#!/bin/bash
# 
#
# Dependencies/Requirements:
# 1. ffmpeg
# 2. ImageMagick with modified policy.xml (avaliable on this git)
#
# Usage:
# . th.sh COLUMNS ROWS SIZE INPUT
#
# COLUMNS means number of columns;
# ROWS means nubler of rows;
# SIZE is the length of the longer side of the output, e.g., 1920 if you want
# to get an 1920*1080 output image;
# INPUT is the path to the input file;
#
# Example:
# . th.sh 3 14 1920 video.mp4
if [[ $# != 4 ]]; then
    echo "wrong number of arguments

Usage:
. th.sh COLUMNS ROWS SIZE INPUT
COLUMNS means number of columns;TILE is in the form 'MxN' (where M * N should match NFRAMES), e.g., 4x4;
ROWS means nubler of rows;
SIZE is the length of the longer side of the output, e.g., 1920 if you want
to get an 1920*1080 output image;
INPUT is the path to the input file;
OUTPUT is the path to the output file (make sure intermediate directories
exist).

Example:
. th.sh 3 14 1920 video.mp4
"
    return 1
fi
NFRAMES=$(echo "scale=0;$1*$2" | bc)
TILE=$(echo "$1x$2")
SIZE=$3
INPUT=$4
DURX=$(ffmpeg -i "$4" 2>&1 | grep Duration | awk '{print $2}' | tr -d ,)
DURATION=$(ffmpeg -i "$4" 2>&1 | grep "Duration"| cut -d ' ' -f 4 | sed s/,// | sed 's@\..*@@g' | awk '{ split($1, A, ":"); split(A[3], B, "."); print 3600*A[1] + 60*A[2] + B[1] }')
RES=$(ffmpeg -i "$4" 2>&1 | grep -oP 'Stream .*, \K[0-9]+x[0-9]+')
FILESIZE=$(du -sm "$4" | awk '{print $1}')
TMPDIR=/tmp/thumbnails-${RANDOM}/
mkdir $TMPDIR
for (( VARIABLE=0; VARIABLE<NFRAMES; VARIABLE++ ))
do
OFFSET=$(echo "scale=2;$VARIABLE*$DURATION/$NFRAMES+$DURATION/$NFRAMES/2" | bc)
if [ $VARIABLE -gt 9 ];then
  ZEROS="00"
  if [ $VARIABLE -gt 99 ];then
    ZEROS="0"
    if  [ $VARIABLE -gt 999 ];then
       ZEROS=""
    fi
  fi
else
  ZEROS="000"
fi
ffmpeg -start_at_zero -copyts -ss $OFFSET -i "$4" -vf "drawtext=fontfile=/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf:fontsize=45:fontcolor=white::shadowcolor=black:shadowx=2:shadowy=2:box=1:boxcolor=black@0:x=(W-tw)/40:y=H-th-10:text='%{pts\:gmtime\:0\:%H\\\\\\:%M\\\\\:%S}'" -vframes 1 ${TMPDIR}$ZEROS$VARIABLE.jpg
done
montage ${TMPDIR}*.jpg -background white -geometry +5+5 -tile $TILE ${TMPDIR}output.jpg
echo $4 >>${TMPDIR}myfile.txt
echo $RES >>${TMPDIR}myfile.txt
echo "$FILESIZE Mb" >>${TMPDIR}myfile.txt
echo $DURX >>${TMPDIR}myfile.txt
convert -size ${SIZE}x150 -fill black -interline-spacing 10 -background white -pointsize 20 -gravity west caption:@${TMPDIR}myfile.txt ${TMPDIR}text1.jpg
convert ${TMPDIR}output.jpg -resize ${SIZE}x${SIZE} ${TMPDIR}th.jpg
thewidth=$(identify -ping -format %w ${TMPDIR}th.jpg)
convert ${TMPDIR}text1.jpg -crop ${thewidth}x150+0+0 ${TMPDIR}text.jpg
montage ${TMPDIR}text.jpg ${TMPDIR}th.jpg -background white -geometry +0+0 -tile 1x2 thumbnails-${RANDOM}.jpg