How to render a self-written widget in Gtk

I've been writing a Gtk+ Widget which plays videos and, using libAV, I can load and read video files but I don't know how to get the frame data rendered as a widget. What do I do to render it? The frame data consists of an array of unsigned chars.

Does anyone actually know how to do this, or should I just spend several hours fucking about with Cairo/Gdk like its nobody's business?