HandBrake is a GPL-licensed, multiplatform, multithreaded video transcoder.
Personally I use it to transcode some videos so that I can see them on my Android smartphone. It has already some presets with enconding settings specific for iPhone, iPad and Android.
It includes one with a graphical interface and one with command line interface. I find them both very useful. For instance, even though we can create a queue of jobs with the graphical interface I use the version with the command line interface when I want to automate some other things with a shell script.
Open a terminal window and run:
If you only want to install the version with graphical interface, type:
If you want to install the version with command line interface, type:
If you want to install both versions, type: