#!/usr/bin/perl
# Purpose:
# read high quality $ORIG_FORMAT files from one directory tree
# and output low quality ogg to a mirror copy tree
#
# It will suffer intteruption and resume where it left off, which 
# is handy if you have a slower box and need to do it over the course
# of several days
#
# The idea here is that I want to listen to my music on 
# my Sharp Zaurus which plays oggs, but to get my whole
# collection on it I need to encode at a pretty low bitrate
#
# This script may be a bit sloppy/crappy/old, but it gets the job done.
# I strongly suggest reading it to make sure it will work for your 
# system before running it.  
#
# To convert from/to other formats is not too hard, just modify what needs modifying
#
# It does assume a directory structure of /artist/album/title_track#_etc.$ORIG_FORMAT
# If your setup isn't like that, you can run it anyway or change the regexp in 
# the convertogg sub.
#
#  You may feel free to use it for personal use only under the terms of the GNU GPL 
#  a copy of which can be found at http://gnu.org/copyleft/gpl.html
#
#  Copyright 2005 Matthew Steven http://www.matts.org/
#
#  Update Mar 2008, added average concurrency for taking advantage of multi core cpus

use strict;
my $ENCODER='which oggenc';
my $WAVMAKER=`which flac`;
my $INFO=`which ogginfo`;
chomp $INFO;
chomp $WAVMAKER;
chomp $ENCODER;
my $TMPDIR='/tmp';
my $PATH_TO_HQ='/home/matt/tunes/All';
my $PATH_TO_LQ='/home/lq2_tunes';
my $OUT_QUALITY=2;			# oggenc encoding quality.
my $AVG_CONCURRENCY=3;			# set this to number of cpu cores + 1
my $ORIG_FORMAT='flac';
$SIG{CHLD}='IGNORE';

main($PATH_TO_HQ);

sub scanit($){

	my $rootdir = shift;
	my($fileinquestion) = $rootdir =~ m/\/([^\/]+)$/;
	my($lqdir) = $rootdir =~ m/$PATH_TO_HQ\/(.*)/;

	if(-d "$rootdir"){

		$lqdir =~ s/[^\w\s\d\/\-\.]+/_/g;
		mkdir("$PATH_TO_LQ/$lqdir") unless (-d "$PATH_TO_LQ/$lqdir");
		main($rootdir);

	}elsif($fileinquestion =~ /$ORIG_FORMAT$/o){

		
		my($outf) = "$PATH_TO_LQ/$lqdir" =~ m:^(.+)\.$ORIG_FORMAT:;
		$outf="$outf.ogg";
		# vfat chokes on all sorts of things in file names so let's keep it clean
		$outf =~ s/[^\w\s\d\/\-\.]+/_/g;
		my($disp) = $rootdir =~ m:^.*/([^/]+)$:;
		print ">>>O) Converting $disp ...\n";
		print "=" x 80;
		print "\n";
		if(!-f $outf){
			convertogg("$rootdir", $outf);
		}else{
			print  "Exists, skipping  $disp";
		}
		print "\n";
		print "=" x 80;
		print "\n";

	}elsif($fileinquestion =~ /m3u$/o){

		print ">>>M) Linking $rootdir to $PATH_TO_LQ/$lqdir\n";
		link($rootdir,"$PATH_TO_LQ/$lqdir");

	}else{

		print ">>>?) '$fileinquestion' skipping\n";

	}

}

sub main($){
	# Cant find a pure perl way so unix it is...
	my $qd=quotemeta($_[0]);
	foreach(`ls $qd`){
		chomp;
		next unless($_ !~ /^(\.|\.\.)$/o);
		scanit("$_[0]/$_");
	}
}

sub convertogg($$){

	my($info) = $_[0] =~ m:$PATH_TO_HQ/(.+)$:;
	my($artist,$album,$title) = $info =~ m:^([^/]+)/([^/]+)/([^/]+).$ORIG_FORMAT$:;
	#die "Artist: $artist Album: $album Title: $title \n $info";
	my $mqp=quotemeta($_[0]);
	my $mqc=quotemeta($_[1]);
	my $pid=-1;
	# Should we fork or should we wait?
	if(`pgrep oggenc|wc -l` < $AVG_CONCURRENCY){
		$pid = fork();
		return if($pid > 0); # if pid > 0 we forked and should jump to the next one
	}else{
		sleep(4);
		return convertogg(@_); 	# we only want forked encoders, no waiting that way.  
					# Recurse until it takes, shouldn't get very deep and will return once it forks off a pid.
	}
	$artist =~ s/[^\w\d]+/ /g;
	$title =~ s/[^\w\d]+/ /g;
	$album =~ s/[^\w\d]+/ /g;
	$album =~ s/^$artist[_\s]+(.*)$/$1/g; 	# strip artist from album name
	$title =~ s/^.+\D(\d\d\D.+)$/$1/g;  # strip off the artist / album info from the song title, this is format-specific- my song files are 01_songname.ogg
	$artist=quotemeta($artist);
	$title=quotemeta($title);
	$album=quotemeta($album);

	# reason for the double-tagging is so that it will have uppercase tags for some players that are case-challenged
	my $progstr = "$WAVMAKER -d -c $mqp 2>/dev/null | $ENCODER -o $mqc -q $OUT_QUALITY -c ARTIST=$artist -a $artist -c TITLE=$title -t $title -c ALBUM=$album -l $album -";

	`$progstr`;
	# id3tag them  if you like, some programs don't read ogg metadata
	#`/usr/bin/id3tag -a $artist -A $album -s $title $mqc`;

	exit if($pid == 0) #this would be a child finished up

}