bryan.taylor
Level 1 (0 points)

Q: iMovie 10 and DV Video Quality

Does anyone know how iMovie handles DV?  Previous versions used Single Field Processing, which threw away every other line of the video.  This resulted in very degraded video quality upon export, especially if exporting to a DVD.

 

I doubt very seriously that this was fixed in the new iMovie, but it’s worth asking.

Posted on Oct 26, 2013 12:42 PM

Close
bryan.taylor

Q: iMovie 10 and DV Video Quality

  • All replies
  • Helpful answers

  • by Pieter_from_Ehv,

    Pieter_from_Ehv Pieter_from_Ehv Jan 12, 2014 7:18 AM in response to bryan.taylor
    Level 1 (45 points)
    Jan 12, 2014 7:18 AM in response to bryan.taylor

    I did some experiments with iMovie 10 and interlaced video, using the method described by Karsten Schlüter.

    https://sites.google.com/site/theimovieoutputproject/chapter-2-how-to-find-out-

     

    The problem seems to be solved in the latest iMovie 10 version. More info (in Dutch) with example pics:

    http://www.macfreak.nl/forums/topic/10/3480/single-field-processing-problem-solv ed-in-imovie-10/

  • by Bengt Wärleby,

    Bengt Wärleby Bengt Wärleby Jan 12, 2014 9:06 AM in response to Pieter_from_Ehv
    Level 6 (19,450 points)
    Jan 12, 2014 9:06 AM in response to Pieter_from_Ehv

    Hi

     

    Is this really true !

     

    As iMovie'08 (v.7) and iM'09 (v.8) and iM'11 (v.9) - all discarded every second line and was not able to keep quality when going from events to projects - and there was NO way to restore this.

     

    Karsten's VERY elaborate way increased the 50% quality significantly - BUT it did not (then) restore full 100% interlaced SD-Video quality - BUT it's fair to say the improvemnt were significant ! (He's magic)

     

    But can one really (as in iM 1 to HD6 and all versions of FinalCut (and Adobe Premiere and Avid Media-100) keep full interlaced SD-Video quality from start to Exported full Quality QuickTime or StreamingDV or AIC (without any loss).

     

    That would really shake my suspiciousness in regard to where iMovie is evolving.

     

    Yours most interested - Bengt W

  • by Pieter_from_Ehv,

    Pieter_from_Ehv Pieter_from_Ehv Jan 12, 2014 9:25 AM in response to Bengt Wärleby
    Level 1 (45 points)
    Jan 12, 2014 9:25 AM in response to Bengt Wärleby

    Hi Bengt,

     

    When I referred to Karsten's method, I meant the way he made an interlaced test movie from a 1920x1080 image using QuickTime Pro 7.

     

    I made another test image using horizontal and vertical lines (see the link given in my previous post) and made a short interlaced movie (AIC) of it.

     

    The interlaced movie was imported in iMovie 9.0.9 and exported to a 1080p movie. Same was done in iMovie 10.

    The resulting video was played back in native resolution on a 1920x1080 screen, and a screendump was made.

    The result of both iMovie 9.0.9 and iMovie 10 can be seen in my link.

     

    To be clear: I didn't use JES Deinterlacer to preprocess the source material, as is Karsten's suggested wordaround.

     

    The result in iMovie 10 is much better than iMovie 9.0.9. No more missing lines!

     

    Regards, Pieter

  • by Pieter_from_Ehv,

    Pieter_from_Ehv Pieter_from_Ehv Jan 16, 2014 12:03 PM in response to Bengt Wärleby
    Level 1 (45 points)
    Jan 16, 2014 12:03 PM in response to Bengt Wärleby

    I've uploaded 4 videos to Youtube that demonstrate the difference between iMovie 9.0.9 and iMovie 10 when using Interlaced source material. Make sure to select 1080p format in the Youtube preferences.

     

    iMovie 9.0.9 1920x1080p 25p Test

    http://youtu.be/-pLWPMSoL-U

     

    iMovie 9.0.9 1920x1080p 50i Test

    http://youtu.be/GrVUgeVTua0

     

    iMovie 10.0.1 1920x1080p 25p Test

    http://youtu.be/zhaNZ6mjJlw

     

    iMovie 10.0.1 1920x1080p 50i Test

    http://youtu.be/3oFWHA0HzMw

  • by Pieter_from_Ehv,

    Pieter_from_Ehv Pieter_from_Ehv Jan 16, 2014 1:53 PM in response to Pieter_from_Ehv
    Level 1 (45 points)
    Jan 16, 2014 1:53 PM in response to Pieter_from_Ehv

    Some additional info.

     

    A 1920x1080 black and white test image was created. The image consists of 120x120 pixel squares. The first two squares in each direction contain 60 black and 60 white lines, i.e. lines with a width of one pixel. The next two squares contain 30 black and 30 white lines, i.e. lines with a width of two pixels. The source image is located here: http://i.imgur.com/AFkrw6L.png

     

    This image was copied 200 times into a numbered sequence. The image sequence was made into a short movie using QuickTime Pro 7. Two versions of that movie were exported: a 25p and a 50i (interlaced) version. Both short movies were imported in iMovie 9.0.9 and iMovie 10.0.1. A text effect was added to add some movement to the movies. The movies were exported to 1080p format via the Share option in iMovie. iMovie 9 exports to .mov files, iMovie 10 exports to .mp4 files.

     

    What can be seen from these 4 exported movies? Both iMovie 9 and iMovie 10 handle progressive video without dropping lines. The full resolution is preserved. iMovie 10 also handles interlaced video without dropping lines. But iMovie 9 (=iMovie '11) and older (since iMovie '8) do not handle interlaced video correctly. Half of the horizontal lines are discarded ("single-field processing"). Also in the horizontal direction resolution is lost; each pair of two horizontal pixels is averaged. Thus a scaled down resolution of 960x540 pixels is used for processing interlaced video in iMovie 9 (and older). This can be seen in the iMovie 9.0.9 50i Test movie. The upper left square is white; the black lines are discarded! The second square is gray; horizontally each pair of two pixels is averaged.

  • by John Cogdell,

    John Cogdell John Cogdell Jan 20, 2014 3:04 AM in response to Pieter_from_Ehv
    Level 5 (4,624 points)
    Jan 20, 2014 3:04 AM in response to Pieter_from_Ehv

    That's a brilliant piece of work Pieter. Thank you very much for sharing! Another good reason for people still using interlaced video to move to iMovie 10 (as I've done).

     

    John

  • by bryan.taylor,

    bryan.taylor bryan.taylor Jan 20, 2014 4:48 AM in response to bryan.taylor
    Level 1 (0 points)
    Jan 20, 2014 4:48 AM in response to bryan.taylor

    So, here's my questions, then:  How do I get the benefit of iMovie 10 correctly handling the interlaced video?

     

    1. Must I convert my imported video footage before I start working with it?
    2. I must re-import all my source video into the new iMovie?
    3. Nothing.  Everything will work magically the way it's suposed to without me doing anything else
    4. Some other way not described above?

    Bryan

  • by Pieter_from_Ehv,

    Pieter_from_Ehv Pieter_from_Ehv Jan 20, 2014 8:46 AM in response to bryan.taylor
    Level 1 (45 points)
    Jan 20, 2014 8:46 AM in response to bryan.taylor

    I would start with a clean iMovie state, i.e. empty Events and Projects (thus not with the contents of the Projects resulting from the conversion step that was executed when iMovie 10 was started for the first time). And reimport the raw material (Events) again in iMovie 10 from the backup made. The raw dv files that have been imported by previous versions of iMovie are ok. Everything (interlaced) that was dragged to the timeline and editted (Projects), is not.

     

    When you start clean (without previous content in iMovie), you can use option 3 (Nothing).