'WAVing' Your Videos

A friend asked tonight if I knew how to strip out the audio from videos, for conversion to things like .ogg and .mp3 formats. This is one of those things I remember doing, but not the details, so below is a script for creating a .wav file for each video .avi file in a directory. Just look up the parameters in man mplayer for a detailed explination.

--

#!/bin/bash



#  Script to extract .wav audios from .avi files
#  04 Sept. 2007  d.e.l.



USAGE="$0 [-h]"



shopt  -q  nocasematch
#   - this seems to be inoperative



# if [[ '-h' = ${1:0:2} ]]
# then
#   echo ${USAGE}
#   exit
# fi



case ${1:0:2}  in
-h | -H | -? | /h | /H | /? )  
      echo ${USAGE}
      exit 
      ;;
-- )
      case  ${1:2:1}  in
      h | H | ? )
        echo ${USAGE}
        exit 
        ;;
      * )
      esac
      ;;
* )
esac



set -o braceexpand  ;



aviconvert ()
{



PATIENT=${1}  ;
CURED="${1%.avi}.wav"  ;
echo "Converting: ${PATIENT}"  ;
#\mplayer -ao pcm:waveheader:fast:file=charley1.wav -vc null -vo null \
#   charly.01.avi




    nice  -20  \
    /usr/bin/mplayer   \
         -ao pcm:waveheader:fast:file=${CURED}   \
         -vc null -vo null \
         ${PATIENT}  



  return  ;



}





for   i  in   *.avi
do 



  aviconvert  ${i}  ;



done  ;   # for

Addenda 30 Dec. 2007

I located this article I'd seen before after a bit of surfing:

http://www.linuxjournal.com/article/9719

which gives what might be considered an intermediate action, conversion to Black and White. Example from the above link:

$mencoder color-video.avi -o black-white-video.avi -vf hue=0:0 -oac copy -ovc lavc

The only problem I noticed was that the final video froze up on playback unless I turned any mplayer.conf video filtering off, but then my computer is somewhat marginal for playing videos to begin with. Besides the Ansel Adams/film noir effect a test on a random video reduced it to 20% of it's original size. I'm unaware of any "LSD/light show" filter that drops the chiaroscuro and spatial forms and keeps the colors. ;-)