Whilst I'm aware that within Quicktime Pro it is easy to export a file for AppleTV, I am curious exactly what codecs and specific settings are a) playable and b) optimum for the highest picture & audio quality on both a second and third generation Apple TV respectively. As a professional video editor I'd like to be able to manually control my encoding settings to ensure that I am pushing the hardware of these AppleTVs to their maximum to deliver the highest bitrate and quality available. I am also curious, if I encode a clip as 1080P for a generation 3 AppleTV, will the same clip be playable on a generation 2 AppleTV, albeit at downrezzed 720P, or will the AppleTV require a separate 720P encoded version to work? Also, what forms of surround sound are supported by AppleTV? Thanks for any help.