Where is metadata for PDF files? Can I insert metadata into any PDF file?

Question

I have many files of music; with the program mp3Tag, I had organized all of it. I have the correct metadata as it allows. I am looking for a free software that does the same, but for PDF files.

Solution 1

Ghostscript can insert or modify document metadata into any PDF.

Caveats: While doing so, Ghostscript will (1) first read in the complete PDF code, (2) second re-process that complete PDF code, (3) write out a completely new PDF file. This process can be wanted (could be for the advantage of the PDF quality, for example by additionally embedding previously missing fonts) or unwanted...

How to do it

1. Create a text file named mydocinfo.pdfmark and put the following content into it:

   [ /Title (Jaziel's Important Document)
     /Author (Jaziel Aguirre)
     /Subject (Mr. Aguirre's experiments with pdfmark)
     /Creator (JA's Metadata Inserter)
     /ModDate (D:19700101000000+01'00')
     /Producer (A 'pdfmark' trick with Ghostscript)
     /Keywords (Metadata, Ghostscript, PDF, Linux)
     /CreationDate (D:20181229104653+01'00')
     /DOCINFO
   pdfmark
   

   Note, that the opening [ does NOT require a closing ] -- it is closed by the 'pdfmark' keyword.

2. Now run this Ghostscript command to insert the new metadata into an existing PDF:

   gs                     \
     -o with-metadata.pdf \
     -sDEVICE=pdfwrite    \
     existing.pdf         \
     mydocinfo.pdfmark
   

3. Check the new metadata:

   pdfinfo with-metadata.pdf
   
     Title:          Jaziel's Important Document
     Subject:        Mr. Aguirre's experiments with pdfmark
     Keywords:       Metadata, Ghostscript, PDF, Linux
     Author:         Jaziel Aguirre
     Creator:        JA's Metadata Inserter
     Producer:       A 'pdfmark' trick with Ghostscript
     CreationDate:   Sat Dec 29 10:46:53 2018 CET
     ModDate:        Thu Jan  1 00:00:00 1970 CET
     Tagged:         no
     UserProperties: no
     Suspects:       no
     Form:           none
     JavaScript:     no
     Pages:          1
     Encrypted:      no
     Page size:      142.8 x 202.08 pts
     Page rot:       0
     File size:      5394 bytes
     Optimized:      no
     PDF version:    1.7
   

(Tested with Ghostscript v9.27.)

Solution 2

pdftk is a command line utility allowing you to extract and modify the PDFs metadata using the dump_data and the update_info options.

The following command will extract the metadata of the input.pdf to metadata file:

pdftk input.pdf dump_data output metadata

Modify the content of the metadata file using your text editor, then update the pdf file to a new output.pdf:

pdftk input.pdf update_info metadata output output.pdf

To check the new pdf file (print to stdout):

pdftk output.pdf dump_data

Solution 3

Instead of writing the metadata into a text file first, you could of course also put it into one single command line:

gs -o with-meta.pdf -sDEVICE=pdfwrite -f existing.pdf -c "[ /Title (Jaziel's Important Document) /Author (Jaziel Aguirre) /Subject (Mr. Aguirre's experiments with pdfmark) /ModDate (D:19700101000000+01'00') /CreationDate (D:20181120102653+01'00') /Keywords (Metadata, Ghostscript, PDF, Linux) /Creator (JA's Metadata Inserter) /Producer (A 'pdfmark' trick with Ghostscript) /DOCINFO pdfmark"

or, with a formatting which is a bit more nice (readable):

gs -o with-meta.pdf  \
   -sDEVICE=pdfwrite \
   -f existing.pdf   \
   -c "[ /Title (Jaziel's Important Document) 
         /Author (Jaziel Aguirre)
         /Subject (Mr. Aguirre's experiments with pdfmark)
         /Keywords (Metadata, Ghostscript, PDF, Linux)
         /ModDate (D:19700101000000+01'00')
         /Keywords (Metadata, Ghostscript, PDF, Linux)
         /Creator (JA's Metadata Inserter)
         /Producer (A 'pdfmark' trick with Ghostscript)
         /CreationDate (D:20181120102653+01'00')
       /DOCINFO pdfmark"

Comments

[user755506]

Ha!, I was thinking about adding pdftk's method a little bit later too. Now I can upvote your answer instead... :-)

[Jaaziel Aguirre]

Hey, that's is simple. thanks for response. My ask was for Win10 but it helps me for the future, I had problems with Computers and just now I have a Pc with only win10. thanks

[Jaaziel Aguirre]

what a useful, I will do this in some future. thanks

[Jaaziel Aguirre]

Mmm Yes, but i am new here, so, I click the up arrow of corner?

[user755506]

@JaazielAguirre: Exactly. Plus, you pick one (or none) of the answers to make it the "accepted" (best) answer for you...

[holzkohlengrill]

Does this also allow to remove metadata? If yes, how?

[user755506]

@holzkohlengrill: Yes, if you create the mydocinfo.pdfmark file with zero content inside the brackets, like this: [ /Title () ....