Having a look at the source code it looks like some dependencies could be dropped as they're handled by FFmpeg
libmad (and most likely libid3tag)
libogg + libvorbis
I see ffmpeg is optional feature and it extends support for some kind of audio files. Also it doesn't exclude vorbis/ogg support if I choose FFMPEG like an option (Take a look into Scons scripts).
Maybe I could make some changes to this port excluding ogg/vorbis and some another dependencies if FFMPEG option is selected. It it is not selected ogg/vorbis (and more) are included like depdendencies. It could be the best to do here.
What do you think?
Sorry for the late reply! I looked at it mainly to reduce the usage of libmad and libid3tag (dated, slow and unmaintained) and I happened to also spot libogg and libvorbis in there. It does look as you say that ogg/vorbis are more tightly integrated however so we probably need to leave that in.