$inputFileName="bachorgan.pdf";
$outputFileName="bachorgan_numbered.pdf";

# first pass -- (1) find number of highest-numbered objects

%offsetByObj=();
$highestObjNum=-1;
open(IN,$inputFileName);
while (<IN>) {
    if (/^([0-9]+) 0 obj$/) {
	$objNum=$1;
	if ($objNum>$highestObjNum) {
	    $highestObjNum=$objNum;
	}
    }
}
close(IN);

# second pass, modify/write file

open(IN,$inputFileName);
open(OUT,">$outputFileName");
binmode(OUTF);

@pages=();
$fontObjNum=$highestObjNum+1;
$highestObjNum++;
$firstPageNumObjNum=$highestObjNum+1;
$inXref=0;
$inStartxref=0;
$offset=0;
$xrefOffset=-1;
while (<IN>) {

    if ($inStartxref) {
	print OUT "$xrefOffset\n";
	$inStartxref=0;
    }
    else {
	if ($inXref) {
	    if (/^trailer$/) {
		$inXref=0;
		print OUT "$_";
	    }
	}
	else {
	    
	    if (/^([0-9]+) 0 obj$/) {
		$objNum=$1;
		$offsetByObj{$objNum}=$offset;
	    }
	  
	    if (/^\/Contents ([0-9]+) 0 R$/) {
		$contentsId=$1;
		$highestObjNum++;
		$_="/Contents [$contentsId 0 R $highestObjNum 0 R]\n";
	    }

	    # type of /Resources /ProcSet that appears in the actual file in music pages.  There are other types, but those appear in the contents.  I ignore the contents, because they define their own fonts.  The sum total is that Acrobat says that it couldn't find a font (for those contents pages), so it replaced it with Helvetica, which is what I wanted anyway.  The warning's a bit scary, but it seems to work.
	    if (/^\/Resources<<\/ProcSet\[\/PDF \/ImageB\]$/) {
		$_="/Resources<</ProcSet[/PDF /ImageC /Text]\n/Font << /F1 $fontObjNum 0 R >>\n";
		$gotResources=1;
	    }
	    
	    if (/^xref$/) {

		# dump the font resource object

		$offsetByObj{$fontObjNum}=$offset;
		$fontObj="$fontObjNum 0 obj\n<<\n/Type /Font\n/Subtype /Type1\n/Name /F1\n/BaseFont /Helvetica\n/Encoding /WinAnsiEncoding\n>>\nendobj\n";
		$offset += length($fontObj);
		print OUT "$fontObj";

		# dump all the page num objects we've made

		$pageNum=1;
		#print "$firstPageNumObjNum < $hi
		for ($i=$firstPageNumObjNum; $i<=$highestObjNum; $i++) {
		    #print "$i\n";
		    $offsetByObj{$i}=$offset;
		    
		    $stream="BT\n/F1 12 Tf\n432 9 Td($pageNum)Tj\nET\nBT\n/F1 12 Tf\n108 9 Td($pageNum)Tj\nET\n";
		    $streamLen=length($stream);
		    $obj="$i 0 obj\n<< /Length $streamLen >>\nstream\n$stream"."endstream\nendobj\n";
		    $offset += length($obj);
		    print OUT "$obj";

		    $pageNum++;
		    
		}

		# now actually do the xref

		$xrefOffset=$offset;
		print OUT $_;
		$numObjects=$highestObjNum+1;
		print OUT "0 $numObjects\n";
		print OUT "0000000000 65535 f \n";
		for ($i=1; $i<=$highestObjNum; $i++) {
		    $s=$offsetByObj{$i};
		    while (length($s)<10) {
			$s="0"."$s";
		    }
		    print OUT "$s 00000 n \n";
		}
		$inXref=1;
	    }
	    
	    if (/^startxref$/) {
		$inStartxref=1;
	    }
	    
	    if (!$inXref) {
		print OUT $_;
	    }
	}
    }
	
    $offset += length($_);
}