The TV networks, meantime, now are delivering even more 5.1 content to local DTV stations. Here’s what they’re doing:

ABC: In the 2001-2002 season, ABC began delivering all HD programming in 5.1, and in the 2004-2005 season, it broadcast more than 800 hours of HD 5.1 programs, including all of its scripted primetime comedies, dramas, theatrical movies, NFL Monday Night Football, and other select sporting events and specials. In primetime, ABC broadcasts 14 hours per week in HD 5.1 to its affiliates.

In turn, a growing number of ABC’s 225 affiliates are transmitting the network’s HD 5.1 programs, ABC reported. As of January 2005, 64 of 132 HDTV affiliates were delivering 5.1 to viewers. That’s up from November 2003, when 50 of 112 HDTV affiliates delivered 5.1.

As of January 2005, ABC’s 31 SD affiliates delivered HD programming in stereo, a spokesperson noted.

CBS: The network added 5.1 soundtracks to select HD programs for the first time in 2003 and began delivering 5.1 with its primetime HD programs during the 2004-2005 season. In 2003, CBS started delivering 5.1 with the Grammy Awards, college basketball and football, the U.S. Open, and select pro football games. The 2004 Super Bowl was broadcast in HD 5.1. Other HD programs are delivered in Dolby Surround, CBS engineering Vice President Robert Seidel said.

By January 2005, CBS was broadcasting six prime time programs in HD 5.1 along with NFL games, NCAA college football and basketball games, the U.S. Tennis Open, select Sunday night movies and the 2005 Grammys. CBS also transmits metadata that enables home theater systems to switch among mono, stereo, Dolby Pro Logic and Dolby Digital 5.1 automatically.

Out of the network’s 207 affiliated stations, 188 were delivering CBS content in digital form in January 2005, up from 175 during the year-ago period, he said. In early 2005, CBS had not surveyed its affiliates to determine how many were broadcasting in HD and 5.1. In early 2004, however, almost half of CBS’s 175 DTV affiliates passed 5.1-channel soundtracks through to their viewers. Of those, 24 delivered SD video, and 151 delivered HD. Of the HD stations, 84 delivered 5.1. None of the SD stations delivered 5.1.

Fox: For the 2004-2005 season, the network dramatically increased the amount of 5.1-channel programming and delivered HD video for the first time, having previously delivered programs only in SD.

Almost all scripted and live-action programs are produced in HD, and many of them are in 5.1, the company said. The rest are in Dolby Surround. More than 100 regular season NFL games and NASCAR races are in HD and 5.1.

Among Fox’s 182 affiliates, about 165 were delivering Fox’s HD signal in early 2005, and all of them delivered 5.1.

The network launched 5.1 with select SD programs in the 2002-2003 season following its 5.1-channel broadcast of the 2002 Super Bowl. In the 2003-2004 season, it delivered two NFL games per week and all NASCAR races in SD 5.1.

NBC: The network went 5.1 in a big way during the 2004-2005 season.

In March 2004, NBC began experimenting with 5.1 soundtracks for scripted HD shows by broadcasting American Dreams through its owned-and-operated HD station in New York City. Then the network broadcast the 2004 Summer Olympics in HD 5.1. When the fall season rolled around, all 14 of the network’s scripted shows were delivered in HD 5.1, as were occasional HD movies and HD sports specials.

By late 2004, 135 of about 213 NBC affiliates delivered HD, up from 115 in February 2004. Of the 135, 69 delivered 5.1 soundtracks. The number of NBC affiliates delivering SD video in 5.1 was unavailable.

For analog and DTV affiliates that broadcast in stereo and aren’t equipped to deliver Dolby Digital 5.1, NBC began delivering matrixed 5.1-channel Dolby Pro Logic II soundtracks during the 2004-2005 season.

PBS: The public network delivers all of its HD programs in 5.1, but only a handful of its programs are available in HD. Of its 349 affiliates, 292 made the DTV transition as of January 2005, and roughly 250 of them are broadcasting some HDTV programming. All DTV affiliates are capable of passing through 5.1, the network said. PBS also broadcasts SD widescreen programs, some in 5.1 and some in Dolby Surround.

WB: The WB network launched HD in the 2002-2003 season and began delivering HD broadcasts in 5.1 and Dolby Surround in the 2004-2005 season. Additional details were unavailable.