Best means of converting azw3 to ePub

Agama · 10-19-2018, 03:22 PM

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.

Quote:

Originally Posted by JSWolf

There is a much much better way to do this. The way to do this is to install the KindleUnpack plugin and format shift from KF8 to ePub. Then load the ePub in the eBook Editor, validate it, fix any errors and you are good to go.

Is this still the best approach or will calibre's azw3 to ePub do just as good a job?

theducks · 10-19-2018, 04:06 PM

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)

Agama · 10-19-2018, 04:45 PM

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.

davidfor · 10-19-2018, 06:29 PM

Quote:

Originally Posted by Agama

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.

Try the conversion on a few and see how it goes. JSWolf has a phobia about how the CSS is changed during a conversion. But, for most cases, it is fine

Quote:

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.

Only if you don't like the results. But, you can always redo ones that don't work that well.

Agama · 10-20-2018, 09:14 AM

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?

stumped · 10-20-2018, 11:03 AM

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.

theducks · 10-20-2018, 11:13 AM

Or turn off font rescaling

Agama · 10-20-2018, 02:21 PM

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.

stumped · 10-21-2018, 12:20 AM

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

jackie_w · 10-21-2018, 08:25 AM

Quote:

Originally Posted by Agama

Incidentally, should I choose the Kobo Reader output profile for conversion? I used the default output profile and it seemed to work just fine.

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

JSWolf · 10-21-2018, 09:39 AM

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.

Agama · 10-21-2018, 11:55 AM

@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.

dwig · 10-21-2018, 12:36 PM

Quote:

Originally Posted by Agama

...
If I was retired and had the time then I would definitely use unpacking but ...

As is obvious, "best" for one person or situation is not always best for another. In the end, "best" is a value judgement only you can decide.

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.

Agama · 10-21-2018, 05:04 PM

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.

10-21-2018, 11:55 AM	#12
Agama Guru Posts: 776 Karma: 2751519 Join Date: Jul 2010 Location: UK Device: PW2, Nexus7	@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.

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10-19-2018, 04:06 PM	#2
theducks Well trained by Cats Posts: 29,800 Karma: 54830978 Join Date: Aug 2009 Location: The Central Coast of California Device: Kobo Libra2,Kobo Aura2v1, K4NT(Fixed: New Bat.), Galaxy Tab A	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
Agama Guru Posts: 776 Karma: 2751519 Join Date: Jul 2010 Location: UK Device: PW2, Nexus7	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.

10-20-2018, 09:14 AM	#5
Agama Guru Posts: 776 Karma: 2751519 Join Date: Jul 2010 Location: UK Device: PW2, Nexus7	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
stumped Wizard Posts: 3,305 Karma: 10259306 Join Date: May 2016 Device: kobo forma, Kobo Libra, Huawei media Tab, fire HD10, PW3 HDX8.9,	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.

10-20-2018, 11:13 AM	#7
theducks Well trained by Cats Posts: 29,800 Karma: 54830978 Join Date: Aug 2009 Location: The Central Coast of California Device: Kobo Libra2,Kobo Aura2v1, K4NT(Fixed: New Bat.), Galaxy Tab A	Or turn off font rescaling

10-20-2018, 02:21 PM	#8
Agama Guru Posts: 776 Karma: 2751519 Join Date: Jul 2010 Location: UK Device: PW2, Nexus7	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
stumped Wizard Posts: 3,305 Karma: 10259306 Join Date: May 2016 Device: kobo forma, Kobo Libra, Huawei media Tab, fire HD10, PW3 HDX8.9,	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, 09:39 AM	#11
JSWolf Resident Curmudgeon Posts: 73,970 Karma: 128903378 Join Date: Nov 2006 Location: Roslindale, Massachusetts Device: Kobo Libra 2, Kobo Aura H2O, PRS-650, PRS-T1, nook STR, PW3	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.

10-21-2018, 05:04 PM	#14
Agama Guru Posts: 776 Karma: 2751519 Join Date: Jul 2010 Location: UK Device: PW2, Nexus7	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.