So I've carefully checked all those similar questions posted, tried their solutions.
Just in case that I've missed anything, here are the packages info for gstreamer installation:
Also ubuntu-restricted-extras was installed.
I'm pretty sure the files are not corrupted since VLC media player plays without a problem, also I used rhythmbox to play them like one week ago, perfectly fine. The error just occurred this time.
Music players I've tried: rhythmbox, banshee, clementine, and all throwing me the same error message.
Any help I can get from here?
p.s I'm using ubuntu 16.04 LTS system, with a windows 10 dual boot
Best Answer
A recent update in Ubuntu 16.04 caused the problem of being unable to play m4a files. The .m4a files are alac which would be decoded by gstreamer1.0-libav. That plug-in is broken and the bug has been reported here. A updated version of gstreamer1.0-libav has been uploaded to the unofficial UbuntuUpdates website, but it has not been officially released by Canonical.
Update: An updated version of gstreamer1.0-libav (gstreamer1.0-libav 1.8.3-1ubuntu0.2) that plays m4a files in Rhythmbox has been officially released as a software update in Ubuntu 16.04.
m4a files can still be played normally in Audacious, Audacity and VLC. The best choice of media player to play them is Audacious music player from the default Ubuntu repositories because you can quickly and easily add your entire music library to Audacious (File -> Add Files…) and also create playlists.
It doesn't seem worthwhile to convert the m4a files to another format, because the problem will be fixed by another update. In fact the update that fixed this bug was released 4 days after this answer was originally posted. Meanwhile I recommend playing m4a files in Audacious which is unaffected by the bug.