Advertisements Correct. The networks take their signal and compress it using MPEG2 and broadcast it out at (we hope with no subchannels) at 18 or 19 Mbps, the max available to an OTA channel. That's as good as it gets. Of course if they have a 3 meg subchannel and a 1 meg weather radar we're down to 14 meg or so which is why OTA quality is all over the place. But in any case it's still better then DirecTV's MPEG2 HD which is even further compressed and/or "bit starved" as they like to say. That's why they don't look as good. The famous "HD Lite" if you will. MPEG4 is simply another compression scheme which allows smaller file sizes (and less bandwidth) then MPEG2. There isn't really anything "better" about MPEG4, just that DirecTV can give it full bandwidth. If they had the room they could give their MPEG2 HD full bandwidth as well and it's PQ would be awesome as well.