For years, broadcasters have told consumers seeking the best high-definition picture quality to use an antenna to receive signals over-the-air, instead of relying on a cable or satellite operator to deliver the programming. That's because many multichannel operators have recompressed, or “rate-shaped,” broadcasters' HD video to reduce the bandwidth needed to pass along the signal. For example, a cable operator might receive an 18 megabit-per-second HD stream at the headend and recompress it to 15 Mbps before passing it down the pipe. So, receiving the signal directly over-the-air would ensure that the viewer got exactly what the station transmitted. But...