tile-thumbnails

#!/bin/sh

# tile thumbnails from a video

# script usage
usage()
{
echo "\
# tile thumbnails from a video into an image

$(basename "$0") -i infile.(mp4|mkv|mov|m4v|webm) -s 00:00:00.000 -w 000 -t 0x0 -p 00 -m 00 -c color -o outfile.png
-i infile.(mp4|mkv|mov|m4v|webm)
-s seek into the video file                : default 00:00:05
-w thumbnail width                         : 160
-t tile layout format width x height : 4x3 : default 4x3
-p padding between images                  : default 7
-m margin                                  : default 2
-c color = https://ffmpeg.org/ffmpeg-utils.html#color-syntax : default black
-o outfile.png :optional agument 
# if option not provided defaults to infile-name-tile-date-time.png"
exit 2
}

# error messages
NOTFILE_ERR='not a file'
INVALID_OPT_ERR='Invalid option:'
REQ_ARG_ERR='requires an argument'
WRONG_ARGS_ERR='wrong number of arguments passed to script'
NOT_MEDIA_FILE_ERR='is not a media file'

# if script is run arguments pass and check the options with getopts,
# else display script usage and exit
[ $# -gt 0 ] || usage "${WRONG_ARGS_ERR}"

# timecode - match 00:00:00
timecode='^[0-9]\{2\}:[0-9]\{2\}:[0-9]\{2\}([.]\{1\}[0-9]\{1,3\})?$'
scale_regex='^[0-9]\{3\}$'
tile_regex='^[0-9]\{1,2\}[x]\{1\}[0-9]\{1,2\}$'
padding_regex='^[0-9]\{1,2\}$'
margin_regex='^[0-9]\{1,2\}$'

# getopts check and validate options
while getopts ':i:s:w:t:p:m:c:o:h' opt
do
  case ${opt} in
     i) infile="${OPTARG}"
	[ -f "${infile}" ] || usage "${infile} ${NOTFILE_ERR}";;
     s) seek="${OPTARG}"
         expr "${seek}" : "${timecode}" 1>/dev/null;; 
     w) scale="${OPTARG}"
         expr "${scale}" : "${scale_regex}" 1>/dev/null || usage;;
     t) tile="${OPTARG}"
         expr "${tile}" : "${tile_regex}" 1>/dev/null || usage;;
     p) padding="${OPTARG}"
         expr "${padding}" : "${padding_regex}" 1>/dev/null || usage;;
     m) margin="${OPTARG}"
         expr "${margin}" : "${margin_regex}" 1>/dev/null || usage;;
     c) color="${OPTARG}";;
     o) outfile="${OPTARG}";;
     h) usage;;
     \?) usage "${INVALID_OPT_ERR} ${OPTARG}" 1>&2;;
     :) usage "${INVALID_OPT_ERR} ${OPTARG} ${REQ_ARG_ERR}" 1>&2;;
  esac
done
shift $((OPTIND-1))

# infile, infile name
infile_nopath="${infile##*/}"
infile_name="${infile_nopath%.*}"

# file command check input file mime type
filetype="$(file --mime-type -b "${infile}")"

# audio and video mimetypes
mov_mime='video/quicktime'
mkv_mime='video/x-matroska'
mp4_mime='video/mp4'
m4v_mime='video/x-m4v'
webm_mime='video/webm'
avi_mime='video/x-msvideo'

# ffprobe get fps and duration
videostats=$(ffprobe \
-v error \
-select_streams v:0 \
-show_entries stream=r_frame_rate:format=duration \
-of default=noprint_wrappers=1 \
"${infile}")

# fps
fps=$(echo "${videostats}" | awk -F'[=//]' '/r_frame_rate/{print $2}')

# duration
duration=$(echo "${videostats}" | awk -F'[=/.]' '/duration/{print $2}')

# check if tile is null
if [ -z "${tile}" ]; then
   : # tile variable not set : = pass
else
   # tile variable set
   # tile layout
   tile_w=$(echo "${tile}" | awk -F'x' '{print $1}')
   tile_h=$(echo "${tile}" | awk -F'x' '{print $2}')
   # title sum
   tile_sum=$(echo "${tile_w} * ${tile_h}" | bc)
fi

# defaults
seek_default='00:00:05'
scale_default='160'
tile_layout_default='4x3'
tile_default='12'
padding_default='7'
margin_default='2'
color_default='black'
outfile_default="${infile_name}-tile-$(date +"%Y-%m-%d-%H-%M-%S").png"

# duration * fps / number of tiles
frames=$(echo "${duration} * ${fps} / ${tile_sum:=${tile_default}}" | bc)

# tile function
tilevideo () {
ffmpeg \
-hide_banner \
-stats -v panic \
-ss "${seek:=${seek_default}}" \
-i "${infile}" \
-frames 1 -vf "select=not(mod(n\,${frames})),scale=${scale:=${scale_default}}:-1,tile=${tile:=${tile_layout_default}}:padding=${padding:=${padding_default}}:margin=${margin:=${margin_default}}:color=${color:=${color_default}}" \
"${outfile:=${outfile_default}}"
}

# check the files mime type
case "${filetype}" in
    ${mov_mime}|${mkv_mime}|${mp4_mime}|${m4v_mime}|${webm_mime}|${avi_mime})tilevideo "${infile}";;
    *) usage "${infile} ${NOT_MEDIA_FILE_ERR}";;
esac