ePUB to AZW3 or still to MOBI

[_kind_le]

Hello folks,

In 2022 Amazon announced a start of deprecation process of MOBI format support. And so far it affected only "Send to Kindle" service (which allows you to send your existing MOBI "3rd party" books to your Kindle device). Also they made a devision - all books from their store are Books and from "Send to Kindle" - now are Docs. Fortunately I'm not using that service so all my books successfully managed by Calibre and are a part of device's Book Library.

Since you can still legally use MOBI files over Calibre/USB and there is no any signs that Amazon will remove MOBI support from e-readers (I guess because of backward compatibility since amount of MOBI books are significant) - is there any advantage to convert ePub to AZW3 instead of MOBI?

I read that AZW3 is the same ePub + Amazon's proprietary DRM, other people say MOBI is the same as ePub but just older. So think it's pretty easy to convert from old one to new one format without any losses but not vice versa so conversion ePub -> AZW3 seems like more robust solution.

Also noticed that publishers aren not supplying small e-book stores with MOBI format anymore (in my case majority are ePub, FB2 and RTF) I have this kind of question:

Does Calibre better do conversion ePub -> AZW3 or ePub -> MOBI (if we're talking about text books, without tons of images/fancy layouts) or better to use some special tool like "Kindle Previewer" to convert from ePub?

What is your experience overall?

[DNSB]

AZW3 is not ePub but it is very similar with Amazon leaving out some features and adding in other proprietary features. MOBI is loosely based on the pre-ePub OEBPS specification but MobiPocket added some proprietary features and removed others which Amazon continued doing after they purchased MobiPocket. Compared to ePub/AZW3, it sucks capability wise.

Personally, in testing Kindle Previewer, Send to Kindle (web version) and calibre to convert ePub to azw3, the visual appearance is pretty much the same with any of them on my Paperwhite 4 (the one with the lousiest display...)

I avoid MOBI since it lacks many of the features I prefer such as being able to use % for widths instead of absolute units which means I either need to use a mass of media queries to set sizes or I need to generate different .mobi files for different screen resolutions. Take a look at the css stylesheets in a Vellum generated ebook. One of them is dedicated to close to 200 media queries taking up over a thousand lines.

If you use Kindle Previewer and split the output file into it's azw3 and mobi components (KindleUnpack does this), it's relatively easy to see the differences though for most fiction books, they aren't all that noticeable.

[JSWolf]

Can you use a custom font from the Aa menu with Mobi?

[_kind_le]

Originally Posted by DNSB

...
If you use Kindle Previewer and split the output file into it's azw3 and mobi components (KindleUnpack does this), it's relatively easy to see the differences though for most fiction books, they aren't all that noticeable.

Thank you for sharing your experience!

I'm not planning to edit/write books so wouldn't have such problems you've described - but it's clear now that for new books which have no MOBI support I'm gonna convert ePub to AZW3 for better format compatibility. However don't see any reason to do so if a book has native MOBI from publisher

[_kind_le]

Originally Posted by JSWolf

Can you use a custom font from the Aa menu with Mobi?

Yessir, I can change Font Family and its size.

[Sirtel]

Originally Posted by _kind_le

Yessir, I can change Font Family and its size.

Jon meant a custom font, i.e. a font you sideloaded to your Kindle. Nope, can't do that with mobi. And you can't use the weight slider either. AZW3 is better than MOBI, unless you don't particularly care about fomatting and how pretty the book looks like.

[_kind_le]

Originally Posted by Sirtel

Jon meant a custom font, i.e. a font you sideloaded to your Kindle. Nope, can't do that with mobi. And you can't use the weight slider either. AZW3 is better than MOBI, unless you don't particularly care about fomatting and how pretty the book looks like.

Oh you're right. No, haven't even try to side load fonts. 10 built-in fonts more than enough for me now and I also can change their size from 1 to 14.

[Quoth]

Originally Posted by DNSB

MOBI is loosely based on the pre-ePub OEBPS specification but MobiPocket added some proprietary features and removed others which Amazon continued doing after they purchased MobiPocket. Compared to ePub/AZW3, it sucks capability wise.

OEBPS specification is 1998 (and indeed a sort of epub1) and was from a US company unrelated to French Mobipocket. Mobi is HTML3 and no CSS files. There were variations for support databases and javascript. Amazon bought Mobipopcket in 2005 and the Lab126 was started in 2004 and bought / renamed by Amazon. First Kindle was in 2007 and used Mobi and then azw (not azw3) which replaces Mobi DRM with Amazon DRM.

OEBPS (Open Book) was open from about 1999 and like epub2 is a ZIP file plus a Manifest file. Inside the package a defined subset of XHTML may be used, along with CSS and Dublin Core metadata. Mobi is simply HTML3 and not a regular zip file.

Mobipocket files originally (2000 when founded) were little more than text. I don't know when they upgraded to HTML3. They always (even the text only versions) had an encryption option. Most implementations of Mobi can't do RTL languages, Cyrillic, Arabic, Asian, Hebrew and only use the pre-installed fonts on the Kindle, which only have a subset of Greek in addition to Latin-Roman

I don't think mobi/azw/KF7 (not azw3/KF8) has any direct connection to OEBPS (Open Book, essentially epub1). It's grossly inferior.
The only thing positive about mobi is that it's better than the earlier Mobipocket formats used on Palm OS, Symbian and Windows CE. The mobi format on Kindle is dreadful compared to AZW3/KF8 which is based on epub2 (HTML5 and CSS).

Only K1, K2, DX and DXG need mobi. The K3, KNT, KT etc all got backported azw3/KF8 in later FW releases. No-one should use mobi for novels and similar as azw3 is far superior. There are a few mobi variations that were never implemented in KF8 or KFX, but ordinary ebooks don't use them. Print Replica on Kindle is either an encapsulated PDF (developed after mobi) or a fixed layout KFX.

Sony (2005 eink) used LRF and changed to epub in 2008, a good while before Kindle had azw3. I don't know what Sony used on their two main ereader / media book / Bookman portable products before eink.


Summary: Mobi is garbage and was obsolete at release and Western European Language-centric. It's not even the original Mobipocket format. I still have a copy of Mobipocket creator which works best with a very limited HTML input, though there is a pre-Word 2007 MS DOC format import. The HTML3 inline styling is limited and basically you can only define sans, sans-serif and monospace (which can't be picked on GUI). The older models with Mobi only have no alternate body font selection, only size.

[JSWolf]

Originally Posted by Sirtel

Jon meant a custom font, i.e. a font you sideloaded to your Kindle. Nope, can't do that with mobi. And you can't use the weight slider either. AZW3 is better than MOBI, unless you don't particularly care about fomatting and how pretty the book looks like.

I know Mobi does not allow embedded fonts. But as I've never see a Mobi on my PW3, I didn't know is side loaded fonts worked.

I agree that Mobi is meh! KF8 is what should be used.

[_kind_le]

Originally Posted by Quoth

Summary: Mobi is garbage and was obsolete at release and Western European Language-centric. It's not even the original Mobipocket format. I still have a copy of Mobipocket creator which works best with a very limited HTML input, though there is a pre-Word 2007 MS DOC format import. The HTML3 inline styling is limited and basically you can only define sans, sans-serif and monospace (which can't be picked on GUI). The older models with Mobi only have no alternate body font selection, only size.

Thanks, very interesting info!

[_kind_le]

Originally Posted by DNSB

If you use Kindle Previewer and split the output file into it's azw3 and mobi components (KindleUnpack does this), it's relatively easy to see the differences though for most fiction books, they aren't all that noticeable.

I can't find how to export AZW3 from Kindle Previewer - it gives me ability to export only .kpf or .mobi

Is there some trick I can use to do that?

[DNSB]

Originally Posted by _kind_le

I can't find how to export AZW3 from Kindle Previewer - it gives me ability to export only .kpf or .mobi

Is there some trick I can use to do that?

You export the .mobi file which is a dual mobi so it has the .mobi and .azw3 files internal to it. You then import the file to calibre and use KindleUnpack to split it.

Edit: attached a couple of images showing the original ePub, KindlePreviewer generated mobi and the two file output by KindleUnpack's split mobi function.

[_kind_le]

Originally Posted by DNSB

You export the .mobi file which is a dual mobi so it has the .mobi and .azw3 files internal to it. You then import the file to calibre and use KindleUnpack to split it.

Edit: attached a couple of images showing the original ePub, KindlePreviewer generated mobi and the two file output by KindleUnpack's split mobi function.

Thanks, I was able to install needed plugin to get KindleUnpack menu icon and split the file!

[_kind_le]

Noticed that kindle treats AZW3 extracted from MOBI as a document instead of as a book and has no cover. Is it something I can change before export to MOBI in Kindle Previewer?

[kovidgoyal]

https://manual.calibre-ebook.com/faq...-generic-cover