Reading the width and height from a RM file

[MikeHunt79]

I'm playing RM files on my webpage, and I want to embed them. The only problem is that all my RM files are different sizes, so I need a way of getting the width and height properties using PHP.

Does anyone know a library or add-on that will allow me to do this?

EDIT: I forgot to mention, I'm using Apache with PHP.