FFmpeg

A complete, cross-platform solution to record, convert and stream audio and video. FFmpeg is a free and open-source project consisting of a vast software suite of libraries and programs for handli...
Language(s): C and Assembly
Operating system(s): Windows, Mac OS, Linux
License: Open source software (Lesser GNU Public License) Portions are under “Dr.DivX DLL EULA” (Freeware)

HandBrake

HandBrake is a free and open-source transcoder for digital video files, originally developed in 2003 by Eric Petit (a.k.a. "titer" from his SVN repository username) to make ripping a film from a DVD t...
Language(s): Objective-C, C, C#
Operating system(s): Linux, Mac OS, Windows
License: GNU GPLv2 (Third-party components have their own licenses)