I'm working in a PHP web service in which I need to concat PDF files into a single file. The problem is: Most PDFs are v1.7 and some are higher versions and I need to downgrade to PDF 1.4. I tried GhostScript and TCPDF but it seems not to work for all PDF versions and I don't know why. I need something that help me downgrade to 1.4 or something that can concat all PDF files regardless of version. It also needs to be something that works in both Linux and Windows OS because this service runs in many servers and there are some linux servers and a few windows servers (that can't be pivoted to linux servers). Do anyone has something that can help me out or give me a better direction? Continue reading...
