File size is huge

Discussion in 'Digital Video' started by Tech198, Jan 5, 2014.

  1. Tech198, Jan 5, 2014
    Last edited: Jan 5, 2014

    Tech198 macrumors G4

    Joined:
    Mar 21, 2011
    Location:
    Australia, Perth
    #1
    Hi all

    Regarding HD content 720p 1280x720, i have two files. one goes for about 1 hour 43 minutes: - 2.49Gig, while is other one goes for 2 hours, 11 minutes and is an whopping 10 Gig

    Is this correct to anyone ? How can a mere hour or so be an extra 8 Gig ? when there both the same resolution ?

    Granted the 10 Gig one was exported from iMovie. The 10 Gig file extension is .mp4, while the other is .m4v (encoded with Handbrake).
     
  2. MacUser2525 macrumors 68000

    MacUser2525

    Joined:
    Mar 17, 2007
    Location:
    Canada
    #2
    It is all about the bitrate of the video the Handbrake encoded one I would bet if you were to check is somewhere around 1500-2K the larger one I would say somewhere in the 7-8K range. The information stored increases in size the higher the bitrate the video is encoded in, so two copies of same file one at 2K the other at 4K the 4K is double the size.
     
  3. Dave Braine macrumors 68040

    Dave Braine

    Joined:
    Mar 19, 2008
    Location:
    Warrington, UK
    #3
    Also, the m4v files that I have are h264 files, which means they've been compressed. The mp4 files aren't compressed.
     
  4. Tech198 thread starter macrumors G4

    Joined:
    Mar 21, 2011
    Location:
    Australia, Perth
  5. barkmonster, Jan 8, 2014
    Last edited: Jan 8, 2014

    barkmonster macrumors 68020

    barkmonster

    Joined:
    Dec 3, 2001
    Location:
    Lancashire
    #5
    iMovie isn't uncompressed. The video format it uses to edit is the Intermediate Codec which uses very low video compression and uncompressed audio. Once you export, it's the standard bitrates iMovie exports to based on the chosen output resolution that's causing the large file sizes.

    Use the export with Quicktime option in iMovie instead and then choose more approriate settings like this: -

    Resolution 1280x720
    File Format: mp4
    Bitrate 1500-2000 (your choice)
    Video: H.254 (2 pass encode)
    Audio: AAC 256Kbps (or 320)

    You'll get your file sizes smaller. I wouldn't recommend going much below 1500 with 720p video even with 2 pass encode, you'll introduce too many compression artifacts.
     
  6. Dave Braine macrumors 68040

    Dave Braine

    Joined:
    Mar 19, 2008
    Location:
    Warrington, UK
    #6
    Sorry, my mistake. Yes they are compressed compared to the original iMovie footage. h264 is more compressed than plain mp4, hence the size difference.
     
  7. Siderz macrumors 6502a

    Joined:
    Nov 10, 2012
    #7
    h.264 is a codec while MP4 is a container, h.264 goes into an MP4 container, there isn't "plain MP4". See this video:

     

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