I receive this error when amarok starts and I am not able to add mp3 files to the playlist. The problem is that I am sure that the message is wrong: gstreamer can play mp3 files; if I switch to arts engine, I add mp3 files to the amarok playlist and I switch back to gst engine to play them, it works.
So when amarok asks gstreamer about supported formats it\'s getting the wrong answer... What can I do? I have already run gst-register-0.8 both as root and as user, if you want I can paste the output. Thanks in advance.

This worked for me:

install ffmpeg, run gst-register, remove the ffmpeg plugin files by hand and run gst-register again - make sure you compiled the mad plugin

It didn\'t work. I removed these two files:
/usr/lib64/gstreamer-0.8/libgstffmpeg.la
/usr/lib64/gstreamer-0.8/libgstffmpeg.so
(yes I\'m on athlon 64), then I ran gst-register-0.8, then I started amarok, and I still get the stupid message.

And I have the mad plugin installed.

It worked for me after emergeing the mad and the lame plugin.

Then i ran gst-register as user and as root.

Cu Hurra