8 Replies Latest reply on Jan 14, 2016 10:30 AM by Rick Gerard

    Rotoscoping at 23.976 fps?

    LexBurgerSupreme Level 1

      Okay, so I've been having this problem for a while and no one, even the highest rank people on other forums can't seem to answer my question.

      So, I'm in Premiere Pro and I use dynamic link to After effects for all my projects. In camera, I'm shooting in 24 FPS. I splice and dice in premiere pro then I dynamic link the clip over to After

      effects, I interpret the footage as 24 FPS and the composition as well, I also duplicate the clip, and when i start rotoscoping on the top clip, AE tells me that I have to set the composition to 23.976. I do so and also go back and interpret the footage as 23.976, so everything matches up. For some reason, when I'm rotoscoping, the duplicated clip I'm rotoscoping on, scoots back and doesnt match up with the bottom layer. So, now I have this "lagging behind" and/or "ghosting effect" instead the two clips being lined up as I roto.

       

       

      Someone did mention removing some type of pulldown, but this is all a new language to me, So i really need someone who knows what they're doing to HELP ME!!!!

       

       

      Someone, please help.

      It's driving me wild.

       

       

       

      Lex

        • 1. Re: Rotoscoping at 23.976 fps?
          Szalam Adobe Community Professional & MVP

          What version of AE are you using?

          What version of Premiere are you using?

          What camera are you using?

          What format and codec is your footage?

          When you talk about rotoscoping, do you mean you're doing rotoscoping with masks or are you using the Roto Brush tool?

          You're saying that, in the same composition, the top layer and bottom layer (of the same footage file) are not matching up in time? Like, there is only one video clip in the project panel and two instances of the same clip are sliding away from each other?

          • 2. Re: Rotoscoping at 23.976 fps?
            Dave LaRonde Level 6

            I bet you shot at 1080, and I bet the original footage is still 29.97.  Oh, you may have shot at 24p, but you didn't remove the 3:2 pulldown before you started cutting.  That's okay in PP, but NOT in AE... and you're now in AE. 

             

            You'll need to remove pulldown, re-cut and THEN use dynamic link to AE.  No shortcuts here.  Nothing automatic. No workarounds.  Well, maybe they know some trick in the Premiere Pro forum, but you'd have to ask there.

            • 3. Re: Rotoscoping at 23.976 fps?
              Rick Gerard Adobe Community Professional & MVP

              If you are going to work with video shot at 24 fps you must know exactly what you are doing and exactly how the camera is achieving 24 or somewhere close to 24 frames per second. Here are the most common but not all ways a video camera can shoot at 24 or close to 24 frames per second listed in easiest ways to work with if your final product is going to be shown on television or cable.

              1. 23.976 progressive - true progressive with a full frame created 23.976 times a second. there are never any partial frames its just that the one second of video will last 1.024 seconds. To display accurate hours minutes and seconds time you must have the timecode display set to drop frame. No frames are dropped, just a frame number so the extra time added to the video every second does not add up and make your program last longer than you think it will.
              2. 23.976 interlaced with two fields per frame. To do your best effects  work you need to separate fields into the correct order so you have full frames to work with
              3. 23.976 with 3:2 pulldown. This is the odd duck but was the most common up until video camera sensor technology got fast enough to shoot progressive. This is the way movies shot on film at 24 frames per second are transferred to video. Here's the important part. The original frames are actually recorded at 29.97 fps interlaced and then the interlaced frames are played back two fields at a time for a while and then a frame is created using a duplicated field from one frame and a field from the next frame. If you step through this footage one frame at a time every few frames you will see a frame that looks a little funny where things are moving because one field is from one point in time and the other field is from the next point in time. So let me review because it's complicated. You get 2 frames each with 2 fields. The fields in this pair of frames are identical. Then you get a frame that has the first field (odd numbered lines) from one frame and the second field (even numbered lines) from the second frame. This odd frame looks like traditional interlaced video with the motion in one field slightly behind the motion in another so you get jagged edges.
              4. True 24 fps progressive. Video that is actually shot at 24 frames per second with each frame as a single slice of time. This frame rate is available on professional CINE type cameras, not usually on consumer video cameras, and, are you ready for this, some mobile phones or mobile phone video apps and some action cameras. The frame rate may be slightly off on mobile devices and action cameras but you are usually not shooting double system sound on those devices so sound sync is not very often a problem.

              So there you go. If you don't know exactly what your footage was shot at you should bring a clip into After Effects and see with the info panel says it is. The meta data should tell you unless the footage has been transcoded into another format. If the footage is interlaced AE will automatically try and guess what's going on. Most of the time it gets it right. Sometimes it gets it wrong. You heed to check the footage to make sure it interpreted correctly.

               

              Here's how you do that. You open the footage interpretation panel. If the footage is interpreted as 23.976 you try separating fields and you try removing 3:2 pulldown. AE will guess at the cadence and usually gets it right. (Note: if the footage does have 3:2 pulldown and is edited the cadence will change with every cut so you have to cut the film apart at each edit and treat each clip separately). The next step is to select the footage in the Project panel and create a new comp from the selection. This will create a 29.97 fps comp. The next step in figuring out if you have done things right is to open up the composition settings and double the frame rate to 59.94 fps. Now you step through the footage one frame at a time and look for frames where the motion is out of sync. If motion goes back and forth on every frame then the field order is wrong. If you run into a pair of frames where the motion goes back and forth on a pair of frames every once in a while then the 3:2 pulldown separation is wrong. You keep messing with the video until you have identical pairs of frames with the motion all moving in the right direction. When you get to that point you change the composition back to 29.97 fps and you have complete frames to work with. Video shot with 3:2 pulldown is still way too common so you need to make sure you know what you have or your effects work will have odd frames where things just don't line up.

               

              I hope this helps. Unless I'm working on something that is going to be projected in a theater I always produce at 29.97 progressive because I live in the US and you have a lot fewer motion problems and image judder problems at higher frame rates.

              • 4. Re: Rotoscoping at 23.976 fps?
                LexBurgerSupreme Level 1

                Yes, Dave. I did shoot at 1080 and 24 fps on a Canon 70D. My problem is that I need someone to tell me how remove the 3:2 pulldown in PP, but no one can.

                • 5. Re: Rotoscoping at 23.976 fps?
                  LexBurgerSupreme Level 1

                  My footage is 23.976 progressive as AE says. I just need to know how to remove the 3:2 pulldown in PP as Dave says, for future reference :/

                  • 6. Re: Rotoscoping at 23.976 fps?
                    LexBurgerSupreme Level 1

                    So, my footage in PP says its 23.976 fps, progressive, 1080x1920. Can someone please tell me how to remove the 3:2 pulldown in PP before I dynamiclink everything to AE for rotoscoping with the rotobrush tool?

                    • 7. Re: Rotoscoping at 23.976 fps?
                      Dave LaRonde Level 6

                      Hmmmm.... a 70D.  A DSLR.  It may already be at 23.976.  You may have set up your Premiere Pro project incorrectly.  No matter what you do, you'll have questions for the PP forum.

                       

                      But the first thing to do -- confirm the frame rate of the footage in PP.  If it's at 23.976, there's no pulldown.  Then you ask the folks in the PP Forum how to set your project up properly to use Dynamic Link in AE.  The frame rate is the key issue.  Since I cut in Avid and Final Cut Pro, I'm no help in PP.

                       

                      But it sounds like you'll be re-editing.  Sorry 'bout that.  But you'll have learned an important workflow lesson.

                      • 8. Re: Rotoscoping at 23.976 fps?
                        Rick Gerard Adobe Community Professional & MVP

                        If it is 23.976 progressive you need to test it in AE to make sure by forcing separation of fields. Separate fields in AE, create a new comp from the clip, double the frame rate of the clip and step through the shot one frame at a time. If you have pairs of identical frames then the footage is progressive and you do not need to remove 3:2 pulldown.

                         

                        If your Premiere Pro sequence frame rate does not match the frame rate of the footage then Premiere Pro will mush the frames together to make the time match. This is normal and there's not much you can do about it except change the file interpretation to interlaced and live with the mushed together frames now and then. Frankly I think that Premiere Pro handles 23.976 fps progressive footage in a 29.97 frame rate better than it does if you monkey with the footage and make it progressive.

                         

                        The problem you are having with doing your roto is that the frame rate of the comp is not matching the frame rate of the clip. If your sequence in Premiere Pro is 29.97 and you used dynamic link this will happen. The solution is to open the clip in AE, create a comp from the trimmed clip in AE that matches the clip's frame rate, then do your roto and export the clip. The best result will be had if you render your 29.97 fps comp in the Render Cue to a good production format and have the render interlace the footage and add 3:2 pulldown. This will give you a 29.97 fps comp in Premiere Pro that matches the frame rate of the sequence.

                         

                        All of these problems can be avoided if you plan your production from the start considering frame rate. As I said before, shooting 24 fps (or there about) requires that you be very careful with panning speeds and motion in the camera to avoid judder (strobing and impossible to watch shots). This requires a camera operator that understands critical panning speeds and all of the other ramifications of shooting at 24 fps. It's actually harder to do well with video than it is with film. Shooting at a higher frame rate gives you more data for tracking an integrating cgi elements in your project also. When I'm going to do something that requires inserting CGI elements in a film most of the time I shoot at 60p because I have much more data to work with for tracking, cleaner edges for roto and the chances of pulling off a perfect composite go up by about 50% over shooting at 30 and about 60% over shooting at 24.

                         

                        Short answer: Match your Premiere Pro sequence frame rate to the footage and dynamic link will work. If the frame rate of the footage and the frame rate of the footage do not match then Dynamic Link will not work well and may not work at all depending on what you are trying to do.