Problem with viewing .prc files

spinoza · 07-21-2009, 07:54 AM

I've imported a number of public domain .prc files into Calibre, but have been unable to view them. When I try to open them I get the error log below. Can anyone explain what the problem is and how to correct? Many thanks in advance!

unpack requires a string argument of length 8
Traceback (most recent call last): File "/Applications/ebook and doc manager apps/calibre.app/Contents/console.app/Contents/Resources/lib/python2.6/site-packages.zip/calibre/gui2/viewer/main.py", line 55, in run Thread.run(self) File "threading.pyo", line 477, in run File "calibre/ebooks/epub/iterator.pyo", line 119, in __enter__ File "/Applications/ebook and doc manager apps/calibre.app/Contents/console.app/Contents/Resources/lib/python2.6/site-packages.zip/calibre/ebooks/epub/from_any.py", line 62, in mobi2opf reader = MobiReader(path) File "/Applications/ebook and doc manager apps/calibre.app/Contents/console.app/Contents/Resources/lib/python2.6/site-packages.zip/calibre/ebooks/mobi/reader.py", line 258, in __init__ self.book_header = BookHeader(self.sections[0][0], self.ident) File "/Applications/ebook and doc manager apps/calibre.app/Contents/console.app/Contents/Resources/lib/python2.6/site-packages.zip/calibre/ebooks/mobi/reader.py", line 154, in __init__ self.exth = EXTHHeader(raw[16+self.length:], self.codec, self.title) File "/Applications/ebook and doc manager apps/calibre.app/Contents/console.app/Contents/Resources/lib/python2.6/site-packages.zip/calibre/ebooks/mobi/reader.py", line 34, in __init__ self.length, self.num_items = struct.unpack('>LL', raw[4:12]) error: unpack requires a string argument of length 8

HarryT · 07-21-2009, 08:17 AM

What format are these "PRC" files? Perhaps they are a format that Calibre does not support. A "PRC" file is just a "wrapper" - a little like a ZIP file is; the data inside it can be in any format whatsoever. Although, for example, Mobipocket books often have a ".prc" file extension, so do a thousand and one other types of data file, too.

What format are these specfic PRC files that you have?

spinoza · 07-21-2009, 08:31 AM

Well, I can read them with my Mobipocket Reader (Windows) without problems, as well as on my old Pocket PC. I can't recall where I got them (they're a few years old), but they're all 19th century (and earlier) texts.

wallcraft · 07-21-2009, 09:43 AM

These are probably PalmDOC ebooks, see wiki: PDB for how to look in the file to tell. Unfortunately, early MobiPocket ebooks also had the identifier TEXtREAd althogh they are not standard PalmDOC files. Calibre 0.6 beta should be able to read PalmDOC files. I don't know if it will need your files to be renamed .pdb first or not.

spinoza · 07-21-2009, 12:28 PM

Interestingly this worked for about half of the ebooks with this problem. When I changed the extension to .pdb, Calibre could import them but it used Stanza to open the files, which is fine.

For the other half Calibre used Stanza to try to open them, but Stanza gave an error message as well ("Cannot open locked file"). I took one of them and tried the new Barnes & Noble reader app, and it opened it without problems! Go figure. In any case, this is what the header looked like at the top of the ebook:

"<HTML><HEAD><meta name="GENERATOR" content="BeMobi MobiBook Publisher 1.0"><TITLE>The Wealth of Nations</TITLE></HEAD><BODY>", [The Wealth of Nations]

07-21-2009, 07:54 AM	#1
spinoza Member Posts: 16 Karma: 10 Join Date: Nov 2006 Location: Boston area Device: PRS-505, iPhone, MacBook Pro	Problem with viewing .prc files I've imported a number of public domain .prc files into Calibre, but have been unable to view them. When I try to open them I get the error log below. Can anyone explain what the problem is and how to correct? Many thanks in advance! unpack requires a string argument of length 8 Traceback (most recent call last): File "/Applications/ebook and doc manager apps/calibre.app/Contents/console.app/Contents/Resources/lib/python2.6/site-packages.zip/calibre/gui2/viewer/main.py", line 55, in run Thread.run(self) File "threading.pyo", line 477, in run File "calibre/ebooks/epub/iterator.pyo", line 119, in __enter__ File "/Applications/ebook and doc manager apps/calibre.app/Contents/console.app/Contents/Resources/lib/python2.6/site-packages.zip/calibre/ebooks/epub/from_any.py", line 62, in mobi2opf reader = MobiReader(path) File "/Applications/ebook and doc manager apps/calibre.app/Contents/console.app/Contents/Resources/lib/python2.6/site-packages.zip/calibre/ebooks/mobi/reader.py", line 258, in __init__ self.book_header = BookHeader(self.sections[0][0], self.ident) File "/Applications/ebook and doc manager apps/calibre.app/Contents/console.app/Contents/Resources/lib/python2.6/site-packages.zip/calibre/ebooks/mobi/reader.py", line 154, in __init__ self.exth = EXTHHeader(raw[16+self.length:], self.codec, self.title) File "/Applications/ebook and doc manager apps/calibre.app/Contents/console.app/Contents/Resources/lib/python2.6/site-packages.zip/calibre/ebooks/mobi/reader.py", line 34, in __init__ self.length, self.num_items = struct.unpack('>LL', raw[4:12]) error: unpack requires a string argument of length 8

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07-21-2009, 08:17 AM	#2
HarryT eBook Enthusiast Posts: 85,544 Karma: 93383043 Join Date: Nov 2006 Location: UK Device: Kindle Oasis 2, iPad Pro 10.5", iPhone 6	What format are these "PRC" files? Perhaps they are a format that Calibre does not support. A "PRC" file is just a "wrapper" - a little like a ZIP file is; the data inside it can be in any format whatsoever. Although, for example, Mobipocket books often have a ".prc" file extension, so do a thousand and one other types of data file, too. What format are these specfic PRC files that you have?

07-21-2009, 08:31 AM	#3
spinoza Member Posts: 16 Karma: 10 Join Date: Nov 2006 Location: Boston area Device: PRS-505, iPhone, MacBook Pro	Well, I can read them with my Mobipocket Reader (Windows) without problems, as well as on my old Pocket PC. I can't recall where I got them (they're a few years old), but they're all 19th century (and earlier) texts.

07-21-2009, 09:43 AM	#4
wallcraft reader Posts: 6,975 Karma: 5183568 Join Date: Mar 2006 Location: Mississippi, USA Device: Kindle 3, Kobo Glo HD	These are probably PalmDOC ebooks, see wiki: PDB for how to look in the file to tell. Unfortunately, early MobiPocket ebooks also had the identifier TEXtREAd althogh they are not standard PalmDOC files. Calibre 0.6 beta should be able to read PalmDOC files. I don't know if it will need your files to be renamed .pdb first or not.

07-21-2009, 12:28 PM	#5
spinoza Member Posts: 16 Karma: 10 Join Date: Nov 2006 Location: Boston area Device: PRS-505, iPhone, MacBook Pro	Interestingly this worked for about half of the ebooks with this problem. When I changed the extension to .pdb, Calibre could import them but it used Stanza to open the files, which is fine. For the other half Calibre used Stanza to try to open them, but Stanza gave an error message as well ("Cannot open locked file"). I took one of them and tried the new Barnes & Noble reader app, and it opened it without problems! Go figure. In any case, this is what the header looked like at the top of the ebook: "<HTML><HEAD><meta name="GENERATOR" content="BeMobi MobiBook Publisher 1.0"><TITLE>The Wealth of Nations</TITLE></HEAD><BODY>", [The Wealth of Nations]

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