10-19-2018, 03:22 PM | #1 |
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Best means of converting azw3 to ePub
I need to convert my Kindle library, (360 books), from azw3 to ePub as I am moving over to Kobo. A couple of years ago, (well, 22 Apr 2016), JSWolf recommended the KindleUnpack plugin for this type of format shift.
Is this still the best approach or will calibre's azw3 to ePub do just as good a job? |
10-19-2018, 04:06 PM | #2 |
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The only EPUB issue I have seen doing this is in the CSS:
AZW3 uses 'REM' instead of em . I just change that (have not seen any change on my EPUB device) |
10-19-2018, 04:45 PM | #3 |
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REM could yield different rendering results depending on the rest of the CSS. I'll see how long it takes to unpack and fix 1 book to see how practical it will be for 360.
Are there any downsides to just doing a mass conversion within calibre? If not then this might be a more pragmatic solution as I could just let it run overnight. |
10-19-2018, 06:29 PM | #4 | ||
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Quote:
Quote:
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10-20-2018, 09:14 AM | #5 |
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Calibre conversion worked well, (4 sec for a 250 page novel), and I think that I see what JSWolf means about the CSS changes: most of the styles end up named ".calibreNN" instead of carrying through the original style names. I'm not bothered about this as the book displays perfectly and the conversion process is so fast.
One thing I did notice when viewing the generated stylesheet.css is that it contains: .calibre { font-size: 0.875em } This is because I change the body style in my Kindle books to have this setting as I find the standard Kindle fonts are too big. Is there any way that I can force this back to 1.0em during conversion or will I have to edit the final ePub to reset it? |
10-20-2018, 11:03 AM | #6 |
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look at the option to add extra css using the calibre conversion. you should be able to add css to force a body text size of 1em.
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10-20-2018, 11:13 AM | #7 |
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Or turn off font rescaling
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10-20-2018, 02:21 PM | #8 |
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Thanks for the suggestions.
I already had font-rescaling off so calibre was probably just faithfully respecting my Kindle CSS mod. However, extra css did the trick using body:1em so I've put this in my defaults for conversion. Incidentally, should I choose the Kobo Reader output profile for conversion? I used the default output profile and it seemed to work just fine. |
10-21-2018, 12:20 AM | #9 |
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glad the extra css worked, I was not 100% sure it would override what you had elsewhere.
i think the different output profiles differ only in how they resize images ( or not). they have no effect on text |
10-21-2018, 08:25 AM | #10 |
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With any modern hi-res ereader you should probably use the "Tablet" output profile which makes no attempt to scale down source images during conversion
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10-21-2018, 09:39 AM | #11 |
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Sorry, but any of the suggestions on how to do a conversion should be ignored. Most KF8 (AZW3) eBooks started life as ePub. So the best way to go from KF8 > ePub is to install the KindleUnpack plugin and shift the KF8 > ePub and then use Calibre's eBook editor to edit what needs to be fixed such as rem in the CSS instead of em and there are a few simple things in the OPF that will need to be fixed. Also make sure you have the epubcheck plugin for the editor installed so you can use that to validate the ePub. This will get you the code as it is instead of as it will be after a conversion. Yes, the filenames are a mess, but that's how they would be after a conversion. A shift is the best way to convert.
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10-21-2018, 11:55 AM | #12 |
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@JSWolf: Thanks for the suggestion. KindleUnpack certainly gives a cleaner result and the post-extraction tidyup is minimal but it does take a lot longer than calibre conversion and is more manual.
If I was retired and had the time then I would definitely use unpacking but right now the pragmatic approach is conversion: calibre gets the job done quickly and the final displayed results are just as good as the unpack method. Filename tidyup is simple enough as I have a small epub post-processor plugin which can do this, (as well as applying a set of predefined regexes). The stylesheet rem unit is subtly different to em and should be able to be left as it is, provided that the ePub 2 spec implements it. A blanket change of rem to em could mess up the rendering. Last edited by Agama; 10-21-2018 at 12:05 PM. |
10-21-2018, 12:36 PM | #13 | |
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Quote:
I've encountered a similar situation more than once. I suspect that in your case "best" is likely something close to "convert with a good enough method and only tweak those few the absolutely need it, and then only when the flaws are seen". For me it is to keep the library in calibre as is and only convert, if necessary, when a particular book is selected for reading. Even with a smaller 300-400 book library (mine's small by MR standards at ~2000) it is unlikely that I would read them all before replacing my reader at least once. Such replacement, whether "reader" means device or merely app, would possibly mean a change in format, leaving any earlier conversion waste. |
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10-21-2018, 05:04 PM | #14 |
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Yes, you are right, "best" is my judgement in my particular situation at this point in time, and what you suspect is my "best" sums the situation up accurately.
Since I'm making the switch to a completely different format I just thought that I might as well do my whole library in one go so that I could have all my books on my new reader. However, your idea of converting only when necessary has a certain appeal to it and would make the unpack method less onerous. Thanks to you all for your help and suggestions. |
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