[VStrip Demultiplexer]
[AC3DEC Freeware Decoder]

An easy and straightforward way of decoding an AC3 Audio Stream is to use the free AC3DEC decoder by Aaron Holtzman. You feed an AC3 Stream to this tool and it produces a .WAV-file. Here is the guide on how to do it:

• Download AC3DEC and unzip in a directory.
  (you may also set a path to this directory for easy accessibility)
  
• Open a command prompt and change directory to where your VOB-Files are lying.
  
• Use the VSTRIP Tool to demultiplex the audio stream from the VOB.
  
  (If you copied the whole vob-file structure to harddisk without joining the VOBs refer to the list-file method)
  
  
• Use the following commandline to demultiplex the audio stream:
  
  vstrip vts_01_x.vob audio.ac3 ! d 0xbd 0x8s
  
  08xs is the language you wanna strip. 0x80 is first language, 0x81 is second a.s.o.
  
  
• If you had several VOB-Files then you can use the list-feature of vstrip:
  
  
  • Generate a listfile movie.lst
  • In each line put the name of the next vts_01_x.vob file
    (including full path !!!)
  • Save this file to disk
  • Use the following commandline to demultiplex the audio:
    
    vstrip @movie.lst -!oaudio.vob 0xbe 0xbd 0x8s = 0x80
    
    As above 08xs is the language you want to strip.
    
    
• After doing so (you may have skipped the vStrip steps if you already had only one vob-file) you have to decode the VOB using AC3DEC :
  
  ac3dec audio.ac3 -o output.wav
  
  
• AC3DEC starts do decode now.
  

After this procedure you have the decoded WAV-File sitting on your harddisk ready for further processing.