- To extract part of a video file
=> you can use avidemux (apt-get install avidemux), usage is pretty straight forward - To convert a dvd into divx
=> you can use dvd:rip (apt-get install dvdrip), usage is pretty straightforward (first, load TOC, then rip selected track, last encode it) - Convert a video into mp3 (ie. extract soundtrack)
=> use either avidemux (select ‘mp3′ as audio output on left menu, the on top menu fo to /audio/save after having loaded the video) or ffmpeg (see similar post on this blog)
sources