Installing FFMpeg

yum install ffmpeg ffmpeg-devel

If you get package not found, then you will need to add few lines in the yum repository for dag packages installation. Create a file named  /etc/yum.repos.d/dag.repo with the following contents on it

[dag]
name=Dag RPM Repository for Red Hat Enterprise Linux
baseurl=http://apt.sw.be/redhat/el$releasever/en/$basearch/dag
gpgcheck=1
enabled=1

then

yum install ffmpeg ffmpeg-devel