MobileRead Forums - View Single Post - KindleUnpack (MobiUnpack): Extracts text, images and metadata from Kindle/Mobi files

AcidWeb · 07-13-2015, 03:46 PM

Very interesting tip - thank you.

Delivered AZW3 have 0,1MB + 47MB AZW6
Downloaded file have 71,6MB.

EDIT:
I preformed extended autopsy.

File delivered wirelessly consists of a hollow AZW3 file and AZW6. I'm confirming KevinH research - AZW6 store images in JPEG XR format. Amazon really like to complicate simple things.

AZW3 downloaded from Amazon Store don't have HD container inside. All images are embedded normally in JPEG format.

Wireless delivery provide technically lower image quality than sideloaded version. Both use same resolution but compression level and bit depth is different.

But it is very hard to see any difference directly on the reader. JPEG XR + reduced bit depth simply provide much smaller files without any quality loss that matter.

HD Container embedded to KindleGen output still use normal JPEG format. EX magic apparently is done on Amazon side.

Sadly this entire corpse cutting not answered my main question: From where Kindle PW3/Voayge read images when we sideload bare KindleGen output with embedded HD container.

EDIT2:
Well. I found reason of bloat. I screwed up EPUB headers. book-type and original-resolution need to be meta name not meta property. I messed that up in last update. With them in place KindleGen don't create HD container at all.

My offer is not valid anymore.

07-13-2015, 03:46 PM	#1175
AcidWeb KCC Co-Author Posts: 845 Karma: 765434 Join Date: Mar 2013 Location: Poland Device: Kindle Oasis 2	Very interesting tip - thank you. Delivered AZW3 have 0,1MB + 47MB AZW6 Downloaded file have 71,6MB. EDIT: I preformed extended autopsy. File delivered wirelessly consists of a hollow AZW3 file and AZW6. I'm confirming KevinH research - AZW6 store images in JPEG XR format. Amazon really like to complicate simple things. AZW3 downloaded from Amazon Store don't have HD container inside. All images are embedded normally in JPEG format. Wireless delivery provide technically lower image quality than sideloaded version. Both use same resolution but compression level and bit depth is different. But it is very hard to see any difference directly on the reader. JPEG XR + reduced bit depth simply provide much smaller files without any quality loss that matter. HD Container embedded to KindleGen output still use normal JPEG format. EX magic apparently is done on Amazon side. Sadly this entire corpse cutting not answered my main question: From where Kindle PW3/Voayge read images when we sideload bare KindleGen output with embedded HD container. EDIT2: Well. I found reason of bloat. I screwed up EPUB headers. book-type and original-resolution need to be meta name not meta property. I messed that up in last update. With them in place KindleGen don't create HD container at all. My offer is not valid anymore. Last edited by AcidWeb; 07-14-2015 at 08:37 AM.