Portrait of the artist as an older man

The music is old-school rockabilly played at punk-rock intensity by a charismatic goofball on guitar. He looks like a man possessed as he tears up a tune, the drummer matching his reckless pace. In the black-and-white footage from 1986, Dexter Romweber appears ready to blow away the rock world.

Two decades later, Romweber still has a powerful voice and puts on a fine show. But color footage from 2004 performances shows him looking tired and puffy as he speaks of his "semi-psychotic spiritual odyssey" in a way that suggests Marlon Brando's Col. Kurtz from "Apocalypse Now," only not as creepy.

The documentary "two headed cow," which has its world premiere Saturday at the Full Frame Documentary Film Festival, captures those whiplash contrasts. It's funny, sad, poignant, bizarre and disturbing, sometimes all at once.

Romweber and Chris "Crow" Smith spent 15 years together as Flat Duo Jets. A fixture on the Chapel Hill music scene since 1984, they appeared on the David Letterman show, toured with the Cramps and recorded nine albums.

Their discs were never big sellers. But they have emerged as influential pioneers. In "two headed cow," alternative-country diva Neko Case and punk godmother Exene Cervenka call Romweber "legendary." Chan "Cat Power" Marshall says she bought her first guitar because of him. Jack White from the White Stripes, a guitar-and-drums duo that picked up where the Jets left off, says they were "showing people what was possible."

Not that Romweber himself is all that impressed -- even by the White Stripes, who have sold millions of records with a similar style of earthy blues-rock.

"I've never really listened to Jack White," Romweber says in an interview. "I don't know the White Stripes' records. We did play a gig with them and he's a nice guy, but I don't know him or their music. But he seems like a swell guy, so more power to him."

Watch the old performance footage and it's hard to fathom why Flat Duo Jets didn't become massively popular. It's what the producers of "two headed cow" expected when they started the film 20 years ago.

In 1986, Lisa Fincannon, Bill Cody and director Tony Gayton made a documentary called "Athens, Ga. Inside/Out," starring B-52's, Pylon and other Athens staples. They also included Flat Duo Jets, who briefly lived in Athens but were a Chapel Hill institution.

The producers were impressed enough with Romweber to begin making a separate film on the Jets. They shot in the style of D.A. Pennebaker's 1960s-vintage Bob Dylan documentaries, mixing black-and-white footage of the Jets' runaway-train shows with high jinks of Romweber and Smith cutting up in motel rooms.

"From about 1988 to '92, short of Nirvana, I don't think there was a better band in the country than Flat Duo Jets when they were on," Cody says.

But the project fell apart. The producers ran out of money, and Romweber was having troubles of his own.

"We 'lost' Dexter for some time," Fincannon says. "He went through a metamorphosis where he came to understand that the things driving him as a musician were not particularly healthy."

The Romweber film went into storage. Gayton went on to write screenplays (including the thriller "Murder by Numbers"). Fincannon became a casting agent with Wilmington-based Fincannon and Associates, casting "The Dukes of Hazzard," "Junebug" and other movies. Cody wrote and produced a 1997 film called "Slaves to the Underground."

"Athens, Ga. Inside/Out" was released on DVD in 2003. Cody saw Gayton at a party, and Gayton told him that they should try to finish the Romweber film.