Highly compressed zipping


G

Guest

I want to send a Microsoft Access database (.mde) file in highly zipped
format to the developer of a system based on Access. The email server has a
limit of 5MB, but the 22MB file is almost 6MB when compressed with WinZip, XP
Zip and several other zipping programs. The developer regularly zips and
sends even bigger files (over 30MB) with XP Zip, which compress to less than
4MB. The developer also receives similar large files from customers using XP
Zip. The question is: why won't XP Zip give me a better compression rate?
 
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B

Bob I

The actual compression ratio achieved is HIGHLY dependent on the actual
contents of the file.
 
P

Patrick Keenan

Maurice IRL said:
I want to send a Microsoft Access database (.mde) file in highly zipped
format to the developer of a system based on Access. The email server has
a
limit of 5MB, but the 22MB file is almost 6MB when compressed with WinZip,
XP
Zip and several other zipping programs. The developer regularly zips and
sends even bigger files (over 30MB) with XP Zip, which compress to less
than
4MB. The developer also receives similar large files from customers using
XP
Zip. The question is: why won't XP Zip give me a better compression rate?

Your file doesn't compress more because of the contents of your file aren't
compressible further.

And, email really isn't an appropriate transport mechanism for files like
this. Find some web or FTP space, send him the link and login information.

HTH
-pk
 
G

Guest

Thanks, Bob.
I appreciate that, of course, but the files I mentioned earlier are all of
the same type…
 
J

JockoBailey

Maurice IRL said:
I want to send a Microsoft Access database (.mde) file in highly zipped
format to the developer of a system based on Access. The email server has a
limit of 5MB, but the 22MB file is almost 6MB when compressed with WinZip, XP
Zip and several other zipping programs. The developer regularly zips and
sends even bigger files (over 30MB) with XP Zip, which compress to less than
4MB. The developer also receives similar large files from customers using XP
Zip. The question is: why won't XP Zip give me a better compression rate?

Some software will allow you to split an archive into several pieces. Winrar
is one.
 
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K

Ken Blake, MVP

On Tue, 24 Jul 2007 08:32:08 -0700, Maurice IRL <Maurice
I want to send a Microsoft Access database (.mde) file in highly zipped
format to the developer of a system based on Access. The email server has a
limit of 5MB, but the 22MB file is almost 6MB when compressed with WinZip, XP
Zip and several other zipping programs. The developer regularly zips and
sends even bigger files (over 30MB) with XP Zip, which compress to less than
4MB. The developer also receives similar large files from customers using XP
Zip. The question is: why won't XP Zip give me a better compression rate?



The compression rate you get (from *any* compression program) depends
very greatly on the actual data content of the file.

Here's a greatly simplified example:

Let's say I have a file that consists of 22 million bytes of random
text, and regular compression algorithms reduce it to 10MB. Now
compare that file to another file that contains 22 million bytes of
just the letter "a," repeated 22 million times.

In the second example I could reduce the file to just a few bytes,
containing something like a;repeat 220000000.

Actual compression algorithms are not that simple, and typically, in a
single file several types of algorithms are used. But this extreme
example should give you some idea of the range of compression that can
be achieved, depending on the file contents.

Some compression programs also achieve higher compression rates than
others, but the tradeoff with the faster ones is that compression and
decompression usually take longer.

You might want to use one of the several file splitter programs
available, so that you end up with two files you can E-mail
separately. Must third-party zip utilities have this capability, and
also permit the parts to be rejoined by the recipient.

Or you could use a service like http://www.yousendit.com/

Alternatively, ftp the file to a web site and send the recipient a
link to that web site.
 
F

frodo

use winzip's "Split" capability to split the large single zip file into
several smaller pieces, and mail each one separately.
 
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M

Mike Lowery

Maurice IRL said:
I want to send a Microsoft Access database (.mde) file in highly zipped
format to the developer of a system based on Access. The email server has a
limit of 5MB, but the 22MB file is almost 6MB when compressed with WinZip, XP
Zip and several other zipping programs. The developer regularly zips and
sends even bigger files (over 30MB) with XP Zip, which compress to less than
4MB. The developer also receives similar large files from customers using XP
Zip. The question is: why won't XP Zip give me a better compression rate?

Consider using 7-Zip:
http://www.7-zip.org/
 

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