There are different methods of compressing files. If you pack a large word document with WinRAR, you normally get a much smaller file. But you are expecting that the file is exactly the same after you unpack it, otherwise it won't work. This compression is lossless.
If you compress a bmp-file (maybe a picture you scanned) to jpg, it will also get much smaller, but if you try to uncompress it again, means save the jpg-file as a bmp-file again, you will never get exactly the same file. You maybe won't see a difference if you do this once, but if you do this three times the picture will look more and more crappy. The compression method that jpg is using is lossy (even if it's adjustable).
Every mp3 or video file around is already compressed by their audio or video codec, which is a more or less lossy compression. So by compressing mp3 or wmv with WinRAR you will get a file that is mostly only a few kb smaller than the original (depending on the compression rate of the music or video, but it will take a lot of time to do so).
As far as i know there is no really useful compression utility that can save a considerable amount of diskspace when compressing mp3 or video files. I heard about a tool called Monkey Audio, which is able to compress wav-files much better than any zip or rar-tool, but the result s an archive file and is not playable. This might only be helpful when posting high quality audio files.
In most cases it's better to re-encode the video files: if you have a HD-wmv video with 1280x720 pixels and a bitrate of 4000kb, you may encode it to a DivX-avi file with 640x380 pixels and a bitrate of 2000kb. The resulting video is only about half as big as the original one, of course it's not HD anymore, but you can see what's going on.
I won't touch mp3 files cause the result is mostly not satisfying anymore. If you have the original wav-file, try to compress it with a lower bitrate depending of course what kind of music it is.
If you have high quality pictures in jpg-format that come in high resolution (maybe 1920x1440) think of resampling them to maybe 1024x768 and adjusting the compression level in the jpg-properties until you are satisfied with file-size and quality.
The main advantage of audio or video codecs is that the files are instantly playable. If you pack the files with any storage utility, you first have to unpack them before viewing.
If you are able to afford it, it's mostly better to buy a second hdd, than to spend lots of hours or days with resampling and reencoding. That's what i learned ...
_________________
> Amateurs | > Handjobs | JAV Movies
