We all know how this happened. There was that thing called MP3 in the mid-90's. It allowed to have compressed music with a decent quality, suitable for playback on a PC. That how it all started. People starting sharing music, making juke-box with a PC, P2P-sharing and Naptser, etc.

But one day, circa 1998, they started asking for royalties on the patent, when the fornat had really become popular through a networking effect. This make any MP3 decoder and encoder impossible to license under GPL or LGPL, and such a decoder or encoder incompatible was a GPL playback software. That is why Fluendo did that Christmas Present to the Linux community: a fully licensed MP3 decoder for gstreamer, available free of charge in binary form to anyone. At the same time, they provide the complete source code for use, under a MIT-like license. That is really open source software, just not compatible with the GPL because of patents. While I actually don't know how much Fluendo paid for it, I'd classify it as a USD$50,000 gift to the open source community.

Thank you Fluendo.

In the mean time do yourself a favor and use Ogg Vorbis to encode your music until the patents expire... or even after (Vorbis encoding produce a better quality output).