29.97 or 30 frame rate. It doesn't necessary for 25 frame rate PAL. Only have to be synch audio carefully for PAL as can be result like chipmunk :p

[Guest]

It can indeed be used for PAL->NTSC.

It can also be used to boost any frame rate by up to a factor of 3/2, e.g., an 18fps silent film to PAL.

Pulldown does not have to be pure 3:2. It can be irregular.

Furthermore, field pulldown is not the only possibility. You can have frame pulldown as well, by means of which you can triple the frame rate.

[laserfan]

well what do u mean by film content? Even Lucas is shooting with digital cameras now not the 35 mmSurely you don't watch only Lucas movies?!?! :rolleyes:

As the others have said, you need, for video, to increase the frame rate from 24 frames/sec film to something greater than that, by duplicating the film frames. I think of the term "pull-down" in terms of film moving thru a projector. For video, you need to "pull-down" that last frame (or frames plural) and show them again.

Instead of duplicating film frames for video, there are "flags" in the video program to say to the player "play that last frame again" i.e. "pull-it-down/back and show it again".

The flag is just a bit vs. including the entire actual frame in the video program (again), so that bit doesn't take up nearly as much space.

Is it important for home video? Not if all you're doing is editing home videos shot with a camcorder. But if you manipulate commercial programs which originate on film (and there are even lots of TV shows that still do) then you want to try to understand some of these basic terms.

[Guest]

laserfan, 3:2 pulldown pulls down fields, not frames. Frame pulldown, although possible, is rarely seen. Your run of the mill pulldown to render 24fps to 30fps is field duplication, not frame duplication.

[laserfan]

Thanks for the clarification; hopefully the OP can go back to his original link and make some sense of it now. :)