24p or 24pA

[Bob Magill]

What is the difference between 24p and 24pA and
which of the two is the best setting to shoot?
What is the best shutter speed in 24p or 24pA mode?
When would 30p be used?

[David Jimerson]

1) 24p (2:3 pulldown) was developed as a method of showing 24 fps films on a 60i TV. It gives the smoothest playback without flickering possible. It does it by splitting up the 24 frames into fields, and then repeating a field for every other frame, so that the pattern of fields from each frame repeats as follows 2:3:2:3:2:3:2:3 . . . and so on, through the whole program.

2) 24pA (2:3:3:2) pulldown was developed for a different reason, for editing in 24p. While 2:3 pulldown gives smooth playback, it's not ideal for extracting the original 24 frames, because you can't just jam the fields back together into frames -- you'd get a mismatched frame every four frames (that is, a frame made up of fields from two different frames). So, to make it easier, the fields are arranged in a different pattern, so that you can just merge the fields into frames and drop every fourth frame, and you've got your original 24 frames back.


When to use:

If you're going to edit in 24p, use 24pA.

If you're going to edit in 60i (NTSC), or not edit at all and just hand over the tape to play, then use 24p.

Now, Vegas lets you use either pulldown and edit in 24p with no problems, but not every editing system does, so just be in the habit -- if it's going to be edited in native 24p, shoot 24pA.

You don't want to shoot 24pA if it's NOT going to be edited in 24p, because the fields are arranged in a way which may produce a more pronounced strobe. It's not meant to be WATCHED, it's meant to be edited. Then, after you edit, you export it in the format of your choice.

On the back end, if you're exporting to DV tape and it's your final render -- if it's meant to be watched -- then use 2:3 pulldown. If it's meant to be recaptured for further editing in 24p, then use 2:3:3:2 pulldown. If it's meant to be recaptured for editing in 60i, then use 2:3 pulldown.

As for shutter, it's an aesthetic choice, but if you want to mimic a standard film camera shutter, use 1/48 or as close as you can get.

As for 30p, that's an aesthetic choice as well. If you like the look, use it. The only problem with it is that you won't get good results if you want to convert it to 24p or 25p, or go out to film.

[Josh Bass]

I have a short film I just shot that mixes 24p footage and 60i footage. To keep the 60i stuff looking like 60i stuff, I'm finalizing it in a 60i/29.97 timeline. I shot the 24p footage in advanced mode on the XL2, and just plunked it in my 60i timeline next to the 60i footage, so as to assemble everything together. Was this a dumb thing to do? I've also done some futher editing to the 24p stuff after dropping it in the 60i timeline, as well as color correcting/FX stuff. . .am I going to run into huge problems when I'm finally ready to export?

[Douglas Spotted Eagle]

24p and 24A in the V1U are different than 24p and 24PA from the DVX100. VERY important to not confuse them.

24p is just that, 24p information in a 60i package.
24A (not pA) is 24p information in a 60i package that assures the stream always starts with a fresh 2:3 cadence. Some NLE's can't manage the stream if it doesn't start with a fresh cadence, which is why this was added to the V1 at the last minute. You won't find it in the owners manuals; it's an addendum, unless you've got one of the newly printed manuals.

[David Jimerson]

Originally Posted by Josh Bass

I have a short film I just shot that mixes 24p footage and 60i footage. To keep the 60i stuff looking like 60i stuff, I'm finalizing it in a 60i/29.97 timeline. I shot the 24p footage in advanced mode on the XL2, and just plunked it in my 60i timeline next to the 60i footage, so as to assemble everything together. Was this a dumb thing to do? I've also done some futher editing to the 24p stuff after dropping it in the 60i timeline, as well as color correcting/FX stuff. . .am I going to run into huge problems when I'm finally ready to export?

You're correct that if you want to keep the video look of the 60i, you need to edit in a 60i timeline.

You MIGHT get away with using 24pA footage that way, but I would strongly advise against it as a practice.

Think of it this way -- the fields are arranged in a 2:3:3:2 pattern, meaning that the first frame is on the screen for two fields (1/30th of a second), the second frame is on the screen for three fields (1/30th of a second PLUS an additional 1/60th of a second), the third frame is on the screen for three fields (same as the second), and then the fourth frame is on the screen for two fields, in that repeating 2:3:3:2 pattern. What that means is that the middle frames are on screen for 50% longer than the "end" frames, and they're back-to-back, so it can cause an apparent hang in the motion. The 2:3 pattern eliminates this, because it alternates evenly between 2 and 3. So, if you're not going to edit in 24p and retrieve the original frames, stay with 2:3 pulldown.

[Josh Bass]

Right,

But you use 24p standard (not advanced) if you want to edit in a 60i timeline, right? so. . .


. . .if I do all this stuff now, the FX, additional editing, etc., and then when it's finally ready to be exported, convert the 24pA footage back to 24P, and then drop it back in the 60i timeline, will that work out? Or should I convert it back to 24p standard first, before all the other tweaking?

[David Jimerson]

You've already done all the FX and further editing, etc.?

I'd do a test render to see how it looks first. If it looks OK, then you're fine.

If you detect motion issues/hang time (and pay attention to transitions, etc.), then you can take your original footage into a 24p timeline and export it as 2:3, keeping the exact same length of the clip(s) -- then just do a media replace in your main project.

But I wouldn't bother until you find a problem.

[Josh Bass]

Yeah, but it wouldn't be that hard if I had to redo it. . .I have the 24p stuff in its own project, so I could drop the FX'd/edited stuff from the 60i timeline back in the 24p timeline, and figure out where each change is between the earlier version and the new one, and change the original. . and then reapply all FX/whatever. It would just suck is all.

[David Jimerson]

Up to you, then. Make your decision based on your test render.

[Josh Bass]

I need to render out to 29.97 interlaced to see if this works, right? 'Cause that's how the final file would have to be to accommodate the 60i stuff, yes?

[David Jimerson]

Definitely.

[Josh Bass]

So you're saying if it doesn't work, I can just take the 24p stuff from the 60i timeline, put it BACK in a 24p timeline, export as 24p/2:3 pulldown, and it should be fine, even with edits/transitions made in the 29.97 timeline?

[David Jimerson]

Well, what you'd do is take your original 24pA clips onto a 24p timeline -- sounds like there's not THAT many -- create loop regions around them (to ensure exact length matching) -- and then render them out individually as 24p clips with 2-3 pulldown. Name them something similar to the original file names so you can keep track.

Once you've done that, you should be able to right-click on a clip in the media pool (main project here, where you've done your editing), select "Replace," and then choose the new 24p (2-3) clip to replace it with. Should match up exactly, though the edges may be 1 field off from the original.

This is, of course, assuming that you're using your original clips in the main project -- I understood you to be saying that you were.

"Replace" won't do anything to your original clips -- it will just redirect your project to the new clips instead of the original ones.

Or, if it seems less complicated to do it the way you were describing above, then go that route. I'm just suggesting a way you can do it while leaving all of your edits and FX in place.

[Josh Bass]

I'm sorry; I may not have been clear before. . .

The stuff I moved from the 24p project to the 60i one, it's edited, but not rendered, footage, so however many clips might comprise a 2-3 minute scene in a movie (several scenes, to be exact), that's what I moved from the 24p project to the 60i one, so it's not just one rendered clip/file that makes up each scene. Does that make sense? If so, does that change things?

[David Jimerson]

Originally Posted by Josh Bass

I'm sorry; I may not have been clear before. . .

The stuff I moved from the 24p project to the 60i one, it's edited, but not rendered, footage, so however many clips might comprise a 2-3 minute scene in a movie (several scenes, to be exact), that's what I moved from the 24p project to the 60i one, so it's not just one rendered clip/file that makes up each scene. Does that make sense? If so, does that change things?

No, that actually means it'll work.

Check to see which clips are in your main, edited, 60i project. Then, leave that project alone.

Go into the folder where you keep those clips. Bring those clips, not from your 60i project, but from your folder, into a 24p project, then render the clips out as 24p with 2:3 pulldown, using loop regions and similar file names as I said before.

So:

1) You're using Clip001 in your 60i project.

2) Go into the folder where Clip001 is. Bring Clip001 into a 24p project.

3) Put a loop region around it (double-click it). Render (using loop region only, of course) using 24p DV inserting 2-3 Pulldown. Call it something similar, like "Clip001A." Or, whatever. Just so you know what it is.

4) Now, back in your 60i project, find Clip001 in your Media Pool. Right-click. Choose "Replace." Then, browse to your folder where you saved Clip001A, and choose it.

You will now have replaced the original 24pA clip with your new 24p (standard) clip, and left everything else alone -- FX, edits, etc..