http://karbownicki.com/2012/01/11/generator-filmowych-miniaturek/

make-thumb.sh

#!/bin/bash

usage()
{
cat << EOF
usage: $0 [options] -i MOVIE-FILE

OPTIONS:
   -h       show this message
   -i       input movie file
   -o       output JPG file name
   -a       percentage or absolute time hh:mm:ss, default 20
   -b       percentage or absolute time hh:mm:ss, default 40
   -c       percentage or absolute time hh:mm:ss, default 60
   -d       percentage or absolute time hh:mm:ss, default 80
   -n       number of columns
EOF
}

FILE=
OUT=
COLUMNS=2
QUALITY=10
T1=20
T2=40
T3=60
T4=80

while getopts "hi:o:a:b:c:d:n:" OPTION
do
     case $OPTION in
         h)
             usage
             exit 1
             ;;
         i)
             FILE=$OPTARG
             OUT=${OPTARG}.jpg
             ;;
         o)
             OUT=$OPTARG
             ;;
         a)
             T1=$OPTARG
             ;;
         b)
             T2=$OPTARG
             ;;
         c)
             T3=$OPTARG
             ;;
         d)
             T4=$OPTARG
             ;;
         n)
             COLUMNS=$OPTARG
             ;;
         ?)
             usage
             exit
             ;;
     esac
done

if [[ -z "$FILE" ]]
then
    usage
    exit 1
else
    ffmpegthumbnailer -t $T1 -s 400 -o /tmp/thumb-1.jpg -q$QUALITY -i "$FILE"
    ffmpegthumbnailer -t $T2 -s 400 -o /tmp/thumb-2.jpg -q$QUALITY -i "$FILE"
    ffmpegthumbnailer -t $T3 -s 400 -o /tmp/thumb-3.jpg -q$QUALITY -i "$FILE"
    ffmpegthumbnailer -t $T4 -s 400 -o /tmp/thumb-4.jpg -q$QUALITY -i "$FILE"

    montage -mode concatenate -tile ${COLUMNS}x -adjoin /tmp/thumb*.jpg "$OUT"
    rm /tmp/thumb*.jpg
fi