strip audio from video using ffmpeg

video_to_audio.sh

#!/bin/bash

# usage:
# ls *.avi | ./video_to_audio.sh

# for f in `ls *.avi`; 
# do
#     echo item: $f
# done

#for src in "$@"; #*.avi;
# IFS= read var << EOF
# $(foo)
# EOF

if [ ! -d "job_done" ] 
then
    mkdir 'job_done'
else
    echo 'job_done dir exists...'
    echo 
fi

# It's to hard to quit the loop....
# while read LINE; do
#     INFILE="$LINE"
#     STRIP_EXT="${INFILE%.*}"
#     OUT_NAME="${STRIP_EXT}.mp3"

#     echo "processing" $OUT_NAME
#     echo "-----------------------------------"
#     echo     
#     # ffmpeg -i 02\ -\ Art\ Of\ Prospecting,\ 5\ Keys\ To\ Sales\ Mastery.avi -vn -ar 22050 -ac 2 -ab 32k -threads 3 -f mp3 damn.mp3
#     ffmpeg -i "${INFILE}" -vn -ar 22050 -ac 2 -ab 32k -threads 3 -f mp3 "${OUT_NAME}"
#     touch "${OUT_NAME}"
#     mv "${OUT_NAME}" 'job_done' 
# done < /dev/stdin

#OUT_NAME="${STRIP_EXT##*/}.mp3"


# an alternative solution:

IN_NAME="$1"
STRIP_EXT="${IN_NAME%.*}"
OUT_NAME="${STRIP_EXT}.mp3"

echo "processing" $OUT_NAME
echo "-----------------------------------"

# wrapping in quote prevent file that has space
# touch "${OUT_NAME}"

## threads = 1.5 x core
## sample rate = 22.05 khz
## channel = 2
## bit rate = 32k bit/s

#### HACK: 2>&1 1>/dev/null
## let 'file descriptor 2', stderr pointer, points to what descriptor 1 points to aka stdout. 
## let 'file descriptor 1', stdout pointer, points to nowhere.
## e.g. ls 2>&1 1>/dev/null | grep '.'
# >/dev/null 2>&1 | grep

# size=     811kB time=00:03:27.46 bitrate=  32.0kbits/s speed=20.6x
ffmpeg -i "${IN_NAME}" -vn -ar 22050 -ac 2 -ab 32k -threads 3 -f mp3 "${OUT_NAME}"

echo "stripping audio from ${OUTFILE} is done !"

echo "Do you want to move file into job_done folder ? [y/n]"
read answer
if [ "$answer" == "y" ]
then
    mv "${OUT_NAME}" ./job_done
    echo "move ${OUT_NAME} done"
fi