FFmpeg is a collection of free software that can record, convert and stream digital audio and video. It includes libavcodec, a leading audio/video codec library. FFmpeg is developed under Linux, but it can be compiled under most operating systems, including Windows. The project was started by Gerard Lantau, an alterego of Fabrice Bellard, and is now maintained by Michael Niedermayer. Notable is that most FFmpeg developers are part of either the MPlayer, xine or VideoLAN project as well.
Threadstarter: I can't help you out either as I'm not too familiar with it.