remove pulldown : 29.97 to 24 without re-edit ?

[Elijah Lynn]

Wow, this is nearly identical to the issue I am having!!! See this thread – https://forums.creativecow.net/readpost/8/1130022

There is a quasi solution in that thread but I am having the same hopes as you, but in the end it appears a redit is what would be necessary, if you don’t you won’t be able to output a progressive file for any webclips. Converting to 23.976 via reverse telecine in compressor is the better option. You can also try setting your editing timebase in a new sequence and FCP will remove pulldown but my test clips were stuttery. Read that link above for some ideas.

[Joseph Owens]

I also posted this to the original thread, and this is the exhaustive answer.

“Pulldown” is introduced into field cadence when making the transition from 23.98P to 29.97 interlaced. FCP doesn’t actually do the pulldown removal correctly because the cadence has been destroyed by the editing process. Been through this a million times, as I used to run a telecine film-to-tape and tape-to-tape operation. Yet it remains very poorly understood.

Four “film or progressive video” 23.98 frames become ten 29.97 interlaced video fields. There are several ways to accomplish this: SMPTE standard is 3:2:3:2 (B-Frame dominant), while what is in general practice is A-Frame dominant (2:3:2:3). There is Advanced Pulldown, which is 2:3:3:2 (which is rather clever for a number of reasons), and then there is what Final Cut does, which is 2:2:2:4, which is unacceptable for anything but previews, but that’s all it can do, because nearly all NLE’s are not field-aware. However, your HDV source material is 2:3:2:3, complicated by the fact that it is IBP-Long GOP. That it has been edited that way has introduced some serious, probably fatal impediments for ever going back to 23.98P.

If you don’t recognize the ABCD notation:
The first 23.98 frame is mapped to the first two video fields (one ‘whole video frame’) and that is an “A” Frame. Example: If film is shot at 29.97 and transferred to video at 29.97, then every frame is an “A” frame.
The next 23.98 frame, the “B” Frame is actually mapped to three video fields, in fact one-and-a-half whole video frames, and straddles video frames 2 and 3. A “C” frame is mapped to the next 2 fields, but straddles two video frames — the second field of Frame “3” and the first frame of Frame “4”. The last 23.98 frame in the sequence, the other 3-field case, the “D” frame, straddles field 2 of Frame “4” (Video) and both fields of Frame 5. and then it repeats.
If you edit 29.97 material that has 2:3 interlaced-field cadence, then every time you make a cut on any random frame (and you can only cut on frames, not fields) you have an 80% chance of disrupting the ABCD field order. That is why some of your clips look great, and some of them look stuttery — mostly bad as the odds are considerably less than 50/50 of getting it right. If you apply the same “reverse telecine” dominance to all the clips, then you will more often than not get converted footage that is “out of step”, since it is looking for ABCD and getting something else, like CDAB, and that ain’t going to be pretty.

Its also why there are black holes in timelines when you simply plunk 23.98 edit sequences into a 29.97 timeline. FCP, for sure, simply can’t do the math with 2:2:2:4, and as I have stated, that is the only practical mode in which it can operate — even though the cadence options exist as selections — they are simply there for cosmetics, because they don’t actually work or affect anything.

It would be nice if FCP-X fixed this, but I get the feeling that the APPLE architect doesn’t understand this concept, either. If it was simply a weakness of Quicktime, that would be great and maybe there is still hope.

If you used SHAKE to remove the ABCD fields, then you would realize that you have to reset the removal dominance to whatever is appropriate for that specific clip. Editing, statistically, is a random reordering process, and that is what you’ve got — random 2-3 field cadence. You are correct that a re-edit, at 23.98, with material from which the pulldown has already been removed, is probably the only thing that will fix this. The Final Cut manual specifically states that you should remove the 3:2 pulldown from this kind of material prior to doing any editing, so that you are dealing with the native framerate of the source material, and editing “whole frames” instead of disrupting the pulldown.

Just as a footnote, the use of the term “pulldown” to describe the repeated-field cadence strategy is not precisely correct. More accurately, the term describes the mechanics of “pulling down” the frame rate of film which was originally shot at 24.000 fps to 23.97659 fps to more correctly match the video field speed of 59.94 fields per second. “Pulldown” started being used as a shorthand term which covered the entirety of that conversion. Like “fonting” a lower-third is not really good technical language either.

But, hey, its all about process, right?

jPo

You mean “Old Ben”? Ben Kenobi?

[Andi No]

Thanx for replying guyz, i’ve managed to edit without fully re-edit from scratch ( or match framing). So i took the footage to any app that can remove pulldown but preserving the IN timecode. As lonng as the frame digit didn’t exceed 23, than i can get the same inpoint timecode. In my case i use discreet smoke on mac to remove pulldown and it has feature to keep the inpoint tc. So now my clips got converted back to original 24fps using the 29.97’s timecode ( i’ve just found out that it was originally shot on 24, then the nano card add pulldown to 29.97)

So when bring back to FCP, duplicate the timeline but now set fps to 24. i ‘force’ reconnect it. Forcing means like ignoring anything. FCP will spit out error msg, about tape name , tc bla bla…. but i just ignore it and force reconnect. The result i got my edit on position with a slight drift , sometime 2 frame ,but mostly only 1 frame. From this starter i can just do ‘better’ re-edit instead doing all over from scratch. FYI when duplicating fcp timeline from 29 to 24, some clip which has speed effect will be cut out 1 frame (blank) so need to be fixed later.

Got no time to do further test, i’m in a sick deadline. So be back later.

thanx a lot.
Andi~

[Andi No]

btw does anyone know any other app on mac that can do removing pulldown 29 to 24 and got perfect result ? I tried compressor but max data rate is at 50mb/s , i can’t go beyond. Any idea or suggestion ?

Thanx

[Matt Lyon]

You can use Cinema Tools to remove pulldown. It will create a new clip that matches the attributes of the source footage, albeit @ 23.976 fps. So your data rate, resolution, etc will be exactly the same.

BTW, using the same frame number for the “IN” timecode in your 29.97 clip and your 23.976 clip does not give you the “same” in-point. For example, frame 15 @ 29.97fps is equivalent to frame 12 @ 23.976

Hope this helps,

Matt Lyon
Editor
Toronto

[Andi No]

Thanx Matt, i’ve been trying Cinema tool but have a bit problem. The ‘reverse telecine’ button at the bottom is always in ‘disabled’ mode. So there’s no way i can convert coz i couldn’t press that button for some unknown reason. Anyway still trying to figure out ……..

About the the ‘IN’ point, you’re right and i didn’t say it will match perfectly , as i clearly mention in my previous post, there will be sliding couple of frames , like 2 to 5 frames. So mapping frames will be like :

1->1 (under frame 5 there will be no shifting, so no fix to be done)
4->5
12->15
16->20
20->25
and 24->30 as well as 23.97 -> 29.98 etc

The good news, there some app which allow u to do some batch processing , like read the TC , check the frame number, then shift the clip to left based on that frame info. So it will auto adjust the IN point. The bad new , that app need u to render :). Or u can just manually do 2 or 5 shifting to fix the IN point in FCP directly. That way you can continue work by fix that couple predictable frames sliding instead of working from scratch which will spend more working days.

Thanx
Andi

[Andi No]

FYI, i also try to reverse telecine using cinema tool via FCP, tools > cinema tool reverse telecine… But again that menu is not activated, so i couldn’t select it. The codec is : XDCAM HD422 1080i60 (1920×1080) .

thanx

[Matt Lyon]

Hi Andi,

I have barely any experience with XDCAM, but my guess is that cinema tools reverse telecine isn’t compatible with long GOP formats, like XDCAM.

If Compressor will do the job, you could consider transcoding to ProRes while you’re at it. Judging from the many problems people on the board seem to have with XDCAM, you’ll probably find that ProRes gives you a more stable editing experience.

Hope this helps,

Matt Lyon
Editor
Toronto