Digital TV brings potential for more channels.

As TV stations prepare to make the federally mandated transition from analog to digital broadcasting, Angelenos have the potential to get dozens of new channels on their digital TV sets.

But what will be on those channels is an open question.

"Basically, the answer is, anything's possible," said NBC network spokesman Mike Nelson, when asked about his network's plans for the digital future.

The conversion to digital is being made to accommodate technology called high-definition television, a new form of digital broadcast that allows for crisper pictures and higher sound quality.

The high-definition signal requires considerably more bandwidth than the standard digital signal. But it may be a decade before stations broadcast in HDTV - giving them the opportunity in the interim to broadcast five program channels apiece.

Analysts say L.A.'s television production industry stands to see boom times as TV stations across the country rash to fill their extra channels with programming.

"I think the need for programming will increase exponentially, and I almost think it will create a hole that's too big to fill," said Sherrie Mazingo, chairwoman of the broadcasting department at USC.

But Mazingo and others caution that the additional programming is likely to be low-quality fare, at least in the early years.

"The owners of broadcast outlets will find that the number of viewers will become so dispersed by the additional channels that it's not going to be financially sound to pay the cost of quality programming," she said.

Station officials say it's far too early to determine what they will air on their extra channels or even if the extra capacity will be used. But the options being considered by local broadcasters are intriguing. They include:

* Simulcasting the same programming on all the extra channels, only in different languages. This makes sense in markets like Los Angeles, which has a burgeoning immigrant population and a high percentage of Spanish-speakers. In other parts of the country, it's less likely to happen.

* Using the extra channels to run infomercials and home shopping programs. Analysts say this is the most likely option for many stations, because such programming more than pays for itself without advertising support.

* Running community programming such as local city council or town hall meetings, that don't require much production expense.

* Using the extra capacity for alternate services, such as two-way Internet communications or interactive television programming.

* Time-shifting - running the same network shows at different times on different channels. Viewers in L.A. could thus watch "Seinfeld" at 6 p.m. on one of KNBC's channels (the same time it is broadcast on the East Coast) and 9 p.m. on another.

* Putting different entertainment programming on several or all of the extra channels. This is the most expensive option, and also the least likely.

The Federal Communications Commission has required affiliates of the four major networks in the country's top 10 markets (L.A. is the nation's second-biggest) to air digital signals by May 1, 1999.

In Los Angeles, three TV stations - KNBC-TV Channel 4, KABC-TV Channel 7 and KTLA-TV Channel 5 - have volunteered to go digital six months earlier, by November 1998.

All other commercial TV stations must transmit digital signals by May 1, 2002, while public TV stations have until the following year. In 2006, stations have to give their analog channels back to the government, which will reallocate them for other uses.

For local stations, the cost of the changeover is significant. Each station will have to install a second antenna and a second transmission facility, because they will continue to broadcast in analog at the same time as they air digital. Cost estimates for the new equipment range from $1 million to $8 million.

The greatest fear among broadcasters is that the increased channel capacity will further fragment a viewing audience that has already eroded with the explosion of new channels on satellite and cable television.

With fewer viewers for each channel, less money can be charged to advertisers.

"If the programming's not good, people aren't going to watch," said William Burton, director of programming services at KABC. "That's why the 500-channel universe never came to be. Quality programming is very expensive, and you can't pay for it without sponsors."

Nonetheless, TV producers are expected to benefit, because once the digital market matures there will almost certainly be a greater demand for programming. Syndicators face an expected bonanza because many stations are likely to fill extra channels with reruns of popular shows.

"I think, no matter what happens, it will create an even greater appetite for product," said Bruce Johanson, president of the National Association of Television Program Executives (NATPE).

That demand could quickly come to an end once stations begin digital broadcasts, which will limit them to one or at most two programming channels.

But it won't happen overnight. Neil Mazur, director of engineering for KCAL-TV Channel 9, said an HDTV studio camera costs up to $500,000, compared to the $100,000 or so for the cameras now in use. As a result, it may be several years before local stations make the conversion; meanwhile, the networks are keeping mum about their HDTV plans.

"Ultimately, when the equipment gets cheap enough, I drink you'll find everyone broadcasting in high-definition," Mazur said.