Ghosting problem / Change field of interlaced AVIs ?

Discussion in 'Amateur Video Production' started by Yvan J. Gagnon, Sep 17, 2003.

  1. How does one determine (and change) the field order of interlaced AVI
    files? I know that tools exist for this sort of thing when dealing
    with MPEG-2 files, .. but I can't seem to find anything appropriate
    for AVI files. I suspect that some 720x480 AVI files that I've
    converted were done so using the wrong field order, as I am getting
    very noticeable ghosting artifacts during playback on the PC.

    I've tried using the "Swap Field Order" filter in VirtualDub, but this
    reduced the image quality significantly, and introduced new
    articfacts. Can anyone here suggest a more practical approach for
    this, perhaps? Can I change the field order of AVI files using Adobe
    Premiere 6.5 or Adobe Premiere Pro, for example? If so, how? Or is
    there some kind of freeware/open-source utilty available for this?

    Thanks in advance,
    - yvan
    Yvan J. Gagnon, Sep 17, 2003
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  2. Yvan J. Gagnon

    Juan Lauda Guest

    Could it be that this is simply the problem with viewing any interlaced
    video on a PC?
    If the AVI files view OK when burnt to DVD or whatever and played back to a
    TV then leave them be.
    If the AVI files are intended to be viewed exclusively on a PC rather than a
    TV then deinterlace them.
    Juan Lauda, Sep 17, 2003
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  3. I appreciate your response, but I am fairly confident that what I am
    looking at is not just normal interlaced video. This is much more
    noticeable than those typical combing artifacts one sees when viewing
    interlaced video on a progressive scan display. And aside from that, I
    work with interlaced video on a PC nearly every day, and I have never
    seen anthing like this before.

    I recall someone having told me once that these ghosting artifacts are
    one of the more common side effects of using the wrong field order,
    which is why I'm inquiring about this. So, .. how does one determine
    (and change) the field order of interlaced AVI files? Can I do it
    using Adobe Premiere 6.5 or Premiere Pro? If so, how? Or is there some
    kind of freeware utilty available for this?

    - yvan
    Yvan J. Gagnon, Sep 17, 2003
  4. Yvan J. Gagnon

    Tony Mueller Guest

    Try to nudge the position of the video by exactly one pixel up or down then
    rerender and see if it cured the problem. Moving the image up or down by 1
    pixel effectively reverses the field order, unless the program recompresses
    the footage when you transform. I would personally do this in After Effects,
    but premiere may be able to do it.

    Tony Mueller, Sep 17, 2003
  5. Yvan J. Gagnon

    Samuel Paik Guest

    Look at some frames. AVI doesn't have a standard for specifying
    field order.
    AVISynth can be used to adjust field order, but you'll really need
    to know what's wrong to fix it.

    Samuel Paik, Sep 18, 2003
  6. It is impossible to judge field order of interlaced video on
    a progressive display when both fields are displayed at the
    same time.

    Your "ghosting" artifacts must be something else.

    Try using VirtualDub internal deinterlacer to look at each field
    separately to see if the "ghosts" are in each source field.

    A lot of NTSC material transffered to PAL has what
    is called "blended fields" and that is what you might be seeing

    Simon Walters, Sep 18, 2003
  7. Yvan J. Gagnon

    - Guest

    Not impossible, just tricky. If you have a clip with a definite
    lateral movement (say a passing lamp/telegraph post filmed from a
    vehicle window) you can zoom in to a frame in VirtualDub and examine
    the position of the post on alternate lines.

    If the object is moving left to right, and the top line has the object
    further to the left that the second line, then the field order is top
    field first.
    -, Sep 19, 2003
  8. I'll give you that one :)

    I meant just watching it as an avi :)

    Simon Walters, Sep 19, 2003
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