On2 had a pile of active patents covering VP3, which they granted irrevocable royalty-free licenses to when they abandoned it to become Theora. Nobody's ever d

On2 had a pile of active patents covering VP3, which they granted irrevocable royalty-free licenses to when they abandoned it to become Theora. Nobody's ever done codec development without either filing a ton of patents or at least publishing rigorous documentation to establish prior art (Dirac). Some of those patents may no longer be in force, but they still exist.