A movie on iTunes store is 1.4gig but in AVI file it's 800mb...Why?

Discussion in 'Apple TV and Home Theater' started by M. Malone, Oct 22, 2008.

  1. M. Malone macrumors 6502a

    M. Malone

    Mar 11, 2004

    So I'm looking at a movie that's on the iTunes Store, its size is 1.4 gig, and at "near DVD quality"

    My friend has the very same movie in AVI file type and at full DVD quality, but at only 800MB.

    can someone explain to me why is this so? is AVI better at being compressed than the file type Apple uses on iTunes?

    Thanks :D
  2. aristobrat macrumors G5

    Oct 14, 2005
    A full DVD is almost always multiple GBs, so an AVI compressed to 800MB isn't "full DVD quality".
  3. Elloise macrumors member

    Aug 21, 2008
    "near DVD quality" and "full DVD quality" are not terms you can really use to accurately gauge the many many different variables in compressing media.

    It's also rare to see a flawless 800 meg compression of dvd media, or maybe I'm out of touch with the latest witchcraft in codecs.

    If you like the 800meg version better having watched them both just get flip4mac, or the VLC player; Win Win.
  4. dynaflash macrumors 68020

    Mar 27, 2003
    Nope, avi is just a container, its the video codec that is paramount for compression.

    As was suggested before, there is no way those two files are the same quality even if they use the most advanced codec, h.264.
  5. torid110 macrumors regular

    Jan 22, 2006
    Jersey City, NJ
    Sound also plays a big part in the size. Most, if not all of the 700-800MB avi files floating around out there are not encoded with dolby digital (AC3). Not sure if the itunes downloads are dolby digital since i have not downloaded any movies from them, but that could explain the size difference.
  6. NightStorm macrumors 68000

    Jan 26, 2006
    Whitehouse, OH
    As dynaflash stated, it's all about the codec used, not the container.

    Without having the specific file, and assuming that the AVI was obtained through "less than legitimate" means, I'm going to guess that they encoders used some advanced h.264 options that result in a smaller file, but takes more processing power to decode. This is fairly common with "scene" releases.

    This is just like the MKV files that everyone wonders why they can't simply extract the h.264 video and audio and mux into an AppleTV-compatible container and have a file that will actually playback on the device.

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