8 Replies Latest reply on Feb 8, 2010 11:42 PM by Mylenium

    Interlaced scaling issue

    JBrown321 Level 1

      I don't have this issue often because I shoot mostly progressive material, but in this case I have 60i 720x480 0.9par footage that I have scaled down in AE in a comp that matches the footage. When I play back the comp, it has a combing effect on the shots, especially noticable in pans and tilts. I have tried rendering out lower field first and also turning off field seperation under the interperlation settings.  Is there a mathmatical formula that needs to be abided by when scaling interlaced footage so it doesn't make these nasty combing effects?  Thanks for any help.

        • 1. Re: Interlaced scaling issue
          bogiesan-gyyClL Level 3

          Do you see these artifacts at 100% scale? If you shot interlaced and your comp is interlaced and your rendering is interlaced, the interlace artifacts you are seeing are most likely caused by viewing your rendered footage on a progressive display.

           

          bogiesan

          • 2. Re: Interlaced scaling issue
            Mylenium Most Valuable Participant

            I'm with David here - there is not much point in gauging the correctness of field interlacing on the computer. Assuming you have set the footage interpretation right and render the correct field order, seeing combing on the computer monitor would be normal. I would only be worried, if there are multiple interlacing patterns that appear to work against one another. In any case, you will only see if it's correct by playing it back on an interlaced target device, that is your video monitor hooked up via your capture card or by burning the output to a test DVD+/-RW, though the latter may add its own level of confusion with regards to field order...

             

            Mylenium

            • 3. Re: Interlaced scaling issue
              JBrown321 Level 1

              It actually looks bad on an NTSC video monitor. The video looks fine as long as I don't change the position or scaling, but once I do, it starts to look nasty and the effect is very evident.  ????

              • 4. Re: Interlaced scaling issue
                TimeRemapper Level 4

                ...that I have scaled down in AE in a comp that matches the footage..

                 

                If you're ever going to scale or reposition interlaced source material, make certain that you have separated the fields in the interpret footage dialog box. Your symptoms sound like you're either not separating fields, or, you're designating the wrong order.

                • 5. Re: Interlaced scaling issue
                  Bill Murphy 2766

                  Need some help.  We been using Final Cut for a number of years and removing the interlace issue is a one click fix. We are changing to after effects and have not been able to find a way to simply delinterlace the video.  For example, our video spokesperson http://www.eggheadproductions.com are recorded in HDV format and the only solution I've found is to select upper or lower field.  I've also seen a number of very compllicated tutorials on the web.  Is this a simple way to deinterlace with AE?

                  • 6. Re: Interlaced scaling issue
                    bogiesan-gyyClL Level 3

                    Might want to start your own thread.

                    Moving into and out of After Effects is not a big deal. Deinterlacing is only necessary if you are moving from an interlaced format to a progressive one. so questions like this make me wonder why you think you need to deinterlace at all.

                     

                    I've never used HDV myself but I hear it's no fun decompressing MPEG2 stuff on the fly in any application. Are you using HDV straight or are you following the recommended path and transcoding to another, more edit-friendly format?

                     

                    bogiesan

                    • 7. Re: Interlaced scaling issue
                      Rick Gerard Adobe Community Professional & MVP

                      bogiesan wrote:

                       

                      ... Deinterlacing is only necessary if you are moving from an interlaced format to a progressive one. so questions like this make me wonder why you think you need to deinterlace at all.


                      Not quite! If you scale, rotate or move your footage at all you must separate fields (delinterlace). Move interlaced video up or down an odd number of pixels and you reverse the field order and end up with a mess. Rotate interlaced footage and you end up with a mess.

                       

                      After Effects, for the most part, properly separates fields. It's not as big a deal as most make of it. Third party plug-ins like the Fields Kit or the original Magic Bullet did a better job than AE, Premiere, or Final Cut, but for most work, and for most work done by pros, AE's field interpretation is plenty good.

                       

                      I can't think of the last time that I did not separate fields. It just works better.

                      • 8. Re: Interlaced scaling issue
                        Mylenium Most Valuable Participant

                        We are changing to after effects and have not been able to find a way to simply delinterlace the video.

                         

                        Effectively, when you set the footage interpretation, you deinterlace. The only real failure here is, that AE only displays frames and never fields, therefore the areas inbetween frames are sometimes a bit of a guess. The program will handle it correctly for final rendering, though, even if you don't see it while working. If you are interested in different ways to deinterlace, then Twixtor, Magic Bullet Frames and an asortment of other tools can help...

                         

                        Mylenium