Recommeded:
MeGUI
Installation Method & MeGUI tools given at thread:
You must be registered for see links
How to encode movies:
You must be registered for see links
Or else
HandBrake is also great program.
and another good program is
VidCoder.
these 3 has great abilities to do x264 encoding But MeGUI is most power and has manuall control to manage x264 enoding or decoding.