This howto requires:

• mplayer
• mkvtoolnix
• your Linux box

Audio from Avi files (es. Xvid + MP3):

mplayer -dumpaudio "mymovie.avi" -dumpfile mymovie_audio_track.mp3

Tracks from Matroska MKV file:

List all tracks:

mkvmerge -i mymovie.mkv

File 'mymovie.mkv': container: Matroska
Track ID 1: video (V_MS/VFW/FOURCC, XVID)
Track ID 2: audio (A_VORBIS)
Track ID 3: audio (A_VORBIS)
Track ID 4: subtitles (S_TEXT/UTF8)
Track ID 5: subtitles (S_TEXT/UTF8)

mkvextract tracks *.mkv 3:mymovie_audio_track.ogg 4:mymovie_subtitle.srt

Creates two files, mymovie_audio_track.ogg (track 3) and mymovie_subtitle.srt (track 4).

I have some DVD to publish on a popular video sharing service on the web. How to do that on Linux? Here a simple howto to achieve this.

First, get some useful software for this task. To do this you should sometimes add the Debian Multimedia repository to your /etc/apt/sources.list:

deb http://www.debian-multimedia.org etch main

Where “etch” is your distribution. Then run:

apt-get update

On sudo / superuser shell run:

1. apt-get install avidemux acidrip lame x264 mplayer vorbis-tools dvdbackup
   Avidemux is a simple cut-and-paste non-linear editor and encoding software, acidrip a DVD-to-file ripper. X264 is a video encoder for the H.264/MPEG-4 AVC standard, lame an MP3 encoder and vorbis-tools contains OGG Vorbis encoders (a libre audio library).
2. If you want to rip directly a DVD, encoding it as you wish without changes (cut and paste) from chapters, then use acidrip. For video use X264, for audio choose MP3 or Ogg Vorbis. (howto ends here)
3. If you want to apply some changes, then first backup your dvd with dvdbackup:
   dvdbackup -i /dev/dvd -o my_destination_directory/ -n myDVDtitle -M
4. Open the first huge .VOB file (eg. VTS_01_1.vob) with avidemux, then choose YES for indexing it
5. Now you can export the whole file or part of it: choose x264 as video codec and Vorbis or Lame (MP3) as audio codec. Leave AVI as Format (or choose another).
6. If you want to extract a portion of the video, move cursor to first frame of the selection and click A (Selection Start). Then go to last frame of the selection and click B (Selection End)
7. Click to File -> Save Video to export the selected portion (read Avidemux wiki to more and detailed options). If files are compatible in width x height you can also use the “Append” function to queue more files generating and exporting a bigger one.

Now you can upload your video to popular online file sharing services. Enjoy!