“No decoder found for (filename)”
There is no plugin installed for the type of file you are trying to play. If you installed Audacious through a package manager, you may need to install additional plugin packages and/or optional dependencies. If you compiled Audacious from source, some plugins may not have been compiled because of missing library dependencies. Run ./configure for audacious-plugins and look for any lines in the output that read “checking for (library name)… no.” Install those libraries, run ./configure again, and then recompile audacious-plugins.
MP3 files show the wrong length in the playlist
The default method used to calculate the length of MP3 files is fast but can be confused by some variable bit rate files. You need to enable the “Use accurate length calculation (slow)” option under File > Settings > Plugins > Input > MPG123 Plugin > Settings.
The GTK interface is ugly and doesn’t fit it with my desktop theme
Audacious uses the GTK+ 3.x toolkit. If your desktop is using GTK+ 2.x (MATE, XFCE) or Qt (KDE), you need to install and configure a theme for GTK+ 3.x. Note: This applies to Audacious 3.5 and earlier. Newer versions use GTK+ 2.x, which is generally integrated better with the desktop theme.
Windows don't behave right in the Winamp Classic interface
The Winamp interface has three separate windows, and sometimes they don't stick together like they should. If your windows are behaving strangely, first try using a different window manager. We've seen some of the best window managers out there hiccup on Audacious. If you've tried two or three different ones and still see the same problem, then come and talk to us.