KFX Format

[mitch13]

I have the same question as to whether kfx files will be eventually downloaded to Calibre.
I know I can get the standard old AZW3 if I go and search for the kfx books that Amazon have sent to my Paperwhite.
This is a pain. I am finding that if I send these books to my Paperwhite they end up with a lot of partial files and quite often missing books I have ordered though they are in the cloud.
So I end up on my Paperwhite with a mixture of KFX, Partial and AWZ3 files all together in the main memory. I prefer to pass them through Calibre and then when downloaded to my Paperwhite they go under an authors name.

mitch13

[darryl]

Originally Posted by mitch13

I have the same question as to whether kfx files will be eventually downloaded to Calibre.

mitch13

In reality we don't know, but the likely answer is not any time soon.

To explain, the situation is similar to when .azw3 files were first introduced. Calibre support could not be added until the format was understood. As Amazon does not release the specifications of its file formats, this involved reverse-engineering that format. I think I recall reading earlier that this took about 6 months. Once the format was understood Calibre support was developed enabling the use of all of Calibres functionality including conversion and viewing of drm-free azw3 files.

My understanding is this. kfx has not long been released, and is not understood. Already it presents additional difficulties to those encountered with azw3. Even drm-free .kfx ebooks are encrypted (or perhaps merely obfuscated). This was not the case with .azw3. This encryption or obfuscation must be broken as a preliminary step to even begin understanding the format. At the moment I am not aware of anyone seriously attempting this task. It has been suggested that no one will seriously bother doing so whilst .azw3 files remain readily available. Some much more knowledgeable than myself seem confident that this will be accomplished if Amazon does cease providing .azw3 files. But there are, of course, no guarantees. And of course this is only the first step.

Whilst I am sure it would be possible to have Calibre import .kfx format books, without an understanding of the format it would effectively only be for cataloguing purposes. Functions such as viewing, converting etc. would not be available. Functionality would be similar to that of a drm infested ebook imported without resort to Apprentice Alf. Even this limited support would present problems as Calibre expects to import a single file, whilst .kfx seems to require multiple files.

So, the most likely answer to your question is that Calibre support for kfx is a long way off, and may well not be seriously pursued whilst .azw3 files remain readily available. This, of course, is up to Amazon.

[HarryT]

Originally Posted by darryl

My understanding is this. kfx has not long been released, and is not understood. Already it presents additional difficulties to those encountered with azw3. Even drm-free .kfx ebooks are encrypted (or perhaps merely obfuscated). This was not the case with .azw3.

This is incorrect. KFX files use AES encryption, yes, but so do KF8 files.

[darryl]

Originally Posted by HarryT

This is incorrect. KFX files use AES encryption, yes, but so do KF8 files.

Thank you for pointing this out. This was not my understanding. I had thought that a drm free kf8 file was not encrypted at all.

EDIT: By the way Harry. What is your source for this?

A quick search through the forums reveals this post by you (https://www.mobileread.com/forums/sho...on#post3201155).

Your post in turn refers to this preceding post by knc1 who I view as an expert on these matters. https://www.mobileread.com/forums/sho...2&postcount=49

Perhaps I am wrong, but I did not interpret knc1's post as saying all kf8's including those without drm were encrypted. In fact, the excerpt from the log which he included in his post related to the decryption of ASIN B00GCIN0OM, an ebook entitled "The Contact Episode One" by Albert Sartison. This book is the first in a series and is available for free. Nevertheless, it is clearly encumbered with DRM. I can't see knc1 proffering a log file from the decryption of a drm infested kf8 file as proof that kf8 files not infested with drm are encrypted. I think the point he was making is slightly different. (Of course, it is possible though I don't think likely that the book concerned was not encumbered with drm at the time of decryption but was nevertheless encrypted).

Do you have another source? If not, I think we need some clarification from kfc1 or someone else with more knowledge than either of us on this topic. As things stand I tend to think that, unlike kfx files, kf8 files without drm are unencrypted.

[pdurrant]

Originally Posted by darryl

Thank you for pointing this out. This was not my understanding. I had thought that a drm free kf8 file was not encrypted at all.

You are right. DRM-free KF8 files are not encrypted at all. And even encrypted ones used the same PDB/MOBIi-based file format as a container.

I haven't looked at KFX at all, but I think it's uses a new kind of container. So perhaps the Topaz format is a better comparison.

[HarryT]

Originally Posted by pdurrant

You are right. DRM-free KF8 files are not encrypted at all. And even encrypted ones used the same PDB/MOBIi-based file format as a container.

The information about AES encryption of KF8 files came from earlier in this thread and it was stated at the time that it applied to both DRM and DRM-free books.

[pdurrant]

Originally Posted by HarryT

The information about AES encryption of KF8 files came from earlier in this thread and it was stated at the time that it applied to both DRM and DRM-free books.

I must have missed it. It's not true. It is true that KF8 uses AES encryption for DRMed ebooks.

[darryl]

Please see my edited post #304. Harry, I think perhaps you may have misinterpreted knc1's post.

[HarryT]

Originally Posted by darryl

Please see my edited post #304. Harry, I think perhaps you may have misinterpreted knc1's post.

Thank you; that probably is the case!

[jhowell]

Has anyone come across files from Amazon with an "apf" extension?

I have some information that this may be a new file type that contains a zipped kfx book along with instructions for unpacking it. When sideloaded, the contents will be extracted and the files placed into the proper locations for the book to function and then the original file will be deleted.

Support for this in future Kindle firmware would allow the "Download & transfer via USB" function of "Manage Your Content and Devices" to deliver books in kfx format instead of azw3.

[JSWolf]

Originally Posted by Rizla

It would seem to me that the ability to have 0 margins on the flat-screen Voyage would make good sense because there is no bezel or bezel shadow to obscure the text. As such, one would be able to use the whole screen for text. In any case, why not add it? People don't have to use it. I can see no good reason for not adding the option.

No, not 0 margins, but maybe a 20-30px margin for the 300dpi screens.

[AaronShep]

As an update to some of the KFX issues discussed here:

I've learned that the Kindle's adding of space between my indented paragraphs was not intentional. It was due to a bug in the new layout engine, apparently triggered by something unexpected in my HTML. I still don't know exactly what caused it, but the bug has now been at least partially fixed by the Kindle team and may eventually be fixed entirely.

In regard to my nonbreaking spaces being ignored: They may have been ignored only because I insert them as characters rather than HTML entities. And this too is likely to be fixed at some time.

The issue of ignored transparency in images is also meant to be fixed eventually.

Aaron

[JSWolf]

Originally Posted by AaronShep

As an update to some of the KFX issues discussed here:

I've learned that the Kindle's adding of space between my indented paragraphs was not intentional. It was due to a bug in the new layout engine, apparently triggered by something unexpected in my HTML. I still don't know exactly what caused it, but the bug has now been at least partially fixed by the Kindle team and may eventually be fixed entirely.

In regard to my nonbreaking spaces being ignored: They may have been ignored only because I insert them as characters rather than HTML entities. And this too is likely to be fixed at some time.

The issue of ignored transparency in images is also meant to be fixed eventually.

Aaron

So does this mean that the current KFX renderer for eInk Kindles is shite and will be fixed in the next firmware where there is no software only JB and people should just buck up,install the new firmware and forget a software JB?

[Dr. Drib]

Moderator Notice

Please settle down, Jon. There's no need for such rhetoric. There are software bugs in all firmware for our Readers of choice. Your language is uncalled for.

Further posts such as yours will be deleted.

[jhowell]

Originally Posted by AaronShep

I've learned that the Kindle's adding of space between my indented paragraphs was not intentional. It was due to a bug in the new layout engine, apparently triggered by something unexpected in my HTML. I still don't know exactly what caused it, but the bug has now been at least partially fixed by the Kindle team and may eventually be fixed entirely.

In regard to my nonbreaking spaces being ignored: They may have been ignored only because I insert them as characters rather than HTML entities. And this too is likely to be fixed at some time.

The issue of ignored transparency in images is also meant to be fixed eventually.

Aaron, it sounds like you have made contact with someone knowledgeable about KFX at Amazon.

Did you discover whether these problems need to be fixed in the central KFX generation process or individual reading devices or both?

I think it is likely that a lot of KFX processing occurs in the file generation process, rather than the renderers. If so then, unlike with AZW3, improvements or fixes to KFX will require that customers re-download books. And for the best reading experience it would be wise to download KFX books from Amazon when you are ready to read them instead of keeping a large number on a Kindle.