image quality problems

Discussion in 'Digital Video' started by redptc, Oct 27, 2011.

  1. redptc macrumors newbie

    Oct 27, 2011
    I am in the market for a new HD camcorder. I tried out a friend's Canon M31 and no matter what video quality setting I used on the camcorder, once I transferred the video to iMovie the edges are very squirmy (I know, not a very technical description). This is most pronounced on horizontal edges. The problem appears when viewing in iMovie and on the finished DVDs played on my TV.

    Is there a problem with his camera?
    Are there some camera settings that I need to change?
    Are there some import or processing settings I need to adjust?

    I can't believe that this problem is common or nobody would buy these camcorders.

    I also tried a Sony model at the store as an alternative to the Canon, recording onto my own SD card. Once I got home I found that I could not import the recording into iMovie. I had the same problem with my friend's Canon. Do you have to upload via the camcorder?

    Thanks in advance for your thoughts and advice.
  2. ppc_michael Guest


    Apr 26, 2005
    Los Angeles, CA
    Hi! Sounds like you're describing interlacing. Do you mean this kind of thing? Interlacing is there for TV screens. But when viewed on a progressive display such as a monitor, they are obviously undesirable. You can get rid of it using a deinterlace filter.
  3. redptc thread starter macrumors newbie

    Oct 27, 2011
    that's not it

    No, it looks more like ants walking along any edges, most notably horizontal ones.

    If the edge is slightly off the horizontal in relation to the camera it looks more like a stair step than a straight line. When the camera is moving (even slightly) the stair steps almost shimmer or squirm as if it can't decide which pixel (but at a larger scale) should be the lower side of the edge and which should be the upper side of the edge.

    I don't have a screen shot handy, but an edge that should appear straight:

    appears more like:
    _^v^v^v^v_ <-- with the ups and downs shifting back and forth/up and down as the camera pans

  4. redptc thread starter macrumors newbie

    Oct 27, 2011
    the plot thickens

    I was just viewing the footage in QuickTime and I am not seeing the edge crawling effect. That tells me that the camcorder is not to blame. It must have something to do with how I am processing the footage in iMovie.

    If you look at a recording of a zipper it seems like the teeth have come alive and start to move. I have a stack of CDs in white paper envelopes and when viewed from the side the CDs seem to writhe. It's almost enough to make you seasick on a big screen TV.
  5. cgbier macrumors 6502a

    Jun 6, 2011
    That definitively sounds like interlacing. Shoot progressive (25/30p) or add an de-interlace filter, if that exists in iMovie, and you should be good to go.

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