if [ "$1" = "" -o "$1" = "--help" ]; then
  echo "Purpose: Read and mix together two audio tracks from same video file."
  echo "Usage: mix.sh file.mp4"
  echo "Outcome: 3.wav"
  echo "Requires: MPlayer, SoX"
  echo "Aftermath: mplayer -audiofile 3.wav file.mp4"
else
  echo Dumping
  mplayer -vo null -vc null -benchmark -ao pcm:fast:file=1.wav -aid 0 $1 &>/dev/null &
  mplayer -vo null -vc null -benchmark -ao pcm:fast:file=2.wav -aid 1 $1 &>/dev/null &
  wait
  echo Resampling
  sox 1.wav 1b.wav rate 44100 vol 1.0 &
  sox 2.wav 2b.wav rate 44100 vol 0.4 &
  wait
  echo Mixing
  sox -M 1b.wav 2b.wav 3.wav
  echo Done
fi