Yep like Leemix says, ARC only supports audio from the tv. Same audio pretty much as an optical connection but no lossless codecs (Dolby TrueHD or DTS-HD MA). Believe the only advantage current version of ARC has vs optical is Atmos meta-data on DD+ streams on some tvs. Future editions of ARC are set to include lossless, tho. If your xbox is plugged into the avr via hdmi then you can utilize the lossless codecs now, it has nothing to do with ARC.