WiDi at least seems to be RTSP with some uPNP trickery over an ad-hoc wifi connection.
Miracast is wireless HDMI replacement with DRM and all that stuff and as such is nogo from the beginning. From what I read, you need special hardware because it uses one or more wifi channels simultaneously. Anything under WIFI-Direct will probably never work with open-source hw/sw.
OK, WiDi as in Intel Wireless Display, not Wifi Direct. I've played a WiDi "stream" in VLC - it will fall back to plain old RTSP in some cases.
Intel have a GPL WiDi archive, but I haven't taken a look yet.