totem player fails to play audio files

… with an error message box stating that :

“The playback of this movie requires a GStreamer element audioconvert plugin which is not installed.”

Googling it produces much useless stuff claiming to have solved the problem - nothing really helped.

Any ideas ?

Install mmcheck diagnostic script per the guide here:
MultiMedia Checker or mmcheck - Check Your openSUSE MultiMedia Setup in Just 16 Steps

then run mmcheck and update your system as recommended by that script.