Does Kobo use more storage space than Sony

[alstein]

Originally Posted by GeoffR

If you put them on the Glo by syncing with Kobo or using the extended driver in Calibre, then the books will actually be in kepub format, and will take up a lot more space (often twice as much space). If you sideloaded them using the standard Calibre driver, or manually, then they will be in plain epub format and should take roughly the same space as on the Sony (maybe a little more, but nowhere near twice as much).

There are other things that consume storage space besides books though, I think the main one is the recommendations you get when you sync with Kobo. Each recommendation has a full set of cover images, and new ones seem to be added faster than the old ones are deleted, so after a while you can end up with a lot of them.

That must be the answer. Almost all of the books on the Kobo Glo are in Kepub, while the books on my Sony Reader are in epub.

Thanks for the information.

[alstein]

Originally Posted by GeoffR

Edit: I see what you mean. The books could be sideloaded and the kepub directory could just contain 709MB of other stuff.

So to be clear, if the books are in kepub format (either because they were synced from Kobo or sideloaded as kepubs) then the books themselves and their associated database entries will take up about twice as much space compared to the same books sideloaded as epubs. But either way, there could be a whole lot of stuff taking up space and database entries other than just the books.

I didn't sideload the books. They were put on my Kobo reader when I synched wiith the Kobo library.

[hleo12]

Also, on your Glo, another way to truly know if your books are really consuming that much space is to get a calculator and get to adding the sizes displayed on your library, which are displayed on the right side of the title.

[Ripplinger]

Or use something like TreeSize that will tell you the size of a directory that includes all subdirectories and files.

If the titles between both readers aren't identical, 165 books can have a hugely wide range of file sizes between them as already said; for instance, the number of images within books and their resolution can inflate them quite a bit.

If the same identical titles are on the Kobo as on the Sony, then it's probably the size difference between kepub and epub.

[ShellShock]

Does anyone know why kepubs are so much bigger than epubs? What are Kobo doing to justify this bloat?

[PeterT]

kEpubs contain many <span id=".....">text.</span> which are used as a part of their bookmarking support.

I am somewhat surprised though that these would make that much difference; I would have thought that the text would have been zipped quite compactly.

[PeterT]

Well, on a self converted kEpub the size went from 224kB to 240kB; there might be more than just that.

[eschwartz]

Why does Kobo need those spans, when no other ereader needs to do so, and they usually still allow annotations?

[PeterT]

It has to do with how the bookmark solution they implemented in the ACCESS renderer works.

[eschwartz]

Originally Posted by PeterT

It has to do with how the bookmark solution they implemented in the ACCESS renderer works.

Yeah, so I've heard, but the why was more directed as a Kobo.

[chrisridd]

Google litters their books with lots of anchors:

<a id="GBS.0229.02"></a>

I would guess these are used for bookmarking as well, similar to Kobo.

[GeoffR]

Originally Posted by ShellShock

Does anyone know why kepubs are so much bigger than epubs? What are Kobo doing to justify this bloat?

The kepub file itself is not always much bigger than the epub, but a lot more data gets stored in the database for a kepub than for an epub. I don't know what it all is for, but some is probably to do with the Kobo DRM scheme, and some to do with the bookstore (links to similar books, etc.), and more detailed statistics. Also there is BeyondTheBook data such as author photographs, etc. that epubs don't have.

[chrisridd]

Originally Posted by GeoffR

The kepub file itself is not always much bigger than the epub, but a lot more data gets stored in the database for a kepub than for an epub. I don't know what it all is for, but some is probably to do with the Kobo DRM scheme, and some to do with the bookstore (links to similar books, etc.), and more detailed statistics. Also there is BeyondTheBook data such as author photographs, etc. that epubs don't have.

Encrypted kepubs are a lot bigger than unencrypted kepubs/epubs.

I just compared a book from my ~/Library/Application Support/Kobo/Kobo Desktop Edition/kepub/ directory after I "liberated" it. The original is 631KB, the liberated one is 303KB.

If Kobo's DRM is any good, it ought to be turning each file into data that's incompressible (Shannon's theory?) and that kind of bears out looking at the zip files. Using "unzip -lv":

 Length   Method    Size  Ratio   Date   Time   CRC-32    Name
   80880  Defl:N    68738  15%  11-02-12 15:23  3ec01420  OEBPS/html/009_chap3.html [original]
   80872  Defl:N    25283  69%  08-16-14 09:49  2c067dd2  OEBPS/html/009_chap3.html [liberated]

All the content that's encrypted can be compressed much better after liberation.

I haven't looked much at what goes in the DB, aside from there being one row in it for each encrypted file in each protected book.

[Aanya]

There is something wrong with your kobo, because it should not happen. As per my knowledge Sony has nothing any features like that to compress the size of ebooks.

You should check your hard ware or battery for charging issue.

[davidfor]

Originally Posted by chrisridd

I haven't looked much at what goes in the DB, aside from there being one row in it for each encrypted file in each protected book.

I said earlier:

Originally Posted by davidfor

• Database records - one row for the book (containing the metadata including the description), two rows for each chapter in the book, one row for each collection the book is in. Exactly how much space depends on the comments in the metadata and the number of chapters, but it shouldn't exceed 100KB. More rows will be added as you read and if you add bookmarks/annotations.

Because the OP was coming from a Sony, I assumed they were comparing sideloaded epubs. For kepubs, there is an extra row per chapter/file in the book. And if the kepub has DRM, there is another row for each encrypted file in the kepub. And of course there are indexes and other database overhead that I didn't mention before. But, would still be surprised if it is more than 100KB per book.