Quod Libet: an audio library, manager & player
Quod Libet is a cross-platform audio / music management program. It provides many ways to view your local library, and supports streaming audio and feeds (podcasts etc). It has extremely flexible metadata editing and searching capabilities.
With over 90 plugins included, you can extend and integrate with almost anything, or write your own!
Ex Falso: just the tag editor
Ex Falso is a bare-bones tag editor with the same editing interface as Quod Libet.
For information on how to build, install or test Quod Libet (and Ex Falso), check out the development documentation.
For how to use the apps, consult the user guide.