Reducing File Size From iMovie

Discussion in 'Digital Video' started by donnie025, Mar 6, 2013.

  1. macrumors newbie

    Joined:
    Mar 6, 2013
    #1
    I am trying to reduce the file size from a movie made with iMovie. It turned out to be 64mg so I "shared" and converted it to a QuickTime file reducing the quality from 720p to "large" and still it was 64mg. The actual size of the player when it comes up on the screen gets smaller but not the actual file size. I am sending video auditions to my agent and they can't be greater than a certain size for some production companies for some reason. Like 20mg. Weird but if I can get some help on HOW to reduce a file size, you rock.
     
  2. macrumors 65816

    phoenixsan

    Joined:
    Oct 19, 2012
    #2
  3. simsaladimbamba

    Joined:
    Nov 28, 2010
    Location:
    located
    #3
    You could also try HandBrake to compress the exported iMovie sequence further.

    Btw, "mg" is short for "milligram", a metric unit for weight. "MegayByte" is abbreviated with "MB".
     
  4. macrumors 601

    talmy

    Joined:
    Oct 26, 2009
    Location:
    Oregon
    #4
    This is always an issue for me as I produce about 3 hours of video a week for classes I teach, and I put the files online so students can download them. Keeping the file size down is important.

    The "trick" is to "Export using QuickTime", "Movie to QuickTime Movie" Then in Video Settings you want Compression Type H.264 (you can also seek out x264 which does a bit better job, but it's not installed on you Mac by default). I reduce the frame rate, but that probably won't be an option for you. Either go with all settings "Automatic" and adjust the Quality to control the size (and always use the Multi-Pass), or you can restrict the data rate to control the size directly. You can also control the image size. If you halve the width you cut the size of the video by 4x.

    One thing you don't want to do is export and then compress again. Every time you decode/encode the quality falls (and usually dramatically).
     
  5. macrumors 68030

    ET iPhone Home

    Joined:
    Oct 5, 2011
    Location:
    Orange County, California USA
    #5
    I tried HB using it to compress an MP4 video to under 25MB for email and it keeps creating the file size from 30MB to 38MB using HB. I don't get it :confused:
     
  6. HobeSoundDarryl, Nov 14, 2014
    Last edited: Nov 14, 2014

    macrumors 601

    HobeSoundDarryl

    Joined:
    Feb 8, 2004
    Location:
    Hobe Sound, FL (20 miles north of Palm Beach)
    #6
    OP, trying to email video is generally a challenging prospect. Better to post the video to youtube, vimeo, dropbox, etc and email a link. Then, you don't have to overly worry about whether a particular email client can actually receive the video.

    BUT, if the goal is file size, export it at high resolution out of iMovie, then run that through Handbrake(HB). To cut file sizes down, you can do various things in HB. For example, moving the "constant quality" slider up (so the quality number gets bigger) will cut the file size of the final render (by sacrificing some detail quality). Try 21, then 22, maybe higher, and see if the quality is "good enough" (in exchange for yielding shrinking file sizes).

    Another option is to reduce resolution. If it's 1080p, do you need it to continue to be 1080p? Consider 720p or even SD resolutions. It sounds like you've shot it at 720p, so consider a switch to SD resolutions. As you cut resolution, you'll cut file sizes.

    Both?

    The game you're playing is tossing out detail to yield a smaller file size. How much of a loss of detail you can tolerate will directly relate to the resulting file size. Reducing resolution and increasing the constant quality slider will yield a smaller file. Reducing resolution more and further increasing the constant quality number will yield an even smaller file. Experiment until you find the "good enough" (quality) tradeoff.

    Lastly, it sounds like the video has already been shot. If there is a lot of camera movement, all that background detail (moving) yields a lot of data in the file. For example, if it's all shot with someone holding a camera instead of using a tripod or stand of some sort, even smallish movements that basically has everything the camera "sees" moving is detail to store in the video file. If you have this problem and a re-shoot is possible, use a tripod or similar to stabilize the camera. If the background is more stable, the file size will be smaller.
     

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