Extract audio track from MKV file

It may be interesting to recover the soundtrack in MP3 format from a MKV file of a concert or a show. Here is how to extract audio part from MKV file and get MP3 or AC3 file according to format contained in MKV file:

• Download the software MKVToolnix and install it
• Download the software gMKVExtractGUI and unzip it into a directory
• gMKVExtractGui uses MKVToolnix to do audio extraction and needs to locate it. If this is not done automatically, use the Browse button (top right of the software) and specify the installation directory of MKVToonix
• Drag and drop the MKV file into gMKVExtractGui
• Check the audio track (s) to extract (they are suffixed by [audio] )
• Choose the destination directory ( Browse button at the bottom right)
  
• Click on Extract

Once the operation is complete, the configured directory will contain one file per box checked.

Note that this technique also works for files other than MKV:

• You can extract the audio track from an AVI or MP4 file by converting it to MKV first
• Apply the technique to the generated file