Now, after years of struggles, the Bay Area vocalist is starting to get his due thanks in part to his contributions to these films.

Los Angeles-based composer Emile Mosseri wrote the score for The Last Black Man in San Francisco, and is among a growing group of industry insiders who have embraced Marshall’s vocal gift.

"Everybody was in tears the first time they heard him sing it," says Mosseri of The Last Black Man production team's response to Marshall's version of "San Francisco." "It was just this incredible performance. They knew right away that they had gold."

Tall, goateed and loosely dressed in sweats and spectacles, the 53-year-old singer says he had no trouble reworking John Phillips and Scott McKenzie’s 1967 hit.

He’s covered other songs by white artists over the years, like Gilbert O'Sullivan's "Alone Again," and says he received an immersion in white, hippy culture as an undergrad at Cal Poly in San Luis Obispo.

"I'm pretty good at singing white people's covers," he says. "Un-soul music, non-soul music—I'm good at singing that."

But the music Marshall grew up listening to and singing in church in the East Bay with his single mom and siblings was gospel.

"We sang a lot of good songs which formed my library of melodies and harmonies," Marshall says. "I learned a lot of harmony placement, how to blend with other singers and how to sing from your diaphragm."

Marshall started out performing in high-school talent shows. It was not long after graduating from Berkeley High that he scored his first hit, “Rumors,” in 1986, with his band, Timex Social Club.

Marshall’s career could have taken off at that point. But instead, his life started to derail.

"I was not prepared," Marshall says. "So I'm bumping my head, skinning my knees at every turn."

Marshall says his troubles started after he passed up a ten-year record deal on the back of the "Rumors" success because he didn’t want to be tied down.

"We read all the stories about how artists were being treated," Marshall says. "Prince was complaining. Michael Jackson was complaining."

He then watched helplessly as Jay King, the producer, formed a new band, Club Nouveau. Marshall says he used some of Timex Social Club's musical ideas to fuel new pop hits like "Why You Treat Me So Bad" from 1987.

Marshall partly blames himself for his lack of business sense. But he says King and others swindled him out of royalties and credit, leading him down a long, self-destructive path of drug abuse.

"It was bad," Marshall says. "I was literally trying to kill myself."

Jay King is based in Sacramento, where he still works in the music business. He says he did nothing wrong, and attributes Marshall’s misfortunes to his drug habit. But King is still in awe of the singer’s voice.