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Old March 25th, 2006, 05:30 PM   #1
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Keeping 24p...24p.

Hey all,
I'm a bit confused about 24p. Once I convert my footage into it (I have DVFilm Maker) how do I keep it 24p? If I take it out to MiniDV I'm assuming the camera or the computer does some weird pulldown thing because the MiniDV standard is 29.97fps? Or does it stay 24p on tape (that would be weird though right?) So I take it to DVD...and I mostly understand that. But is DVD my only option for sharing it? Say I want to send it to a film festival on something other than DVD but I want to keep it 24p...what do I do? Is taking it to tape OK? I feel dumb...
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Old March 25th, 2006, 10:48 PM   #2
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Most video formats are 60i (29.97fps interlaced / 2 fields per frame)... so for these formats, you will need 3:2 pulldown to put the 24p footage in these 60i formats.

Some tape formats like HDCAM (?SR?) can do 24psf, which is 24 frames per second (progressive) displayed twice per second (or something like that... I forget). But honestly you likely won't encounter this.

DVD players will need to add pulldown, unless the material is viewed on a computer monitor.

2- Anyways, I don't think this is something worth worrying about.

If you want to shoot 24p, watch out for problems inherent to 24p... i.e. bad motion on fast pans.
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Old March 26th, 2006, 01:33 AM   #3
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i just did some true 24 fps work tonight, and i took the true 24fps (not fake 24 fps) but true, shot from a network camera. and transfered over into my old sony handycam digital 8 format. not far from minidv tape. which is the 29.97 fps standard. basically, i opended the true 24 fps avi file in Adobe After effects. Created a new Composition that had the settings of standard DV(720x480, 29.97, the whole shebang). and then drag and drop the 24 fps footage onto the timeline. it automaticly does the 3:2 pulldown to match time.

basically 3:2 pulldown does this: to change the 24 to 29.97 it plays 3 full frames in order, then plays the next frame for 2 frames instead of just once. So instead of being A,B,C,D,E,F,G,H it goes: A,B,C,D,D,E,F,G,H,H etc. you probally get it. i guess thats why its called 3:2. anyways, in After effects, it automatcly does the pulldown when you drag a none 29.97 fps clip into a 29.97 timeline. but find a program that can do a 3:2 pulldown. and convert the file using that. then just export it to tape and your good to go. And by the way, the whole playing 1 frame twice doesnt seem to make the footage jumpy, but i hadnt done anything fast motion. but in short, thats how the real Filmmakers get their film from 24 to a 29.97 DVD anyways. hope i helped Ben.
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Old March 26th, 2006, 10:05 AM   #4
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If by "fake 24 fps" you're referring to the 23.976 shot by the DVX100/XL2/XLH1/SDX900/SPX800/HD100/DSR450/HVX200, well, that's unnecessarily inflammatory and misleading. It's true that it's not 24.00 fps, but that .024 frames per second is of no consequence whatsoever when it comes what makes 24p a desirable format. The onscreen difference between 24.00p and 23.976p is exactly nil.

To say it's "fake" is to say it's some kind of trick, gimmick, or dodge, and that's just patently untrue. If that's not what you meant, then I apologize for the implication, but it's very important to make clear that there's nothing "fake" about 23.976.

Ben, how are you exporting from DVFilm Maker -- and at what point are you doing this? Is this before your edit or after your edit? What are you editing WITH? Which NLE?

Are you exporting, from DVFilm Maker, a 23.976 file? Or, after conversion to 24p, are you exporting a file with pulldown? (My guess is the former, or you probably wouldn't be asking.)

If you converted to 24p before your edit (which is ideal) and edited on a 24p timeline, then your NLE should have a print to tape function which will automatically insert pulldown as it does so. The only NLE with a 24p timeline which can't do this, to my knowledge, is Avid Liquid (formerly Pinnacle Liquid Edition) -- though to do it with many versions of Avid Xpress Pro, you'll need the Mojo box.

If you edited in 60i and then used DVFilm Maker to convert your finished product to a 24p file (NOT the ideal workflow), you should be able to use it AGAIN to take your 24p file and have it insert pulldown to make a 29.97 file for going to tape.

When given options for inserting pulldown, if it's for delivery (to anyone to watch, like a film festival), you want 3:2 pulldown (most other programs call it 2:3), NOT 2:3:3:2.

The MOST IMPORTANT THING TO REMEMBER, though, is that when you take 24p and insert a pulldown to make it 29.97, you do NOT lose any of the aesthetic of 24p. It will still look the same, with the same motion characteristics, etc..

Again, let me know what your workflow steps are, and the software used, and I can give you specific guidance.

(Another thing to note -- when delivering on DVD for someone to watch, it's not necessary to insert any kind of pulldown. Hollywood DVDs are burned to disk as 24p MPEGs, not as 29.97. It's the player which will add pulldown for display on interlaced sets. If it's a progressive-scan player displaying a progressive TV (like HDTVs or some EDTVs and LCDs), it will only show the 24p frames. The player takes care of everything for you.)

Last edited by David Jimerson; March 26th, 2006 at 12:04 PM.
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Old March 26th, 2006, 12:54 PM   #5
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David, sorry to have offended you. what i meant was exactly that, the reason dvx can't film true 24fps is because its stuck in the video world. it has to compy to the rules, wether it performs a 3:2 pulldown, 2:3:3:2. whatever it is. And you are completly correct that it keeps all the look of true 24fps of film. it looks exacltly right. but to say your camera can shoot true 24 fps, without conforming to the 29.97 video standard rules, youd just be lying to yourself, and thats why you got defensive in your post. i meant no offence. but there are cameras that are now capable of shooting "true 24fps" with no pulldown. one being the high definition Elphel network camera. and the result is exactly that of film. of course, when going to DVD's or DV tape or otherwise, it will have do a 3:2 pulldown. which is entirley ok. and looks just the same. (because thats how film movies do it also). For that reason, the Dvx already made itself compliable with 29.97 format tapes. For "film look" yes, i see no difference in true 24fps and the Dvx's 23.97 fps. hope you understand.
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Old March 26th, 2006, 01:34 PM   #6
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Forrest, my issue isn't being "defensive" about a camera; it's the implications of the term "fake." It's a not matter of being "offended," it's matter of not confusing or misleading people.

The DVX and similar cameras sample their CCDs progressively, 24 times per second. That is to say, it takes 24 progressive (whole) pictures per second. It doesn't shoot 60i and convert it to 24p; it shoots 24p. There are no gimmicks or dropping of frames or sleight of hand or fakery of any kind.

What you're talking about is how it's recorded on tape, not how it acquires its footage, and as you say, it's the same way 24 fps film is transferred to tape. I don't think you'd say that film is "fake" 24 fps.
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Old March 27th, 2006, 07:54 AM   #7
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I think I understand now. The only other question I have is concerning converting 60i to 24p; why is it ideal to convert footage before you edit? Is there a disadvantage to editing in 60i and then converting that to 24p in DVFilm Maker? And my workflow is this: Edit in 60i in Ppro --> export to .avi DV codec 60i --> convert into 24p using DVFilm Maker --> burn to DVD at 24p. Or export to tape or whatever.

So the pulldown is exact? It's not like deinterlacing where one company's method/algorithm works better than another?
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Old March 27th, 2006, 04:59 PM   #8
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Quote:
but to say your camera can shoot true 24 fps, without conforming to the 29.97 video standard rules, youd just be lying to yourself.
You can shoot 24p advanced with the DVX100 and remove the advanced (quasi-)pulldown in post, obtaining the original 24p footage.

For pratical purposes, I don't see how that's different from real 24p.

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and the result is exactly that of film
In my opinion, motion is only a small part of why video and film have different looks. But that's another story...
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Old March 27th, 2006, 05:03 PM   #9
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Originally Posted by Glenn Chan
You can shoot 24p advanced with the DVX100 and remove the advanced (quasi-)pulldown in post, obtaining the original 24p footage.
You can do it with standard pulldown, too. In Vegas, anyway. Some say the slightly different compression makes standard pulldown lower-quality, and there's a mathematical argument to be made, but I've never seen this "inferiority" manifest itself in any way where it counts.
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Old March 27th, 2006, 05:14 PM   #10
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Quote:
Originally Posted by Ben Winter
I think I understand now. The only other question I have is concerning converting 60i to 24p; why is it ideal to convert footage before you edit? Is there a disadvantage to editing in 60i and then converting that to 24p in DVFilm Maker? And my workflow is this: Edit in 60i in Ppro --> export to .avi DV codec 60i --> convert into 24p using DVFilm Maker --> burn to DVD at 24p. Or export to tape or whatever.
You can do it the way you've been doing it; it'll work. But consider:

When you convert 60i to 24p, you're taking on the motion characteristics of 24p, which are not the same as 60i. If you move the camera too quickly, you may end up with some bad strobing that you won't have in the 60i footage -- it's not because there would be anything wrong with the conversion; it would be the same strobing you would have gotten if you had moved the camera that way while shooting 24p natively. The problem is, you won't know it until you convert, because it won't be apparent in 60i, where anything goes as far as moving the camera. Better to see what you've got as it will be in 24p then going through the whole project and finding problems when you're finished. Doing it beforehand gives you the option of choosing different takes, etc..

Similarly, fades and dissolves are particularly susceptible to problems with conversion, again, because of the difference in motion sampling between the two formats. Remember, you're throwing out 60% of your temporal information when you're converting to 24p. Better to be editing in a 24p environment; your transitions will be the better for it. This includes fade-outs, especially short ones of a half-second or less.

Also, if you do any color-correction or (especially) effects, it's better to do after conversion. You'll be suffering a generational loss at conversion, and you (may) know what that can do to color, etc..


Quote:
So the pulldown is exact? It's not like deinterlacing where one company's method/algorithm works better than another?
There's an exact formula to it, but not all software is created equal.

Premiere Pro 2.0, while being one of the very few NLEs which can convert 60i to 24p directly from the timeline, does a terrible job of it (because of how it deinterlaces), and only gives you 2:3:3:2 pulldown, not 2:3. (And their own ABBCD pattern, which I have no idea why you'd ever want to use.)

Inserting pulldown to go to 60i is pretty straightforward, but there's a compression step involved when going to 2:3 (or 3:2, same thing) which I suppose an inferior program could botch.
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Old March 29th, 2006, 03:18 PM   #11
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Ben,

Your process is fine, with some drawbacks as noted. Disolves, effects, titles, etc, may not convert well. Even straight cuts may turn into quick fades using Maker after you edit.

If you can, convert prior to editing.

Also, the pulldown process is well-established and well-standardized. You need to add the pulldown when you go to tape. Your DVD player will add the pulldown on the fly when playing back. Everything you see on TV that is film shot has had pulldown added. It's quite normal.

If you want to go to tape to show people, add 2:3 pulldown (Standard). If you want to go to tape to edit in the future, add 2:3:3:2 pulldown (Advanced).

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Old April 6th, 2006, 01:24 PM   #12
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Hello,

This has been an interesting thread, but I’m left a little confused on the issue of transferring 24P to a DVD.

“Hollywood DVDs are burned to disk as 24p MPEGs, not as 29.97. It's the player which will add pull down for display on interlaced sets.”

” that’s how the real Filmmakers get their film from 24 to a 29.97 DVD anyways”


Are Hollywood DVDs transferred to 29.97 when the go to DVD? Are they transferred as a 24P mpeg? Does it make a difference?

Thanks for any clarification,

James
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Old April 6th, 2006, 01:35 PM   #13
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James,

Film are encoded on to DVD as 24p MPEG-2. On playback, the DVD player adds 2:3 pulldown to generate a 29.97 (60i) signal "on the fly."

It does make a difference. If they "burned-in" the 2:3 pulldown to create a 60i DVD, the result would be lower quality. Some of the bits would be used to encode the extra pulldown fields, and that would be wasteful.

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Old April 6th, 2006, 01:49 PM   #14
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Thanks!

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Old April 6th, 2006, 02:20 PM   #15
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It would definitely be wasteful -- 24p files are 20% smaller.

But it wouldn't be lower-quality at the same bitrate. It's true that you could encode a longer video at a higher bitrate in 24p than you could in 60i, and maybe that's what Joshua meant.

At the same bitrate, and on a standard TV, you won't see a difference, though.

Now, where you will see a difference is on a progressive TV with a progressive-scan player. Interlace artifacts, etc.. When it happens, it ain't pretty.
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