5 Replies Latest reply on Jul 30, 2011 4:31 AM by Andrew Yoole

    De-interlace 1080i 50

    martinjamesroberts1 Level 1

      Hi there,

       

      I have a HDV camcorder and record in 1080i and have been for quite some time, as I know the quality is very high on tape driven camcorders..

       

      The only problem I have is I would like to watch the footage (family videos etc.) back on a 1080 24p TV which is connected as a second display.

       

      The footage is interlaced so when any sort of panning or pretty much any movement occurs I get lines all over the place.

       

      Question is. How can I deinterlace the video without loosing all of the quality so I can:-

       

      a) watch the films back on the tv without the lines and

       

      b) make it the best possible quality for future editing.

       

      I have seen that fieldskit is a fantastic plugin to acheive this but it is not an option with my current budget.

       

      I have also tried importing the file and running Effect / Blur & Sharpen / Reduce Interlace Flicker at 1.6.

       

      The problem I had with the above is that on import of the file (1440x1080) it became immediately distorted as if it had been squashed on the horizontal axis.

       

      Many Thanks for you help

       

      Martin

        • 1. Re: De-interlace 1080i 50
          Rick Gerard Adobe Community Professional & MVP

          Your video looks distorted in AE because the HDV footage is non square pixels. Read the help files on Pixel Aspect Ratios.

           

          You can separate fields in AE by checking the interpolation, then render without adding fields. This will remove the interlacing artifacts, but 24 P has problems with slow panning introducing judder. I'm not sure that separating fields will fix your problem. It would help to know more about your original footage. Playing 1080i 50 footage on a 24p monitor will always give you some motion artifacts because of the frame rate mis match.

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          • 2. Re: De-interlace 1080i 50
            martinjamesroberts1 Level 1

            Hi Rick and thanks for your response..

             

            I've found a very interesting help file on seperating fields here :-

             

            http://help.adobe.com/en_US/aftereffects/cs/using/WS725e431141e7ba651e63e3d124985b84f9-800 0.html

             

            and I have read up on the pixel aspect ratios, I believe mine is 1.33 for HDV 1080...

             

            I'll try seperating the fields and exporting the file this evening..

             

            If I leave the aspect ratio as is, it will only be the preview that is effected, is that correct ?

             

            How can I export the file to ensure the highest possible quality file ?

             

            Can I further modify the resulting file to make it more suitable for viewing at 24p ?

             

            I've read that using JES I could create a 60p file which would be very smooth, but that would require a quicktime and my file is a .mpeg2

             

            Many Thanks again and please excuse my ignorance, I am very new to video !!

             

            Martin

            • 3. Re: De-interlace 1080i 50
              Dave LaRonde Level 6

              I would like to watch the footage (family videos etc.) back on a 1080 24p TV which is connected as a second display.

               

              Are you SURE about that?  A TV set in PAL-Land that ONLY plays 24p video?  That seems kind of strange to me. 

               

              I'd double-check the owner's manual to see the playback devices you can attach to this thing.  Checking the manual also might reveal how it can display 1080 50i video with no problems whatsoever.

              • 4. Re: De-interlace 1080i 50
                martinjamesroberts1 Level 1

                I am sure I want to playback the footage on my TV which is connected via HDMI to my computer at 1080p. Despite what it is capable of playing, that is how I will be viewing the files.

                • 5. Re: De-interlace 1080i 50
                  Andrew Yoole MVP & Adobe Community Professional

                  In my opinion, converting your footage to 24p is a mistake, except in VERY special circumstances.  If it's your intention to store the material in the best way possible for future editing/processing, deinterlacing and converting frame rates will notably diminish the quality of your footage before you've even started.

                   

                  The fact that your TV is capable of 24p isn't really the issue.  That feature is designed to support films that were shot in 24p: ie on film.

                   

                  Your footage is presumably shot at 25fps or 29.97fps interlaced (?) which your TV can also handle natively.  As your playback machine is a computer, you'll note that it is probably NOT capable of running at 24p, or any other refresh rate that's a multiple of 24 (like 48Hz or 96Hz).  That means the mismatch between your computer's refresh rate and the TV's will introduce some motion defects.

                   

                  Converting from 25/50i or any other frame rate to 24p will require frame blending, which will introduce motion artifacts and softening.  If you do it without frame blending, you'll get a noticeable kink in the motion once per second as one frame or more is removed.  As mentioned above, non-interlaced footage will also exhibit motion "judder", particularly during fast motion or horizontal camera movement.  Good cinematographers know how to hide motion judder, by keeping camera movement speed very slow, and distracting the audience when the camera needs to move faster.  (Take a look at an old episode of MASH, for example, and note the first shot of almost every episode includes a pan across the opening scene, like the compound or the Officer's Club.  Then note that the camera always follows a moving target, like a walking person or a jeep or a truck, until it hits it's target.  This is done on purpose - the moving target distracts you enough to hide the judder caused by a rapidly moving camera, but still manages to set the scene reasonably quickly.)

                   

                  So, the point is, unless you're extremely conscious about how to use your camera within the restrictions of a non-interlaced medium, why throw away all that beautiful temporal information that interlaced footage provides?

                   

                  If you want to provide a lot more specifics about your source footage and playback requirements, it will be a lot easier to make stronger suggestions about what you are trying to achieve.  The fact that you're seeing interlace artifacts on your playback probably has more to do with your hardware than your software.

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