4 Replies Latest reply on Sep 2, 2013 8:54 AM by wideEyedPupil

    Smooth credit roll — not yet!

    wideEyedPupil Level 1

      I'm rendering at 1920x1080HD 25fps. Used the expression found on numerous threads including this one to generate whole number pixel shifts per frame.

       

      t = time;
      fr = t/thisComp.frameDuration;
      x = value [0];
      s = 4; //Speed in pixels per frame

      [x, fr*s]

      I generated the text and images in InDesign and exported as a PDF. Imported PDF into AE. Have tried a few whole number values for s including 4 and still getting judder.

       

      Generated to H264 and Apple Pro Res codecs doesn't seem to make much difference to judder.

       

      Here is my AE project with PDF. Here is output as H264 (40MB).

       

      Also included a Quartz Composer file (if anybody is interested) where I created the same whole number pixel movement as AE but rendering it out in Quartz Crystal I get different judder but no better. Quartz Composer previews in real time and Quartz Crystal renders same project that took some 16min+ in AE in about 30 seconds. But no smoother output — even when applying AA and Motion Blur at render time.

       

      Can anyone recommend a video encoder where I can down-sample say a 75 fps render to 25 fps with frame blending? Does Apple's Compressor do frame blending? What about some other app that I can get this out smoothly from. I have FCP installed but have never done a title in it either.

       

      Since my Dell only has 60Hz at full native res (2560x1440) I set it to 1080p and selected 50Hz to see if that effected anything but it makes absolutely no difference to playback smoothness.

       

      AE CS6

      OS X 10.7.5

      AMD Radeon HD 6750M 1024 MB

        • 1. Re: Smooth credit roll — not yet!
          Rick Gerard Adobe Community Professional & MVP

          You are moving your titles at 6 frames per frame and that's too fast or not fast enough. The pixel accuracy is perfect but the speed does not follow the rules so you are ending up with stroboscopic judder. Try 3 or 2 and the playback should be fine. Generally, follow the seven second rule.

           

          BTW, you didnn't include the pdf so I made one of my own.

          • 2. Re: Smooth credit roll — not yet!
            wideEyedPupil Level 1

            Oh thanks, Rick. Sorry I thought PDF was in the Zip file. PDF is here. Im using quite thin type may have to fatten it up. FWIW I tried a bunch of speeds, (int values for s variable), 4 was recommended and it was a bit too slow and juddery. I tried adding a Reduce Interlace Flicker blur = 1.5 but it ate into the text too much (text too thin).

             

            What's the seven second rule, again?

             

             

            The pixel accuracy is perfect but the speed does not follow the rules so you are ending up with stroboscopic judder. Try 3 or 2 and the playback should be fine. Generally, follow the seven second rule.

            What exactly are the rules I'm not following?  I thought it was whole number increments per frame and that's it. I seem to be missing something.

            • 3. Re: Smooth credit roll — not yet!
              Rick Gerard Adobe Community Professional & MVP

              Ever see stage coach wheels turn backwards in a western? Ever see helicopter blades behave oddly in a film? These stroboscopic effects depend on frame rate and motion. That's what is causing judder. Varying edge aliasing, especially in interlaced footage, cause edge flicker and are removed with whole number pixel movement per frame. The 4 pixels per frame suggestion is for interlaced footage because you need even numbers for interlaced footage. 4 does not work for 25fps footage, 3 does. If you don't want judder (strobing) at 25 fps then slow or fast is your only option. The range between 4 and about 8 is unusable.

               

              The seven second rule is a cinematographers rule for doing camera movement when shooting at 24 fps (25) and it's in any good cinematography manual. There are speeds that just strobe. The strobing action is different on TV than it is on the big screen with a film projector. Basically, if an object of interest takes about 7 seconds to cross the screen the motion will appear to be smooth.

               

              Read this from the FAQ on this forum.

              • 4. Re: Smooth credit roll — not yet!
                wideEyedPupil Level 1

                Thanks Rick. Yeah I read that already :-) Oh that seven second rule!

                 

                I understand the problem but I don't have any experience in crafting the solution.

                 

                I'm doing it in Motion now and results are significantly better at any gven speed but not 100% smooth yet. Slower seems to be better but not by much. I've read that there's a BorisFX plugin for AE and NLE apps that offers "butter smooth" credit rolls but haven't trialed it yet.

                 

                Back to first principles, I'm wondering if I can output at say 50fps in ProRes 4444 then resample footage down to 25fps with an application that will blend the frames.

                 

                I know a technique from back in the day video where animators outputting from a computer display to a 16mm film camera would expose each frame of film twice at one stop down. They would expose the film frame to a video frame, advance the video frame and then reexpose the film frame. Advance the film frame, expose again to same video frame then advance video. Repeat loop. Apparently it made for smoother motion.

                 

                Do you think the type is too thin? Would that help reduce strobing or not so much? What if I type the characters into the text editor of AE or Motion is it going to make the slightest bit of difference to the way that anti-aliasing / flicker blur is calculated?