$ LANG=C sudo apt-get install        phonon4qt5-backend-gstreamer -o debug::pkgproblemresolver=1
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Starting pkgProblemResolver with broken count: 1
Starting 2 pkgProblemResolver with broken count: 1
Investigating (0) phonon4qt5-backend-null:amd64 < 4:4.8.3-0ubuntu3 @ii mK Ib >
Broken phonon4qt5-backend-null:amd64 Conflicts on phonon4qt5-backend:amd64 < none @un H >
  Conflicts//Breaks against version 0.8.2-1ubuntu3 for phonon4qt5-backend-vlc but that is not InstVer, ignoring
  Considering phonon4qt5-backend-gstreamer:amd64 9999 as a solution to phonon4qt5-backend-null:amd64 1
  Removing phonon4qt5-backend-null:amd64 rather than change phonon4qt5-backend:amd64
Investigating (0) libphonon4qt5-dev:amd64 < 4:4.8.3-0ubuntu3 @ii mK Ib >
Broken libphonon4qt5-dev:amd64 Depends on phonon4qt5-backend-null:amd64 < 4:4.8.3-0ubuntu3 @ii mR >
  Considering phonon4qt5-backend-null:amd64 1 as a solution to libphonon4qt5-dev:amd64 0
Broken libphonon4qt5-dev:amd64 Depends on phonon4qt5:amd64 < none | 4:4.8.3-0ubuntu3 @un uH >
  Considering phonon4qt5:amd64 1 as a solution to libphonon4qt5-dev:amd64 0
  Try Installing phonon4qt5:amd64 < none | 4:4.8.3-0ubuntu3 @un uH > before changing libphonon4qt5-dev:amd64
  Or group remove for libphonon4qt5-dev:amd64
Done
Suggested packages:
  gstreamer1.0-plugins-ugly
The following packages will be REMOVED:
  libphonon4qt5-dev phonon4qt5-backend-null
The following NEW packages will be installed:
  phonon4qt5-backend-gstreamer
0 upgraded, 1 newly installed, 2 to remove and 0 not upgraded.
Need to get 110 kB of archives.
After this operation, 185 kB disk space will be freed.
Do you want to continue? [Y/n] n
Abort.