Quote:
Originally Posted by FrustratedReader
Yes, Calibre has a setting for internal file size, default about 260K.
That said, quite obviously Kobo test their sw better on kepubs than epubs, but it's also obviously buggy.
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There were pretty decent reasons as to why the original epub 2.0 spec set the maximum file size to 300KB. While improvements have reduced the effects of overly large file sizes due to the limited RAM in most ereaders, large chunks of text still have issues. I have noticed this with a couple of omnibus volumes where each of the original items was stored as a single html file. One nasty noted is that when a link to a footnote in one large chunk pointed into another large chunk, the ereader appears to be paginating every page between the link and it's destination. So if I was in the first book and went to a footnote, the ereader was forced to paginate hundreds if not thousands of pages to get to the footnote.
Please note that in my testing, I found I could trigger this behaviour on my laptop which is a pretty decent machine (i7, 32GB RAM, 2TB NvMe SSD). Simply breaking up the books so each chapter was it's own file made that hesitation disappear.
Also please note that Kobo does not write either of the renderers used in it's eInk ereaders.
For epub2 with Adobe DRM support, they use RMSDK which is an Adobe product though it seems to be commercialized through 3rd parties such as Datalogics.
For epub3 with support for Kobo's proprietary DRM, they originally used the ACCESS NetFront BookReader EPUB Edition. ACCESS donated a good chunk of their WebKit based code to the Readium project. While I haven't run into mentions of Readium in the Kobo firmware, Tolino's firmware does make mention of Readium in a couple of modules though oddly, there seems to be no support for epub3.
From Datalogics' website, it appears that RMSDK 11 also uses the Readium codebase (might that be the reason that RMSDK gets excellent ratings for rendering epub3s?
). However if Kobo was planning on going to a single renderer, they would run into a licensing issue where you are prohibited from using non-Adobe DRM with the RMSDK renderers.