Oct 22 2005

Radio Capture and Self Podcasting

Published by at 10:07 am under Declan,Fun,Tech

For a long time I’ve wanted to capture radio shows on public radio and play them back on the iPod. This article describes the process of using the RadioShark to get the content (boring, I know, others have done this) but then describes how to make the content a podcast that can be added you your iTunes or other podcast aggregator.

I got a Radio Shark, hooked it up to my PC, and used its TIVO-like software to record the shows I wanted.

I’ve read that the Mac version of the software will save in a number of formats, but the Windows version only saves as WAV files. I wanted to get these into a format that works well on the iPod – either MP3 or AAC.

These are big files, some of them over 2 hours and gigabytes in length. I needed to compress them. I also wanted to use the iPod’s bookmarking feature so that I could pause a file, jump to another playlist for a while, then come back where I left off – a feature iTunes and the iPod call bookmarking. MP3s don’t do this, only AAC files work. The trick is to name the AAC filename with an extension of .m4b (rather than the default .m4a) – this makes it a bookmarkable file.

I found a WAV to AAC converter called FAAC at http://www.audiocoding.com/modules/mydownloads/ and loaded it up on my Linux box which serves as a local Samba fileserver and Apache web server. This is the address referenced in the scripts below. FAAC takes a little while to compile, so don’t get impatient and break out of the compile when it looks like it’s hung like I did the first couple of times.

Here’s the process to convert the files:

I unmount then remount the Windows drive from the Linux box (clunky but ensures I have a clean mount), copy the WAVs over into a /tmp directory named after the date, then delete them from the Windows box to keep it from filling up. Next I run the FAAC converter on them, dropping each completed file into a web directory so it will be accessible to iTunes later. Note again that my output file has a .m4b extension to support bookmarking.

I’m not sure if ‘basename‘ is a common command in unix. I used it to strip the filename of all extensions and make it easy to rename.

Here’s the script for all of this (sound-convert.sh):

umount /var/netshare/dshare/radio
mount -t cifs // /var/netshare/dshare/radio -o credentials=/root/.cred2

DATE=`date +"%Y-%m-%d"`
echo $DATE

mkdir /tmp/$DATE-soundconv
cp /var/netshare/dshare/radio/* /tmp/$DATE-soundconv
rm -f /var/netshare/dshare/radio/*
for i in /tmp/$DATE-soundconv/*.wav
j=`basename "$i" .wav`;
echo $j;

/usr/local/bin/faac -w -q 150 -c 22000 /tmp/$DATE-soundconv/$j.wav -o /var/www/html/radiofiles/$j.m4b --artist "NPR" --title "$j" --album "$j";


I added the script to cron and run it every night at 2am. I end up with a directory full of compressed, bookmarkable radio shows! But, to get them to the iPod, I had to manually drag them into iTunes every few days and synch the device.

Automating the Process

Then iTunes 5 came out with podcast support and I wondered if I could somehow automate the process. It turns out I can! I started with Apple’s instructions for how to create an XML RSS file that specifies the details iTunes wants to define a podcast. Here’s the link for that:


From the examples at that site, I cut down fields until I got down to the bare minimum that would still function. Note that the site does not say you can use .m4b files, but I just tried it and it worked. Now I needed a method of creating an RSS file that specified my files. I whipped up a brute force script that runs right after the nightly conversions and just echoes every .m4b file in the radiofiles directory surrounded by enough XML formatting to make it a proper RSS Podcast feed.

Here’s that script (podcast-rss-maker.sh):

DATE=`date -R`

echo "< ?xml version=\"1.0\" encoding=\"UTF-8\"?>"
echo "<rss xmlns:itunes=\"http://example.com/DTDs/Podcast-1.0.dtd\" version=\"2.0\">"
echo "<channel>"
echo "<title>Private NPR Collection</title>"
echo "<link></link>"

for i in /var/www/html/blog/radio/*.m4b

j=`basename "$i" .m4b`;

echo "<item>"
echo " <title>"$j"</title>"
echo " <enclosure url=\""$j".m4b\" type=\"audio/x-m4b\"
echo " <guid>"$j.m4b"\"</guid>"
echo " <pubdate>"$DATE"</pubdate>"
echo "</item>"


echo "</channel>"
echo "</rss>"

This will create output that looks like this:

< ?xml version="1.0" encoding="UTF-8"?>
<rss xmlns:itunes="http://example.com/DTDs/Podcast-1.0.dtd" version="2.0">
<title>Private NPR Collection</title>
<enclosure url="
0.m4b" type="audio/x-m4b" />
<pubdate>Sat, 22 Oct 2005 11:54:46 -0700</pubdate>
<enclosure url="
0.m4b" type="audio/x-m4b" />
<pubdate>Sat, 22 Oct 2005 11:54:46 -0700</pubdate>

[ ... ]


Now just add this line to the end of the sound-convert.sh file:

podcast-rss-maker.sh > /var/www/html/radiofiles/podcast.xml

Finally, go to iTunes, Select the Advanced Menu – Subscribe to Podcast…:

Then enter the URL for the podcast.xml file:

Now the listing shows up in your Podcasts Menu in iTunes:

I hope this all works for you too!


There are a few things I need to clean up and understand better.

First, my RSS file grows without bound as new files are added to the directory. This is a larger problem as I need some way to clean out old files that I’ve already heard. Since the RSS file only contains the files that are present, once I solve the bigger problem, this won’t be a problem for the RSS file anymore.

I don’t really understand how iTunes decides which files to download fully when it subscribes to a new Podcast. I bet it has something to do with the pubdate attribute which I am blasting with the newest date each time I run the script. I could do something smarter and pull the date from the file if it already exists. That would take being smarter though… 🙂

I always mess up the pathing when I add something to cron. Be careful to add absolute paths to the scripts you add to cron.

Please leave comments with ways I could make this better!

UPDATE v 2.0!

Logan Browne mailed me (again!) a much cleaner version of rss-maker.sh (thanks Logan!):

# credit for this script goes to Declan
# http://www.declan.net/?p=160

DATE=`date +"%a, %e %b %Y %H:%M:%S %Z"`
TITLE="Logan's Local Feed"

echo "< ?xml version=\"1.0\" encoding=\"UTF-8\"?>"

echo "<rss xmlns:itunes=\"http://example.com/DTDs/Podcast-1.0.dtd\" version=\"2.0\">"

echo "<channel>"

echo "<title>"${TITLE}"</title>"

echo "<link>"$URI"</link>"

for i in ${MYDIR}*.mp3
j=`basename "$i" .mp3`;
k=`echo $j | sed -f urlencode.sed`;

# grab the creation date as a string and format it to RFC 2822
DATE=`stat -f "%Sc" -t "%a, %e %b %Y %H:%M:%S %Z" "$i"`

echo "<item>"
echo " <title>"$j"</title>"
echo " <enclosure url=\""$URI$k".mp3\" type=\""$l"\" />"
echo " <guid>\""$URI$k".mp3\"</guid>"
echo " <pubdate>"$DATE"</pubdate>"
echo "</item>"


echo "</channel>"
echo "</rss>"

Here are the contents of the urlencode.sed file to handle special characters:

s/ /%20/g
s/ /%09/g

11 responses so far

11 Responses to “Radio Capture and Self Podcasting”

  1. Jason Lutheron 23 Oct 2005 at 11:58 am

    find /var/www/html/radiofiles -mtime +7 -exec rm -f ‘{}’ \;

    Add this to your crontab or the RSS script to delete any files older than 7 days in the /var/www/html/radiofiles directory. You will want to add something like ‘-name \*.m4b’ if you have other files in the directory.

  2. El Payoon 24 Oct 2005 at 2:49 am

    Brilliant! This is a teriffic ‘fair use’ hack you’ve come up with – I’m on a Mac, but with my RadioShark and your instructions, including the podcast RSS maker shell script.

    It’s only a matter of time before someone mods this technique to grab shows off the TiVo, convert them and dump them onto an iPod via iTunes.

  3. Logan Browneon 25 Oct 2005 at 1:48 am

    I added a few additional variables to your podcast-rss-maker.sh script to make it easier to move around on my servers. I’ve also added accurate file date stamping and am looking into better handling of RFC 1738 URL encoding.

    I’ll send you the script if you’d like.

  4. […] Radio Capture and Self Podcasting Filed under: Declan, Fun, Tech — Administrator @ 10:07 am […]

  5. Michael Roligon 28 Oct 2005 at 7:06 pm

    I got the radioSHARK working under linux.


  6. Jason Lutheron 20 Jan 2006 at 5:27 pm

    Here’s another version of the script that is written in Perl. It tries to pull out the ID3 Title and Artist.

    #!/usr/bin/perl -w
    use strict;
    use Image::ExifTool qw(ImageInfo);
    use HTML::Entities qw(:DEFAULT encode_entities_numeric);
    use URI::Escape;
    use File::stat;
    use POSIX qw(strftime);

    # Make an iTunes/RSS(?) feed for a directory of MP3 files.
    # Perl version by Jason Luther
    # Rewrite of Declan Fleming’s shell script at http://www.declan.net/?p=160;

    my $feed_title = ‘Feed Title’;
    my $url = ‘http://www.example.com/directory’;
    my $dir = ‘/var/www/html/directory’;

    print “Content-type: application/rss+xml\n\n”;

    print ”;
    print “\n\n”;
    print “\n”;
    print “$feed_title\n”;
    print “$url\n”;

    opendir(DIR, “$dir”) or die “opendir: $!”;
    my @files = grep { /\.mp3$/ } readdir(DIR);

    my %mtime_by_file;
    foreach my $file (@files) {
    my $sb = stat(“$dir/$file”);
    my $mtime = $sb->mtime;
    $mtime_by_file{$file} = $mtime;

    my @sorted_files = sort { $mtime_by_file{$b} $mtime_by_file{$a} } @files;

    foreach my $file (@sorted_files) {
    my $file_url = “$url/” . uri_escape($file);
    my $date = strftime “%a, %e %b %Y %H:%M:%S %Z”, localtime $mtime_by_file{$file};

    my $title = $file;
    my $artist;
    my $info = ImageInfo(“$dir/$file”);
    if ($info) {
    $title = encode_entities_numeric($info->{Title}) if exists $info->{Title};
    $artist = encode_entities_numeric($info->{Artist}) if exists $info->{Artist};

    print “\n”;
    print ” $title\n”;
    print ” \n”;
    print ” $file_url\n”;
    print ” $date\n”;
    print ” $artist\n” if defined $artist;
    print “\n”;

    print “\n”;
    print “\n”;

  7. Administratoron 21 Jan 2006 at 8:36 am

    Thanks Jason!

  8. […] Declan’s Blog »Blog Archive » Radio Capture and Self Podcasting […]

  9. Dinoon 22 Jun 2006 at 12:32 pm

    My version of the RadioShark installed on Windows XP does record in the WMA compressed format. Actually, the software lets me choose between 48kbps, 96kbps or 128kbps.
    I do not have your problem because my mp3 player is not an iPod, so it will play WMA formatted files. I would like if the RadioShark did give you the mp3 option because one day I might want to make the plung to the world of iPod mania, but until then, the recorded radio programs
    in the 96 or 128 speed format works just fine.
    I do have a problem with my RadioShark that I have not resolved yet. I usually check my RadioShark files about once a week, and once in a while many of the files are only about 28 kb in size. Sometimes it is every recording since that first one that malfunctioned, but sometimes the computer issue that caused it resolved itself and some of the recorded programs after the malfunctioned recordings are of normal size. ( 26kb, 36kb, etc…)
    I usually just restart my P4/2000mhz WinXP computer and it doesn’t happen for weeks.

    Good luck, Dino.

  10. Jason Horneon 23 Jun 2006 at 3:46 pm

    Thanks for the great write-up! My situation was slightly different, in that I had to use FTP to transfer my files up to the server, and I used a different library for encoding the audio.

    I wrote up my own process (with a link back here) in this (gratuitous blog) article: http://drjason.com/?q=node/85


  11. […] then make them available as a Podcast so iTunes can automatically sync them to your iPod.” Link. Clever hack to get all the podcasts that aren’t in the iTunes directory from NPR. Share […]

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