To say I'm very disappointed in KF8 would be an understatement. One major source of that disappointment is in the requirements for Fixed Layout, which differ markedly from that used by iBooks on iOS and Kobo Vox. In other words, you can't use the same files.
I used KindleGen2 to convert some of my fixed layout EPUBs to mobi, and then I opened up the mobi files with mobi_unpack to see what had happened. (Well, I looked at them in the Kindle Fire too, and though they did open, I'm almost embarrassed to show you screenshots here. Certainly, not acceptable for sale.) So much for "easily portable with minimal effort".
Original on iPad:
After conversion with KindleGen2 on Kindle Fire, that single page is displayed on several:
So what happened inside? Mobi, from what I'm learning (just a beginner still), is a database, with no individual files, and thus no individual file names. mobi_unpack is a Python script that goes through the mobi database and generates what would be individual files from the data.
There are a couple of interesting things here. First, there are non-KF8 mobi files and KF8 mobi files. I'm guessing that's so your mobi file will work in both KF8 compatible devices as well as legacy ereaders. Second, the original EPUB is also included (shown at the bottom, in a zip file), completely unaltered, which presumably means it sits unaltered in the actual mobi file as well, and adds to its size. Finally, there is an EPUB file that is generated from the KF8 files which is a lot smaller than the original EPUB because KindleGen reduces the size of the images. The mobi_unpack script generates this standard-format file so that you can use it to create new versions of the book. It's not an Amazon thing.
So, let's really look inside. The new specs say require a lot of things I don't see in the file that KindleGen2 created. My intepretation of that is that KindleGen2 doesn't create a fixed layout KF8 mobi from my fixed layout EPUB, it just creates a flowing KF8 mobi file.
But what if you create your own fixed layout file?
First of all, Amazon wants you to add a bunch of meta tags to the OPF file (and not to the com file, as Apple and Kobo do). These meta tags determine if the book is fixed layout, what the viewport size is, and in which orientation it should be locked, as well as what kind of book it is (for children?), and whether or not you're using "region magnification". The first three are required, which means that you can't have a book that can be viewed in both portrait and landscape modes. You have to choose.
Next, and most inexplicable of all, it says you should create a single page for pages in portrait mode, and a single HTML page for a two page spread in landscape mode. (Again, this necessitates completely redoing your original Fixed Layout book.) OK. What I completely don't understand is, if you're designing a two page spread in a single HTML page, why on earth do they want you to create it in two separate blocks that you then float next to each other? It seems like a lot of busy work.
Why not just create a single image on your single HTML page for the two page spread? Is there some benefit to dividing it up into two chunks of code on the single HTML page? I don't see it, if there is.
After much wrangling, I was able to manage to create a Fixed Layout in KF8 format and view it on the Kindle Fire. Here's the original on the iPad:
And let me tell you, it was a pain.
And led to my post from yesterday about aspect ratio (what timing, huh?) Because there was no way I was going to crop all of my pictures from that book so they would fit an entirely new aspect ratio, they simply would not have fit. Indeed, when I think of the way most people take pictures in 4:3, or similar, I consider the Kindle Fire's aspect ratio to be very problematic for the kind of books that might showcase photography in fixed layout. I'm not sure if kids' books are often found in an aspect ratio of 1.7, like the Kindle Fire.
So yeah, I'm disappointed. Just the same, I probably will get around to explaining how to do it all. And I promise more on regular flowing books for KF8 as well. Soon.