what is it?
just a few days ago i downloaded some files which were packed 680 mb, yet unpacked it was almost 4 GB.
was a regular zip file.
whenever i zip something up with highest compression setting it may gets a 5th smaller but thats about it.
what do i do wrong?

im always struggeling with free HD space, so this would be really useful for me

I'd go for 7-Zip on "Ultra" - best to set it to self-extracting, though, as most people don't have 7-Zip.

It depends entirely on what kind of file you're trying to zip up. Something that already has a lot of compression like a movie, an mp3 or another zip file will hardly compress at all, wheras something like a .bmp or a word document will compress quite well as they don't have much compression used when they were originally saved.

Also, certain file types compress better with certain compression techniques. Some files, LZMA (7-Zip) works best, others, RAR.. text files often compress best with gzip / bzip etc.

There's no definitive answer to this really, you'll either need to run a few tests and pick the best if a few kb matters (there's not usually _that_ much difference between most compression techniques, especially RAR and LZMA) or use a high compression engine (again, the likes of RAR / LZMA) for "everything" for simplicity / ease of use.

As crashgate says though, already compressed files (MP3, JPG, AVI etc) don't recompress very well as they've already been compressed previously.



Regards,

Ian

Layout [lyt] files compress like crazy btw.

I use WinRAR all the time but that is just me.

Best compression I ever saw was for a video file. Granted it was an RGB format video of a simple animation, but people were none-the-less impressed when I extracted a 30GB file off a floppy disk.

Quote from Bob Smith :

Best compression I ever saw was for a video file. Granted it was an RGB format video of a simple animation, but people were none-the-less impressed when I extracted a 30GB file off a floppy disk.

try 100gig worth of 0s

on the actual topic... honestly just buy a new hdd... zipping everything up wont achieve much and it will get annoying really quick

7zip by far offers the best compression of any archive software i've found, followed by rar and zip. Additionally .exe's can be compressed with upx which also has the advantage of making hex scanning a little bit more awkward (until they realise it is upx'd).

Thing is both zip and rar are both capable of much better compression than the standard compression they come with, in both cases they default to 'medium' compression. Windows by default (compress as) uses medium compression also. Be sure to check the archiving software to set the compression level - the speed loss is mostly in archiving rather than when unarchiving at the end user end.

Auto extractor facilities are well worth looking into with 7zip because not only do most users not have any unarchiving software but also the 7zip interface last time I used it was quite aweful.

The last solution is to buy better broadboand and bigger hard disk

Quote from Becky Rose :

7zip by far offers the best compression of any archive software i've found, followed by rar and zip. Additionally .exe's can be compressed with upx which also has the advantage of making hex scanning a little bit more awkward (until they realise it is upx'd).

I found PECompact to be slightly better here than UPX and offers a few additional options to make it harder to RE it or obtain info in general.. resulting EXE is usually slightly smaller than a UPX'd one too.

Quote :

Thing is both zip and rar are both capable of much better compression than the standard compression they come with, in both cases they default to 'medium' compression. Windows by default (compress as) uses medium compression also. Be sure to check the archiving software to set the compression level - the speed loss is mostly in archiving rather than when unarchiving at the end user end.

Again, compression strength isn't always a fixed value either. Some things compress better when using a mid-point value than the max. IIRC, I set the compression strength to something like '6' in LFS Replay Mgr as it resulted in smaller archives than using max compression when dealing with SPR / MPR files (uses Zip format).

Quote :

Auto extractor facilities are well worth looking into with 7zip because not only do most users not have any unarchiving software but also the 7zip interface last time I used it was quite aweful.

The last solution is to buy better broadboand and bigger hard disk

I'd agree with 7-zip's UI being aweful(sic).. non-bloated, to the point... works for me(tm)

It does miss some useful functions over RAR (like recovery records etc), but I can't think of many times 7z has let me down



Regards,

Ian

best way to compress?
ARJ

aahhhh the memories..

ARJ a A:myfile -r -vvas -a1 -b1 -js -jt -jiC:\mygame\*.* -wC:\ -m3