I bought Serengeti‘s album Standing Steady on MP3 from Bengans and wanted to play it in Spotify as “Local Files”. It worked perfectly in MS Windows, but on Ubuntu I got “File is an unsupported format”. WTF?
Spotify uses the system-supplied MP3 decoder on all platforms, and during our limited testing we found the Wine decoder to be excessively unstable on quite a few MP3 files, including some from our purchase partners. We are therefore blocking codecs with the identifier “WINE-MPEG3″ until the Wine system works satisfactorily.
One workaround I found involved recompiling or binary-patching WINE. Not so fun.
The official support forum contained a solution based around installing Windows Media Player 10. I have downloaded and installed it now according to the instructions, but already the playback froze once. Well, Spotify isn’t perfectly reliable in WINE anyway, so this is probably Good Enough.