4 Replies Latest reply on Oct 25, 2008 9:57 AM by (ahu_huroti)

    Grrr! Smooth Animation problem -  AE7

      Hi. I'm trying to get a PNG image to travel L to R across the screen, starting and finishing off-screen. This is a white/grey image layer against a plain black background.

      The image when travelling looks slighty jittery (almost vibrating), and when rendered and burnt onto DVD a lot of shaking is evident.

      My PC is dual core XP 4GB ram and plenty of drive space. I'm rendering at 30fps (no noticable difference at 40 or 50 either) progressive to uncompressed AVI.

      I've tried adding and removing keyframes, changing the motion blur options, changing the keyframe interpolation options, but nothing seems to get rid of the jitter. All my other compositions on this project work ok, just this one causing a problem!

      Any ideas? Thanks
        • 1. Re: Grrr! Smooth Animation problem -  AE7
          XxMontyxX Level 1
          The left right movement is not favorable in video. However, you can render your DVD in fields, and then when you play it back on a CRT monitor or television, the "chatter" you see should disappear. It won't look right on a computer monitor, only on a CRT. Field rendering is set in the Render Queue and is in the first set of options with frame-size, pull-down etc....

          Hope that helps.
          • 2. Re: Grrr! Smooth Animation problem -  AE7
            Mylenium Most Valuable Participant
            As Timothy said - fields, fields. fields and checking on the target device. Also consider giving your greyscale artwork some slight tint or reducing the contrast a tiny bit. By its nature, as pure "luminosity", black&white graphics have strong impact technically and how they are perceived. The human eye prioritizes brightness over color, thus making any flaws there more pronounced and when such stuff is encoded e.g. to YUV, all its values will be in the Y component, thus leaving limited space for instance for color reduction methods in compression algorithms.

            Mylenium
            • 3. Re: Grrr! Smooth Animation problem -  AE7
              Level 1
              You've most likely experiencing a stroboscopic effect caused by the relationship between the frame rate, the distance the image moves across the frame and what is called persistence of vision which is why movies work in the first place. There are only two options to fix this problem. You must either change the speed of the movement or mask the effect with motion blur. The higher the contrast in the image, especially the higher the contrast between the edge and the background, the harder it is to hide this problem.

              This problem is not unique to motion graphics or animation. Cinematographers also face the same problem. Any DP worth his day rate will know about critical panning speeds. They are referenced in cinematography manuals so that you can avoid the judders. Interlaced video (normal video cameras) are not as subject to this problem because they shoot 50 or 60 fields per second.

              One suggestion you might try is to feather the edges a bit by creating a mask that's the same width but taller than the image, then feathering the edge edge a bit. Removing the juddering in the detail of the image requires additional motion blur.

              You can use the following expression to the layer's position property to move the image from left to right. Change the + to a - to move from right to left. This will keep the movement in whole pixel values. You change the speed value to any whole number.
              spd = 2; //speed setting
              move = time/thisComp.frameDuration * spd;
              x = value[0];
              y = value[1];

              [x + move, y]
              This expression will work for any frame rate. If you want to roll instead of pan add move to X. This works great for credit rolls. You can find a sample project http://www.hottek.net/samples/perfectMove.zip%3Ehere%3C/a%3E.
              • 4. Re: Grrr! Smooth Animation problem -  AE7
                Level 1
                Thanks guys, you've given me lots more options to consider! I'll play with the panning speed and contrast, maybe add to or change the background, and see what happens!

                Cheers