13 Replies Latest reply on Nov 6, 2009 10:06 AM by rickmorton

    Jerky render of QT movie

    rickmorton Level 1

      I have a new iMac and AE CS4.

      I created a short animation - nothing fancy - an image going across the screen in front of a background.

      First.. it seems to take a long time to render.

      Second, even on QT output, it jerks a bit on playback in QT player.

      It's ANIMATION codec, which I guess could be the problem, but I thought

      a 3.2 gig Intel would be fairly powerful. Haven't checked it on my G5.

        • 1. Re: Jerky render of QT movie
          Mylenium Most Valuable Participant
          First.. it seems to take a long time to render.

          Second, even on QT output, it jerks a bit on playback in QT player.

           

          Well, that's in all fairness a bit vague, to say the least. What is the resolution of the clip/ comp? What are the sources? You could be using a compressed clip for the background and its decoding could make up a considerable amount of the render time. You realyl need to be more specific. The video stuttering is a whole different matter, but may also be related to the clips size. Animation is a visually lossless compression, yes, but it does not guarantee low data rates. If the content is such, that it has lots of fine detail, the compression is less efficient than with latrge uniform areas. It's in the nature of the thing. Only destructive compressions like H.264 can give guaranteed data rates. that aside, your could be seeing screen refresh issues, which would hinge on your resolution and what graphics card/ chipo you have in your iMac.

           

          Mylenium

          • 2. Re: Jerky render of QT movie
            rickmorton Level 1

            Ok. Fair enough.

            Actually, there's more to the comp than it appeared in my first post.

            I have a pre-comp containing the wave warp filter.

            I have applied the snow effect to the final composited comp.

            Size is widescreen DV.

            iMac is 27 inch, 3.2 ghz intel core 2 duo.

            Resolution is 2560x1440

            4gb menory

            ATI Radeon HD 4670 card with 256 MB

            • 3. Re: Jerky render of QT movie
              Mylenium Most Valuable Participant

              rickmorton wrote:

               

              Ok. Fair enough.

              Actually, there's more to the comp than it appeared in my first post.

              I have a pre-comp containing the wave warp filter.

              I have applied the snow effect to the final composited comp.

              Size is widescreen DV.

              iMac is 27 inch, 3.2 ghz intel core 2 duo.

              Resolution is 2560x1440

              4gb menory

              ATI Radeon HD 4670 card with 256 MB

               

              Stylish machines, those 27" iMacs. Not enough RAM and a bit weak on graphics, though. I think we can exclude the effects from our considerations, as in terms of processor power, they would probably be pretty near-realtime on such a machine. As stated in my initial post, I suspect it's the graphics. 256 MB is not much for so many pixels. going with one of the 512MB cards would probably have been a better choice. Additionally, there may be some lag in reading the files from the disk during playback. One thing I forgot to mention are fields. If you render with fields or your soure footagte has fields and you did not set footage interpretation accordingly, it may look jittery on teh computer, but would probably look just fine on a normal TV. So look into that as well, if you haven't already. In any case, try to render a H.264 version of your stuff and see, if it plays any better. At least it would rule out the data rate issue.

               

              Mylenium

              • 4. Re: Jerky render of QT movie
                rickmorton Level 1

                Thanks, again.

                I'm thinking of taking the duo core back and getting the entry quad machine with the stronger graphics card.

                The project I'm talking about has no video. All animated photoshop images and only the one precomp.

                • 5. Re: Jerky render of QT movie
                  rickmorton Level 1

                  And the render is definitely NOT in real time. Frame by frame.

                  • 6. Re: Jerky render of QT movie
                    Mylenium Most Valuable Participant

                    Mmh, if they are not realtime (as in you can scrub through the timeline and see them updated smnoothly), then that sounds quite fishy. By all means it should. Those two effects are pretty lo-fi in terms of processor demand. Maybe that makes swapping your machine an even better idea...

                     

                    Mylenium

                    • 7. Re: Jerky render of QT movie
                      rickmorton Level 1

                      Yup. I'm taking it back tomorrow and getting the quad core. That should make a difference!

                      • 8. Re: Jerky render of QT movie
                        Rick Gerard Adobe Community Professional & MVP

                        It sounds like there are things moving across the screen and that you're getting some kind of jitter in the playback even though you've rendered to a codec designed for playback. It also sounds like you've got plenty of processor power and that the animation looks just fine when you step through it a frame at a time.  You may not be getting dropped frames on playback. You may be seeing stroboscopic jittering caused by the speed of movement in the pixels.

                         

                        Cinematographers face a problem called critical panning speed. This is much more problematic at 24 or 25 fps than at 30i, but it's common to film and video cameras. Whether your shooting or animating, there are certain speeds where objects moving across a screen will jitter. The stroboscopic effect is caused by the interaction between movement, frame rate and the way human eyes and the brain interpret motion. This is most often seen in things like credit rolls. Without seeing the video or the project file it's impossible to tell if this is the cause of your playback problem.

                         

                        If you can post a link to the project or upload the video we'll have a better chance of figuring out a solution.

                        • 9. Re: Jerky render of QT movie
                          rickmorton Level 1

                          Thanks for the info,

                          This is just a simple animation with a graphic element moving across the screen.

                          I was surprised at how slowly it rendered on the new iMac and even when rendered

                          I still see some little jerks in QT player. As you say, maybe it's just the horizontal

                          movement, but I've certainly done a lot of this and haven't had this problem. This is

                          the first animation on the new machine. I'm exchanging for the quad core tomorrow,

                          if the Apple Store has them yet!

                          • 10. ok. now I've made a test comp. Just
                            rickmorton Level 1

                            ok... now I've made a test comp. just a red square going right to left across the screen.

                            It doesn't render in real time and is very jerky.

                            Ecen when I render the timeline, the square stops and starts across the screen. Frustration on a

                            dual core new iMac and new CS4 software.

                            • 11. Re: ok. now I've made a test comp. Just
                              rickmorton Level 1

                              Well, I restarted the computer and the problem has gone away!    

                              It's only the first time the new iMac has been restared.

                              WHat's up with that!

                              I'm calling Apple.

                              • 12. Re: ok. now I've made a test comp. Just
                                Mylenium Most Valuable Participant

                                Mmh, perhaps some system library stuff needing to configure itself? Some software update that just needed a restart to finish? Still strange, that it would affect the system in this manner.

                                 

                                Mylenium

                                • 13. Re: ok. now I've made a test comp. Just
                                  rickmorton Level 1

                                  I called Apple. They said that since the computer hadn't been restarted since installing the software, that

                                  the system hadn't "adjusted" to it. I forget the exact term. Apparently, there is some stuff that the system does

                                  to accommodate some new software. They actually said the software could run slowly and not act normal.

                                  After the restart, all is well. I'll see if it starts to slow down.