Make Enhanced Podcasts

by Phillip Torrone
January 03, 2006

Editor's note: This How-to was originally posted in the MAKE blog.

Apple's iTunes 4.9 or later on the new iPod (color screen) allows you to view and listen to "enhanced podcasts." These are audio files that can have slideshows, URLs, and other cool extras. I referred to Apple's documentation and the Voxmedia Wiki to produce our MAKE enhanced podcasts, and then wrote up this how-to to summarize the process. Here's everything you need to know about enhanced podcasts: how to get them, how to make them, and some fun ideas for what you can do with them. So if you already know how to make enhanced podcasts, skip to the end of this article for some new tools, ideas, and experiments.

If you're a technical person, you might want to just check out the Voxmedia Wiki (props to Walter!), download all the files you need from Apple, and follow Apple's own guide.

If you just want to see what an enhanced podcast looks like (and you have iTunes on a Mac or PC), download ours. Click this link and then click SUBSCRIBE. Or, here is a direct link to the file. You might need to rename it so that it only has the .m4b extension (some systems will add .txt--we'll fix that ASAP). You can also download a zip file that contains all the source files for our enhanced podcast.

If you don't have iTunes, here is a video of what the podcast looks like on a PC (.wmv) and on a Mac (.mov)

As the podcast plays, watch the album area. Double-click the images as they play, for a larger view. We got carried away with the images and examples, but that was the point, so enjoy!

What Is an Enhanced Podcast?

Enhanced podcasts are AAC-encoded audio files with additional time-based "chapter" data inside them, such as images or URLs that are programmed to appear at a certain time as the audio plays. They're like slideshows synchronized to music (or any other audio). The formats for these files are M4A, M4B, or M4P.

Here's an explanation from the text document that comes with Chapter Tool: You can use Chapter Tool to create Enhanced Podcasts that work with iTunes 4.9 or later. Enhanced podcasts are podcasts that contain chapters. Chapters can be modified to display pictures or web links that can be displayed within the iTunes song artwork pane.

On a color iPod, these "chapters" can be skipped and navigated, and when the playhead reaches a new point in the audio, the image with the corresponding timestamp is displayed.

In iTunes, the listener can click on the image and/or the URL as the audio plays. There's also a new bookmark section/icon that lets you navigate all the chapters.

On a PC:

On a Mac:

For us here at MAKE, we see this as a better, more informative way to distribute how-tos, slide shows, and other content. We're going to do a few different types of enhanced podcasts, and as we experiment, you'll get to see our handiwork! Here's how we made our first one, a cool how-to with images and URLs, on making a USB-cable PlayStation PSP charger.

The bad news (for some) is that enhanced podcasts only work with Apple's AAC audio encoding (M4A/B). This means that the only way to view the enhanced content is on an iPod or through iTunes. I'm actually not 100% sure that this is true, since there are a couple of phones, players, and other devices that can also handle audio-only in M4A format, but I'm pretty sure none of them will display an enhanced podcast (yet). The AAC format's support for chapters, which is what enables enhanced podcasts, is great, but it's too bad that this wasn't part of a new, open format that everyone can use.

I'd like to see a new Macromedia Flash Lite spec that wraps SWF-type interactivity around MP3 audio. SWF files actually will play on many MP3 players now, if the files contain MP3 audio. This combination would deliver the same audiovisual presentation capabilities as M4A/B format, plus scriptability and the ability to make games. Of course, it should be an open source thing too, MP3 + SWF lite? OOG + SVG? Anyway...

Another thing: the new iPod doesn't output enhanced podcast images through its TV signal--the composite video and stereo audio which you can get with the iPod AV Cable. So if you want to use your iPod to play a slideshow with music on your television, you have to do it the old-fashioned way, using iTunes and the iPod photo. I bet Apple will fill in this missing capability soon in future iPod firmware upgrades.

Ingredients

To make an enhanced podcast, you'll need:

• Chapter Tool Beta (Mac only at this time)
• Mac OS X version 10.3.8 or later (Mac OS X version 10.4.1 or later is recommended)
• QuickTime version 6.5.2 or later
• iTunes 4.9
• Text editor to edit an XML file
• A music/audio file
• iPod color/photo

Procedure

1. Assemble your materials.

Download the Chapter Tool and drop the folder in your Music folder inside of your Home folder. Here are all of our source files, audio, pictures, and the XML file.

You'll now want to plan what type of enhanced podcast you want to create. I made a slideshow-like how-to on making a USB charging cable for the PSP (PlayStation Portable). It will have images and, at the end, a URL for more information. As the listener hears the content, they can pause it or click the album art panel to get a larger view. They can also click the URL (link) to get to a page with more information.

I put all my photos together in a folder called Pictures. iTunes supports the GIF, JPG, PNG, and TIF picture formats.

2. Record the audio.

Next up, you'll need an audio file that will be the sound track. Apple's Preview app, part of Mac OS X, acts as a useful "script" or prompter to read from. Just click the down arrows as you read, and record!

I recorded my audio track in GarageBand. I picked some intro music, then just started talking.

From GarageBand, I ran "Export to iTunes," which saves the audio into AIFF format.

In iTunes, I selected the new audio file and ran Convert Selection to AAC, which generates M4A-format audio. Depending on how your iTunes is set up, you might need to change your preferences in order to convert to AAC/M4A.

To change your "Importing" settings to convert to AAC, go to iTunes > Preferences > Importing. I selected AAC Encoder and Podcast for the setting.

Once the file is converted, you can do a Get Info on the file to make sure it was encoded properly. Drag the new file to the desktop or a new folder; I called mine usbpsp.m4a

If you're hardcore about recording podcast audio, be sure to check out MAKE Volume 02 for our Podcasting 101 article, or just do a web search. There are tons of great resources online on recording audio.

3. Make the XML file.

Now we're going to create a file in XML format that contains all the times, pictures, and URLs (links) that the Chapter Tool app needs to look at to create the enhanced podcast. I used TextEdit to start a new document and pasted in:

<?xml version="1.0" encoding="utf-8"?>

Next, you need to let Chapter Tool know that you are about to define chapters within an audio file. To do this, you must first specify the <chapters> tag within an audio file as follows:

<chapters version="1"> </chapters>

Once you've specified the chapters tag, you may now begin to specify individual chapters for the audio file. All chapters must be specified using the chapter tag, as follows:

<chapters version="1"> <chapter starttime="00:00"> </chapter> </chapters>

Each chapter needs to have a start time, specified in mm:ss format. The first one is easy: it's 00:00. For each start time, Chapter Tool lets you define three attributes: title, picture, and URL.

Title

We're calling our podcast "PSP USB Charger," so here's how we set the title:

If we didn't want a picture or a URL, we would be finished with this chapter definition. But we at least want a photo, to get started. Note that you don't need a title for each chapter; you can just have an image or URL.

Here's our full chapter definition, with a title and image:

Make sure that you place the folder of pictures in the same directory as your audio file and XML file, so that Chapter Tool can find everything.

File Naming

Avoid spaces in the filenames you're using, or else refer to them in the XML by substituting "%20" for any space. From Apple's Chapter Tool documentation: Please note that Chapter Tool cannot read file names with spaces, such as "My Photo.jpg" In order for Chapter Tool to work properly, you may either remove all spaces from within the picture file name in Finder, or type the URL within the XML with "%20" instead of spaces, for example "My%20Photo.jpg".

Also, your XML should refer to files with "file://", full URL, or relative path. If you put all your local files in the same folder/directory, this won't be a problem.

Image sizes?

Apple's examples use 300x300 pixel images, and that's what we used too. That size fits nicely in the album art window.

Links

At the beginning and end of our "PSP USB Charger" enhanced podcast, we show a link to subscribe to MAKE magazine. The URL displays when the audio file plays, and if the listener clicks on it, the corresponding page opens in a browser as expected. Here's how this link is defined in the XML:

Notice how I put in an affiliate link to Amazon.com. If you're doing book, DVD, or product reviews, this shows how you might interest folks in paying you for your podcasts!

Naturally, Apple made it easy to link enhanced podcasts to iTunes Music Store pages. From their documentation: You may create links that direct iTunes directly onto specific iTunes Music Store pages. To do this, drag any picture or text link within the Music Store and place it within the href portion of the Link tag.

This is really neat, and we'll talk about specific examples soon. Basically, it means you can make an enhanced podcast "concert" with links to all the artists in iTunes, so listeners can buy their music. By linking to your own web pages, you can create an audio "choose your own adventure" that's composed of multiple podcast files that point to each other in sequence. This would let the listener make their own story as they listen, clicking and "unlocking" new narrative directions as they download new enhanced podcast files.

Link Be Gone

Note that once a link is displayed, it'll stay there unless you clear it, by using a blank link like this:

Apple's documentation calls this inheritance: When working with chapters, it is important to remember that chapters will inherit attributes from previous chapters. This means that any image or link that you put up will stay there until you show a new one.

4. Compile the enhanced podcast.

Save the XML file to the same directory as the audio file and pictures folder. Now we're going to run Chapter Tool, which will read our XML file and combine our audio, pictures, and links to create one enhanced podcast file.

Chapter Tool runs from the command line, rather than using a graphical interface, so the next step is to open up your Mac's Terminal application (Utilities folder), and use the cd command to navigate to the directory you've been working in. NOTE: If you're not comfortable with Terminal, check out the "Other Tools" section at the end of this article, for helpful tools and scripts.

Here's the syntax for running Chapter Tool. Type this text into your Terminal window, substituting filenames as appropriate:

./ChapterTool -x [xml_file_name].xml -a [input_audio_file].m4a -o [output_audio_file].m4a

Follow "-x" with the name of your XML file. Follow "-a" with the name of your source audio file, which must be a MPEG4 AAC file. Follow "-o" with the filename of the new combined file you want Chapter Tool to create.

For example, from the terminal, prompt on my Mac (pts-Computer), working in my Music/Chapter Tool directory, I typed this:

pts-Computer:~/Music/ChapterTool pt$ ./ChapterTool -x usbpsp.xml -a usbpsp.m4a -o usbpsp.m4b

m4b versus m4a

Why the .m4b for the output file extension, instead of .m4a? That's a bit complicated. Basically, specifying an .m4b file type will help some users bookmark your podcast more easily. The Voxmedia Wiki explains: You may have noticed that the Podfinder and New Music Tuesday podcasts names their files m4a instead of m4b. If you name your file m4b, then your AAC file will be "bookmarkable" on non-clickwheel iPods as well because that is the filename used for audiobooks; however, clickwheel iPods with the new firmware installed will be able to bookmark m4a files too and also view chapters/chapter art/chapter links in m4a files as well. It is recommended that you name your file m4b so that even the nonclickwheel iPod listeners will at least get the added benefit of being able to bookmark where they've left off in your podcast.

For now, I always specify m4b so that more people can easily navigate files. But note that when I generate an m4b file and do a Get Info, it says that the file is "protected."

Despite what it says, the new m4b file is not actually protected. I think this is just a remnant from the OS always assuming that m4b files are protected, DRMed audio books. The files play fine on any other system I've tried. I suspect that when Apple first spec'd out iTunes, they never expected that users would be making bookmarked files with images and URLs for podcasts. It's cool that we can do this now.

If Chapter Tool encounters any errors in your XML or can't find the XML file or any of the files it refers to, it will tell you by spitting out some error messages. If it encounters no problems, then once the file is complete, you'll see something like this:

...and you'll find your new enhanced audio file in the folder:

5. Check your podcast in iTunes.

After Chapter Tool does its work, open up the new m4b file in iTunes. From here, you can add album art and index information to the podcast. You can also play the podcast, of course. It's a good idea to to a little testing to see that all the time codes, images, and URLs work as intended.

That's it--you're done!

Viewing the Podcast

In QuickTime and iTunes:

From the last step, you already have your podcast open in QuickTime. Here's mine playing in QuickTime on my PC, which lists the sequence of chapters in a drop-down box:

Note that on a Mac, you can double-click the new file to play it, but it won't work to drag it onto QuickTime. The Voxmedia Wiki explains: You must choose to open the podcast through the "open movie in player" menu option instead of dragging and dropping the podcast into the player.

In iTunes on the Mac, one thing you might notice playing your podcast is a new little book icon. When you press and hold this icon, you'll see all the podcast chapters listed with thumbnail images. Select one, and it jumps to that chapter.

As the audio plays in iTunes, you'll see the artwork change in the album art section.

If you double-click the art, it will pull up a larger view.

If there's a URL, you'll see a button over the artwork. Click that, and you'll go to the website specified in the XML file.

That one opens up Amazon to get MAKE!

On the iPod:

On the iPod, press the center button as the image appears to get a larger view. You can also click forward or back to navigate around the podcast chapter-by-chapter.

Uses for Enhanced Podcasts

I really like these enhanced podcasts--so much so, that I'm considering only podcasting in m4bs for a while.

Here comes the fun part! You may already be thinking, "Oh my, this is amazing--there are TONS of things to do with this!" But if not, here are some of things I've spotted, thought up, made, am working on, or some combination of all of that:

pCommerce

This term comes from the Voxmedia Wiki: ...podcasters can discuss a product or website, place a graphic representation for it on the screen, and simultaneously provide a hyperlink that, when clicked, would give the podcaster credit for that clickthrough and tie in to existing e-commerce systems (Amazon, etc).

Podcast Tracking

Following the same theme as pCommerce, aside from analyzing downloads, it's hard to know who listens to an audio show. But if you ask people to click a link during the audio, you have a feedback system. If you provide enough value in clicking a link, you may gather some useful data to make your shows better. You could even do a contest where the 100th person to listen to the show and click through will win something.

American Idol-Style Music Voting

Instead of (or in addition to) competing on one of those American Idol-like shows, artists can publish their songs/podcasts in the iTunes Music Store, and the audience can download and vote by clicking the URL link. Any type of voting will work with this, as long as you make the voting via an http:// call.

Diggnation-Type Podcasts

I really enjoy the Diggnation podcast with Kevin Rose and Alex Albrecht. They talk about all the cool links on Digg, and with an enhanced podcast, each segment of their show can link to the site they're talking about.

Choose-Your-Own-Adventure Audio Books

Imagine listening to an audio novel, and based on your choices, you automagically download a new audio file with more choices. You can build branching narratives by linking enhanced podcast files to each other.

One of the neat things about the linking in enhanced podcasts is that you can link to other parts of the iTunes music store. Apple's Chapter Tool documentation: You may create links that direct iTunes directly onto specific iTunes Music Store pages. To do this, drag any picture or text link within the Music Store and place it within the href portion of the Link tag. Another example: if you're doing a podcast about an audio program on NPR, just put in a link so that folks could stop, click, and download the program you're talking about.

Here's the XML you would use to link to a past MAKE: Audio show about DIY Robotics:

<chapter starttime="00:00"> <link href="http://phobos.apple.com/WebObjects/MZStore.woa/wa/viewAlbum?playlistId=74069835&selectedItemId=138280" /> DIY Robotics! </link> </chapter>

How-Tos, Flash Cards, Instructions

This is a pretty obvious one: how-tos. Not everything can be explained with small pictures on a computer or iPod screen, but many things can. For example, I really like what the K9cast folks have done with dog training. For MAKE, we're going to release some of our articles in spoken word format with added pictures. This wouldn't work for all types of articles, but the "Maker Profile" is a great example of a good listen that only gets better with extra info, like links and photos. For language learning, seeing a word as you hear it spoken, flash-card style, is pretty helpful. I've learned a bit of Japanese here and there, but now I'm thinking of relearning it by using enhanced-audio flash cards.

Lyrics

You can't really do complete lyrics in real time (yet) with enhanced podcasts, but you can put a few key lyrics on the screen, timed to a song. Or, you can provide a link to the full lyrics online.

"Brandstand" Music Links

There's a neat site by Agenda Inc., BrandStand, that rates brands by counting their mentions in popular songs. Why not have the brands appear as they're mentioned in the song, with links to buy the products or learn more. Here's some of Agenda's research:

2004 BRANDS

• The winning brand this year... CADILLAC, (taking over from last year’s winner MERCEDES). CADILLAC wins by just one point after moving ahead of HENNESSY in the final week of 2004.
• Runners up... 2nd HENNESSY (69 mentions), 3rd MERCEDES (63 mentions), 4th ROLLS ROYCE (62 mentions), and 5th GUCCI (49 mentions)
• The most brand-dropping rapper... KANYE WEST, who mentioned 19 brands in his 4 singles of 2004. He beats 2003 winner 50 CENT who drops to 7th place.

You get the point... anyway, Kayne West clearly needs to make an enhanced podcast! You could also have a link to buy tickets to a show at the end of the 'cast.

Flickrcast?

Well, maybe not a Flickrcast--but you "could" write a tool that pulls URLs in your Flickr photo set down, and then you match them up to your audio.

Advertising (the good way)

I really like Hugh's work on English Cut. It's a site about making suits by an expert tailor. It would be great to have a few audio explanations of what goes into a suit, synched to pictures of the parts, tools, stitching, etc. And then the last link goes to a page that lets you set up an appointment to get measured. You could apply this to many other products and services. I tend to think that the more special something is, the more folks will want to know about what goes into it.

PBS, NPR, and other audience-supported broad/podcasters could have a pledge link at the end of their programs.

My pal Leander Kahney, who wrote Cult of Mac is now working on Cult of the iPod. His first book had many amazing photos and stories, and it would be cool for him to read a chapter that's timed with enhanced podcast images and links that show who and where the iPod cultists are.

Meta Walking Tours and Enhanced Acoustiguide Museum Tours

Imagine walking around a town, listening to commentary, and seeing photos, blueprints, and other related "metadata" on your iPod. In NYC, lots of people are distributing their own museum audio tours, which you download to your iPod before you head in. Read more about that here. Adding chapters and images could enhance the experience.

Use Chapter Tool to Create Gapless Playback CDs

From the Voxmedia Wiki: The Chapter Tool can also be used to create chaptered AAC files which allow the gapless playback of CDs where tracks run into each other (e.g. Pink Floyd's Dark Side Of The Moon).

Tiny Animations and Video (sorta)

I think you could have an image come up every second during a podcast, and it would make a tiny animation, like a flip book. Kinda silly, but it's fun to watch a little dog run or something as your audio plays. Perhaps a dancer, or something like that, at one frame per second. You could also convert a video: keep the original soundtrack, and play it against one frame grab per second of the original video.

Gadget and Product Reviews

I'm probably going to make a few of my gadget and other product reviews products in enhanced podcast format, and see what the response is. Please let me know what you think! You'll likely see these on some of the gadget sites that are most popular with iPod owners.

Other Tools

If you made it this far, you might be interested to know if there are any other tools that can help you make enhanced podcasts. Several have emerged, even in the short time since Chapter Tool came out. Walter from K9cast sent these along to me:

My ChapterTool XML file generator

Gijs van den Heuvel's Podcast Enhancer.

RB Software's ChapterToolMe (requires Tiger)

Walter says: I've tried out Gijs' tool and I can say that it works great. I haven't gotten a chance to check out the RB Software tool yet, though, but it looks promising. Of course you've probably read my how-to.

That's it for now. Of course, I'll post more as interesting things develop. I welcome any comments and questions, and please click this link and SUBSCRIBE to our podcast in iTunes 4.9. We're going to experiment a lot, and you're likely to discover many new things--and get free stuff from the magazine too!