http://ffmpeg.org/index.html#pr3.3
3.2.2 https://git.ffmpeg.org/gitweb/ffmpeg.git/shortlog/n3.2.2
3.2.1 - fix for jrottenberg#29
Merge pull request jrottenberg#15 from jrottenberg/automate-dockerfil… …e-gen templating the builds
ubuntu the default
centos is bigger than ubuntu base also it's centos ;-)