#!/usr/bin/perl -w
#
# Given a video file as argument, generate a "poster" of screen shots from the
# video. Assumes the video has a valid index and I can seek in it.

my $newpath=`dirname $0`;
chomp($newpath);
$newpath=`$newpath/echo-path`;
chomp($newpath);
$ENV{'PATH'}=$newpath;

my $vidfile = $ARGV[0];
my $poster = $ARGV[1];

my $vidwidth;
my $vidheight;
my $vidsecs;

my $idh;
open($idh, '-|', "mplayer -frames 0 -identify -vo null -ao null $vidfile 2>/dev/null");
while (<$idh>) {
   if (/^ID_VIDEO_WIDTH=(\d+)$/) {
      $vidwidth = $1;
   } elsif (/^ID_VIDEO_HEIGHT=(\d+)$/) {
      $vidheight = $1;
   } elsif (/^ID_LENGTH=(\d+\.\d+)$/) {
      $vidsecs=$1;
   }
}

my $incsec = $vidsecs/17.0;
my $ss = $incsec;
my $i;
my $montage="montage";
for ($i = 0; $i < 16; ++$i) {
   my $fs = sprintf("%04.6f",$ss);
   system("mplayer -nosound -ss $fs -frames 1 -vo png:z=1:prefix=mptmp $vidfile");
   $fs = sprintf("%02d",$i);
   system("convert mptmp00000001.png -resize 25\% sstmp$fs.png");
   $montage .= " sstmp$fs.png";
   unlink("mptmp00000001.png");
   $ss += $incsec;
}
my $qh = int($vidheight / 4);
my $qw = int($vidwidth / 4);
$montage .= " -tile 4x4 -geometry ${qw}x${qh}+0+0 $poster";
system($montage);
system("rm -f mptmp*.png sstmp*.png");