The fix-qdf program is part of the qpdf package. With no arguments, fix-qdf reads from standard input and
writes to standard output. With one argument, it reads from that file and writes to standard output.
The fix-qdf program reads a PDF file in QDF form and writes out the same file with stream lengths, cross-
reference table entries, and object stream offset tables regenerated.
For details about fix-qdf and about PDF files in QDF mode, please see the qpdf manual, which can be found
at https://qpdf.readthedocs.io.