Why is my iMovie video so big???

Discussion in 'Digital Video' started by audiokeeffe, Sep 25, 2010.

  1. audiokeeffe macrumors member

    Aug 18, 2010
    I just made a collage of photos and added an audio for the backing track. The movie was only 6 minutes and 53 seconds long, but when I exported it to .avi file, it is 151mb !!!! Why is it so big? It's only less than 7 minutes long...
  2. xStep macrumors 68000

    Jan 28, 2003
    Less lost in L.A.
    The data rates for the codecs (video & audio) used determine the size and quality of the output file. To create a smaller file will require reducing those but if you go to far the quality will suffer noticable.

    See my guides for mor info.
  3. spinnerlys Guest


    Sep 7, 2008
    forlod bygningen
    That is because if the CODEC iMovie uses for exporting .avi files, as .avi is only a container/format to store video and audio (AVI = Audio Video Interleave) using lots of different codecs. The most prominent ones are Divx and Xvid, which are highly compressive.
    Open the .avi in QT Player and/or VLC and press CMD+I to see, what codec is used.

    You can use MPEG Streamclip to further the compression if you want, using whatever codec you like and depending on where that video goes to.

    Btw, 151MB for 7 minutes of video is quite low. That is less than 15KB per frame if one uses 25fps.
  4. knello macrumors member


    Dec 2, 2004
    If you think that's bad, wait until the Pros show up in this thread with their stories.

    Most of use use ProRes, so 151MB = about 9 seconds.

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