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

KevinH · 07-05-2015, 06:49 PM

Hi,
You really don't seem to understand what an mobi ebook actually is, so please let me try to explain a bit.

It is a compiled ebook format that uses a palm database structure - a set of starting offsets to binary data referred to either as sections or records depending on who you ask. What KindleUnpack does is examine these binary sections, identifies any sections that are headers and then use them to identify starting section numbers where images are stored, text is stored, index information, and etc. and then extract them to files. The data from these files are used to create html3.2 code that can be used to input back into kindlegen for the older mobi 7 pieces and used to create an epub-like structure for the kf8 pieces. If you actually want to see the rawml you can dump that as well.

The header sections also have EXTH records that contain the MetaData information. If you want to understand the exact layout of the mobi file, simply run DumpMobiHeader_v018.py or later and look at the description of what is stored in each section of the palm database file.

For joint mobis, the images are not duplicated, they are stored after the mobi7 header and before the kf8 header. Later mobis can also have a completely separate container of HDImages and placeholders.

When Kindleunpack unpacks image sections (and fonts and RESC sections) it stores them all in a mobi 7 folder and copies the correct piecs to the mobi 8 folder as needed. When Kindleunpack unpacks from the HD Container, it will store these images in their own HDImage folder as they can notbe shared with a mobi 7. There is a switch to have the HDImages overwrite their low resolution cousins.

So please run DumpMobiHeader and examine the section map to see what is actually being stored i side the palm database structure.

If you have further questions, post the output of DumpMobiHeader from running on your mobi so that I understand exactly what it is you are askng. It will even work on DRMd ebooks since the headers themselves and most images are not typically encrypted.

Hope this helps,

KevinH

07-05-2015, 06:49 PM	#1168
KevinH Sigil Developer Posts: 8,884 Karma: 6120478 Join Date: Nov 2009 Device: many	Hi, You really don't seem to understand what an mobi ebook actually is, so please let me try to explain a bit. It is a compiled ebook format that uses a palm database structure - a set of starting offsets to binary data referred to either as sections or records depending on who you ask. What KindleUnpack does is examine these binary sections, identifies any sections that are headers and then use them to identify starting section numbers where images are stored, text is stored, index information, and etc. and then extract them to files. The data from these files are used to create html3.2 code that can be used to input back into kindlegen for the older mobi 7 pieces and used to create an epub-like structure for the kf8 pieces. If you actually want to see the rawml you can dump that as well. The header sections also have EXTH records that contain the MetaData information. If you want to understand the exact layout of the mobi file, simply run DumpMobiHeader_v018.py or later and look at the description of what is stored in each section of the palm database file. For joint mobis, the images are not duplicated, they are stored after the mobi7 header and before the kf8 header. Later mobis can also have a completely separate container of HDImages and placeholders. When Kindleunpack unpacks image sections (and fonts and RESC sections) it stores them all in a mobi 7 folder and copies the correct piecs to the mobi 8 folder as needed. When Kindleunpack unpacks from the HD Container, it will store these images in their own HDImage folder as they can notbe shared with a mobi 7. There is a switch to have the HDImages overwrite their low resolution cousins. So please run DumpMobiHeader and examine the section map to see what is actually being stored i side the palm database structure. If you have further questions, post the output of DumpMobiHeader from running on your mobi so that I understand exactly what it is you are askng. It will even work on DRMd ebooks since the headers themselves and most images are not typically encrypted. Hope this helps, KevinH