ffmpeg autocrop

#!/bin/bash
function cropdetect ()
{
    FFOUT=/tmp/ffout
    CROP="1"
    TOTAL_LOOPS="10"

    A=0
    while [ "$A" -lt "$TOTAL_LOOPS" ] ; do
    A="$(( $A + 1 ))"
    SKIP_SECS="$(( 120 * $A ))"

    ffmpeg -ss $SKIP_SECS -i "$@" -vframes 20 -an -sn -vf \
    cropdetect=30:2 -y /tmp/crop.mp4 2>$FFOUT
    CROP[$A]=$(grep -m 1 crop= $FFOUT |awk -F "=" '{print $2}')

    done


    B=0
    while [ "$B" -lt "$TOTAL_LOOPS" ] ; do
    B="$(( $B + 1 ))"

    C=0
    while [ "$C" -lt "$TOTAL_LOOPS" ] ; do
    C="$(( $C + 1 ))"

    if [ "${CROP[$B]}" == "${CROP[$C]}" ] ; then
        COUNT_CROP[$B]="$(( ${COUNT_CROP[$B]} + 1 ))"
    fi
    done
    done

    HIGHEST_COUNT=0

    D=0
    while [ "$D" -lt "$TOTAL_LOOPS" ] ; do
    D="$(( $D + 1 ))"

    if [ "${COUNT_CROP[$D]}" -gt "$HIGHEST_COUNT" ] ; then
        HIGHEST_COUNT="${COUNT_CROP[$D]}"
        GREATEST="$D"
    fi
    done
    rm /tmp/crop.mp4
    CROP="${CROP[$GREATEST]}"
    CROP=$(echo $CROP|awk -F ":" '{print $1-4":"$2-4":"$3+2":"$4+2}')
    echo $CROP
    rm $FFOUT
}
cropdetect "$@"
exit 0