george@george-PC:~$ apt-cache policy libavcodec-extra-53 ffmpeg libsox-fmt-base
libavcodec-extra-53:
  Installed: (none)
  Candidate: 4:0.8.3ubuntu0.12.04.1+medibuntu1
  Version table:
     4:0.8.3ubuntu0.12.04.1+medibuntu1 0
        500 http://packages.medibuntu.org/ precise/non-free amd64 Packages
        100 /var/lib/dpkg/status
     4:0.8.3ubuntu0.12.04.1 0
        500 http://us.archive.ubuntu.com/ubuntu/ precise-updates/universe amd64 Packages
        500 http://security.ubuntu.com/ubuntu/ precise-security/universe amd64 Packages
     4:0.8.1ubuntu1 0
        500 http://us.archive.ubuntu.com/ubuntu/ precise/universe amd64 Packages
ffmpeg:
  Installed: 4:0.8.4-0ubuntu0.12.04.1
  Candidate: 4:0.8.4-0ubuntu0.12.04.1
  Version table:
 *** 4:0.8.4-0ubuntu0.12.04.1 0
        500 http://us.archive.ubuntu.com/ubuntu/ precise-updates/main amd64 Packages
        500 http://security.ubuntu.com/ubuntu/ precise-security/main amd64 Packages
        100 /var/lib/dpkg/status
     4:0.8.1-0ubuntu1 0
        500 http://us.archive.ubuntu.com/ubuntu/ precise/main amd64 Packages
libsox-fmt-base:
  Installed: 14.3.2-3
  Candidate: 14.3.2-3
  Version table:
 *** 14.3.2-3 0
        500 http://us.archive.ubuntu.com/ubuntu/ precise/universe amd64 Packages
        100 /var/lib/dpkg/status