Add "MemoryError" to FAQ

This commit is contained in:
NoDRM 2022-01-02 19:13:15 +01:00
parent b2b55531d3
commit f17b255159
3 changed files with 11 additions and 4 deletions

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@ -54,4 +54,5 @@ List of changes since the fork of Apprentice Harper's repository:
- ineptpdf: Support for V=5, R=5 and R=6 PDF files, and for AES256-encrypted PDFs.
- ineptpdf: Disable cross-reference streams in the output file. This may make PDFs slightly larger, but the current code for cross-reference streams seems to be buggy and sometimes creates corrupted PDFs.
- Drop support for importing key data from the ancient, pre "DeDRM" Calibre plugins ("Ignoble Epub DeDRM", "eReader PDB 2 PML" and "K4MobiDeDRM"). These are from 2011, I doubt anyone still has these installed, I can't even find a working link for these to test them. If you still have encryption keys in one of these plugins, you will need to update to DeDRM v10.0.2 or older (to convert the keys) before updating to DeDRM v10.0.3 or newer.
- Some Python3 bugfixes for Amazon books (merged #10 by ableeker).
- Some Python3 bugfixes for Amazon books (merged #10 by ableeker).
- Fix a bug where extracting an Adobe key from ADE on Linux through Wine did fail when using the OpenSSL backend (instead of PyCrypto). See #13 and #14 for details, thanks acaloiaro for the bugfix.

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@ -31,13 +31,14 @@
# 7.0 - Python 3 for calibre 5
# 7.1 - Fix "failed to decrypt user key key" error (read username from registry)
# 7.2 - Fix decryption error on Python2 if there's unicode in the username
# 7.3 - Fix OpenSSL in Wine
"""
Retrieve Adobe ADEPT user key.
"""
__license__ = 'GPL v3'
__version__ = '7.2'
__version__ = '7.3'
import sys, os, struct, getopt
from base64 import b64decode
@ -442,7 +443,7 @@ if iswindows:
for j in range(0, 16):
try:
plkkey = winreg.OpenKey(plkparent, "%04d" % (j,))
except WindowsError:
except WindowsError, FileNotFoundError:
break
ktype = winreg.QueryValueEx(plkkey, None)[0]
if ktype == 'user':

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@ -153,10 +153,15 @@ Remove the DRMed book from calibre. Click the Preferences drop-down menu and cho
## Is there a way to use the DeDRM plugin for Calibre from the command line?
See the [Calibre command line interface (CLI) instructions](CALIBRE_CLI_INSTRUCTIONS.md).
## The plugin displays a "MemoryError" in its log file during DRM removal.
A "MemoryError" usually occurs when you're using the 32-bit version of Calibre (which is limited in the amount of useable RAM). If you have a 64-bit installation of your operating system (on Windows, press Windows+Break, then make sure it says "64-bit Operating System" under "System type"), try downloading the 64-bit version of Calibre instead of the 32-bit version.
If the error still occurs, even with the 64-bit version, please open a bug report.
# General Questions
## Once the DRM has been removed, is there any trace of my personal identity left in the ebook?
That question cannot be answered for sure. While it is easy to check if a book has DRM or not, it is very difficult to verify if all (traces of) personal information have been removed from a book. The tools attempt to remove watermarks when they are detected, but that will not be the case for all watermarks.
That question cannot be answered for sure. While it is easy to check if a book has DRM or not, it is very difficult to verify if all (traces of) personal information have been removed from a book. The tools attempt to remove watermarks when they are detected (optionally, there's an option in the plugin settings to enable that), but that will not be the case for all watermarks.
## Why do some of my Kindle ebooks import as HTMLZ format in calibre?
Most Amazon Kindle ebooks are Mobipocket format ebooks, or the new KF8 format. However, some are in a format known as Topaz. The Topaz format is only used by Amazon. A Topaz ebook is a collections of glyphs and their positions on each page tagged with some additional information from that page including OCRed text (Optical Character Recognition generated Text) to allow searching, and some additional layout information. Each page of a Topaz ebook is effectively a description of an image of that page. To convert a Topaz ebook to another format is not easy as there is not a one-to-one mapping between glyphs and characters/fonts. To account for this, two different formats are generated by the DRM removal software. The first is an html description built from the OCRtext and images stored in the Topaz file (HTMLZ). This format is easily reflowed but may suffer from typical OCRtext errors including typos, garbled text, missing italics, missing bolds, etc. The second format uses the glyph and position information to create an accurate scalable vector graphics (SVG) image of each page of the book that can be viewed in web browsers that support svg images (Safari, Firefox 4 or later, etc). Additional conversion software can be used to convert these SVG images to an image only PDF file. The DeDRM calibre plugin only imports the HTMLZ versions of the Topaz ebook. The html version can be manually cleaned up and spell checked and then converted using Sigil/calibre to epubs, mobi ebooks, and etc.