24pA vs 24pN in the Editing Process...

S

stidle

Active member
Okay -- I've read through this message board and I've read the Barry Green book twice in the last two days (and it's been great!), but I have yet to get a clear answer to this question:

As far as I can tell, the difference in the EDITING stage between shooting in 24P ADVANCED vs 24P NORMAL is that, in both cases you capture at 30fps, but in 24pA, the "Advanced Pulldown" (2:3:3:2 in FCP 4.5 or whatever) eliminates all but 24fps after capturing, so that you can edit on a 23.98 timeline.

Am I correct in saying that, if the footage was shot in 24pN RATHER THAN Advanced, you can still edit on a 29.97 timeline?

If this is true, would it make more sense to shoot at 24p Normal if you are going to be inserting 30fps clips into your film, interspersed with the 24fps clips?

Thanks!
-matt
 
Yes. The reason for the advanced 2:3:3:2 pulldown is to make it easier for your NLE to extract the progressive frames for a filmout or true 24p viewing. If you're going to be editing within a 60i timeline and your final output will be 60i (NTSC), it would be wise to just shoot 24pn.
 
Thank you very much for your help. In this case, I believe that I will shoot the documentary that I'm planning in 24pN so that I can intercut news footage and the like in a regular 29.97fps timeline.

A second question, then: If I do choose to make a fiction film at some point, and I would like to preserve as close to a filmic look as possible, I will probably want to shoot in 24pA and edit on a 23.98fps timeline....

...In this case, is there some particular way in which to make sure that the exported file that I use to make the DVD (in, say, DVD Studio Pro 3) preserves this 24fps play? Or will it do this automatically?

Thanks,
-matt

P.S. I have a lot of experience with shooting (4 years of film school!), but am a total newbie to working in digital 24p. I apologize for asking you all to hold my hand, but please humor me...
 
stidle said:
A second question, then: If I do choose to make a fiction film at some point, and I would like to preserve as close to a filmic look as possible, I will probably want to shoot in 24pA and edit on a 23.98fps timeline....
Click to expand...

Yes you would definitely want to shoot in 24pa assuming that your NLE can properly remove the pulldown. Doing this, you can edit frame accurately and it is in effect, just like cutting actual film.

stidle said:
...In this case, is there some particular way in which to make sure that the exported file that I use to make the DVD (in, say, DVD Studio Pro 3) preserves this 24fps play? Or will it do this automatically?
Click to expand...

Well the DVD format is basically the same as the NTSC format. To put 24p footage onto a DVD you will need to insert a pulldown (usually 3:2). Most DVD authoring programs will insert the proper pulldown automatically if you feed them a 24p file. Many newer TV's can actually remove the 3:2 pulldown on the fly which is very nice.

If I have something wrong in there, someone please correct me. I'm pretty sure that it's the DVD authoring program that inserts the 3:2 pulldown not the DVD player, but I could be wrong. In my research and experimentation, this it what I have come to understand about authoring a 24p DVD.
 
It's the player which will add the pulldown. That reduces the size required on the DVD itself (better compression quality)
 
Hmm...that's interesting. I haven't thought about it TOO hard, but it just seems kind of incredible that a DVD player would be able to differentiate between 24 and 30 somehow.
 
stidle said:
Hmm...that's interesting. I haven't thought about it TOO hard, but it just seems kind of incredible that a DVD player would be able to differentiate between 24 and 30 somehow.
Click to expand...
they had better be able to, they're a whopping $20 now!!
 
For a project that originates at 24 fps (23.976) from either film or a progressive video source, the project can be MPEG encoded with one of two methods. The first method is it to apply pull up (either 2:3,2:3 or 2:3,3:2) to make for a compliant 29.97 fps (15 frame) GOP. The second, and preferable method is to MPEG encode as a 24 fps project (12 frame GOP) with the appropriate frame repeat flags. The second technique has the advantage of 20% reduction in data rate or a corresponding increase in quality.

Regardless, the output of any DVD player will be 29.97 fps with the repeated frames coming from either the longer (15 frame) GOP or via the repeated frames from the shorter (12 frame) GOP.
 
That sounds a little better. I was pretty sure it was a DVD authoring thing not a DVD player thing. Doubt it'd work out very well if the DVD player was handling that. Thanks for the clarification.
 
Very true, but if the player was actually inserting the pull up there could be compatibility issues. I dunno. As long as it works. All I know is that the way I have been doing it works and works well.

I author a 24p MPEG-2 from Premiere then feed that into Adobe Encore and burn from there. Never had any problems and the result is beautiful looking footage on the TV. My TV also removes the pulldown on the footage which is nice.
 
You must log in or register to reply here.
Back
Top