how to extract text from djvu and other ebooks format (possibly in Python)
djvu, full-text-search, pdf, python
Solution
Assuming the djvu files contain OCR-ed text, a fast way on Linux to get that out is to use Popen to run `djvutxt` and grab the output.
The text in a `.djvu` file is compressed with a `djvu` specific compression algorithm, `bzz`, for which no simple C interface exists which you could load as an shared object in Python. It is a C++ implementation based on some framework.
Shameless self promotion: I contributed to Calibre the conversion from OCR-ed `.djvu`, which uses `djvutxt` in this way. However it falls back to my pure python decoder implementation (sloooow) if `djvutxt` is not available. So you could use that code if you cannot use `djvutxt`.
I have not yet put out the Python source seperately from Calibre. But after downloading and extracting Calibre's source:
curl -L http://status.calibre-ebook.com/dist/src | tar xvJ
find . | fgrep djvu
The relevant files are `djvu_input.py`, `djvu.py` and `djvubzzdec.py`
Problem
I have a collection of ebooks in djvu, pdf, chm format and I am looking for a way to search the keyword in the content. I have been researching around and find couple suggestion to parse pdf content but there seems to be no way to convert the content in djvu into text. By any chance, does anyone know a way to decode djvu content into text so that I can search it easily? Thanks