Creating a mobi from an epub

[gmw]

Up to now I've been creating a nice clean epub and then using kindlegen to create a mobi file. The only reason I've been doing this is to check that it comes out okay in the Kindle Previewer. My assumption has been that my distributor (or Amazon) will be using a similar conversion tool when they get my epub, so it seemed like a good thing to check. The result, in Kindle Previewer, has always looked very good, so I didn't worry any more about it.

But now I'm thinking of rearranging my distribution options and may want to produce a mobi file that readers will actually use, so I've been looking at mobi files in more detail.

One thing that I've noticed is that kindlegen creates a file around three times larger than the epub. I recently read in the MR Wiki that this is because the mobi file actually does contain three copies of the book. This may be fine for sending to Amazon, who will send whichever bit of the file is appropriate for the device at the other end, but if I want a mobi to put on Smashwords (for example) then do I really need a three-in-one file? (And there's a note in the Calibre conversion that suggests some devices might have trouble with such files.)


I've tried following instructions on the wiki to use Mobipocket Creator v4.2 (I get the impression it's now long out of date) to create a PRC file - and it produces a file slightly smaller than my original epub. Great, but along the way it seems to be getting unicode characters corrupted and distorting some of the styles.

I've tried using Calibre to do the conversion (I've read both recommendations and denigrations of this option). It also produces a smaller file (if you don't ask it to install "both" formats), but it distorts the layout of the front matter (something that kindlegen never did).


So who should I believe? Since kindlegen gives me a good, albeit very big, result, should I be happy with that? Or should I keep playing with my epub in the hope of producing some variation that Calibre (for example) can convert consistently? Do Kindle users downloading from sources like Smashwords care if the mobi file is three times larger than the epub?

These are all questions I don't know how to answer, and I'm sort of hoping the good folks here may be able to offer some suggestions.

[Doitsu]

Originally Posted by gmw

One thing that I've noticed is that kindlegen creates a file around three times larger than the epub. I recently read in the MR Wiki that this is because the mobi file actually does contain three copies of the book.

The KindleGen output file contains a mobi file (the old mobi7 format), an azw3 file (the new KF8 format) and the source files. You can extract whatever format you need with the KindleUnpack plug-in.

Originally Posted by gmw

(And there's a note in the Calibre conversion that suggests some devices might have trouble with such files.)

IIRC, this refers to hybrid mobi files and non-Amazon ebook readers.

Originally Posted by gmw

I've tried following instructions on the wiki to use Mobipocket Creator v4.2 (I get the impression it's now long out of date).

It is indeed out of date and only marginally useful for generating dictionaries, because KindleGen's dictionary code hasn't been updated in ages.

Originally Posted by gmw

Do Kindle users downloading from sources like Smashwords care if the mobi file is three times larger than the epub?

I've never used SmashWords, but from what I've heard, they've only recently accepted ePubs and don't accept the direct upload of .mobi files.

IMHO, the best strategy for creating small files is using KindleGen with the -c2 (compression) switch and then extracting both .mobi and .azw3 files with KindleUnpack.

If you use the -c2 switch on the command line, for example:

KindleGen -c2 mybook.epub

the resulting .mobi and .azw3 files are generally only 10 to 20% larger than the orginal .ePub file.

[gmw]

Thanks very much for that.

I'm not sure what the deal is with Smashwords and mobi files (I haven't tried to distribute through them yet, but it is one I'm considering) it was mainly as an example that I knew supplied mobi files for some books - and, curiously, mobi files smaller or similar size to the epubs on the couple of free books I checked out. (If Smashwords do their own mobi creation I will need to be careful, after what I've seen in my own testing.)

Is it safe to assume that "the old mobi7 format" will be readable on all current Kindle readers? So if I extract that, and test it out on the Kindle Previewer, I can make it my reasonably sized "Kindle version" for any place that needs it. I'm presuming I should still send Amazon the full file, after testing, and let them deal out the bits they want.

[Doitsu]

Originally Posted by gmw

I'm not sure what the deal is with Smashwords and mobi files (I haven't tried to distribute through them yet, but it is one I'm considering) it was mainly as an example that I knew supplied mobi files for some books - and, curiously, mobi files smaller or similar size to the epubs on the couple of free books I checked out.

AFAIK, they automatically generate .mobi files from MS Word docs that need to be formatted according to their very strict style guide. If the SmashWords .mobi files are smaller than the ePub versions, they're most likely mobi7 files.

Originally Posted by gmw

Is it safe to assume that "the old mobi7 format" will be readable on all current Kindle readers?

The old mobi7 format can indeed be read by all Kindles (and some ePub readers with mobi support). However, since it's based on the old HTML 3.2 standard, the mobi7 version might look very different from the ePub version, depending on the styles that you used.

Most likely you won't have to worry about this at all, because if you upload your book to KDP as an .ePub file, Amazon will automatically send the new, better-looking AZW3 format to those devices and apps that support it and the old mobi7 format to the owners of older readers.

[gmw]

I've just run through the extraction process now and tested both the mobi and the azw3 output files in the Kindle Previewer.

Strangely the mobi file is behaving perfectly while the azw3 seems to have lost some of the styles - or that's how it appears in the previewer. Some text I had in italics (using styles) doesn't show as italics in the azw3 file, and the scene break "* * *" which was centred using a style is left justified. And yet it all shows fine in the mobi file.

Given that all my testing had been good before, I must assume it was always looking only at the mobi part of the file. Now I'm left wondering if there is a problem with my files, of if this is just the nature of the previewer. I'm using previewer v2.9 and see there's a v2.92, I'll give that a go.

ETA: Whoops - it helps if you read the fine print, or the FAQ anyway. Got to select Kindle Fire or later to view azw3, and that works fine. Both extracted files working great.

Thanks heaps for your help.

[nikkie]

Doitsu is correct that our Smashwords Direct feature only accepts epubs at this time. If you want to have other formats in addition, you should upload a word document in addition to your ePub. Depending on what you are using to create your ePub, if you start with html, you may be able to convert a reasonable clean word document from the ePub document. (Pandoc can convert form html to docx if you need it.)

Most of the people who have trouble with their Word document uploads don't actually know how to use Word styles, which is important to keep the document clean for the conversion *to* ePub. If you're coming *from* a reasonable clean conversion engine, you should be fine.

[gmw]

Thanks for that confirmation Nikkie. I've yet to decide whether I will bother with other formats at Smashwords (having gone to considerable trouble to get a good clean epub), but it has been useful to work out how to get a good (and small) mobi file if/when I do need one.