Amarok 1.4.10 and M4A audio files.

Hello, I'm still running Amarok 1.4.10. My desktop computer is running Leap 15.5. I've a number of audio files with extension m4a. When I try to play them I get "Error Loading Media There is no available decoder." I've the gstreamer libraries installed, but whatever decoder is needed by this version of Amarok is, it's missing or not compatible. Amarok 9 has no issues with these files. Does anybody know if there's a particular package I'm missing or it's just not possible? Rafael