Comment 3 for bug 1340907

As I understand, rhythmbox was using a GStreamer plugin to edit m4a tags, named qtdemux (for "Quick Time demuxer")

But this plugin disappeared(?) since Ubuntu Precise.

It appears in Ubuntu Lucid [1], but is not anymore in Ubuntu Trusty [2]

Lucid has gstreamer0.10-plugins-good 0.10.21-1ubuntu2 [3]
Trusty has gstreamer0.10-plugins-good 0.10.31-3+nmu1ubuntu5 [4]

[1] http://packages.ubuntu.com/search?suite=lucid&arch=any&mode=filename&searchon=contents&keywords=qtdemux
[2] http://packages.ubuntu.com/search?suite=trusty&arch=any&mode=filename&searchon=contents&keywords=qtdemux
[3] http://packages.ubuntu.com/lucid/gstreamer0.10-plugins-good
[4] http://packages.ubuntu.com/trusty/gstreamer0.10-plugins-good