HandBrake for Windows and Linux is an Open Source, multiplatform, multithreaded video transcoder for converting video from nearly any format to selecting modern, widely supported codecs. Stable version is also available.
With HandBrake, you can convert from many common multimedia file formats, including unprotected DVD or BluRay sources, to a handful of modern output file formats.
HandBrake is the ideal tool for converting DVDs to MPEG-4 format or even backing up to a disk. It can easily convert your videos and subtitles and write them into AVI, MPEG-4 format, OGM video or AAC, MP3, and Ogg Vorbis audio. You also can preview results, create task lists (for batch conversions), and configure the program's settings, among many other useful advantages included with this audio and video tool.
Multi-platform, Multi-threaded Video Transcoder
Video Encoding to several popular formats (H.264, Mpeg-4, Mpeg-2, Theora)