View source for Convert MP4 to MP3

Intrepid Ibex and above:
Code:

 ffmpeg -ss 00:05:00:00 -t 00:02:00:00 -i input.mp4 -acodec libmp3lame -ab 128k output.mp3

Hardy Heron:
Code:

 ffmpeg -ss 00:05:00:00 -t 00:02:00:00 -i input.mp4 -ab 128k output.mp3

    ss: time offset from beginning of input in hh:mm:ss:frames.
    t: duration of encode
    ab: audio bitrate