HandBrake is a free multithreaded video transcoder for MacOS X, Linux and Windows.
Main features:
Chapter selection, Chapter Markers
Subtitles
Vobsub and Closed Captions
SRT import and passthru
SSA passthru or burn-in
Constant Quality or Average Bitrate Video Encoding
Support for VFR, CFR and VFR
Video: Deinterlacing, Decomb, Detelecine, Cropping and scaling
Live Video Preivew
Supported Output:
File format: MP4(M4V) and MKV
Video: MPEG-4(ffmpeg), H.264(x264), or Theora(libtheora)
Audio: AAC, CoreAudio AAC (OS X Only), MP3, or Vorbis. AC-3 pass-through, DTS pass-thorugh (MKV only)
