Thread: managing the space available for books on kobos
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Old 06-13-2016, 09:21 PM   #3
davidfor
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Posts: 24,905
Karma: 47303824
Join Date: Jul 2011
Location: Sydney, Australia
Device: Kobo:Touch,Glo, AuraH2O, GloHD,AuraONE, ClaraHD, Libra H2O; tolinoepos
Quote:
Originally Posted by anacreon View Post
Looking at the library parameters on my Kobo Glo today, there were 389 Mo available from 3232 according to kobo: 1.9 Go occupied by the books, 58 Mo by the 15 installed dictionaries. It didn't add up.

So I scanned it with the Where is it app:
- the capacity is 3.15 go, similar to kobo's 3,2
- .kobo is 374 Mo : 259 sqlite database, 109 dictionaries (twice kobo's 58 Mo for the same 15 dict.)
- .kobo-images 505 Mo
- fonts plus calibre metadata 30 Mo
- the rest calibre book files: I didn't add it up but the difference with the rest is close to kobo's 1.9 Go.

I discovered the compression tool only recently, and I've slowly modified old covers, but 505 Mo for images? I regularly clean the image directory.

The biggest on the kobo, an Atwood book has 4 files: 1081 ko N3-full (the size of the cover in calibre), 650 ko Android aspect, 650 ko library-full, 609 ko library grid, total 3Mo.

I experimented compressing the cover in Calibre to 79 kb then uploading the cover with Kobo utilities: only the 3 smaller files were reduced, the biggest unchanged. How can I get all the files to adjust?
In all that, the only thing you have direct control over are the sideloaded books and the fonts. The database is dependent on the number of books on the device plus recommendations and others from Kobo. The dictionaries on how many you install.

The cover images you don't have direct control over. The device either downloads the images (for purchase kepubs and recommendations) or generates them for sideloaded books. For most of the sideloaded books formats, the cover is simply the first page of the book rendered and saved. For sideloaded kepubs, the covers are generated from whatever image in the book is marked as the cover image.

There are three or four sizes generated depending on the firmware version you are looking at. The sizes generated are fixed for the device. The images are generated as needed and stored for later use. You have no control over any part of this. But, you can sideload the images. The KoboTouch driver in calibre has options to generate and sideload all the cover images when the book is sent. The driver should be generating images similar to the firmware.

There are only two ways that I can think of to reduce the size of the images directory:
- Delete the generated images. This is only temporary as they will be regenerated as needed. But, if you keep all your books on the device, you could delete the images for books you have read or are not likely to read in the near future.
- Generate your own images to your own specs. The simplest way to do this would be to run calibre from source and change options used for generating the images. Or you could create a driver subclassed from the KoboTouch driver that does this. Either is easy to do, but I have now idea how much benefit it would be.

You can also do is what rroad suggests: Use an external SD card. The firmware doesn't save generated images for books on the SD card. But, if they are there, they will use them.

Another possibility is to change the internal SD card. People have put 32GB cards in their Glo's so they can store more books. Even a 4GB card will give you a lot more space.
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