How do you make MB of music smaller?

Answer 1

That depends on the music you want to compress.
If it's stored as a raw waveform, you can use lossless compression formats such as FLAC to store it without any signal degradation - the music will only be about 1/3rd smaller, but the quality will not suffer.

If you prefer lower filesize at the expense of quality, use a lossy compression format such as MP3 or OGG. The quality and size will depend on the compression settings - remember that the smaller the file, the worse it will sound!

If the music is stored as a lossy format already, you still can reencode it at lower bitrate settings. This WILL, however, cause quality loss, as the signal loss and compression artifacts of the first encode will compound with the signal loss and compression artifacts introduced during the reencode.

To explain this simpler: A music file encoded from a music track of a CD directly to 128 kbps Mp3 will sound better than one that has first been encoded to 320 kbps Mp3 and then reencoded to 128 kbps one.

There is a large variety of tools that can perform this function. My preferred one is Foobar2000 - you can get it at http://www.foobar2000.org/