There are a lot of video editing/ripping/encoding, etc… tools for Linux OS.
Some of them are missing basic functions, others have extremely complicated user interfaces with tons of parameters that have to be specified even for the most simple transformation.
Avidemux has an intuitive UI, can convert/encode/export your video in nearly every possible format.
I use avidemux to convert videos recorded with my digital camera (which has little processing power and therefore does a very weak compression) to MPEG-4 ASP(Xvid) – format using a two-pass encoding which allows setting a targeted video size.
Give it a try:
sudo apt-get install avidemux