Questioning Panasonic 24P Advanced
Published : 19th April 2005
I've always understood the reason to use 24P Advanced mode (DVX-100) is for outputting to film, 24P HD, or cutting alongside film.
I've shot a number of 24P projects and have used advanced mode for both film and HD output. Each time, however, the question has come up, "Why are we editing in a 24 frame environment? What are we gaining?".
With respect to HD, why not just output to 1080i? The footage already has the quality of film so converting from 29.97 on tape to edit in a 24 frame environment just to get it on an HD 24P master seems like a lot of extra unnecessary work.
For film, the process of reverse telecine was mastered years ago and is a non-issue. A trailer from a movie I shot was cut in a 29.97 environment and output to film. It looked great.
And if cutting alongside film, the film needs to be telecined to edit in an NLE anyway, so there you go.
And then there's the drawback (though slight if even noticeable) of 24P Advanced's non-symmetrical cadence.
I feel like I must be missing something, but I can't think of what.
Dan "This Is My Mid-Life Crisis (Ain't It Sad?)" Coplan
Cinematographer / DIT
>question has come up, "Why are we editing in a 24 frame >environment? What are we gaining?".
Well, for one thing, the editor doesn't have to worry about editing on a pull-down frame.
Plus you should got more storage on your non-linear system once the redundant fields are removed....
>Well, for one thing, the editor doesn't have to worry about editing on a >pull-down frame.
What's the difference? Rather, what's the noticeable difference? The footage is laid to tape and editable at 29.97 just as if you had shot 29.97 in the first place. You can edit anywhere you please.
>Plus you should got more storage on your non-linear system once the >redundant fields are removed....
Storage is so cheap and plentiful that this is a non-issue.
Cinematographer / DIT
Dan Coplan wrote:
>What's the difference? Rather, what's the noticeable difference?
There isn't any, no matter how many times you read about the "problem" of cutting on a "pulldown frame." In the 25 or so years in which I've been involved in film to tape transfer and editorial, it's never been a problem and it isn't one now.
Honestly, Dan, if you're looking for permission or validation for cutting film or 24p video footage at 30 frames, you really don't need it. I do it all the time, and prior to the advent of 24p HD, it's the way film television programs posted on video have been done since the mid 1980's. And I agree that storage is now a non-issue.
IATSE Local 600
The reason for advanced pulldown is to avoid the inherent challenges of using the standard 2:3 pulldown with a desktop editing system. The C frame in the sequence has the field order reversed and is comprised of fields from two different frames of video or film, if you were doing a transfer.
The desktop system must change the order and recompress that frame. Advanced pulldown eliminates this problem so there are no quality differences between the A,B, D frames and the C frame. After the show is edited as 24fps it will be output to a master using traditional 2:3 pulldown. Of course, you won't have to edit this tape so the pulldown order presents no challenges.
Properly managed, 24p native editing solves many cadence housekeeping problems across the various scanning standards. Note that opportunities for international release are greatly assisted by working in 24p. 65% of the world is PAL at 25i in the standard def space. Easier to get there correctly from a 24p "Slow PAL" master.
If you ever wish to burn back to film then 24p is a big deal. Trying to convert 30i back to film with high temporal quality is awkward at best, and almost impossible if you didn't preserve the proper 24p cadence during a 30i edit. A normal 24p 2:3:2:3 sequence generates many spurious stray fields in a 30i edit if you don't do the proper timecode housekeeping.
The Panasonic 24p Advance Pulldown sequence, 2:3:3:2, is also very easy to implement in NLE's and other downstream processes, making USB and firewire connections easier as well.
Fellow, Advance Development
Co-founder, Avid Technology
Sorry Mike, I'm not completely clear on what you're saying - are you saying that cutting on a pulldown frame ISN'T a problem? Or that it's so easy to avoid that it's not a serious issue?
If the latter, I think that now with 24P so commonly available in an inexpensive camera like the DVX-100, lots of people who have never edited film transferred to 29.97 will be doing this on their FCP systems in their basement, and finishing projects completely, so no one will ever get a chance to clean the EDL.
The point of 24P Advanced is to be able to easily remove the pulldown in digitizing and editing, so it's "odd cadence" is a non-issue -- when you need a 60i final master with 3:2 pulldown, you add back a normal pulldown.
And the advantage of having a 24P master compared to a 60i master is that it can more easily be converted to other formats like 50i PAL or 24 fps film, not to mention that a DVD can store 24P without a pulldown. Plus there are situations where you might want to see a progressive scan recording, like on the web, and you can always make a 60i master from your 24P master.
David Mullen, ASC
I understand the technology behind the differences and the advantage of using 24P Advanced in order to extract 24 whole frames/sec, but what I'm questioning is why bother extracting the 24 frames in the first place?
I've been preaching "Use 24P Advanced for film out or 24P HD blowup" for a long time until projects for which I did both these led me to question the need to do so.
For 24P HD, yes, I had problems not using Advanced mode, but then the solution was to simply go 60i. The film look is already built-in. No advantage that I see going to a 24P HD master as opposed to 60i.
Pete Fasciano mentioned compatibility with European standards and that makes sense to me. He also mentioned converting 30i to film as awkward, but I've seen a lot of movies shot on video that were transferred to film that looked great including my own. I don't have a lot of video-to-film experience, but understand that it's been happening for so long and has been perfected that it's not awkward at all. I'm confused about Pete's comment regarding the high temporal quality since the temporal quality of 24P is captured to tape upon acquisition. This doesn't change just because you do a transfer (does it?).
Cinematographer / DIT
George Hupka wrote :
>are you saying that cutting on a pulldown frame ISN'T a problem? Or >that it's so easy to avoid that it's not a serious issue?
It ISN"T a problem. Never has been. In the few cases where there might be a noticeable glitch (the VERY few cases) you simply slip the edit one frame in online. We assembled television programs shot on film on NTSC video, on both analog and digital formats for years without regard to 3:2 cadence, it was never a problem and it isn't one now.
Having said that, I will also say that the other comments here regarding some advantages of continuous cadence or, in some cases, a 24 frame master, are certainly valid, but only if PAL conversions, film recordings, or 24 frame DVD's are part of the picture. If you're simply doing a video piece to be presented from videotape, 24 frame editorial does not accomplish anything, plain and simple. And that's the question that began this thread.
IATSE Local 600
Michael Most wrote:
>There isn't any, no matter how many times you read about the >"problem" of cutting on a "pulldown frame."
But, of course, you do have to be careful not to cut on a frame that may have different images on two fields. Not a likely case in telecined rushes, but a problem that crops up in telecined films. Often, NLEâ€™s only display a single field, and people are shocked when on lining to find a field of garbage that they didn't expect to find.
But, again, that's more of an issue for people cutting up already
edited films, not fresh dailies.
>If you're simply doing a video piece to be presented from videotape, 24 >frame editorial does not accomplish anything, plain and simple.
Actually, the topic that began this thread was not about [SD] video presentation from a video piece, but whether it really is necessary to edit in a 24 frame environment for eventual blowup to film or HD.
In my personal experience, the answer has been no, though through this discussion I've heard some good reasons in support of editing in a 24 frame environment thus validating the use of 24P Advanced mode in the DVX-100.
Cinematographer / DIT
Dan Coplan wrote :
> I've been preaching "Use 24P Advanced for film out or 24P HD blowup" >for a long time until projects for which I did both these led me to >question the need to do so.
The only virtue of 24P advanced is that the pulldown scheme is remapped so that one full frame (instead of two separate fields) can be removed from each pulldown sequence, to go from 29.97 to 23.976. This means that Firewire-based editing systems can easily take the footage and by dropping those frames (not a destructive process) end up with 24P material.
Conventional pulldown would requiring removing two separate fields every pulldown sequence, which is much messier, and can't easily be done.
Of course, systems like my overpriced Avid Symphony can't currently deal with Advanced 24P, only conventional 3:2 pulldown. So choice of pulldown scheme has more to do with what editing system you are using than anything else. Oh, remember that 24P advanced looks really crappy at 29.97, as you get a stutter-frame that is meant to be removed.
However, either will look the same when used at 24 fps.
24p HD is quickly becoming the accepted standard for delivery, as it is a somewhat agnostic format that can be easily converted to other deliverables. So that's one good reason to going to 24pHD instead of 60i or 50i HD. And if you want to get to 24p it is better to start out at 24p.
As far as film outs are concerned, there is a difference between "pure" 24p burned out to film and "shot at 24p but posted strictly 60i" and burned to film. There can be ghosting and odd blurring in movement as frames are either interpolated or dropped. Sticking 60i in the middle of two 24p levels can only detract from the image. You may find the difference slight, but then again you might like more salt in your soup than I.
Dan Coplan wrote:
>Actually, the topic that began this thread was not about [SD] video >presentation from a video piece, but whether it really is necessary to >edit in a 24 frame environment for eventual blowup to film or HD
Sorry then, I misinterpreted. In that case, the answer is a bit different. It is not "necessary," but it is very helpful, for the simple reason that any other method will require either frame interpolation (you don't want that), 3:2 detection and removal (that's fine as long as you don't have a lot of cuts with broken cadence), or both. If you're going to wind up on 24 frame media, you might as well start with 24 frame media and keep it that way if possible. If you're shooting using the Panasonic scheme, this means either shooting in 24p (standard) and removing the pulldown when loading into a "traditional" system like the Avid Media Composer or Symphony, or Discreet Smoke or similar, or shooting in 24p (advanced) for removal when loading into a Firewire based system like Final Cut or Avid XPress Pro.
The bottom line is that, yes, there are definite advantages to staying 24 frame if you're starting out that way and delivering that way. It isn't technically "necessary," but it will save you trouble, expense, and confusion later.
IATSE Local 600
So Mike, now that we're all talking about the same thing, would your earlier reply to me be different? (I agree with your comments about the cadence on a video-only finish not being a big deal...)
The point I was trying to make was that at 29.97 people with their own edit systems and little experience could produce a "master tape" with all kinds of cadence issues that would be a major headache to fix later - avoidable with a 24P master. (It was the unspoken print-to-film that got us mixed up!)
George Hupka wrote:
>So Mike, now that we're all talking about the same thing, would your >earlier reply to me be different?
Well, yes, clearly there are issues involved in one set of circumstances that are not present in another. However, I would still venture to say that there are many more people who don't understand the issue than those who do. And even fewer who understand what 24p Advanced is, and even less who understand how the Panasonic products do 24p in the first place.
IATSE Local 600