ffmpeg , separating the audio from a video

If you ever wanted to grab the audio from any kind of video file, ffmpeg seems to be easiest way.  

If you aren't familiar with ffmpeg, it is a free software project that produces libraries and programs for handling multimedia data - on just about every operating system you can think of.  Amazingly powerful Swiss Army knife - this is just one of many things it can do.

Below are some examples of extracting audio out of a video file.  (ffmpeg runs from the command line)

In this example 

• i indicates the input
• ab indicates the bit rate (in this example 160kb/sec)
• vn means no video ouput
• ac 2 means 2 channels
• ar 44100 indicates the sampling frequency. 
• "video.m4v" is the full path to the video file 
• audio.mp3 is the audio file that gets created as an output

ffmpeg -i "video.m4v" -ab 160k -ac 2 -ar 44100 -vn audio.mp3
In this example the -vn switch extracts the audio portion from a video and we are using the -ab switch to save the audio as a 256kbps MP3 audio file.

 ffmpeg -i "video.mp4" -vn -ab 256 audio.mp3

After you have the audio file I recommend using Audacity to manipulate it if needed.