Compressing and decompressing are vital parts of daily computer life. When you “rip” a song from a CD onto your computer and then onto a personal digital music player, creating an AAC, MP3, or WMA file, you’re compressing the original AIFF file into a smaller, more portable size. When you play back the song, your computer or iPod decompresses, on the fly, the song file so that it plays with good fidelity. Same thing goes with QuickTime movie files. AAC, MP3, WMA are all called “codecs”, which is short for compression/decompression.
Compression/decompression has been around for a long time. Back in the days of 56k modems (sorry, Georgetown folks, for bringing up the painful subject) and floppy disks, people used to compress anything they sent or stored. The standard on the PC side-of-the-house has always been the Zip format, while until recently Mac users relied predominantly on the Stuffit application.
Simple file compression systems replace strings of similar characters with coding that signifies the entire string. For example, a data string of XXXXXXXXXX would be replaced with a two-or-three-character code that means “10 X’s in a row” that takes up less space in the file. More complex systems are in use as well, but discussing those would raise the “geek quotient” of this column well past humanly-tolerable limits.
Mac OS X now includes built-in support for the Zip format. In fact, get a new Mac, or do an Erase and Install to Mac OS 10.4 Tiger, and you’ll discover that the venerable Stuffit Expander is no longer bundled with the system. And, if you just do a straight upgrade and leave you older version of Stuffit installed, you may find that Tiger “breaks” it. However, you can download a new version of the free Stuffit Expander from www.stuffit.com. And you should, because even though the Mac OS doesn’t come with Stuffit anymore, many software developers (and heck, even old Mac OS 9 users) still use it to compress the stuff they share.
So, which is better? The Quicken User Guide PDF file I used in the Preview vs. Reader Shootout, goes from 7.7 MB to 6.2 MB when Zipped. The same file, using Stuffit, shrinks to 6.1 MB. However, Stuffit takes about ten times longer to do it. More on the pros and cons next time.
© 2005 Peter F. Zimowski