FFmpeg

Website: http://www.ffmpeg.org/

FFmpeg is the project that hosts the libavcodec codec library that forms the basis of most free software multimedia programs. It aims to support all known and unknown formats and is closer to that goal than any other program.

FFmpeg also contains libavformat, a library for multimedia container formats and libpostproc for postprocessing. ffplay is a simple media player that uses libavcodec and libavformat. ffmpeg is a transcoding application.