String concatenation breaks extraction for translation
In the file ogginfo/ogginfo2.c there is this code
warn(_("WARNING: Expected frame %" I64FORMAT ", got %" I64FORMAT "\n"), inf->framenum_expected, framenum);
The xgettext tool can't handle that, since it doesn't know what I64FORMAT will become. Only "WARNING: Expected frame %" turns up in the message file. (And that will remain unused; that is not what the argument will be at run time.)
There are a few other similar cases in the same file, search for I64FORMAT.