Kindlegen, Kindle Previewer, and KF8 format

[Julien Pham]

Hi,

According to the specs, new kindlegen and Kindle Previewer can convert an ePub to the new KF8 format.

But the generated file still has the .mobi extension. Is it normal? I mean is this mobi file still a KF8 file? How can I check if it is a standard mobi file or the new KF8 one?

When I upload this .mobi file to my amazon space, according to amazon it is a AZW file, not a AZW3 file.

Another question, are there tools to edit mobi files, and especially new KF8 files? Or do I have to convert them to ePub, edit them with a tool like Sigil, then convert them back to KF8?

Thanks

[dwig]

Originally Posted by Julien Pham

...According to the specs, new kindlegen and Kindle Previewer can convert an ePub to the new KF8 format.

But the generated file still has the .mobi extension. Is it normal?

Yes, normal.

I mean is this mobi file still a KF8 file? How can I check if it is a standard mobi file or the new KF8 one?

The resulting file is not a "KF8" file, in the purest sense. It is a hybrid file containing a legacy MOBI (v7??) data section and a KF8 data section. The reading software/device decides which to view.

[Julien Pham]

Ah ok. This is so even when we purchase a KF8 file we can read it on older devices?
Is there a way to check if there is really a KF8 section somewhere? Or I should just trust Amazon for this?

Thanks

[ATDrake]

Yes, it's normal for KF8 to have .mobi/.azw as the filename extension as they are really just specially-assembled files within the old Mobipocket-style wrapper. Amazon only gives filename distinctions on files downloaded via the hardware devices and via the USB transfer option on their website. Otherwise stuff coming through the K4PC/Macs all has the same extension regardless of what type it is.

I'm not sure there's an easy way to tell the difference, but you can use the kindlestrip.py script within Mobiunpack utility (go to the latest post for the newest version) in the Mobipocket forums to see what parts exist by splitting them if they're there.

There's no way to direct-edit any Mobipocket/KF8 files and you'll have to unpack or convert and recompile (best to keep an ePub source and make changes there before converting to "final" mobi format).

[dwig]

Originally Posted by Julien Pham

Ah ok. This is so even when we purchase a KF8 file we can read it on older devices?
Is there a way to check if there is really a KF8 section somewhere? Or I should just trust Amazon for this?

Thanks

Actually, I've read that Amazon splits the hybrid files that are uploaded for sale and sends only the appropriate Mobi7 or KF8 version to the readers based on their abilities, apparently to save bandwidth. I haven't seen such files myself so I can't speak firsthand.

Still, KindleGen, standalone or via Previewer, always generates a hybrid and the current "beta" functionality in calibre does likewise.

Originally Posted by dwig

Actually, I've read that Amazon splits the hybrid files that are uploaded for sale and sends only the appropriate Mobi7 or KF8 version to the readers based on their abilities, apparently to save bandwidth. I haven't seen such files myself so I can't speak firsthand.

Still, KindleGen, standalone or via Previewer, always generates a hybrid and the current "beta" functionality in calibre does likewise.

To create a dual KF8/mobi7 you need only define specific CSS styles for each and use @media to define when to use them. You shouldn't use different text for each format, just redefine the styles for each. See explanation below. So the textual content is not much bigger for a dual formatted file compared to a single formatted file. It would be a minute difference in size. However, if the book contained media such as audio and video, that could add a substantial amount to the file size. I have no idea if Amazon filters out the KF8 media portion when sending to a non-KF8 capable device, but I hope note. I can imagine that two different files might not whispersync correctly. Plus if you sync via WiFi then Amazon would not really save much by sending a smaller file. They would only save if the file was sent via 3G.

Example explanation:

Define a standard paragraph style for each format but keep the style name the same, for example p.myStandardParagraph. Use @media within the CSS to define p.myStandardParagraph as using black text for mobi7 and blue text for KF8. When the book is displayed on a non-KF8 device the CSS will format the text for p.myStandardParagraph in black and when the book is displayed on a KF8 device the CSS will format the text in blue.