screen shots

unset a b c d e
mkdir -p ~/.fonts
if [ -z "$1" ]; then
  echo Usage: ss1 filename sub_track_number \(or blank if raw\)
  exit
fi
if [ -z "$2" ]; then d=-1; else d=$2; fi
b=$1
ln "$b" c.mkv
echo Creating screenshots for $b
if [ $d -ne -1 ]; then
  ffmpeg -dump_attachment:t "" -i c.mkv
  mv *.ttf *.TTF *.otf *.OTF *.ttc *.TTC ~/.fonts
  fc-cache -fv ~/.fonts
  ffmpeg -i c.mkv -map 0:s:$d subs.ass
fi
e=$(($(mkvinfo-text c.mkv | grep \+.Dur | cut -f4 -d' ' | cut -f1 -d'.')*3/4))
# make 24 screenshots, or at least every 10 seconds
if [ "$e" -gt 230 ]; then f=$((e/23)); else f=10; fi
for ((b=1,c=1;(e-b)>0;b+=f,c++))
do
  if [ $d -ne -1 ]; then
    ffmpeg -ss $b -i subs.ass subs2.ass
    ffmpeg -probesize 100M -analyzeduration 100M -ss $b -i c.mkv -vf ass=subs2.ass -vframes 1 -pix_fmt rgb24 $c.png
    rm subs2.ass
  else
    ffmpeg -ss $b -i c.mkv -vframes 1 -pix_fmt rgb24 $c.png
  fi
done
if [ $d -ne -1 ]; then rm subs.ass; fi
rm c.mkv
unset a b c d e