Are HDTV and multicasting competing technologies?

This is archived content from Digital TV Facts. For up-to-date information on the digital TV transition, see the federal government’s site, www.DTV2009.gov.

In some ways, yes.

To provide high-definition television (HDTV) images with surround sound, broadcasters must send huge chunks of information over the airwaves. During HD broadcasts, a local station has only enough room left in the digital pipe (”bandwidth”) to provide one or two more multicast programming streams, rather than perhaps four more otherwise.

A station may “downconvert” a program that was produced in HD into a lower-quality form of HD, or even into standard definition, to make room for more multicast channels. Viewers equipped with HD displays may notice diminished quality in such cases.

It’s a classic case of quality vs. quantity—and a zero-sum choice.

Station owners must weigh the costs and benefits of providing a single program in high-def or multiple programs in standard definition (SD). Will one show in HD bring in as many viewers in the desired demographic as multiple shows in SD? In this calculation, a key consideration for broadcasters is whether cable systems would carry the additional multicast channels, vastly increasing the size of the potential audience.

HDTV and multicasting may also be seen as complimentary, in that many stations offer high-definition programs at certain times of the broadcast day (especially during prime time) but add additional multicasts at others.

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