3 Replies Latest reply on Feb 21, 2014 2:21 AM by Mylenium

    Rendered Movies are Jerky after timestretch

    toolance

      Hi,

       

      I'm new to After effects so I accept in advance that I'm doing something wrong with my timelapse movies. Here's the problem.

       

      After importing my timelapse image sequence and interpreting the footage I am able to render out a 1080p video file that runs

      nice and smooth. If I try to speed up my footage from lets say 9 seconds to 6 seconds using 'Timestretch', I notice that the rendered

      video of that 6 second clip is kind of jerky, it's not smooth like the original length movie.

       

      Obviously I'm missing a step in the process or not fully understand how this works. I suspect it's something to do with frame rates.

       

      My composition is 30fps and so is my rendered video file. I use the H.264 compression in both cases.

       

      What is this newbie doing wrong?

       

      Thanks in advance

      Gavin

        • 1. Re: Rendered Movies are Jerky after timestretch
          Rick Gerard Adobe Community Professional & MVP

          Try changing the frame rate of your imported image sequence.

           

          Try turning on frame blending

           

          Going from 9 seconds to 6 seconds is a 33% change in time. Without frame blending of some kind you are not going to get an even distribution of your original frames. Try 25% or 50% and see if that is smoother.

          • 2. Re: Rendered Movies are Jerky after timestretch
            toolance Level 1

            Thanks Rick,

             

            How would this work when using timewarp? Let's say I have a few clips and I'd like to alter their speeds at various points. Would I require a math degree to figure it all out? Is there no way to manipulate dynamic speeds of footage and then just have that render smoothly when it's time to render it all down to one movie?

             

            Forgive my ignorance if I'm asking the world without knowing all the complexities of video.

             

            Cheers

            Gavin

            • 3. Re: Rendered Movies are Jerky after timestretch
              Mylenium Most Valuable Participant

              Timewarp works no different than the normal time-remapping, it only offers more refined control and more sophisticated algorithms. since all effects in AE follow a WYSIWYG approach, you will always see the result of the remapping as you scrub the sliders, so I'm not sure what you are asking. If you ask for an mathematically exact formula or some overlay text that tells you "You are now seeing frame X", then that would have to be done by adding a linear counter in a pre-comp that matches the frame count and would then respond to the time-remapping as well. Otherwise I don't see much of a problem here, though of course complicated remapping back and forth can become confusing. that's why in such cases I usually split the clips into multiple layers and tackle one at a time, only taking care to match the in and out points. You'll get the hang of it, just try and don't let yourself be scared witless just because it looks complicated, which realyl it isn't.

               

              Mylenium