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. You can find the latest source code at the SourceForge.net project, but the Winamp plugin and test decoder builds there are probably out of date.
Builds are more frequently available in the vgmstream directory on this site. foobar2000 builds are on Josh W's site.
Please submit bugs to the bug tracker. You can also ask for help on the HCS Forum, but please consult the readme.txt file first.
Halley's Comet Software