如何在Perl中阅读和操作PDF 1.5文件？

There doesn't appear to be any Perl libraries that can open, manipulate, and re-save PDF documents that use the newer PDF version (1.5 and above I believe) that use a cross-reference stream rather than table. Does anyone know of any unix/linux-based utilities to convert a PDF to an older version? Or perhaps there's a Perl module in CPAN I missed that can handle this?There doesn't appear to be any Perl libraries t