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Forums Compression Techniques picture jumps during the horizontal pan

  • picture jumps during the horizontal pan

  • serkan ertekin

    June 16, 2009 at 12:31 am

    Hi everybody,

    I would be very happy if anyone can share their thoughts about the following problem I am having:

    I am making a quicktime movie that will be for web use (mainly streaming but also downloadable).
    The movie has parts where I have a camera that pans horizontally and shows still images of objects. Imagine a horizontal movement in a museum.

    The problem is that, even though I don’t see any jumps in the after effects RAM preview, I always see some after I render the composition. Plus, even though they look like they happen on the same spot every time i play, I guess they are not, cause if I go to the jump and play it from there, then the jumps happen slightly later. This tells me that the problem is coming from compression?

    I think it may also be caused by the sped of the movement, but i am trying not to change that, instead I am in search of a good compression that can solve it.

    So far I’ve been experimenting with h264. My composition is 30fps, I also tried to bring it up to 60fps, the general motion got a lot smoother but I am still seeing jumps.

    Any help would be greatly appreciated.

    Thanks in advance!


  • Chris Blair

    June 17, 2009 at 2:10 am

    You really can’t trust RAM preview to give you a true indication of what a rendered file will look like…and I doubt it’s the compression causing this. It’s likely a field/frame issue.

    Are you rendering directly from AE to H264? We need more info to help. Like frame size (HD, SD etc.), your compression settings (be detailed, read the post at the top of this forum on what to include).

    If you could give us more info…lots of people could give you some tips.

    Chris Blair
    Magnetic Image, Inc.
    Evansville, IN

  • serkan ertekin

    June 17, 2009 at 6:06 am

    Hi Chris, thanks for your time, here is some more info:

    the video is 720*480, it will be on both DVD and online (as quicktime, 2 different resolutions, one full, one half). but my main concern is the online version for now.
    It is progressive, there is no video footage that I am using in my comp, it is all still images.
    I first tried 24fps, but the whole move was too jerky due to lack of frames, so I believe I will keep it at 30fps.
    I’ve done some renderings right from AE but I thought the quality wasn’t there (could be user error) and was taking long, the way I am working now is that I am first rendering a tiff sequence (no compression) , then I am taking that into quicktime pro and rendering an uncompressed mov file. Then I’ve tried using Squeeze and again quicktime pro to render the h264 and sorenson3 versions, but all have the same problem: it jumps at certain parts.
    I checked for duplicate frames, there is none.
    Plus, if I play the movie from lets say from the 3rd second on, then the jumps happen slightly later then before. which kind of tells me that the computer needs to refresh to buffer again? but I have rendered very small sized tests, like around 4-5 MB, and they still had the same problem.
    Thanks in advance

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