What You Can & Cannot Compress
Last Updated: Jul 02, 2013 01:24PM PDT
Compressing your files to save space is all well and good, but what happens if the files you really want to squeeze just don't want to compress? For many of us, our hard drives have tons of virtually uncompressible files. Items such as MP3 music files, MPEG (Moving Picture Experts Group) movies, and JPEG (Joint Photographic Experts Group) images are already in a compressed form, so trying to compress these files even more is only going to waste your time and processor's energy. Zipping all of your Beatles MP3s into a single archive might help organize them, but it won't do much to save hard drive space.
Instead, concentrate on what you can successfully compress. Just about any document a word processor, spreadsheet program, database application, and similar software created has a lot of what's known as "white space." White space refers to blank areas in a file where there is no real data.
For instance, in a Microsoft Word document, every blank line and space character has a placeholder and size in bytes, but no real data. Compression tools identify white space and condense it accordingly, such as compressing 4 bytes down to 1 byte. In a large file, this simple savings really adds up. AVI (Audio-Video Interleaved) movie files and GIF (Graphics Interchange Format) image files are both good examples of formats that typically consume a lot of space but compress well when you use compression software to shrink them.