How to listen to your audio books using your favorite podcast app

This post talks about two things:

  1. how to save backup copies of your Audible audio books
  2. how to create an podcast feed of your audio books

Update 2018-05-27: Audible stopped offering to download the audio files in "Format 4". There are solutions out there, but I haven't gotten around to studying them, yet.

Update 2018-05-29: The solution is on GitHub and is called KrumpetPirate/AAXtoMP3. Thanks to @igami@social.tchncs.de for the tipp!

Why?

I buy all ebooks from the Amazon Kindle store, because I know I can save a backup copy of each book in a non-DRM format. This is not about sharing ebooks but rather about making sure that I can keep a copy of my books in a digital format that I will be able to read in the future, too. Also, I want to be able to use any ebook reading app or device I want to, not just Amazon's Kindle apps. Incidentally, I read most of my ebooks on a Kindle Paperwhite because it's just a great device. I sync the books via the Calibre app, though, and the Kindle device is not registered with my Amazon account.

Anyways.

I want the same for my for Audible books. I love audio books, but I hate that I have to rely on the Audible app, with no protection against someone closing down my Amazon account or what not. Turns out, there is a way to do that, without even removing any DRM, because, apparently, there is no DRM on these files.

How to backup your Audible books

Creating a backup mp3 of audible books is surprisingly simple. Thanks to @octotherp for this tipp!

  1. Go to your Audible library.
  2. In the upper right hand corner, select "Format 4" as the download audio format.
  3. Use ffmpeg to convert the downloaded files to mp3.

To convert a single audio book, the shell command is:

$  ffmpeg -i IAmABook.aa -codec copy IAmABook.mp3

To convert all downloaded audio files, use a shell for loop:

$ for file in *.aa; do ffmpeg -i "$file" -codec copy "${file/%aa/mp3}"; done

This converts all files with the extension .aa and renames them with the extension .mp3.

How to create a podcast feed of your audio books

To create a podcast (RSS) feed from a collection of mp3s is surprisingly easy, too. Because others have solved the problem for us.

I'm using the PHP script DirCaster and my shared hosting account at my favorite web host DreamHost.

Download and unzip DirCaster in a directory

    $ wget http://dircaster.org/DirCasterV09k.zip
    $ mkdir audiobooks
    $ cd audiobooks
    $ unzip ../DirCasterV09k.zip

Edit config_inc.php to set the title and description of the feed. I also add a feed image:

$rssImageUrlTAG   = "https://myaudiobookfeed.com/books.png";

To keep thinks neat, I put the mp3 files into a subfolder books and edit the config_inc.php accordingly:

$mediaDir = "./books"

The audiobooks directory now has to be served by a web server. A simple one that runs PHP is enough though. I put my feed at a random subdomain that no-one is going to find by accident.

At least my favorite podcast app Pocket Casts has no problem subscribing to it. I also tried adding password protection using HTTP auth, but that didn't work.

If you have questions about any of this, please send me a message.