I have never used ffmpeg on my Ubuntu Linux 12.04 (Precise Pangolin) box until now. Typing 'ffmpeg' at the command prompt revealed that ffmpeg 0.8.17 (listed as ffmpeg 0.8.17-4:0.8.17-0ubuntu0.12.04.2) was installed. Seeing as I need to convert h.265 to h.264, an update was obviously required.
Following posted instructions, I installed a ream of packages:
$ sudo apt-get install faad libmp4v2-dev libfaac0 libfaac-dev
libxvidcore4 libxvidcore4-dev liba52-0.7.4 liba52-0.7.4-dev libx264-dev
libgsm-tools libogg-dev libtheora-bin libfaad-dev libvorbis-dev
libtheora-dev libdts-dev git-core yasm texi2html checkinstall
$ sudo apt-get purge ffmpeg
You should find out which package provides this old binary in
/usr/bin by running
dpkg -S /usr/bin/ffmpeg
Then remove that package in turn.
Note that if that file is a symlink, esp. to
/etc/alternatives, you should follow the trail of symlinks and then run the above command on the actual binary.