pdfjam seems to change the margins when printing A5 pages to A4 as booklet

[rrthomas]

If I run:

pdfjam --landscape --suffix book foo.pdf --booklet true --paper a4

where foo.pdf is A5, then the A5 pages are not simply impressed on the A4 sheet; the margins are changed. See jenom/pdfbook2#10

[DavidFirth]

My usual approach to diagnosing a problem like this is to run again with --no-tidy, and then get the resulting .tex file, to check that against the documentation of the pdfpages package.

[rrthomas]

Thanks for the hint! So in my case, a.tex is:

\batchmode
\documentclass[a4,landscape]{article}
\usepackage[utf8]{inputenc}
\usepackage{pdfpages}

\begin{document}
\includepdfmerge[booklet=true]{/tmp/pdfjam-tZUmNi/source-1.pdf,-}
\end{document}

No mention that I can find of any margins. I tried adding the noautoscale=true option to \includepdfmerge, which changed the margins but without fixing them. Removing booklet=true and changing to a4,landscape to a5paper restores the correct margins (the process is now logically a no-op). Adding back a4,landscape and adding the option nup=2x1 to \includepdfmerge makes the margins go wrong again, suggesting the problem is with the nup option: both delta and offset default to zero, and centring A5 pages on A4 2up should obviously not change them.

I've written to Andreas Matthias with a bug report for pdfpages.

[rrthomas]

I found the bug:

LaTeX Warning: Unused global option(s):
    [a4].

That should be a4paper. In this case it's my error (because I typed --paper a4), though it would be nice if pdfjam gave a warning at least.

[rrthomas]

For example, by treating warnings as errors? Would this be a reasonable thing to do with pdfjam?

https://stackoverflow.com/questions/3244908/how-do-i-treat-latex-warnings-as-errors

[rrthomas]

There's one remaining problem I realize I haven't gotten to the bottom of: I shouldn't've needed to specify the paper size in the first place, as pdfjam should have the right default. When I execute pdfjam --help it says:

                  [Default for you at this site: paper=]

So either TeXLive, or Ubuntu's packaging of it, have not wired it up with appropriate defaults? (Looking at the rest of the --help output, no default is set.

[DavidFirth]

I found the bug:

LaTeX Warning: Unused global option(s):
    [a4].

That should be a4paper. In this case it's my error (because I typed --paper a4), though it would be nice if pdfjam gave a warning at least.

I agree, that would be nice.

[DavidFirth]

For example, by treating warnings as errors? Would this be a reasonable thing to do with pdfjam?

https://stackoverflow.com/questions/3244908/how-do-i-treat-latex-warnings-as-errors

Well, LaTeX does tend to give a lot of warnings. So this might not be a great idea I suspect.

Worth noting that the values allowed for --paper are all the ones allowed by LtTeX, plus all the ones allowed by the geometry package. That's a potentially moving target. So constructing a reliable test for a valid --paper setting might not be so easy. (I guess that's why I didn't do it from the start.)

[rrthomas]

Yes, I thought about that: in general it gives a lot of warnings, but I'm not sure that it should for a document constructed by pdfjam. Maybe worth a try…

[DavidFirth]

There's one remaining problem I realize I haven't gotten to the bottom of: I shouldn't've needed to specify the paper size in the first place, as pdfjam should have the right default. When I execute pdfjam --help it says:

                  [Default for you at this site: paper=]

So either TeXLive, or Ubuntu's packaging of it, have not wired it up with appropriate defaults? (Looking at the rest of the --help output, no default is set.

Oh, this is indeed unfortunate, and not intended. I can confirm that the same holds on my fresh install of TeXLive in Fedora 33.

The relevant part of the README at https://github.com/rrthomas/pdfjam#config tells someone how to configure their installation of pdfjam. But of course TeXLive does not actually do any of that; instead it just keeps a copy of the pdfjam.conf template in the pdfjam directory inside the TeXLive installation. I don't know what would be a good way around this, ie something that robustly helps users who have installed pdfjam via TeXLive.