What is (or was) XMMS?
XMMS - the X MultiMedia System - is the historical media player on which Audacious was originally based.
The XMMS project was started in 1997 and was built on the technologies of the time, such as the the GIMP ToolKit (GTK) version 1. XMMS was eventually (around 2003) ported to GTK 2, but the name remained with the GTK 1 version, while the GTK 2 port was (briefly) called the Beep Media Player, or BMP. In 2005, the developers of that project abandoned it, intending to start a completely new media player, which was also short-lived. Meanwhile, the XMMS code changed hands and names again, and became Audacious. The original GTK 1 version of XMMS also continued to be updated through 2007.
Is modern-day Audacious still a fork of XMMS?
Yes. Modern-day Audacious represents over 20 years of continuous development, starting with the original XMMS code. Parts of the code (in particular, the Winamp-like user interface) still clearly reflect that heritage, and source files in some of the older plugins still retain XMMS copyrights.
But in a different sense, no. The core of Audacious has been completely (if gradually) rewritten, and has very few similarities to what it was in 1997 or even in 2005. Two completely new user interfaces (first the GTK UI and now the Qt UI) have been developed, enabling features that would never have been possible within the more-or-less fixed layout of the original XMMS player.
XMMS does not have an official website any longer. The xmms.org domain still exists but is under the control of an unknown party with no connection to the original project. The XMMS 2 project (also unrelated to the original XMMS, except in name) hosted a copy of the old XMMS website for several years (archived here), but as of early 2021 that website also appears to be gone.
BMP still has a SourceForge project.
As a tribute to our history, and to preserve it, the final release of each project is available from our own site: