how to compress? .zip always same size???

Discussion in 'Mac Apps and Mac App Store' started by dougens, Jun 16, 2010.

  1. macrumors member

    dougens

    Joined:
    Aug 22, 2007
    Location:
    London
    #1
    I am using stuffit (dropstuff) to compress a folder of photos (28mb) to semd via email to windows user.

    I tried using the mac ctrl menu compress and it creates a zip but of the same size. I tried using dropstuff on stuffit to compress but .zip is the same size as original too!!

    Please help driving me crazy - sorry so simple!!!!

    I am running 10.5.8 (ignore signature below) on 15inch mbp (not the new one)

    thanks
     
  2. macrumors Westmere

    GGJstudios

    Joined:
    May 16, 2008
    #2
    Some things don't compress as much as others. Some little or none at all. For example, text documents will compress a lot, while movies and photos, not so much.
     
  3. macrumors G4

    Joined:
    Jul 17, 2002
    Location:
    USA
    #3
    I assume that your photographs are in JPEG (.jpg) format. This is a lossy compression format. Images compressed with this format cannot be compressed further using a lossless compression scheme like .zip.
     
  4. macrumors G3

    QuarterSwede

    Joined:
    Oct 1, 2005
    Location:
    Colorado Springs, CO
    #4
    Right, and as MisterMe said, movies and photos are already compressed.
     
  5. macrumors member

    Joined:
    Jul 28, 2008
    Location:
    Philadelphia
    #5
    (not trying to hijack your thread)

    completely off-topic... for the most part; (but my interest has been piqued)

    since movies are already compressed, how do you uncompress say an .avi or .mpg to it's original format, or is this impossible?

    lossless audio and movies and lossy digital, it's all confusing to me.


    not trying to hijack the thread, but quarterswede you got me interested
     
  6. macrumors 6502a

    Joined:
    Jun 29, 2008
    Location:
    Finland
    #6
    No. Lossless can be decompressed to the same quality as the source, lossy can not. (There are lossless video codecs that you can put into AVIs, but you won't find many of those online.)
     
  7. macrumors newbie

    Joined:
    Apr 6, 2014
    #7
    Thank you! Very quick and helpful!

    Thank you! Very quick and helpful!
     
  8. macrumors 601

    eXan

    Joined:
    Jan 10, 2005
    Location:
    Russia
    #8
    You don't compress images with zip. What you can do is open them in any image program (even Preview) and export using lower resolution and/or quality.

    Same goes with video and music.

    You can't. The only way to get "full" quality out of "compressed" music is to decode lossless. Some of the most popular lossless formats are .flac, .ape, .alac

    EDIT: old thread... I knew something was up ;)
     

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