HV20 and Pulldown

[Kevin Camp]

yes ae can handle the pulldown, and it should work as well as any other software to remove a pulldown. however, if the footage has been edited with a pulldown in place, or if several shots were captured in one capture (one file) with the pulldown in place you will have problems in ae, and will need to edit/export out the individual shots to effect in ae.

but after that the process is easy… bring the footage into ae. select the footage in project window and choose file>interpret footage… set to separate fields (with proper dominance), and hit the guess pulldown (ae can handle the standard 3:2 pulldown or advanced pulldown).

you should now be able to put the footage into a 23.976 comp and see all the progressive frames.

you should also be able to remove the pulldown at capture from most nle’s, just check your manual for dealing with 24p projects. it’s a much better practice to remove the pulldown at acquisition to avoid problems later on. you never want to edit or effect with footage that has a pulldown, you want to work in 24p natively throughout, waiting until the project is done before reintroducing a pulldown to put a it to tape or final delivery for broadcast)

Kevin Camp
Designer – KCPQ, KMYQ & KRCW

[Sam Rose]

Hi
Thanks for the reply.

I imported my unedited m2t video into After Effects. I chose interpret footage and then clicked guess 3:2 Pulldown and then I clicked ok.

There is a very little difference between the original and the one with the 24P pulldown. I have seen images on the net with bigger quality differences.

Here is the original footage screenshot:
https://img67.imageshack.us/img67/2663/normalof8.jpg

This is the one with the pulldown:
https://img67.imageshack.us/img67/3937/24pnh6.jpg

What does 24P actually do? What are the differences meant to be and have I done something wrong?

Thanks

[Steve Roberts]

When a video camera shoots “24P”, it shoots 23.976 frames per second. But videotape runs at 29.97 fps, so the camera takes those shot frames and splits them up to make 24 into 30, basically. This is called adding 3:2 pulldown. Nothing is lost. Some frames are unchanged, but some are split, where every other line is interlaced every-other-line with the next frame.
This looks like film transferred to video, which we’re all used to seeing.

But we often remove pulldown so we editors and MG artists are not working with interlaced frames and copies of frames — it’s just easier to work with.

When software removes pulldown, it reassembles and restores the frames so they now run at 23.976 fps (close to 24) within the computer. Each frame is “progressive” (not interlaced), as the video was originally shot.

The purpose of 24P is to make video that has the same frame rate as film, to give a filmic look. It doesn’t make each frame look better than “video”, it makes it run differently.

[Kevin Camp]

as steve said, the only difference between the 24p with a pulldown and 24p without a pulldown is the interlaced frames (with a 3:2 pulldown, you would see 3 progressive frames, then 2 interlaced frames).

to see the difference between the 24p with a pulldown and with the pulldown removed, duplicate you footage in the project window, with that duplicate selected, go to file>interpret foootage and turn separate fields off. put that version into a 29.97 comp, advance a few frames through the timeline until you find an interlaced frame (you may want to find a section where there is more movement, it will be easier to see the interlacing).

now drag in the 24p footage that has had the pulldown removed. you can toggle between them to see the difference with pulldown and without.

Kevin Camp
Designer – KCPQ, KMYQ & KRCW

[Sam Rose]

Hi
Thanks very much I think I am understanding this better. If the footage is then progressive does that mean that slow motion will be a lot better quality aswell?

[Kevin Camp]

not really… you will still need to interpolate new frames between the progressive frames. you do, however, have better resolution to work with (when you slow down interlaced footage, you need to deinterlace first, sacrificing some resolution to do so).

however if you slow down interlaced footage to exactly half speed you actually benefit from the interlaced frames, using alternating fields to generate each frame.

that may sound a bit confusing, but if you have some interlaced footage, take it into ae, use interpret footage to make sure fields are being separated correctly (check the smooth edges box too), drop it into a 29.97 comp. with the footage selected, choose layer>time>time stretch… and set it to 200%. you should get surprisingly good (and fast) slow motion video.

the main advantage of progressive footage is the cleaner, sharper progressive footage for effecting.

Kevin Camp
Designer – KCPQ, KMYQ & KRCW