You can do the same in 12.04 by using several software.

Using WinFF

1. Install winff and libavcodec-extra first

   
   
   

    sudo apt-get install winff libavcodec-extra
   
   




2. Open Winff from dash

   
   
   

   




3. Then in Winff window, do these

   
   
   
   
   

   1. Add file

   
   

   2. Select what catagory to convert (select Audio)

   
   

   3. Select Audio file format (mp3)

   
   

   4. Type the output folder for converted file

   
   
   
   
   

   

   
   
   
   
   
   5. Then click the Convert button. You can also click Options button to file tune the audio format and other options.
   
   
   
   
   

   

   
   
   

   

Using VLC

1. Install VLC and "libavcodec-extra" package first

   
   
   

   sudo apt-get install vlc libavcodec-extra
   
   




2. Open VLC from dash by pressing Super key and typing "VLC" there

   
   
   

   




3. Then from top panel menu, Select Media → Convert/Save.

   
   
   

   




4. Then Add file to convert in the new window. Then click Convert button.

   
   
   

   




5. In the new window, Select the directory for output file, select the conversion profile (Audio mp3) and click Start button.

   
   
   

   

Using command line

1. First install the tools

   
   
   

   sudo apt-get install ffmpeg libavcodec-extra libav-tools
   
   

   
   
   

   If you are using




2. Use this simple command to extract the audio file

   
   
   

   avconv -i /input-file-name-with-path output-filename.mp3
   
   

   
   
   

   For example to convert the "How fast.ogg" video file into how-fast.mp3 use this command:

   
   
   

   avconv -i /usr/share/example-content/Ubuntu_Free_Culture_Showcase/How fast.ogg how-fast.mp3
   
   

   
   
   

   See the manual page for more options and information.

To Just extract audio

Check these answer

• https://askubuntu.com/a/234197/61218


• ffmpeg to extract audio