We was looking for smart software to convert video formats in Ubuntu before. But, that is, mostly, did not achieve my desires. Normally I would use Audacity or Avidemux to change my audio format. But now, HandBrake will simplify your life to change the video format, handBrake can be downloaded for Linux, Mac, and Windows.

Handbrake screenshoot
Handbrake Support this Video Format:
  • Any type of DVD: VIDEO_TS folder, DVD image or real DVD, VOB and. TS files
  • Most of the multimedia file. This is because there libavformat Handbrake to read and to decode livavcodec
Handbrake Output Video Format:
  • MP4 and MKV
  • Video: MPEG-4, H.264, or Theora
  • Audio: AAC, AAC CoreAudio (OS X Only), MP3 or Vorbis. AC-3 pass-through, DTS pass-thorugh (MKV)
Handbrake  Features:
  • Chapter Selection
  • Subtitles
  • Integrated bitrate calculator
  • Deinterlacing picture, the crop and scale images
  • Preview video clips
You can view the website here http://handbrake.fr/ Handbrake Want to try to produce a different kind of video? Ubuntu / Linux: Open your terminal and copy paste this:
sudo add-apt-repository ppa:stebbins/handbrake-releases && sudo apt-get update
sudo apt-get install handbrake-gtk
Other: You can go to this link http://handbrake.fr/downloads.php