An easy to use FFmpeg code generator by RodrigoPolo.com
In order to encode audio/video with FFmpeg you will need to download the source code of FFmpeg along with some other libraries and then compile everything. I know that sounds very very interesting, that's why I have here a full set of FFmpeg compilations for Windows, GNU Linux and Macintosh OS X (Inel).
You can also use this extremely easy guide to install FFmpeg on your Windows, GNU Linux or Macintosh machine:
http://www.rodrigopolo.com/about/wp-stream-video/ffmpeg-binary-installers-for-win-mac-and-linux
Select the output format: Use "command" to paste the command to your Windows command prompt or your Mac-Linux terminal. Use "Script" to copy and paste your code on a ".bat" or ".sh" file.