When you encode your music into MP3 format, you lose 92% of your data.That's right, encoded at the standard 128 kilobits per second, only 8% of your music is kept. The rest is simply thrown away.
MP3 is a very clever system that analyzes your track to assess what sounds the ear can hear, and what subtleties it won't be so concerned about. The most important information is allocated more bits, the less important stuff is more coarsely encoded (or not encoded at all).
There are a number of software's that can convert a file to MP3, but you need to know which codec they use. The codec is the heart of the software and has a significant effect on how good your MP3 will sound -at least the encoder part will ('codec' = 'encoder-decoder').
Some encoders are designed by hobbyists in their bedrooms. Some have been designed by teams of top scientists, engineers and musicians. The one to look out for is the Fraunhofer codec. This is the benchmark forMP3 encoding and will produce results significantly better than most of the others, whatever player (decoder) is used.
The moral is to know your codec. If an MP3 software uses Fraunhofer, it will say so. If it doesn't say so, then your MP3's probably don't sound as good as they should.