| 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 increasingly it is local broadcasters, not multichannel operators, that are degrading their hi-def picture quality. The culprit is multicasting, i.e., transmitting digital subchannels alongside the primary HD stream within a station's 19.4 Mbps digital TV pipe. While such subchannels are finally starting to gain traction and generate meaningful revenues (see Station to Station, June 22), many are doing so at the expense of the high-definition images that were the primary impetus for the DTV standard. Engineers and HD aficionados note, with considerable irony, that while there is far more HD content available today, the relative picture quality may not be as good as the first HD broadcasts more than a decade ago.
Monday, July 6, 2009
Broadcasters downgrading OTA HD signals for fun and profit.
First it was the cable companies and now its the broadcasters themselves downgrading the signal quality to shove two or more channels in their feed. When does it get to the point that consumers can take action against them?