UPDATE 2: Please see this post for the latest working version of this module.
UPDATE 1: This code works with XML::RSS version 1.05 or so. The newest versions of this library removed the encode() method for reasons beyond my reckoning. You can either use this code as a starting point for porting to the new XML::RSS module (and tell me how you did it!) or simply use the older version, which is still available on CPAN.
Like searching for Bigfoot, creating a podcast feed that’s recognized by Apple can be an elusive, furtive and lonely process. Most know that podcasts are really just RSS 2.0 feeds with some extra tags. This seems like something perl should handle. The perl module XML::RSS nearly has everything necessary, but there’s always a catch: the itunes namespace.
All is not lost, because XML::RSS is a class that can be inherited from. With a little overriding goodness, you too get make valid feeds that even Apple’s iTunes music store will accept. Here’s my module that inherits from XML::RSS. While it’s not a complete solution, it works well enough for me.
package XML::RSS::Podcast;
use XML::RSS;
@XML::RSS::Podcast::ISA = qw[XML::RSS];
sub as_string {
my $self = shift;
return $self->as_podcast_rss;
}
sub as_podcast_rss {
my $self = shift;
my $enc = $self->{encoding};
my $output = <<EOT;
<?xml version="1.0" encoding="$enc"?>
<rss xmlns:itunes="http://www.itunes.com/dtds/podcast-1.0.dtd"
version="2.0">
EOT
$output .= $self->podcast_start_channel;
for my $i (@{$self->{items}}) {
$output .= $self->podcast_item($i);
}
$output .= $self->podcast_end_channel;
return $output .= "n</rss>n";
}
sub podcast_start_channel {
my $self = shift;
my @fields = qw[ttl title description link language
pubDate lastBuildDate creator
webMaster copyright
];
my @image_fields = qw[title url description link
width height];
my @itunes_fields = qw[subtitle author summary
image];
my $output = "<channel>n";
for my $f (@fields) {
if (length($self->{channel}->{$f})) {
my $s = $self->encode($self->{channel}->{$f});
$output .= "t<$f>$s</$f>n";
}
}
my $seen_image = 0;
for my $f (@image_fields) {
if (length($self->{image}->{$f})) {
unless ($seen_image) {
$output .= "t<image>n";
$seen_image = 1;
}
my $s = $self->encode($self->{image}->{$f});
$output .= "tt<$f>$s</$f>n";
}
}
if ($seen_image) {
$output .= "t</image>n";
}
# Owner name/email not handled
for my $f (@itunes_fields) {
if (length($self->{channel}->{itunes}->{$f})) {
my $s=$self->encode($self->{channel}->{itunes}->{$f});
$output .= "t<itunes:$f>$s</itunes:$f>n";
}
}
# FIXME: Doesn't handle sub cats.
if (ref $self->{channel}->{itunes}->{category}) {
for my $c (@{$self->{channel}->{itunes}->{category}}) {
my $s = $self->encode($c);
$output .= qq[t<itunes:category text="$s" />n];
}
}
return $output . "n";
}
sub podcast_end_channel {
return "</channel>n";
}
sub podcast_item {
my $self = shift;
my $item = shift;
my @fields = qw[title guid pubDate description];
my @itunes_fields = qw[author subtitle summary
duration keywords explicit];
my $output = "t<item>n";
for my $f (@fields) {
if (defined $item->{$f}) {
$s = $self->encode($item->{$f});
$output .= "tt<$f>$s</$f>n";
}
}
if (ref $item->{enclosure}) {
$output .= "<enclosure";
for my $f (qw[url length type]) {
if (defined $item->{enclosure}->{$f}) {
$output .= qq[ $f="$item->{enclosure}->{$f}"];
}
}
$output .= "/>";
}
for my $f (@itunes_fields) {
if (defined $item->{itunes}->{$f}) {
$s = $self->encode($item->{itunes}->{$f});
$output .= "tt<itunes:$f>$s</itunes:$f>n";
}
}
return $output .= "t</item>n";
}
A word about the RFC822 pubDate. This seemingly arbitrary date format
can be easily generated with a call to strftime(). The
format string is "%a, %e %b %Y %H:%M:%S %z". You might think
that you can use mysql’s DATE_FORMAT() to replicate this, but you’d be wrong.
Instead, generate mysql queries with UNIX_TIMESTAMP(), feed the result of
that to localtime() and feed that to strftime(). Simple, no? No, but such
are the challenges in programming.
Here’s a sample of how I use this for pseudocertainty.com.
use strict;
use DBI;
use POSIX qw[strftime];
use MP3::Info;
my $rssfile = shift || "./ps-pod.rss";
my $dbh=DBI->connect("dbi:mysql:pseudo", "pwrUser", "s3cr3t")
or die "connect: $DBI::errstr";
my $shows = get_shows($dbh);
$dbh->disconnect;
my $rss = XML::RSS::Podcast->new(version => "2.0");
my $rfc822_fmt = '%a, %e %b %Y %H:%M:%S %z';
my $iMeta = { "author" => "Joe Johnston and Mike Lord",
"summary" => 'UFOlogy, Cryptozology and
the people who love them are
discussed on this
internet-only radio show',
"subtitle" => "Don't be Certain.
Be PseudoCertain.",
"category" => ["Talk Radio"],
};
$rss->channel(title => 'PseudoCertainty',
"ttl" => 60, # time to live
link => 'http://www.pseudocertainty.com/',
language => 'en-us',
description => 'UFOlogy, Cryptozology and the
people who love them are discussed
on this internet-only radio show',
copyright => "Copyright Joe Johnston and Mike Lord",
webMaster => "jjohn@pseudocertainty.com",
pubDate => strftime($rfc822_fmt,localtime()),
"itunes" => $iMeta,
);
for my $r (@$shows) {
# no more than 30 words
my @words = map { s/(<+>)//g; $_; }
split /s+/, $r->{about};
my $desc = "not set";
if (@words > 30) {
$desc = join " ", @words[0..29], "...";
} else {
$desc = join " ", @words;
}
my $finfo = get_mp3info("/path/to/shows/$r->{mp3_filename}");
my $pl = qq[http://pseudocertainty.com/$r->{mp3_filename}];
my $enc = { url => $pl,
length => -s "/path/to/shows/$r->{mp3_filename}",
type => "audio/mpeg",
};
my $itunes = {
explicit => "N",
keywords => "UFO aliens zorknapp",
summary => $desc,
duration => $finfo->{TIME},
}
$rss->add_item( title => $r->{title},
link => $pl,
pubDate => strftime($rfc822_fmt,
localtime($r->{pretty_created})),
enclosure => $enc,
permaLink => $pl,
description => $desc,
"itunes" => $itunes,
);
}
$rss->save($rssfile);
#------------------------
# subs
#-------------------------
sub get_shows {
my ($dbh) = shift;
my $sql = qq[
SELECT *,UNIX_TIMESTAMP(created) as pretty_created
FROM shows WHERE publish = 1 ORDER BY created DESC;
];
my $sth = $dbh->prepare($sql);
die "get_shows: '$sql': " . $sth->errstr unless $sth->execute;
return $sth->fetchall_arrayref({});
}
And they called me a fool for wanting to make XML::RSS spew podcast RSS. But I showed them! I showed them all! Bwahahhaha!