How to get it
svn co svn://svn.mplayerhq.hu/ffmpeg/trunk ffmpeg cd ffmpeg ./configure && make && make install
FFmpeg supports many formats and containers, including: mpeg-1, mpeg-2, DIVx, H.263, H.264, MP2, MP3, and MP4.
How to use it
Here's an example how to convert example.dv to a .mpg file:
ffmpeg -i example.dv -f avi -vcodec mpeg4 -b 1800 -g 300 example.mpg
FFmpeg also includes FFplay, a media player and streaming client.
FFmpeg also includes FFserver, used to stream media to clients over a network.