I'm currently making a game where every format for every asset is either opensource/freeformat, or requires no license fees to use.
I've pretty much settled happily on .ogg for audio, vorbis/webm for video, .png for pictures and openoffice for documents (or .pdf files since they were free standard since 2001?)
What I'd like to know though is, if I make a 3d model in a .fbx format, do I owe any royalties/fees to autodesk for using fbx files in Unity?
If not, does this apply to every 3d model format, or only certain ones? Do software companies like Blender/Unity pay for the privilege to import fbx files so that users like me don't have to?