CHM -> EPUB conversion not finding right content

Britpunk · 05-18-2023, 02:00 PM

I have been tasked with converting some CHM files to EPUB. I suspect the CHM may have an unusual structure as it seems to be causing Calibre some problems. The CHM file opens as expected if I use the Windows Help application, so I am certain the file itself is intact.

If I unpack the .chm file I see the following files at root:
#IDXHDR
#ITBITS
#STRINGS
#SYSTEM
#TOPICS
#URLSTR
#URLTBL
#WINDOWS
cbr.css

and the directories:
chmfile
images

Within the 'chmfile' directory is the actual core content - approximately 1,250 HTM files, a 'Downloads' directory containing some Word documents, and an 'images' directory containing some JPG images.

Calibre appears to be detecting the wrong structure, as what gets produced is an .epub file, but all of the content is just the contents of the cbr.css file from the root. I'm certain there's some way to get it to pick up the correct content from the chmfile directory, but I'm not familiar enough with the tool yet.

Any help will be tremendously appreciated.

David

kovidgoyal · 05-18-2023, 09:02 PM

Since you have the unpacked HTMl you can just convert that directly, see https://manual.calibre-ebook.com/faq...specific-order

Britpunk · 05-19-2023, 04:46 AM

Thank you, I'm very grateful for your suggestion. Unfortunately I have a couple of thousand to convert so was trying to complete this as a batch process without regular manual intervention.

Speaking generally is there a way to force the structure detection to go deeper than it is?

kovidgoyal · 05-19-2023, 05:48 AM

No there is no way you can change what the chm input plugin reads from the chm file, short of modifying the code of chmlib.

Quoth · 05-19-2023, 06:34 AM

Try a 3rd party chm converter, there are ones that "unpack" to html on Linux. Not sure about Windows, but I'd assume they exist. Though conversion of a set of HTML files in a directory (I've saved websites with wget) works with calibre, the results sometimes need edited.

Not sure if any of the 3rd party viewers export to docx or html, but unless there is a command line interface that's tedious.

Conversion to PDF exists, but PDF is really a terminal format that's a disaster to convert to anything other than paper, screen or images!

Britpunk · 05-19-2023, 07:20 AM

Great, I appreciate the responses thank you.

05-18-2023, 02:00 PM	#1
Britpunk Junior Member Posts: 3 Karma: 10 Join Date: May 2023 Device: Fire	CHM -> EPUB conversion not finding right content I have been tasked with converting some CHM files to EPUB. I suspect the CHM may have an unusual structure as it seems to be causing Calibre some problems. The CHM file opens as expected if I use the Windows Help application, so I am certain the file itself is intact. If I unpack the .chm file I see the following files at root: #IDXHDR #ITBITS #STRINGS #SYSTEM #TOPICS #URLSTR #URLTBL #WINDOWS cbr.css and the directories: chmfile images Within the 'chmfile' directory is the actual core content - approximately 1,250 HTM files, a 'Downloads' directory containing some Word documents, and an 'images' directory containing some JPG images. Calibre appears to be detecting the wrong structure, as what gets produced is an .epub file, but all of the content is just the contents of the cbr.css file from the root. I'm certain there's some way to get it to pick up the correct content from the chmfile directory, but I'm not familiar enough with the tool yet. Any help will be tremendously appreciated. David

05-19-2023, 06:34 AM	#5
Quoth Still reading Posts: 14,010 Karma: 105092227 Join Date: Jun 2017 Location: Ireland Device: All 4 Kinds: epub eink, Kindle, android eink, NxtPaper	Try a 3rd party chm converter, there are ones that "unpack" to html on Linux. Not sure about Windows, but I'd assume they exist. Though conversion of a set of HTML files in a directory (I've saved websites with wget) works with calibre, the results sometimes need edited. Not sure if any of the 3rd party viewers export to docx or html, but unless there is a command line interface that's tedious. Conversion to PDF exists, but PDF is really a terminal format that's a disaster to convert to anything other than paper, screen or images! Last edited by Quoth; 05-19-2023 at 06:36 AM.

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05-18-2023, 09:02 PM	#2
kovidgoyal creator of calibre Posts: 45,345 Karma: 27182818 Join Date: Oct 2006 Location: Mumbai, India Device: Various	Since you have the unpacked HTMl you can just convert that directly, see https://manual.calibre-ebook.com/faq...specific-order

05-19-2023, 04:46 AM	#3
Britpunk Junior Member Posts: 3 Karma: 10 Join Date: May 2023 Device: Fire	Thank you, I'm very grateful for your suggestion. Unfortunately I have a couple of thousand to convert so was trying to complete this as a batch process without regular manual intervention. Speaking generally is there a way to force the structure detection to go deeper than it is?

05-19-2023, 05:48 AM	#4
kovidgoyal creator of calibre Posts: 45,345 Karma: 27182818 Join Date: Oct 2006 Location: Mumbai, India Device: Various	No there is no way you can change what the chm input plugin reads from the chm file, short of modifying the code of chmlib.

05-19-2023, 07:20 AM	#6
Britpunk Junior Member Posts: 3 Karma: 10 Join Date: May 2023 Device: Fire	Great, I appreciate the responses thank you.

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