GhostScript creating extra page when font errors occur - pdf

Question

I have a process that needs to write multiple postscript and pdf files to a single postscript file generated by, and that will continue to be modified by, word interop VB code. Each call to ghostscript results in an extra blank page. I am using GhostScript 9.27.
Since there are several technologies and factors here, I've narrowed it down: the problem can be demonstrated by converting a postscript file to postscript and then to pdf via command line. The problem does not occur going directly from postscript to pdf. Here's an example and an example of the errors.
C:\>"C:\Program Files (x86)\gs\gs9.27\bin\gswin32c.exe" -dNOPAUSE -dBATCH -sDEVICE=ps2write -sOutputFile=C:\testfont.ps C:\smallexample.ps
C:\>"C:\Program Files (x86)\gs\gs9.27\bin\gswin32c.exe" -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -sOutputFile=C:\testfont.pdf C:\testfont.ps
Can't find (or can't open) font file %rom%Resource/Font/TimesNewRomanPSMT.
Can't find (or can't open) font file TimesNewRomanPSMT.
Can't find (or can't open) font file %rom%Resource/Font/TimesNewRomanPSMT.
Can't find (or can't open) font file TimesNewRomanPSMT.
Querying operating system for font files...
Didn't find this font on the system!
Substituting font Times-Roman for TimesNewRomanPSMT.
I'm starting with the assumption that the font errors are the cause of the extra page (if only to rule that out, I know it is not certain). Since my ps->pdf test does not exhibit this problem and my ps->ps->pdf does, I'm thinking ghostscript is not writing font data that was in the original postscript file to the one it is creating. I'm looking for a way to preserve/recreate that in the resulting postscript file. Or if that is not possible, I'll need a way to tell ghostscript how to use those fonts. I did not have success attempting to include them as described in the GS documentation here: https://www.ghostscript.com/doc/current/Use.htm#CIDFontSubstitution.
Any help is appreciated.

Answer 1

I've made this an answer, even though I'm aware it doesn't answer the question, becasue it won'f fit as a comment.
I think your assumption that the missing fonts are causing your problem is flawed. Many PDF files do not embed all the fonts they require, I've seen many such examples and they do not emit extra pages.
You haven't been entirely clear in your description of what you are doing. You describe two processes, one going from PostScript to PDF and one going from PostScript on to PostScript (WHY ?) and then to PDF.
You haven't described why you are processing PostScript into a PostScript file.
In particular you haven't supplied an example file to look at. Without that there's no way to tell whether your experience is in fact correct.
For example; its entirely possible that you have set /Duplex true and have an odd number of pages in your file. This will cause an extra blank page (quite properly) to be emitted, because duplexing requires an even number of pages.
The documentation you linked to is for CIDFont substitution, it has nothing to do with Font substitution, CIDFonts and Fonts are different things in PDF and (more particularly) PostScript. But I honestly doubt that is your problem.
I'd suggest that you put (at the least) 'smallexample.ps' somewhere public and post the URL here, that way we can at least follow the same steps you are doing. That way we can probably tell you what's going on. An explanation of why you're doing this would be useful too, I would normally strongly suggest that you don't do extra steps like this; each step carries the risk of degarding the output in some way.

Answer 2

Thank you for the response. I am posting as an answer as well due to the comment length restrictions:
I think you are correct that my assumption about fonts is wrong. I have found the extra page in the second ps file and do not encounter the font errors until the second conversion.
I have a process that uses VB MSWord Interop libraries to print multiple documents to a single ps file using a virtual printer set up with ghostscript and redmon. I am adding functionality to mix in pdf files too. It works, but results in an extra page. To narrow down where the problem actually was, I tried much simpler test cases via command line to identify the problem. I only get the extra page when ghostscript is converting ps to ps (whether or not there is a pdf as well). Converting ps to pdf I do not get the extra page. Interestingly, I can work around the problem by converting the ps to pdf and then both pdfs back to ps. That is a slower and should not be necessary however, so I would like to identify and resolve the extra page issue. I cannot share that particular file. I'll see if I can create an example I can share that also exhibits the problem. In the meantime, I can confirm that the source ps file is six pages and the duplexing settings are as follows. There is duplex definition in the resulting ps file with the extra page. Might there be some other common culprits I could check for in the source ps? Thank you.
featurebegin{
%%BeginFeature: *DuplexUnit NotInstalled
%%EndFeature
}featurecleanup
featurebegin{
%%BeginFeature: *Duplex None
<</Duplex false /Tumble false>> setpagedevice
%%EndFeature
}featurecleanup