Recommendations for epub construction?

johnc.eire · 02-09-2015, 02:51 PM

I've finally got to the point of retiring my venerable PRS-505 & replacing it with a Kobo. Got the new reader yesterday - a Kobo H20. That was the only one immediately available at the W H Smiths branch I went to. (Why would anyone want to try and read a book under water??

).

I create my own epubs. Have done since I first found out that they are just slightly specialised zip files. For the Sony, there was a restriction of about 260K on the size of 'sections' of text, making it necessary to split a book into several bits, then join them together in the 'content.opf' file. My understanding was that the Sony was so short of memory that it could only make 260K's-worth available at any one time. Don't know whether that is right or not, but as explanations go, it suited me.

The Kobo comes equipped with far more memory, so I ran an experiment with an existing book, joining all five of the original the 'parts' into a single part and rebuilding the epub.

This works fine on the kobo... up to a point. It appears that page turning progressively slows down as you go through the book. Turning a page at the start of the book is practically instantaneous, but towards the end (415 pages in the case in question) moving to the next page can take up to 10 seconds.

Can anyone advise on a recommended max. size for sections of an epub? And any other ideas, etc would be more than welcome.

GeoffR · 02-09-2015, 03:19 PM

The best size is as small as you can possibly make them. The larger the files, the worse the performance will be, but also the epub reader will insert page breaks at awkward places if the file is too large.

It is best to start a new file at each natural page break, and I would avoid anything larger than about 120KB in any case. I think it is better to choose where to split the file yourself rather than let the epub reader insert a page break or Calibre split the file automatically in an unexpected place.

eschwartz · 02-09-2015, 03:23 PM

If you use a separate chapter for each file, you will almost certainly stay below the maximum size.

And additional advantages include an automatic pagebreak between chapters, as well as being able to easily see the structure and possibly fix things if you plan on editing the contents later.

I believe calibre can and will automatically split files at pagebreaks (like chapter headings

) during conversion.

DNSB · 02-09-2015, 10:08 PM

Quote:

Originally Posted by johnc.eire

I create my own epubs. Have done since I first found out that they are just slightly specialised zip files. For the Sony, there was a restriction of about 260K on the size of 'sections' of text, making it necessary to split a book into several bits, then join them together in the 'content.opf' file. My understanding was that the Sony was so short of memory that it could only make 260K's-worth available at any one time. Don't know whether that is right or not, but as explanations go, it suited me.

The Kobo comes equipped with far more memory, so I ran an experiment with an existing book, joining all five of the original the 'parts' into a single part and rebuilding the epub.

This works fine on the kobo... up to a point. It appears that page turning progressively slows down as you go through the book. Turning a page at the start of the book is practically instantaneous, but towards the end (415 pages in the case in question) moving to the next page can take up to 10 seconds.

Can anyone advise on a recommended max. size for sections of an epub? And any other ideas, etc would be more than welcome.

AFAIR, the recommended maximum size for epub2 was 300K chapter files prior to compression so ~100K compressed. For an old Sony ereader, exceeding those sizes made the epub unusable.

Personally, I split the files at the "natural spots" -- chapter breaks, end of dedication, epigraph, etc., copyright, publisher info, etc. This makes page breaks between chapters automatic (the way I prefer it) and allows a cleaner ToC. Happily, it often results in an ebook that responds faster.

I've merged the files within an ebook that has "unnatural" file splitting into a single file and then resplit them to get the file structure I want.

BTW, the record holder for an epub around here was a purchase by my wife. A "boxed set" in a single epub file with all 5 books in 3 files. Once the file had been restructured, opening and navigating was much faster -- opening and parsing a 100Kbyte file compared to opening and parsing a 1.2MB file.

johnc.eire · 02-10-2015, 02:03 PM

Thanks for the responses, people.
I'm going to take the general advice and re-split all my books down to chapter-sized sections.
I've got to change the font size everywhere, too. Where I used to have 1.1em - which was just right for the Sony - I need to reduce that to 0.76em for the Kobo.
Ah well. I can't say I've got nothing to do...

jackie_w · 02-10-2015, 04:39 PM

Quote:

Originally Posted by johnc.eire

I've got to change the font size everywhere, too. Where I used to have 1.1em - which was just right for the Sony - I need to reduce that to 0.76em for the Kobo.

That sounds like a lot of 'make work'. Are you sure one of Kobo's huge range of font-sizes (40, I think) can't scale your existing books to 'just about perfect'.

dickloraine · 02-10-2015, 05:40 PM

Changing font sizes does not make much sense. Just use 1em (or normal) for the main text and give other classes bigger or smaller sizes. Font size is one of the things the user changes to his liking. As is the font itself. And some fonts are bigger or smaller then others. So don't obsess over these things. Set reasonable defaults that scale with user settings and let the user decide what he likes. This is one of the main differences between paper books and eBooks. EBooks allow the user to change the formating to his liking, on the flip side they have not a perfect typography. Paper Books can have very good typography but are in no way customizable by the user.

02-09-2015, 02:51 PM	#1
johnc.eire Member Posts: 13 Karma: 10 Join Date: May 2010 Device: kobo H2O	Recommendations for epub construction? I've finally got to the point of retiring my venerable PRS-505 & replacing it with a Kobo. Got the new reader yesterday - a Kobo H20. That was the only one immediately available at the W H Smiths branch I went to. (Why would anyone want to try and read a book under water?? ). I create my own epubs. Have done since I first found out that they are just slightly specialised zip files. For the Sony, there was a restriction of about 260K on the size of 'sections' of text, making it necessary to split a book into several bits, then join them together in the 'content.opf' file. My understanding was that the Sony was so short of memory that it could only make 260K's-worth available at any one time. Don't know whether that is right or not, but as explanations go, it suited me. The Kobo comes equipped with far more memory, so I ran an experiment with an existing book, joining all five of the original the 'parts' into a single part and rebuilding the epub. This works fine on the kobo... up to a point. It appears that page turning progressively slows down as you go through the book. Turning a page at the start of the book is practically instantaneous, but towards the end (415 pages in the case in question) moving to the next page can take up to 10 seconds. Can anyone advise on a recommended max. size for sections of an epub? And any other ideas, etc would be more than welcome.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
ePub reader recommendations	soondai	Apple Devices	46	03-08-2015 12:57 AM
I need some website construction tool recommendations for my book's site	krausj	General Discussions	2	10-04-2013 03:04 AM
Windows epub viewer/reader recommendations?	phossler	Sigil	19	02-25-2013 05:01 PM
Best epub reader/library manager - recommendations?	fbrII	Android Devices	9	10-30-2011 11:41 PM
Forum under construction	Alexander Turcic	Announcements	0	04-30-2006 07:44 AM

02-09-2015, 03:19 PM	#2
GeoffR Wizard Posts: 3,821 Karma: 19162882 Join Date: Nov 2012 Location: Te Riu-a-Māui Device: Kobo Glo	The best size is as small as you can possibly make them. The larger the files, the worse the performance will be, but also the epub reader will insert page breaks at awkward places if the file is too large. It is best to start a new file at each natural page break, and I would avoid anything larger than about 120KB in any case. I think it is better to choose where to split the file yourself rather than let the epub reader insert a page break or Calibre split the file automatically in an unexpected place.

02-09-2015, 03:23 PM	#3
eschwartz Ex-Helpdesk Junkie Posts: 19,421 Karma: 85400180 Join Date: Nov 2012 Location: The Beaten Path, USA, Roundworld, This Side of Infinity Device: Kindle Touch fw5.3.7 (Wifi only)	If you use a separate chapter for each file, you will almost certainly stay below the maximum size. And additional advantages include an automatic pagebreak between chapters, as well as being able to easily see the structure and possibly fix things if you plan on editing the contents later. I believe calibre can and will automatically split files at pagebreaks (like chapter headings ) during conversion.

02-10-2015, 02:03 PM	#5
johnc.eire Member Posts: 13 Karma: 10 Join Date: May 2010 Device: kobo H2O	Thanks for the responses, people. I'm going to take the general advice and re-split all my books down to chapter-sized sections. I've got to change the font size everywhere, too. Where I used to have 1.1em - which was just right for the Sony - I need to reduce that to 0.76em for the Kobo. Ah well. I can't say I've got nothing to do...

02-10-2015, 05:40 PM	#7
dickloraine Guru Posts: 631 Karma: 7544528 Join Date: Apr 2013 Location: Berlin Device: PRS 350, Kobo Aura	Changing font sizes does not make much sense. Just use 1em (or normal) for the main text and give other classes bigger or smaller sizes. Font size is one of the things the user changes to his liking. As is the font itself. And some fonts are bigger or smaller then others. So don't obsess over these things. Set reasonable defaults that scale with user settings and let the user decide what he likes. This is one of the main differences between paper books and eBooks. EBooks allow the user to change the formating to his liking, on the flip side they have not a perfect typography. Paper Books can have very good typography but are in no way customizable by the user.