Best compression-compression software

[staknhalo]

I use Winrar, and I know there are people who say 7zip. But I'll be honest I've never seen a difference in terms of the resulting file size that much. Does any one know of a compression software out there that does the best compression, but isn't recommended because it takes a long time and therefore isn't ideal for everyday use or something? Basically I'm looking to get the smallest file regardless of time or cpu cycles. BTW Windows, and can be free or pay software. Thanks guys.

 

[Joe Average]

Compression will ALWAYS TAKE TIME, suffice to say some compression formats take longer because they compact the files even more. I believe most people will automagically recommend 7Zip because: a) it's free, and b) it can offer smaller resulting compressed files depending on the compression chosen.

Personally, I'll stick with WinRAR myself. I bought WinZip almost 14 years ago now and then gradually stopped using it in favor of WinRAR which is amazing and integrates so damned well into the Explorer shell.

 

[Eva_Unit_0]

For most people, the limitation isn't what compressed format they use, but what kinds of file they're compressing. If you're zipping up a bunch of pictures, movies, and music (probably the most common things that people store as archival data) then it's already been compressed a shitload and you're not going to get much more out of it, regardless of the container.

If you want to see this firsthand do this: take a large video file (like several gigs or something) and compress it into a .rar or something. Then take a text editor and make a several gig file of nothing but zeros. Compress it. The video file will hardly change size, the text file will go from several gigs to like a couple kilobytes.

Anyway, bzip2 is the most compact (and most cpu-hogging) of the common compression schemes. It can take a very long time though...it's much much slower than gzip, for example


lol check this out:

keith@macbeth ~ $ du -h compress_me 
183M    compress_me
keith@macbeth ~ $ tar -cjvf compressed.tar.bz2 compress_me 
compress_me
keith@macbeth ~ $ du -h compressed.tar.bz2 
4.0K    compressed.tar.bz2

The initial file was only 183 megs because I started overflowing the emacs buffer and I figured it was big enough. Notice it compressed to 4k haha. Probably could get it smaller if I cared enough to remove all the line breaks and crap like that.

Now compare to a 175mb episode of divx-encoded southpark:

keith@macbeth ~/storage/Movies $ du -h southpark.avi 
175M    southpark.avi
keith@macbeth ~/storage/Movies $ tar -cjvf /home/keith/southpark.tar.bz2 southpark.avi 
southpark.avi
keith@macbeth ~/storage/Movies $ du -h /home/keith/southpark.tar.bz2 
173M    /home/keith/southpark.tar.bz2

 

[Rurik]

.7z and .rar use very similar compression algorithms that sacrifice compression time for smaller files. You won't find a huge difference between the two. After using RAR for over a decade, I've moved completely to 7zip just for its explorer support and compatibility across OSs.

 

[staknhalo]

stuff

Thanks for the thorough answer. What I will be compressing is .iso files (Windows installation disks, multiple versions of XP and up) along with .exe files. I'm assuming the .exe files are pretty well compressed. But probably not to the full extent. Am I pretty much expecting miracles, or can there be some gain from compressing the .iso and .exe files? I'll check bzip2 out though.

And Rurik, this is going on my ftp for personal use; so cross compatibility isn't an issue here. But that is a good point for others to maybe consider.

 

[Joe Average]

Windows installation discs already have content on them that is highly compressed, as either the old format (with _ appended to the filenames, like mshtml.dl_ or whatever), or in the new .wim (Windows Image) format. Either way, you can forget getting any more compression with those, just stash the ISO in ISO format and be done with it. You won't do anything but waste a lot of processor time for no good reason...

As for compatibility, every platform supports every compression format, so it's not an issue. ARJ, RAR, ZIP, 7Zip, BZip, GZip, LZH, etc, you name it, you can use it on any OS known to mankind...

 

[Eva_Unit_0]

^ what he said. The guys as microsoft aren't going to waste disks or disk space if they don't need to. You can be pretty sure that they've compressed everything just about as far as it will go. As I test, I'm compressing a windows xp sp2 ISO (pirate police: it's a legit download from MSDNAA) with bzip2 and we'll see what happens.


Results: it went from 580 megs to 540 megs. It took about 5 minutes to compress, as opposed to probably 1/3 (or less) of that for gzip. I don't routinely use 7zip or zip files because they don't preserve file permissions, so I can't comment on their speed.

Either way, it's not a whole lot of difference between just leaving them uncompressed.

 

[staknhalo]

Gotcha guys. Thanks everyone for all the help. I know the .wim files and the .**_ files are compressed. I was interested in the uncompressed files. But Eva did the test for me which is above and beyond and appreciated. Again thanks.