Creating an Audio CD in K3B (my favourite CD burning software) I received an error that MP3 format was not supported and that the files need to be converted to WAV format first.
Problems while adding files to the project.
Unable to handle the following files due to an unsupported format:
You may manually convert these audio files to wave using another application supporting the audio format and then add the wave files to the K3b project.
So I closed K3B and installed mp3 support at the command line (for GUI use Synaptic Package Manager or Software Center) as follows:
sudo apt-get install libk3b6-extracodecs
Restarted K3B and all is well.