Comment 7 for bug 1029254

Justin, just one legal notice: MP3 format is protected by a software patent. In case you live in a country, where software patents do apply (e.g. USA), you cannot legally use the open-source MP3 decoder provided by the package gstreamer0.10-fluendo-mp3, unless you have obtained a patent license from patent holders.

However, there are two ways how to get non-free (=restricted usage) no-cost binary MP3 decoder with valid license:
1) You can install MP3 decoder from package gstreamer0.10-fluendo-plugins-mp3-partner from Ubuntu Partner repository.
2) You can download MP3 decoder provided by Fluendo at http://www.fluendo.com/shop/product/fluendo-mp3-decoder/

More legal details are available at http://www.fluendo.com/shop/product/fluendo-mp3-decoder/