> However, as of 2016-11-10, Fedora is now able to include MP3 decoding functionality. MP3 encoding functionality is still not permissible, because it requires patented technologies and the patent holder has not provided licenses that are compatible with Fedora's requirements.

So it looks like there are some patents relevant to modern encoders.

Edit: The wiki page[0] links to the Fraunhofer page[1] saying that the licensing program has been terminated...

[0]: https://fedoraproject.org/wiki/Multimedia/MP3

[1]: http://www.mp3licensing.com/ which redirects to https://www.iis.fraunhofer.de/en/ff/amm/prod/audiocodec/audi...