Quod Libet is a GTK music player written in Python with support for various audio formats, including Ogg Vorbis, FLAC, MP3, WAV, MP4 and WMA. Quod Libet has a different interface and a slightly different approach compared to players like Rhythmbox or Banshee, for example.
The version I will review in this article is Quod Libet 2.0 running in Ubuntu 9.04. Quod Libet features a simple interface where the playlist occupies almost all the space available. Scanning large collections of music (>5000 songs) can take a while. After this Quod Libet can be a little confusing, since the default view mode is Search playlist, and the songs will not be listed there. You can switch the mode in the View menu, and select Playlists or Album Lists or whatever. To use the search field, after adding a music folder you will have to place a pattern in the Search field in order for the tracks to appear. For example, after adding a directory with songs, you can fill in a filter like #(playcount >= 0), which will show all songs who have never been played or have been played more than 0 times (that's all songs). Default filters include listing of songs not played today, in a week or month, top 40 or bottom 40 songs (taking play counts). You can also edit and save your own filters and load them automatically. This is just like smart playlists in Amarok if you like. The only problem I encountered with the search field is that for large music collections it takes too long to filter them and can make Quod Libet freeze for a while.