guessing 3:2 pulldown when interpreting

[Kevin Camp]

is the clip you are working on edited at all, or is it just a single clip straight off the camera?

if it is a single clip straight off the camera, and you don’t trust the guess pulldown result, go back to the interpret footage settings, turn off separate fields and drag the footage to the new comp icon. step through the first 5 frames taking note of which frames are interlaced (‘s’ for split) and which are progressive (‘w’ for whole). if you can’t tell by the first 5, try the next 5 frames, just remember that the frame you start counting on has to be a multiple of 5.

once you are done you should have something like swwws. go back to the interpret footage settings and choose the cadence that matches (if it’s not one of the standard pulldown cadence, try one of the advanced pulldown cadences).

now drag you footage into a new comp (or set the frame rate of the other comp to 23.976) scan thru to see if it looks good.

now you can work with it as progressive footage in a 23.976 comp. when it’s time to render, and you think you need to add the pulldown back in, in the render settings (click the best settings from the render queue) the set it to render fields, set the correct order and add the pulldown. that’s it, there are no extra comps or steps.

now, if the clip has been edited, thing may get more complicated… try the method above to determine the cadence. once you done all that, put the clip into a 23.976 comp and see how the first shot looks, then go to the next shot and go frame by frame to see how it looks. do this for each shot in the clip. if you find that all the shots look good, great the editors handle the 24p footage correctly, and you good to go….

however, the fact that they sent you a file that was shot in 24p but had a pulldown in it makes me think that if the clip is edited, they edited with the pulldown in it…

just some background on 24p, when shooting 24p to tape, the camera will add a pulldown. this is due to tape being 30i, so to get 24p to 30i, a pulldown needs to be introduced. the pulldown should then be removed at capture, or at least before editing. then when the edit is done, if it needs to go to tape/broadcast, then a pulldown can be added back in.

however, people often edit with the pulldown left in, which will make it very difficult to remove the pulldown. what you would need to do is duplicate the clip 4 time (5 total clips) interpret a different pulldown for each clip. then try to reconstruct the edited clip using a correctly interpreted shot for each edit… essentially, re-edit the clip. or, send it back to the editor and make then remove the pulldowns for all their shots, re-edit and send you progressive footage. or, you could just try to work with it the way it is in a 29.97 comp, but if you manipulate the footage by scaling, rotating or positioning, you will struggle getting good results. if you are just color correcting or overlaying graphics, you’ll probably be ok.

if you do work with it in 29.97, when you render just render normally, do not set field render, or try to add a pulldown, that stuff is already there…

Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW

[Terry Coolidge]

Hi Kevin,

Thanks for your thorough and thoughtful reply.

“is the clip you are working on edited at all, or is it just a single clip straight off the camera?”

I believe it was shot as 24p (stopping and starting the camera for multiple takes, I’d say), captured to disk as one long segment, and then split into separate clips when exporting out for me. I have 20 similar shots, and they seem to vary in their pulldown removal cadence. Some are WWSSW, some are SWWWS, some are WSSWW, etc. I don’t think any of the individual clips is “edited” if I understand what you mean. Each individual clip appears to be a single shot segment. From what I’m seeing, I am fairly confident that the pulldown removal cadence is consistent throughout each clip. There don’t appear to be any edits within a single clip.

Out of 20 clips, AE is able to provide a 3:2 pulldown removal guess for 17 of them. The other three give me an error beep after trying to come up with a guess. I don’t know what “24Pa Pulldown” means.

Is there any reason to not trust AE’s guess? I’d love to think that I could just trust AE, and then avoid using the three problematic clips. That seems like the easiest (laziest?) solution.

I believe I understand what you’re telling me in your post, but I am curious about what I should do about framerate for my final comp. Should I choose 23.976, 24, or 29.97? My final output will need to be 29.97 (interlaced) as it will be played back on an NTSC device, but what should my comp be as I assemble everything? Does it make a difference as long as I handle the final render properly? I’ll force render output to be 29.97 interlaced, but can I make my workflow less problematic by the framerate I select for my working comp? I’m just as happy to have a “24p look” for the graphics I’m adding, but I’m sure it’s fine to have the smoother (more video-y) look of 29.97 interlaced for the graphics I add as well. Maybe that preference is what drives the decision, but I’ll only start expressing a preference if it truly doesn’t matter. My first priority is to make sure I don’t get interlacing goofiness going on as a result of the way I choose to handle these green-screen clips. I did post a sample of what one of the frames looks like in my comp:

https://gallery.mac.com/terrycoolidge/100100

(It looks like this no matter what framerate I set the comp to… 23.976, 24, or 29.97)

I guess I’ll have to hook up a camera, dump this to tape, and then play it back on a TV in order to see if it’s working, right? Can you tell from this still image whether or not I should raise or lower my expectations that all is well? You talked about checking to see if it “looks good.” Does this look good to you?

Thanks again for your help. Any further information/advice you can provide would be greatly appreciated.

– Terry

[Kevin Camp]

well, from what you describe, the good news is that the pulldown cadence should be consistent and removing it will be easy. the proper workflow with 24p, after removing the pulldown, is to work with it at 23.976fps until you are ready to render. then if, it needs to go to 29.97, add the pulldown in the render settings… don’t try to change the comp frame rate or you’ll just get duplicate frames.

however, from the looks of the still, you have some problems (at least for that clip)…

it looks like the video was scaled without being deinterlacing. there is really nothing you can do to fix that except get the original clip sent to you. it’s hard to say how it got scaled, it may have happened at export from the nle… it could have happened at some point within the nle, then exported out to right size, but once the fields are mushed up, they are mushed, up and trying to scale them back won’t fix it. they will have to go back to the original media and export out a new clip.

if it is only 3 clips that have this problem, my guess is that they were just exported differently… asking them to re-export them, making sure the exported frames size matches the media. even better might be to ask them to remove the pulldown and send you 23.976 progressive footage.

Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW

[Terry Coolidge]

Much gratitude for helpful responses from both Dave and Kevin. I really appreciate your continued support as I work through this challenge. Thank you very much!

In response to Kevin’s most recent post, there were only 3 out of 20 clips that were causing problems when trying to guess how to remove pulldown. However, all 20 clips are at an odd size in terms of image dimensions. All 20 clips are 800 x 450. Your most recent post leads me to believe that the clips were scaled to this size when exported, and that this has made it impossible for me to properly remove pulldown. I actually mentioned something about odd image dimensions back at the beginning of my very first post, but I didn’t realize that l this could be affecting everything else.

I’ve sent an email to my client asking them if they can provide me with the original footage before it got scaled since it sure seems like this is what must have happened. I’ve explained that I don’t think there is anything I can do to properly deinterlace the footage (remove pulldown) with what I currently have. We’ll see what they say. Stay tuned…

[Terry Coolidge]

Update…

So they managed to re-export the clips for me. Came in completely differently this time. Now the clips are 720 x 486, and defaulted to .9 pixel aspect ratio (they’re supposed to be D1 WS). I simply opened the interpret footage dialog box for each clip, set the PAR to 1.2, and then clicked on “Guess 3:2 Pulldown.” AE very quickly came up with a “guess” for each, and the clips look infinitely better now in my 23.976 comp.

I think I’m on my way. Some wasted time, I suppose, but the silver lining is that I now understand this concept even better than before. Nothing like running into bad assets to help get a better grip on what is required to have good assets. I’ll now know what to ask for and look for when getting footage from these folks.

My only lingering question would be about the “conform framerate” option in the interpret footage dialog. Previously the bad clips were conforming to 23.976 after AE had guessed. The good clips are now conforming to 29.97. However, when scrolling through the clips in the Project pane, the info at the top for each clip shows a framerate of 23.976. I’m not saying this is wrong, I just don’t completely grasp what’s going on here. Based on Dave’s and Kevin’s recommendations, I will work in a 23.976 comp and then output with interlacing turned on to create a 29.97 final piece. I don’t really need to hear back from anyone, I don’t think, but if this is a loose end that can be tied up, I’m happy to have a more rock-solid understanding of these various framerate issues when working with 24fps and NTSC.

Thanks again for all the patience and help.

[Kevin Camp]

[Terry Coolidge] “My only lingering question would be about the “conform framerate” option in the interpret footage dialog. Previously the bad clips were conforming to 23.976 after AE had guessed. The good clips are now conforming to 29.97. However, when scrolling through the clips in the Project pane, the info at the top for each clip shows a framerate of 23.976.”

what you should see with a clip that has a pulldown added… when you first bring it in, it should have a frame rate of 29.97. when you choose to separate fields and remove the pulldown, the frame rate should change to 23.976. you should be able to see that change in the interpret footage window under the remove pulldown section… it would say something like ‘effective framerate 23.976 fps.’ you would also see it in the project pane when you select a the clip.

you shouldn’t need to use the ‘conform framerate’ unless you know the original framerate is incorrect, or you are purposely changing the framerate for an effect like slow/fast motion…

so, from what you describe, i think you are fine…

Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW

[Terry Coolidge]

You have described exactly what I observed. Sounds like this second attempt went just as it is supposed to.

I appreciate having your explanation to help solidify my confidence in the process. Thank you.

Thank goodness for computers that can handle all these processes and calculations for us. It’s challenging enough sometimes with all of these fantastic tools. Hard to imagine how the eggheads figured out television and video tape way back when. Mind boggling, really.