What patents exist on MPEG-1?

jrincayc writes: "Is MPEG-1 still patented, and if so when do the patents expire? MPEG-2 is still patented, and some of the patents may apply to MPEG-1, but to the best of my knowledge, there are no lists of patents that apply to MPEG-1. MPEG-1 Layer-3 audio is still patented, and will be for awhile. Snazzizone claims there are no license restriction that require payment, but absent a careful study of the problem, Fedora and other US based Linux distributions will not include MPEG-1 support. If MPEG-1 with Layer 2 audio was free of patents, that would allow one video file to be created that could be played almost anywhere since both Quicktime and Windows Media Player already support it. So, does anyone know what patents MPEG-1 requires?"