Audio-Video Converter on Linux

Soundconverter
Soundconverter can convert between various audio formats like Ogg/Vorbis, MP3, FLAC, and WAV.

Install Gstreamer Codecs

$ sudo apt-get install gstreamer0.10-plugins-ugly gstreamer0.10-plugins-ugly-multiverse gstreamer0.10-ffmpeg gstreamer0.10-plugins-bad

Install Soundconverter

$ sudo apt-get install soundconverter

Soundconverter will be at Applications > Sound & Video

MEncoder
MEncoder is a command-line tool to encode and decode videos.

Install MPlayer

$ sudo apt-get install mplayer

Install MEncoder

$ sudo apt-get install mencoder

Howto MEcoder

http://wiki.qwdrama.com/Mencoder_howto