I've recently upgraded to Oneiric, and I've noticed that Spotify no longer plays local files.
I've found that the reason for this is that "[...]Ubuntu has changed the Qt media backend from libavcodec to gstreamer. Now, gstreamer is capable of playing mp3 files just fine (and about any other audio file format too), but spotify refuses to play any of them and complains about audio decoder problems." and that the solution is to do as following: "I copied the following libraries from Ubuntu Natty to Oneiric: libavcodec.so.52 libavformat.so.52 libavutil.so.50 libQtWebKit.so.4 libsndfile.so.1 libx264.so.106 and used LD_LIBRARY_PATH environment variable to point spotify binaries to use them. Voila, spotify started to play mp3 files again just as before. And none of those libraries is an actual mp3 decoder!"
Now, this just got a bit too technical for me. Anyone care to explain where to move these libraries, and how to link using LD_LIBRARY_PATH?