Possible to control compression level of zipping a file?

[Hosh]

Hi to all!
When I choose a file and send to zip, it compresses MAYBE 5 or 10 bytes.(not
kb. bytes.) That's it! What good is that? Surely there must be a way to
adjust the level of compression that it can do, no?
Any help would be greatly appreciated.
Thanks,
Hosh

 

[Phil]

What type of file are you zipping up and compressing? Sounds like your
trying to compress a file that is already compressed, thus it doesn't
compress very much. MP3 files are typical files that users don't realize are
already compressed. I use the xp zip program all the time and compression on
non-compressed files is a large, noticeable, compression.

 

[Hosh]

Hmmm, interesting answer. The files that I was trying to compress were
pdf's. Their very nature is probably compressed. I'll go now and experiment
with a few different file types and see if that's the case.
Thanks!

 

[Phil]

Yes I think pdf's are already compressed.
You're welcome.

 

[Ken Blake]

In

When I choose a file and send to zip, it compresses MAYBE 5 or
10
bytes.(not kb. bytes.) That's it! What good is that? Surely
there
must be a way to adjust the level of compression that it can
do, no?
Any help would be greatly appreciated.

How much a file *can* be compressed depends on two things:

1. The type of file it is.

For example, some files (just as .jpgs) are already compressed
and can hardly be compressed more at all. As a matter of fact,
compressing an already-compressed file sometimes even makes it
bigger, since you add the extra overhead of compression without
deleting anything.

2. The specific contents of the file.

For example, a text file that consists of
"aaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbb" will probably
compress a lot more than one that reads "The quick brown fox
jumped over the lazy dog."

If you are seeing very little compression, it's likely that you
are trying to compress an already-compressed file.

 

[Alex Nichol]

When I choose a file and send to zip, it compresses MAYBE 5 or 10 bytes.(not
kb. bytes.) That's it! What good is that? Surely there must be a way to
adjust the level of compression that it can do, no?

You are probably trying to compress something like a jpg picture, mp3
music, mpg video or the like. These are already as heavily compressed
as can be achieved, and zip will do no more - its overheads for its
tables may even make the file slightly bigger. The compression used in
zip is fixed.