Remova o pacote libavcodec-extra-54
sudo dpkg -r --force-all libavcodec-extra-54
Faça o download e instale libavcodec54
apt-get download libavcodec54
sudo dpkg -i libavcodec54_*.deb
Para ter certeza, corra
apt-cache policy libavcodec54 libavcodec-extra-54
você deve ver algo assim
libavcodec54:
Installed: 6:9.18-0ubuntu0.14.04.1
Candidate: 6:9.18-0ubuntu0.14.04.1
Version table:
*** 6:9.18-0ubuntu0.14.04.1 0
500 http://archive.ubuntu.com/ubuntu/ trusty-security/universe i386 Packages
500 http://archive.ubuntu.com/ubuntu/ trusty-updates/universe i386 Packages
100 /var/lib/dpkg/status
6:9.11-2ubuntu2 0
500 http://archive.ubuntu.com/ubuntu/ trusty/universe i386 Packages
libavcodec-extra-54:
Installed: (none)
Candidate: 6:9.18-0ubuntu0.14.04.1
Version table:
7:1.2.6-1~trusty1 0
100 /var/lib/dpkg/status
6:9.18-0ubuntu0.14.04.1 0
500 http://archive.ubuntu.com/ubuntu/ trusty-security/universe i386 Packages
500 http://archive.ubuntu.com/ubuntu/ trusty-updates/universe i386 Packages
6:9.11-2ubuntu2 0
500 http://archive.ubuntu.com/ubuntu/ trusty/universe i386 Packages