iPhone 4 + iMovie 11 = Jerky Video Motion (Please Help)

Discussion in 'Digital Video' started by boltjames, Jul 12, 2011.

  1. boltjames macrumors 601


    May 2, 2010
    Went to Europe, shot an hour of HD video on the iPhone 4. Looks good on the phone, smooth video playback.

    Got home, imported the video into iMovie '11, arranged the clips sequentially, left all settings at default, added a little background music, nothing fancy.

    Hit the Export > 720p button, waited 3 hours, got my completed video, runs 35 minutes.

    Upon playback on that MacBook or my iPad or my Apple TV, the video is jerky. Whenever the camera pans and there's motion on the screen, it stutters or hesitates for a quarter-second approximately every 3 seconds.

    When the camera's not moving, can't notice it. But if you're watching the glass elevator ascend the Eiffel Tower, you can see the stuttering. If you're watching a car drive next to the tour bus, you can see it 'jump' forwards a few feet every few seconds instead of moving smoothly.

    When I use iMovie on the iPhone I never see these issues. I used the MacBook to do it because there are too many clips to edit on the iPhone, thinking that if anything the playback quality would be better on the high horsepower notebook, not worse.

    Can anyone tell me what settings I should be using to eliminate this issue? iMovie has a bunch of options, including one called "stabilization" but I take that to mean that if I have a shaky hand it'll steady the image. That's not my issue. I'm rock-steady when I shoot video. The issue is somewhere in the iMovie '11 conversion process.

    TIA if you can point me in the right direction.

  2. iDisk macrumors 6502a


    Jan 2, 2010
    Menlo Park, CA
    Doesn't hurt to just try clicking on "stabilization" to make sure. Technically your right, it is for a shaky hand scene etc...
  3. sth macrumors 6502a

    Aug 9, 2006
    The old world
    I don't think stabilization has anything to do with it.
    My guess is that the project framerate in iMovie doesn't match the iPhone's framerate.
  4. cgbier macrumors 6502a

    Jun 6, 2011
    Yep no stabilization issue. What is your bitrate? When it is too low, AVCHD is unusable for anything than talking heads or flowers (no wind allowed!).
  5. sth macrumors 6502a

    Aug 9, 2006
    The old world
    At what point do you think is AVCHD involved here? I thought iPhone->iMovie->AppleTV is all H.264.
  6. cgbier macrumors 6502a

    Jun 6, 2011
    Sorry, mixed that up, but is the same smell: Bitrate too low gets you in trouble with motion.
  7. zblaxberg Guest


    Jan 22, 2007
    It kind of sounds like a rolling shutter issue because you say that it only really becomes a problem when you pan.
  8. acearchie macrumors 68040


    Jan 15, 2006
    I'm for rolling shutter as well which you may not notice on the smaller screen.

    Is there any chance you could post a short example (maybe a 5 second recording of it playing back on your Apple TV made with your iPhone) it would probably be diagnosed very quickly then!
  9. kolohe macrumors newbie

    Jan 29, 2012
    Codec conversion?

    It's not a stabilization issue, it's obviously a codec issue. I've even copied the raw .mov file from the iPhone and it still plays back jittery in various players. Up to now I've been uploading directly from the iPhone to Youtube but I now have a larger piece to put up and iMovie for iPhone does not support my extended length ability, d'oh. Does anyone know of any cheap or free software that can manipulate the codec of these .mov containers? Clipwrap doesn't seem to open them...

    Many thanks in advance.

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