vgmstream

vgmstream is a library for playing a wide variety of streamed audio formats used in video games. It currently comes with source for Winamp, Audacious, and foobar2000 plugins, and a command line decoder that outputs PCM .wav. The last Winamp and Windows command line build I posted is r1040 (2014-10-20).

Since version r1040 there has been no more development on the "official" repository on SourceForge, and the last build there (r659) is many years out of date.

The best place to look now for active development is in kode54's GitHub repo. He maintains the foobar2000 component, which is (as of 2015-07-28) the most up-to-date build I know of.
Halley's Comet Software