28 Replies Latest reply on Dec 16, 2010 1:56 AM by Powered by Design

    Viewing a single field of an interlaced frame

    geobrick

      Is there a way to view the contents of a single field in Premier Pro?

       

      I want to be able to see the detailed contents of a film transfer. The film was transferred to an interlaced NTSC format (720x480 29.97fps) but I specified the transfer capture each frame of film to a frame of digital video (2 video fields for each frame of file). In other words, each field pair scanned the same frame of film but was offset by the alternate scan line position. The combined fields would produce the full resolution equivalent to a progressive video frame.

       

      If I export a frame, am I getting both fields or am I getting just the upper, lower or a blended output?

       

      When I export to a progressive format will I get the desired combined fields into one progressive frame without any blend processing?

       

      These are the questions I hope answer by being able to isolated each field in the source material.

       

        • 1. Re: Viewing a single field of an interlaced frame
          shooternz Level 6

          Now ..I am not in front of my CS5 puter but I think ( I am sure)  that there is an option in the Playback Menu  to view uppper, lower or both fields.

           

          I was checking an AVCHD mts file "issue" in a project the other day and ran across it.

          • 2. Re: Viewing a single field of an interlaced frame
            geobrick Level 1

            Yes. I see that I can choose which field in the current frame I'm viewing. Thanks.

             

            The only thing that would make it more useful to me would be if when premiere displays the single field, it would display it without processing the single field into a single frame (line doubling or whatever it's doing to make the field appear as a full resolution frame. I'd prefer to see the gaps between the lines than for it to be filled in with processed video. Then I'd know for sure that premiere is using both fields to produce the film frame instead of throwing away one field and doubling it when I render it to a distribution format.

             

            I tried exporting the frame to view it in photo shop but there doesn’t seem to be an option for exporting a single field. Maybe there's some way in After Effects. Thanks for your quick reply. 

            • 3. Re: Viewing a single field of an interlaced frame
              Colin Brougham Level 6

              Then I'd know for sure that premiere is using both fields to produce the film frame instead of throwing away one field and doubling it when I render it to a distribution format.

               

              Well, if you're using an interlaced sequence and are exporting to a progressive output, then yes, Premiere just chucks away one of the fields. The deinterlacer in Premiere leaves a lot to be desired; using the Maximum Render Quality improves things a bit, but not enough to call it "good" in my opinion. If you're going to an interlaced format, however, the fields will be preserved.

               

              I'm not clear on what your source material is or your intended use; can you explain a bit more fully? It sounds like you're using telecined film footage (presumably 24fps) from DV tape. Is that the case? If so, what is it exactly that you're trying to preserve (or remove)? I just get the feeling that there's a bit of information missing that would make this more usuable to you...

              • 4. Re: Viewing a single field of an interlaced frame
                geobrick Level 1

                Here's the full story. I may have made things more complicated than it needs to be.

                 

                About two years ago I had some 8mm and 16mm film transfered to digital by Debenham media group (Mymovietranfer.com). They use 

                Rank Cintel Turbo II Telecines for the transfer and the final format (at the time before they offered HD) was uncompressed 4:2:2 formatted for a PC in .mov files. These files have a 720 x 486 resolution at the NTSC interlaced format (29.976 fps) (using the black magic codec).

                 

                Their typical solution would have used the standard film to digital method using where the 16fps film frame rate would be manipulated into the 29.976fps interlaced format. At the time I thought all this extra processing seemed unnecessary. We were in the digital video age. Many TVs can display progressive formats. Why not scan the film progressively.

                 

                I knew premiere pro had the ability to “interpret footage”. Instead of manipulating the transfer frame rate to fit the NSTC format, what if I had the film transferred where one frame of film equaled one frame of video? Two fields per frame of film without any pull down frame sequencing manipulation. I talked to Stuart Debenham and he said it could be done.

                 

                So long story short (too late?)….

                The source material includes 8mm and 16mm film captured at 29.976 fps. Each film frame is one video frame made up of two fields.

                 

                Since the original film is mostly at 16 fps, the transferred video files would naturally play back at about double the actual speed. At this point I’d have several options in converting the file to a true progressive format.

                 

                1) Interpret the footage as 16fps and format the sequence as 24p. There would be some repeated frames but it’s an even calculation (every third frame is repeated).

                2) Interpret the footage as 15 fps and format the sequence as 30p. The speed wouldn’t be as accurate (if even noticeable) but the playback would be smoother with just a doubling of each frame).

                2a) I could theoretically also format the sequence to 30i since each interlaced field is made from the same film frame. The two fields would make up the full frame.

                 

                What I don’t want is to lose the video content in one of the fields or I’d be throwing away half the real resolution. That is the intent of my original question. How do I insure premiere pro isn’t throwing away (or blending) these fields with content vital to the full resolution of the captured film.

                • 5. Re: Viewing a single field of an interlaced frame
                  Colin Brougham Level 6

                  OK, that's much more clear now

                   

                  Well, to my mind, this is a task better suited for After Effects, which can separate out the fields of an interlaced video and then do some more exacting manipulation on those fields. Premiere Pro is going to be more limited in this regard, and I'm not quite positive about how to achieve precisely what you're looking for. I think that, no matter what you try, you're going to end up with some frame interpolation, simply because of the nature of any film-video transfer, but it sounds like you're already aware of the issues and how to best address them.

                   

                  I think the bottom line is that, if you're hoping to create a progressive source out of this interlaced material, with Premiere at least, you'll have to accept some compromises. That's why I say that After Effects is likely to be a better tool for this job, as you have much more finite control over how the interlacing will be handled and how you will interpolate any necessary frames to get to a real-time playback. A video scripting tool like AviSynth would also probably be an option; I'm sure you're not the first person to do this, so hit up Google about using AviSynth to retime this footage.

                   

                  This is actually a pretty interesting challenge; I wish I had more coherent advice to offer as to how to complete it, but without being able to test some workflows, it would all be conjecture. I hope someone else can offer some insight for you!

                  1 person found this helpful
                  • 6. Re: Viewing a single field of an interlaced frame
                    geobrick Level 1

                    Thanks, I'll try some experimenting. After effects may be the right tool to ensure I get both fields making up the frame in the edited distribution format.

                    • 7. Re: Viewing a single field of an interlaced frame
                      SteveHoeg Adobe Employee

                      Premiere Pro's high quality deinterlacer came from AE. For frame rate mismatches we will only blen frames if frame blending is on, which is now off by default in CS5. Going 30i to 60p will deinterlace each field to one frame. If you want to know what fields and times are sampled for each rendered frame use the timecode effect. Note that it renders at sequence framerate, not media, so some nesting may be required to achieve the desired result.

                      • 8. Re: Viewing a single field of an interlaced frame
                        geobrick Level 1

                        Thanks, I'll have to learn what nesting is (sounds like what I want to do if it means nesting two interlaced fields into one progressive frame).

                         

                        I get that frame blending is off by default (thanks for that) but what am I looking at in the monitor when I select "display first field"? What does premiere do to display the 240 line field as if it's 480 lines? Does it double each line or is there some interpolation? It must be doing something otherwise I'd see the blank lines or a squashed image. 

                         

                        Are you saying that putting the 30i source into a 60p sequence takes each field and puts it in its own frame? Interesting but I don't know if that will help with my end goal.

                        • 9. Re: Viewing a single field of an interlaced frame
                          Colin Brougham Level 6
                          What does premiere do to display the 240 line field as if it's 480 lines? Does it double each line or is there some interpolation? It must be doing something otherwise I'd see the blank lines or a squashed image. 

                           


                           

                          I don't know officially what is happening, but my guess would be line doubling; interpolation of a new line would incur too much of a processor hit, and since you're looking for field artifacts/issues, interpolation would cover those up. One way you could test this would be to set the zoom for the monitor to 400%, and then toggle between the first field/second field/both fields option. At least in the footage I'm looking at, the lines appear to double when you're in first/second field mode.

                           

                          Ultimately, it's important to note that these are viewing settings only, and have nothing to do with the sequence or the eventual output. They're merely for confidence checking within the Source and Program Monitors.

                          • 10. Re: Viewing a single field of an interlaced frame
                            Jim_Simon Level 8

                            Another thing to note is that all computer monitors are progressive display only.  You can't get a truly interlaced image out of them.  Even if you send it one, the monitor itself will turn it into progressive.  This is one reason why anyone working with interlaced media needs to use an external CRT for quality control.  Progressive monitors (which includes all flat panel models) simply do not have the capability of properly showing an interlaced image.

                            • 11. Re: Viewing a single field of an interlaced frame
                              geobrick Level 1

                              Colin, Confidence building is what I'm looking for at that step. I want to insure that I can see the two independent fields of the frame. The next step would be to make sure they are used to produce the progressive frame without any processing beyond using each alternating line.

                               

                              I do see a shift up (or down) in the image when I select "display first field or 2nd field. That indicates to me that the two fields are there. I could probably zoom in on the frame while displaying both fields to see that there's no line doubling with both fields while it would be apparent if I had one field displayed.

                               

                               

                              • 12. Re: Viewing a single field of an interlaced frame
                                geobrick Level 1
                                function(){return A.apply(null,[this].concat($A(arguments)))}

                                JSS1138 wrote:

                                 

                                Another thing to note is that all computer monitors are progressive display only.  You can't get a truly interlaced image out of them.  Even if you send it one, the monitor itself will turn it into progressive.  This is one reason why anyone working with interlaced media needs to use an external CRT for quality control.  Progressive monitors (which includes all flat panel models) simply do not have the capability of properly showing an interlaced image.

                                 

                                Understood.

                                At this point, I'm just trying to see how premiere is handling the interlaced image.

                                 

                                I suppose a good test would be to take a real interlaced source and try to output a progressive file and if I see interlacing artifacts, I'll know I have the right solution. I know most people try to avoid the artifacts but in the case of my source file, both fields have scanned the same image so the result will be a true progressive image not one made up of only 1 field or a blend of the fields.

                                 

                                All this information is a great start to my experimenting and I'll let you all know what worked.

                                 

                                Thanks for all the quick replies on a sunday. 

                                • 13. Re: Viewing a single field of an interlaced frame
                                  Jim_Simon Level 8
                                  I'm just trying to see how premiere is handling the interlaced image.

                                   

                                  In an interlaced sequence, going to an interlaced export, it will leave things as they are.  Using a progressive sequence or export is where things change.

                                  • 14. Re: Viewing a single field of an interlaced frame
                                    geobrick Level 1
                                    function(){return A.apply(null,[this].concat($A(arguments)))}

                                    function(){return A.apply(null,[this].concat($A(arguments)))}

                                    JSS1138 wrote:

                                     

                                    I'm just trying to see how premiere is handling the interlaced image.

                                     

                                    In an interlaced sequence, going to an interlaced export, it will leave things as they are.  Using a progressive sequence or export is where things change.

                                     

                                    That is true. Interlaced to interlaced is fine.

                                     

                                    In my interlaced source, every pair of interlaced fields have scanned the same image (one frame of film). If I can deinterlace it without throwing out one of the fields or without any blending process between the fields, I will end up with a true, full resolution progressive frame.

                                     

                                    I did some experimenting on an interlaced HDV source. By interpreting the footage as progressive and putting it into a progressive sequence, it seems to maintain both fields in each frame (when setting the monitor to display both fields). You can clearly see the interlacing artifacts but I can't tell if there was any attempt at processing (had to tell in the fuzziness of the zoomed in image - I can try some experiments with some deinterlaced tiff exports to compare the frames. 

                                     

                                    So far this is leading me to believe that if I interpret my source material as progressive, it will maintain both fields of the original transfer.

                                    • 15. Re: Viewing a single field of an interlaced frame
                                      Jim_Simon Level 8
                                      If I can deinterlace it without throwing out one of the fields

                                       

                                      It's my understanding that such is not possible within Premiere.  Unless things changed for CS5 (and it could well be they have), Premiere's only option for deinterlacing is to throw out one field.

                                      • 16. Re: Viewing a single field of an interlaced frame
                                        geobrick Level 1
                                        function(){return A.apply(null,[this].concat($A(arguments)))}

                                        JSS1138 wrote:

                                         

                                        If I can deinterlace it without throwing out one of the fields

                                         

                                        It's my understanding that such is not possible within Premiere.  Unless things changed for CS5 (and it could well be they have), Premiere's only option for deinterlacing is to throw out one field.


                                        You are probably right that you can't deinterlace without tossing out a field or processing of some type. That's the whole point of deinterlacing.

                                         

                                        I should probably call what I need to do something else. I really want to combine two interlaced fields into a progressive frame. That's kind of the opposite of deinterlacing.

                                         

                                        It seemed that interpreting the footage as progressive and putting it on the timeline in a progressive sequence does just that,  I need to try a few more experiments to confirm.

                                         

                                        For the purposes of this thread, my initial question on whether you can see both fields in the monitor was answered. If there are anymore suggestions on accomplishing my goal of combining two interlaced fields into a progressive frame I welcome them (even if it just confirms the path I'm heading down or offers a good test I can try.)

                                        • 17. Re: Viewing a single field of an interlaced frame
                                          Powered by Design Level 4

                                          I wonder if Photoshop could be used to cut the interlaced images then merge them.

                                           

                                          Not sure.

                                           

                                           

                                          GLenn

                                          • 18. Re: Viewing a single field of an interlaced frame
                                            geobrick Level 1

                                            For just a frame verification, I'm sure it could do something. There's an After Effects tutorial that describes deinterlacing using a scan line mask. Something along those lines in reverse could work.

                                             

                                            If you mean for the full film transfer, it would have to be in After Effects.

                                            • 19. Re: Viewing a single field of an interlaced frame
                                              shooternz Level 6

                                              Wonder if the 'Field Fixer' on this link is of any use to you.

                                               

                                              http://www.frischluft.com/free/index.php

                                               

                                              I dont even know what it does myself and have never tried it!

                                               

                                               

                                              Described as :  Field Fixer Allows the user to correct field problems manually by selecting upper and lower field for the current frame.

                                              • 20. Re: Viewing a single field of an interlaced frame
                                                Jim_Simon Level 8

                                                It seemed that interpreting the footage as progressive and putting it on the timeline in a progressive sequence does just that

                                                 

                                                That's not really surprising.  And you're right, that's not really 'deinterlacing' either.

                                                • 21. Re: Viewing a single field of an interlaced frame
                                                  geobrick Level 1
                                                  function(){return A.apply(null,[this].concat($A(arguments)))}

                                                  shooternz wrote:

                                                   

                                                  Wonder if the 'Field Fixer' on this link is of any use to you.

                                                   

                                                  http://www.frischluft.com/free/index.php

                                                   

                                                  I dont even know what it does myself and have never tried it!

                                                   

                                                   

                                                  Described as :  Field Fixer Allows the user to correct field problems manually by selecting upper and lower field for the current frame.

                                                   

                                                  I love the phrase after the description "Mostly useless?"

                                                  • 22. Re: Viewing a single field of an interlaced frame
                                                    shooternz Level 6

                                                    Note how I edited that out ..so that you could get a surprise!

                                                     

                                                    Did you try it anyway?

                                                    • 23. Re: Viewing a single field of an interlaced frame
                                                      geobrick Level 1

                                                      I downloaded it but I'm heading out of town for a few days and won't get to it until I get back.

                                                      • 24. Re: Viewing a single field of an interlaced frame
                                                        geobrick Level 1

                                                        OK, I've done a bunch of experimenting and determined how to ensure the field pairs of each film frame stick together. I had to interpret the interlaced source material as progressive. Once that was done, I could pull the clips into a progressive sequence and play with the speed or frame rates and the original field pairs of the film transfer would always remain intact. I can also use the interpret footage to set frame rates for one of two methods of restoring the speed to 16 fps.

                                                         

                                                        1) interpret the rate at 16fps (progressive) and put it into a sequence set to 24p (repeats every 3rd frame).
                                                        2) interpret the rate at 15fps* (progressive) and put it into a sequence set to 30p (doubles each frame).
                                                            - Speed will actually be about 15 fps (not exactly 16 but probably unnoticeable and probably within the camera's variation)  

                                                         

                                                        Here's how I set up the experiment to prove it (for anyone interested).

                                                        Experimenting with the actual film transfer files was too hard. I couldn't tell from the monitor if I was looking a full resolution frame or one that was made from a single field and processed into a full frame.

                                                         

                                                        So I created an NTSC 30i DV sequence with alternating black and white frames (32 total) and exported it to an NTSC 30i DV file named "black and white can test.avi". Then I pulled that into a new NTSC 30i DV sequence called "Labeling the fields and Frames" and tediously added titles with frame numbers and the letters "L" and "U" to represent each field. The frame numbers spanned 2 frames each while the "U"s and "L"s spanned one frame each.

                                                         

                                                        The exported file from the "Labeling the fields and Frames" sequence was called "Labeled scan lines test.avi". I pulled that file into a NTSC 30i DV sequence called "Labeled Scan Lines" and set the clip speed to 200%. Premiere's process for doubling the speed of the clip interlaced adjacent frames. The resulting exported file had each lower field made up of only black lines with the letter "L" while each upper field was made of white lines and contained the letter "U". The frame numbers span both fields.

                                                         

                                                        The file was perfect for my situation because when I experimented with how to restore the film to a pure progressive format. I used the "Interlaced Labeled Scan Lines.avi" to prove the fields were kept intact when I attempted various methods of creating a progressive version of the film transfer.

                                                         

                                                        I was able to prove that simply halving the speed of clip, without first interpreting it as progressive, resulted in the fields being pulled apart. This was easy to see because the result separated the black and white interlaced lines into black and white frames clearly labeled with the "U" or "L". In the case of my film project, this would have resulted in each frame being a half resolution version of the original. Interpreting the footage as progressive maintains the field pairings (therefore the full natural resolution). Now when the speed is halved, premiere doubles the frames instead of separating the fields. Perfect!

                                                        • 25. Re: Viewing a single field of an interlaced frame
                                                          Powered by Design Level 4

                                                          Nice.

                                                           

                                                          Can you post some screen captures of that ?

                                                           

                                                           

                                                          GLenn

                                                          • 26. Re: Viewing a single field of an interlaced frame
                                                            geobrick Level 1

                                                            I can post the 1 second avi file somewhere if there's a place. In the mean time, I'll grab some screen shots.

                                                            • 27. Re: Viewing a single field of an interlaced frame
                                                              geobrick Level 1
                                                              function(){return A.apply(null,[this].concat($A(arguments)))}

                                                              Powered by Design wrote:

                                                               

                                                              Nice.

                                                               

                                                              Can you post some screen captures of that ?

                                                               

                                                               

                                                              GLenn

                                                               

                                                              Here are the screen shots. Hope they help explain what I did.

                                                              The first one shows the 30i sequence with the alternating black and white frames.

                                                               

                                                              B&W.jpg

                                                               

                                                               

                                                              The next one below shows the labeling step where the frame number crosses 2 frames and the field labels cover one frame each (so later when the speed is doubled it results in adjacent frames being interlaced). The image shows the title indicating frame 5's lower field.

                                                               

                                                              http://i525.photobucket.com/albums/cc333/geobrick/LowerLable.jpg

                                                               

                                                               

                                                              Below is the clip resulting from the above step. The clip is set for a speed of 200% which results in the individual black and white frames becoming interlaced. The monitor is set to display both fields. This screen shot doesn't clearly show the interlaced lines but they are clean individual black and white lines.

                                                              http://i525.photobucket.com/albums/cc333/geobrick/both.jpg

                                                               

                                                              The next 2 screen shots show what happens when I change the monitor to display the "first" then "second" fields. This demonstrates that the interlaced frames are truly made up from unique individual fields.

                                                               

                                                              http://i525.photobucket.com/albums/cc333/geobrick/ShowUpper.jpg

                                                              http://i525.photobucket.com/albums/cc333/geobrick/Label5L.jpg

                                                               

                                                               

                                                              The next screen shot shows the clip resulting from above being used in a 24p progressive sequence. The interlaced source clip is now "interpreted as" 16 fps progressive. Note how the fields stay interlaced even at the slower 16 fps rate. The "interpret as progressive" is the key to keeping the fields paired.

                                                              http://i525.photobucket.com/albums/cc333/geobrick/24pInterpret.jpg

                                                              Below shows what happens when you don't interpret the interlaced source material it as progressive.

                                                              http://i525.photobucket.com/albums/cc333/geobrick/pulled-apart.jpg

                                                              The fields get pulled apart. This shows frame 15 but it's the same with all frames.

                                                              • 28. Re: Viewing a single field of an interlaced frame
                                                                Powered by Design Level 4

                                                                Thanks for the images.

                                                                 

                                                                That was interesting.

                                                                 

                                                                 

                                                                Glenn