From Ulrich Hertlein, "I got the following type error from gcc 4.0.1 on OS X 10.5.6:
/Users/uli/Projects/osg/OpenSceneGraph/src/osgPlugins/ffmpeg/FFmpegDecoderVideo.cpp: In member function \u2018int osgFFmpeg::FFmpegDecoderVideo::convert(AVPicture*, int, AVPicture*, int, int, int)\u2019:
/Users/uli/Projects/osg/OpenSceneGraph/src/osgPlugins/ffmpeg/FFmpegDecoderVideo.cpp:245: error: invalid conversion from \u2018int\u2019 to \u2018PixelFormat\u2019
/Users/uli/Projects/osg/OpenSceneGraph/src/osgPlugins/ffmpeg/FFmpegDecoderVideo.cpp:245: error: initializing argument 3 of \u2018SwsContext* sws_getContext(int, int, PixelFormat?, int, int, PixelFormat?, int, SwsFilter?*, SwsFilter?*, double*)\u2019
It expects 'src_pix_fmt' and 'dst_pix_fmt' to be of type 'PixelFormat?' rather than int. The attached cast fixes this (for me).
I've also added Matroska video to the list of supported extensions"