Peace For All

July 31, 2008

ZIPing a self extracting ZIP does not make it smaller

Filed under: Stupidity, technology — Tags: , — Devlin Bentley @ 10:28 am

I have been witnessing the stupidity of people putting their self extracting ZIP files into a ZIP file for years now, and it still pisses me off.

If grouping files together then ZIPing them up in “no compression” or “archival” mode may be useful, but that is it.  A single lone file?  Pointless!  (And yes, I will explain why at the bottom of this post!)

Here is a list of other things that do not belong inside of ZIP files:

  • Any other compresses sound or video file
    • MP3
    • AVI
    • MPEG
    • MPEG2
    • WMV
    • etc
  • Any file already compressed with another compression program
    • JPEGs
    • RAR files
    • .ACE files
    • .7z Files

The reason for this is actually easy to understand.

Imagine taking a piece of paper and folding it up really small so you can fit it in a really tiny envelope to mail off.  You fold the paper up as small as you possibly can, and put it in the envelope.  The paper is your original data file and the envelope is the ZIP file.

Now imagine trying to take that envelope with your paper inside of it, already folded up as tight as possible, and putting it inside another envelope.  You cannot fold the paper any more, so nothing is any smaller.  In fact by adding another envelope you have actually made your package larger!  It is only a little bit larger because an extra envelope is not all that thick, but it still is larger.

This is exactly what happens when you try to ZIP a ZIP file, or any other type of already compressed file.  In some cases when you ZIP up a compressed file of some other type (e.g. JPEG) you may save a little bit of space, typically a a kilobyte or two if it is a really huge image that is in the megabyte range, but the time it takes users to open up the ZIP file and hit ‘extract’ is longer than it would take them to download the extra few kilobytes.

This seems like only a minor annoyance, but it because a huge pain when some fools who should know better put huge 2GB+ self extracting game demos inside of a ZIP file.  They save maybe one megabyte overall (if even that), but it can take 15-20 minutes to extract their stupid EXE, which then takes another 10-15 minutes to extract the installer.

Bonus points go to the real idiots who do all of the above, and then their installer is itself a single compressed setup.exe when when run then extracts files to a temporary directory before copying them to their final location.

2GB ZIP -> 2GB self extracting EXE -> 2GB Setup.exe -> 2GB temporary files -> 4-5GB installed game

And that is why the tag stupidity is on this post!

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