#!/usr/bin/perl
# Author: Alan J. Pippin
# Description: Take a list of video files and create a single mkv video file from them

# Pre-requisites:
# mkvtoolnix - http://www.bunkus.org/videotools/mkvtoolnix/
# ffmpeg

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# Includes
use File::Copy;
use File::Basename;
use Getopt::Std;
use File::stat;
use DateTime;
use DateTime::Duration;
use DateTime::Format::Duration;

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# Configuration parameters - CHANGE THESE TO SUITE YOUR NEEDS
my $mkvmerge=`which mkvmerge`; chomp($mkvmerge);
my $ffmpeg=`which ffmpeg`; chomp($ffmpeg);
my $tmpfile = `tempfile`; chomp($tmpfile);
my $chapter_file = $tmpfile;
my $input_file_options = "-S";
my $output_file_options = "--chapters $chapter_file";
my $timezone = `cat /etc/timezone`; chomp($timezone);
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# Command Line Options
getopts("st:o:i:h");

if(! -x $mkvmerge) { die "-E- Unable to find required program: mkvmerge\n"; }
if(! -x $ffmpeg) { die "-E- Unable to find required program: ffmpeg\n"; }
if(! defined $opt_t) { &usage(); die "-E- Missing required title: -t <title>\n"; }
if(! defined $opt_o) { &usage(); die "-E- Missing required argument output video names: -o <output.mkv>\n"; }
if(! defined $opt_i) { &usage(); die "-E- Missing required argument input video names: -i <input,input,...>\n"; }

sub usage {
    print "usage: $0 -t <title> -o <output.mkv> -i <input,input,...>\n";
    print "  -t <title>            Sets the general title for the output video file\n";
    print "  -o <output.mkv>       Sets the name of the output mkv file\n";
    print "  -i <input,input,...>  Sets the name of the input files to make into an mkv file\n";
    print "  -s                    Simulate mode. Don't actually make the video, but tell us what you will do\n";
    print "\n";
    return 1;
}

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# Helper Subroutines
sub epoch_to_date {
    my ($epoch) = @_;
    my $mtime = DateTime->from_epoch(epoch => $epoch);
    $mtime->set_time_zone($timezone);
    return sprintf("%4d",$mtime->year)."-".sprintf("%02d",$mtime->month)."-".sprintf("%02d",$mtime->day)." ".$mtime->hms;
}

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# MAIN

# Turn the list of input videos into a hash with a value equal to the modification time in epoch seconds
my %videos;
foreach $video (split(/,/, $opt_i)) {
    if(! -r "$video") { die "-E- Unable to read input video file: $video\n"; }
    my $mtime_epoch = stat("$video")->mtime;
    my $mdate = epoch_to_date($mtime_epoch);
    $videos{$video} = $mtime_epoch;
}

# Create the chapters file for the mkv file.
# Make each video file it's own chapter in the MKV file.
# Name the chapter with the date and time the video clip was taken (modified date).
print "-> Creating $opt_o with title '$opt_t' from the following video files in last modified date order:\n";
open(CHAPTERS,">$chapter_file") || die "-E- Unable to create chapter file: $chapter_file\n";
my $chapter_num = 0;
my $chapter_timecode = DateTime::Duration->new(years => 2000, hours => 0, minutes => 0, seconds => 0);
my $timecode_format = DateTime::Format::Duration->new(pattern => '%H:%M:%S.%3N', normalize => 1);
foreach my $video (sort{$videos{$a} <=> $videos{$b}} keys %videos) {
    $chapter_num++;
    my $hour = 0;
    my $min  = 5;
    my $sec  = 0;
    my $mtime_epoch = stat("$video")->mtime;
    my $mdate = epoch_to_date($mtime_epoch);
    my $duration = `$ffmpeg -i "$video" 2>&1 | grep Duration`;
    if($duration =~ /Duration: (\d+):(\d+):(\d+)\.(\d+)/) {
	$hour = $1;
	$min = $2;
	$sec = "$3.$4";
    }
    my $timecode = $timecode_format->format_duration($chapter_timecode);
    print "$mdate $hour:$min:$sec  -> $video \n";
    print CHAPTERS "CHAPTER".sprintf("%02d",$chapter_num)."=".$timecode."\n";
    print CHAPTERS "CHAPTER".sprintf("%02d",$chapter_num)."NAME=".$mdate."\n";
    my $dt = DateTime::Duration->new(years => 2000, hours => $hour, minutes => $min, seconds => $sec);
    $chapter_timecode = $chapter_timecode + $dt;
}
close(CHAPTERS);
print "\n-> Creating the following chapter file for this video:\n";
$chapter_file_contents = `cat $chapter_file`;
print "$chapter_file_contents\n";

# Create the mkv video
print "-> Creating the MKV video file '$opt_o'\n";

my $cmd = "$mkvmerge --title \"$opt_t\" $output_file_options -o \"$opt_o\"";
my $video_count = 0;
foreach my $video (sort{$videos{$a} <=> $videos{$b}} keys %videos) {
    if($video_count == 0) {
	$cmd .= " $input_file_options \"$video\"";
    } else {
	$cmd .= " $input_file_options + \"$video\"";
    }
    $video_count++;
}
print "$cmd\n";
if(! defined $opt_s) { 
    my $errno = system("$cmd");
    $errno = $errno >> 8;
    if($errno > 1) {
	unlink "$opt_o";
	die "-E- mkvmerge encountered some errors with exit code $errno\n";
    }
}

# Remove the temporary file used for the chapter generation
if(-e "$tmpfile") { unlink "$tmpfile"; }

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