How can I convert audio from MP4 or FLV video files to mp3?

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

you can do it using ffmpeg. Install ffmpeg using following command:

sudo apt-get install ffmpeg libavcodec-unstripped-52

The package libavcodec-unstripped-52 is available in Multiverse repo, so you will need to enable it.
After installing these packages, you can use a command like the one below to extract the audio as mp3:

ffmpeg -i video.mp4 -f mp3 -ab 192000 -vn music.mp3

The -i option in the above command is simple: it is the path to the input file. The second option -f mp3 tells ffmpeg that the ouput is in mp3 format. The third option i.e -ab 192000 tells ffmpeg that we want the output to be encoded at 192Kbps and -vn tells ffmpeg that we dont want video. The last param is the name of the output file.

soundconverter is another tool that can convert audio formats and also video to audio only:

or via the terminal:

sudo apt-get install soundconverter