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tomsem · 10-21-2011, 12:01 PM

The way this works is that kindlegen2 will build a 'full' k8 file, including archived source, multimedia content etc. That's what you submit to Amazon. When you download an .azw from Amazon, you only get the parts that that particular Kindle understands, i.e. no source archive, if your Kindle doesn't have audio/video capabilities you won't get those parts, etc. So to some extent there is 'graceful degradation' built in.

So even now 'enhanced' ebooks (the ones with audio and video that's playable with Kindle4iOS) can be downloaded to a Kindle 1—but you don't get the audio/video as part of the file. The file you get depends on the capabilities of the device.

This contrasts with ePub in that the file is the same regardless of the device, and it is up to the device to decide to do with what is in there.

So there's 'full' backward compatibility.

The other point is that the output of Kindlegen is 'binary', whereas epub it is just compressed source files. The analogy is that Kindle format is 'byte code' that can be loaded directly into memory, whereas with epub, you must do this each time a book is opened (usually a 'chapter' at a time). Amazon has always claimed this 'precompiling' reduces the work required by the reading system, and makes it more responsive. Indeed, with virtually every epub reading system I've used, there's a slight delay as each new chapter is loaded in, and often when the book is loaded.

The advantage of ePub is that (in the absence of DRM encryption) you can simply un-zip the content and the source can be examined and modified in its original form. With azw, the 'compiling' process is 'lossy' and while you can 'disassemble' it, you lose things like comments and markup that kindlegen decided to ignore (which is why it archives the source in the file submitted to Amazon).

Topaz is entirely outside this system, and with K8 it will be deprecated since things like font embedding and better CSS support are now directly supported by kindlegen. Topaz is dead! Long live Topaz!

This will be a boon to ebook designers as they no longer need to concern themselves nearly as much with designing for 2 formats.

Remaining questions: what about JavaScript support in K8? (note: the original mobipocket format specification included JS support). What about other epub3 features such as media overlays, accessibility, epub navigation documents?

Also what about <mbp:..> tags? deprecated?

10-21-2011, 12:01 PM	#68
tomsem Grand Sorcerer Posts: 6,949 Karma: 27060153 Join Date: Apr 2009 Location: USA Device: iPhone 15PM, Kindle Scribe, iPad mini 6, PocketBook InkPad Color 3	The way this works is that kindlegen2 will build a 'full' k8 file, including archived source, multimedia content etc. That's what you submit to Amazon. When you download an .azw from Amazon, you only get the parts that that particular Kindle understands, i.e. no source archive, if your Kindle doesn't have audio/video capabilities you won't get those parts, etc. So to some extent there is 'graceful degradation' built in. So even now 'enhanced' ebooks (the ones with audio and video that's playable with Kindle4iOS) can be downloaded to a Kindle 1—but you don't get the audio/video as part of the file. The file you get depends on the capabilities of the device. This contrasts with ePub in that the file is the same regardless of the device, and it is up to the device to decide to do with what is in there. So there's 'full' backward compatibility. The other point is that the output of Kindlegen is 'binary', whereas epub it is just compressed source files. The analogy is that Kindle format is 'byte code' that can be loaded directly into memory, whereas with epub, you must do this each time a book is opened (usually a 'chapter' at a time). Amazon has always claimed this 'precompiling' reduces the work required by the reading system, and makes it more responsive. Indeed, with virtually every epub reading system I've used, there's a slight delay as each new chapter is loaded in, and often when the book is loaded. The advantage of ePub is that (in the absence of DRM encryption) you can simply un-zip the content and the source can be examined and modified in its original form. With azw, the 'compiling' process is 'lossy' and while you can 'disassemble' it, you lose things like comments and markup that kindlegen decided to ignore (which is why it archives the source in the file submitted to Amazon). Topaz is entirely outside this system, and with K8 it will be deprecated since things like font embedding and better CSS support are now directly supported by kindlegen. Topaz is dead! Long live Topaz! This will be a boon to ebook designers as they no longer need to concern themselves nearly as much with designing for 2 formats. Remaining questions: what about JavaScript support in K8? (note: the original mobipocket format specification included JS support). What about other epub3 features such as media overlays, accessibility, epub navigation documents? Also what about <mbp:..> tags? deprecated? Last edited by tomsem; 10-21-2011 at 12:25 PM.