Police recordings are rarely as spectacular as the Modesto police's wiretaps of Scott Peterson now being used by the prosecution in his murder trial.

But that doesn't make the job of recording and retrieving them any less vital. And it's a market niche in which one Oakland company has carved out a nice business.

Capture Technologies Inc. has sold digital recording equipment to more than 300 police departments from Oregon to Los Angeles, says Lou Parrague, head of the equipment distributor.

Founded in 1948 as a supplier of office recording equipment such as Dictaphones, Capture now sells security devices such as retina and fingerprint scanners to offices, along with digital phone recording equipment to police departments, air traffic controllers, hospital emergency rooms, and even stock brokers who need to keep phone records of stock trade orders from clients.

Digital recording and other communications equipment sales make up about half of Capture's bottom line, and are contributing to the privately held 40-employee firm's expected 51 percent year-over-year growth in sales to $9.9 million for this fiscal year.

Among its customers locally have been the police departments in Pleasanton and Fairfield, the city of Oakland, the Hayward airport and the Bay Area Rapid Transit District.

Much more advanced than the large reel-to-reel tapes that were still being used by police dispatchers as recently as the 1990s, PC-based digital recorders help police solve crimes and save time.

"If a caller is agitated, cryptic or his voice is low, you need the ability to play that call back, slow it down, pull it apart, just to try to discern what's going on, so the dispatcher has a chance of helping him," said Parrague.

By state law, California police departments are required to record 911 calls, all conversations between officers and dispatchers and all radio conversations between officers - and keep them for 100 days. And if cases go to court, the police department needs to provide the calls as evidence.

That's a lot of search and retrieval work, even more so in the days before digital, when recordings were made on those pancake-sized reels, remembers Margaret Mary Goulart, who started as a Pleasanton police dispatcher 14 years ago.

"They used to be this big," Goulart said, holding her arms apart as if showing off the size of a large tuna she had caught. "We had a big supply room where we'd store them by law for 100 days. Afterward, we'd run the reels through a demagnetizer to erase them. You'd still end up with bleed-through from the old recordings, though."

Searching tapes for specific conversations for an attorney was laborious.

"It was really a nightmare," said Goulart. "You'd have to keep fast-forwarding and rewinding to find what you'd need, and that would usually take hours."

Goulart, who oversaw the police department's upgrade to a digital recording system five years ago, says the PC-based system made by Nice Systems Ltd., an Israeli firm, records every single one of the more than 500 phone calls a day the department gets from the general public. They range from calls to remove dead animals from the street to tips about unsolved crimes.

Each call is saved onto a computer hard drive, along with indexing information, such as the time and date. A backup digital audio tape is recorded at the same time. If dispatchers know that a certain conversation will probably be used as evidence in court or otherwise be accessed repeatedly, they can type comments next to specific conversations, such as case numbers or the officer's name.

What would be ideal, says Goulart, would be a Google-like search engine for audio content: something that can recognize words or individuals' voices in order to further speed up the process of finding and retrieving recordings.

In fact, the latest systems from Nice, a firm founded by former military intelligence officers, do sport content analysis features such as the ability to differentiate between individual "voiceprints" and also scan for certain keywords and phrases.

The new systems can even go Google one better and detect "heightened emotions" in conversations, said Parrague.