Is there a libav 9 porting guide available somewhere?
The 0.8 deprecated (= 9 removed) list (http://libav.org/doxygen/release/0.8/deprecated.html) has suggested replacements for most of them.
PixelFormat is now AVPixelFormat, and its entries are similarly renamed: http://libav.org/doxygen/release/9/pixfmt_8h.html#a9a8e335cf3be472042bc9f0cf80cd4c5