Ebook Formats

Nov 01 2009 Published by under General, Kindle, Technology

As I’m considering picking up a Nook next month, I’ve been thinking about the possibility of transferring my Kindle books over to it. This has led me to do a bit of research into ebook formats.

First of all, we have the Kindle format, .azw, which is actually just a slightly modified version of the Mobipocket .mobi format with some changes to the DRM and the way the serial number is stored.

And how about the Nook? It supports eReader .pdb and EPUB .epub formats (as well as PDF, but that’s a bit different).

So, how to turn an .azw into an .epub or .pdb ? Well, first you need to turn the .azw into a .mobi. This can be done with the free tool called MobiDeDRM. I have no idea how legal this tool is, so I’m not going to directly link to it or tell you how to use it. But there’s this site called Google that should help you find out all you need to know about it. But I will say that it’s a Python based, command line tool. No fancy UI or anything, but all in all, not too difficult to use. The result is a non-DRM .mobi version of your book.

I’ve actually been using MobileDeDRM for a while, for a couple of reasons:

1. The whole thing where Amazon went and deleted books from users’ Kindles made me want to have a non-Kindle backup.

2. Occasionally I like to use the text-to-speech feature, and this is disabled on many books. By converting it to a .mobi you can get the text-to-speech back, but this sometimes requires some other steps, which I’ll cover below.

Note, I’m not advocating removing DRM for any kind of illegal purposes, such as sharing, torrenting, reselling, or otherwise ripping off the publisher/author/Amazon. But I do believe you have a right to personally use your own purchased content in the way you want, including listening to it, viewing it on another device, and protecting it from being deleted.

Anyway, now you have a non-DRM, .mobi version of your Kindle book. There are two free tools you can use at this point to convert it to something Nook-ready.

1. Calibre. This is a hard core ebook conversion tool. It reads a number of different formats, and though it only ouputs to three (.mobi, .lrf, .epub), it gives you all kinds of options on how to convert, including editing of metadata, look and feel, page layout, chapter detection, and bulk conversion. Generally, the defaults work pretty well. Calibre also deals with images in ebooks pretty well and has some other neat features I haven’t even tried, such as converting RSS feeds to ebooks, and direct device integration.

2. Stanza. This is actually a desktop ebook reader application, but once you load up your ebook into it, you can export it into something like 16 different formats, including .epub and .pdb. The one thing Stanza doesn’t do so well is images. And by “doesn’t do so well” I mean it ignores them. At least in the version I’m using. Not sure if they’ve improved that or plan to. But mainly it’s good for straight text.

So, using either of these tools to convert the .mobi to either .epub or .pdb, you should be able to view these books on a Nook. I did convert a Kindle book down to a .pdb via Stanza and tested it on the Barnes and Noble desktop ebook reader, and that worked fine, which is promising.

As far as enabling text-to-speech, in the few I tested, I converted the Kindle book to .mobi with MobiDeDRM and put that back on the Kindle. While it worked fine, the text-to-speech was still disabled. I think what I did was open up the .mobi in Stanza and re-exported it as another .mobi and put that back on the Kindle, and voila, text-to-speech re-enabled. Unfortunately, this kind of threw off the formatting of the book a bit. The text seemed a lot more squished together. Might want to try that with Calibre, which gives you more control over stuff like that.

At any rate, I think it’s cool to know about all these different formats and how to convert them. Even if you don’t plan to get a Nook or Kindle, you might have another device you want to read books on, with the eReader software, for example. That also takes .pdb files, so the techniques here should work the same way.

More info on various ebook formats here: http://en.wikipedia.org/wiki/Comparison_of_e-book_formats

12 responses so far. Comments will be closed after post is one year old.

  • Ash says:

    KP, Thank you for the writeup, I too plan on picking up a Nook and have been following your e-book posts recently. How viable is a reader for technical books with images and specific code style typefaces? Do you currently read any technical manuals/books on your Kindle? Could I say read one of your books on these devices?

    Thank you!

  • Don says:


    Sorry, this has nothing to do with e-books! I just started your AS3 Animation book – terrific! Thanks, it’s brilliant!



  • […] this little tid-bit on Keith Peters blog. basically it breaks down how to convert your Kindle purchased ebooks to other […]

  • Eugene says:


    Is there any way to covert a Kindle PC book to an audio book? The text-to-speech is not present in the Kindle PC version.


  • mandy says:

    Hi, Can you convert Barnes and noble to read on a Kindle?
    If so how.

  • Marcia says:

    Hi, has anyone used these methods on the iRiver? I have a number of Kindle books that I have read on one of the other option, i.e. laptop, BlackBerry. I have been holding out since the Kindle doesn’t offer the use of an SD card to store more books. However, the iRiver Kindle look a like does. Thanks, Marcia

  • Nathanael says:

    “I do believe you have a right to personally use your own purchased content in the way you want”

    And there’s your fundamental error. You have never “purchased” an ebook from Amazon. You LICENSED them. All you purchased was permission to read them.

    Because you do not own the ebook, you are not entitled to do anything with it that Amazon has not specifically authorized. You’re not entitled to read it on any device Amazon hasn’t authorized; you cannot loan it, give it away or resell it (first sale rights don’t apply). And I’m quite certain converting it to other formats is a violation of the contract you agreed to when you paid your money.

    That being said, my sentiments are with you (which is why I won’t buy a Kindle or any DRMed content). Just don’t expect your arguments to hold up in court.

    Always remember; you don’t BUY ebooks (not even at B&N), you license them.

  • Vikarti Anatra says:

    Well, if I _license_ kindle books – then amazon’s website is broken for me.
    I see Buy now with 1-click button on kindle editions,same as on paper ones,NOT ‘License now for use as Amazon want with 1-click’ . So if Amazon’s site VERY CLEARLY tells me to BUY e-book – why I should not think I bought it?

  • Kandi73 says:

    can you please explane on how to use MobiDeDRM. I have it and I don’t know how to work the program.

  • Ihatekindle says:

    Vikarti Anatra, I think Nathanael was warning, not saying that OP or yourself are wrong.

    Doesn’t matter what it says, reading the small print is a must, Amazon (and other big corps) have successfully sued people an organisations in the past, despite there being obvious ‘markers’ like you have mentioned.

    These organisations have even enforced a different literal meaning to words, making any word that they use not actually binding in law.

    If you were to search long enough in both Amazon’s own reams of legal talk, and through the many test cases around the world, you may find that the word “Buy” is redefined as “To purchase or Loan or borrow, with no legal rights or duties to anyone but Amazon” or such-like.

    It’s simple, and worth remembering, these giant Corps own everything you do, and that means they own you.

    • Vikarti Anatra says:

      I understood your idea…
      except that in my case(and many related ones) it will be a little difficult for them to sue me for broken DRM. (I’m not in USA).

      And simple fact I _can_(technically,if I want to) remove Kindle’s DRM was one of big reasons for me buy Kindle 3(and use Kindle Store)(and plan on Kindle DX)

      Strangely -:), sometimes when I browse Kindle Store I see link to author’s website – and from it – link where I can get same book(and for same _or lower_ price) in DRM-free version

  • Alex says:

    Nathanael and friends are missing the point that folks like keith and myself are of the opinion that placing more restrictions on what a person can do with an electronic book than already exist for paper books is unreasonable. We therefore ignore Amazon’s attempts to control things that they have no business controlling.

    Are we breaking the law? Yes. But then so are those African-Americans sitting in the front seats of busses in the USA.

    If I buy the paper book, I can annotate it, read it aloud to my friend, cut the spine, laminate each page and bind it again so I can read it in the bath (or while SCUBA diving), etc. The rights of the author or publisher to control what I do with the book after selling it to me are non-existent. I still have to abide by Copyright (i.e.: don’t try to make money off the author’s work without cutting them in on the deal, don’t try passing the author’s work as my own, etc), but there are no limits on where and when I’m allowed to read the book.

    If I buy the electronic book from Amazon, I’m limited to only reading it on my Kindle. I’m not allowed to read the book aloud to my friend unless I pay an extra licence fee.

    Anyone who thinks it is somehow fair and equitable for publishers of electronic books to control what the customer does with an electronic book any more than they control what is done with a physical book, should have a read of “The Right To Read”, an essay by Richard Stallman: http://www.gnu.org/philosophy/fsfs/rms-essays.pdf

    DRM controls, like locks on doors, only hinder honest people. In my case, the only time I buy electronic books from Amazon is when there are no other avenues for acquiring that publication. The “pirates” will simply get the DRM-free version from their anonymous friend on the Internet.

    O’Reilly, Pragmatic and Packt Publishing all sell DRM-free books, and as a result they are my first ports of call when looking for technical texts. Most of my library consists of O’Reilly books, a fair chunk are Pragamatic, with a couple from Packt. Out of sixty-odd books, I have two from Amazon because they were the only house offering “Refactoring: Improving the Design of Existing Code”, and “Working Effectively With Legacy Code”. I have no books from the Apple iBookstore.

    The corporations do not own everything you do, unless you let them claim it as their own.