HandBrake is a multithreaded tool for converting video from nearly any format to a selection of modern, widely supported codecs. A beta (nightly) version is also available.
HandBrake is the perfect tool for converting DVDs to MPEG-4 format or even backing up to a disk. With it, you 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)