“When did I get on board?” filmmaker Edgar Wright asks himself, repeating the question about when, over Sparks’ five-decade career, he first took a liking to the band. “I saw Sparks for the first time on TV when I was 5. And even when I was 5…”

“What kept ya?” interjects singer Russell Mael. “What were you waiting for?”

Everything in good time — and the timing is finally right for Russell and his brother Ron to get their filmic due in the form of “The Sparks Brothers,” a rollicking documentary that will premiere Jan. 30 as part of this year’s virtual Sundance Film Festival.

The Mael brothers’ story is one of unusual endurance in the world of rock ’n’ roll; yes, the group’s two mainstays are united by blood, which should help, but then, that was never any guarantee for Oasis or the Kinks in the end. It’s also a tale of eternally delayed gratification, for any fans who ever felt Sparks was deserving of a plateaued level of rock stardom. Wright’s doc won’t singlehandedly push them up to the level of a Who or Stones, to name two other outfits who’ve soldiered on that long. But it’s one sweet explainer for an act that has always been just offbeat enough to require one, for the intrigued uninitiated.

“I’d always been curious about doing a documentary,” says Wright, the director of “Shaun of the Dead,” “Scott Pilgrim vs. the World” and “Baby Driver,” the last of which was successful enough that his agent must’ve done a double-take when he indicated he wanted to spend two or three years on a rock doc as its follow-up. “I was always impressed by directors who could seem to sort of be doing a feature film and a documentary in tandem, like Scorsese. But most of all, I felt like making the film was easier for me than to carry on telling my friends how great I thought Sparks was — easier for me to make a two-hour film than spend four hours at dinner trying to extol my love.”

Wright was born in 1974, the same year that the L.A.-based Sparks became a sensation in his native England with the archly titled album “Kimono My House” and its single “This Town Ain’t Big Enough for the Both of Us,” which, in retrospect, sounds like something Queen might have done if they’d listened to a lot more Gilbert and Sullivan. When he became intrigued as a tot five years later, Sparks was already onto a third or fourth life in a lifetime of reinvention with the Maels’ prescient, Giorgio Moroder-produced all-synths album. That was before they became a core KROQ band in L.A. in the ’80s with “Angst in My Pants,” had their breakthrough in Germany in the ’90s with a song called “When Do I Get to Sing ‘My Way’?” or wrote an operetta about Ingmar Bergman in the 2000s.

Sparks’ latest project, a collaboration with director Leos Carax on an Adam Driver-starring movie musical, “Annette,” was supposed to premiere at Cannes last year but should see daylight, like this doc, later in 2021. They’ve always been a hard act to follow, but have maybe an even tougher arc to follow.

Says Wright: “Every time they came back, I was more sort of confounded by it” — in a good way. The general public was easily baffled by a group made up of a high-voiced, long-haired sex-symbol singer and a keyboardist-songwriter with a slicked-back ’do, a Hitler/Chaplin mustache and a deep glare — and that was before the 25 studio albums that contained almost as many reinventions. But Sparks became like the secret handshake of rock — a fraternity where if you got it, you got it. Among the superfans who show up to be interviewed in the doc are Mike Myers, Patton Oswalt, Duran Duran, Beck and Flea. They share screen time with figures ranging from their 1972 debut album’s producer, Todd Rundgren, to the return of a woman seen leaping onto the stage in the mid-’70s and wrapping herself around the supposedly lesser sex god of the two.

“Most of the girls jumped up to stomp on Russell, but this one girl was of more of an intellectual bent or something,” explains Ron, the recipient of the tackle. “She insulted me,” says Russell, mock-upset, “saying that she wanted Ron because she felt that she could connect with him on a cerebral level, and she couldn’t with me.” Anyway, Ron says, “I love that Edgar interviewed a girl that stormed the stage in 1975, and it’s still so vivid in her mind — and then there’s Neil Gaiman, and they’re all equally important.” Wright crystallizes the funny-but-serious mystique that intrigued him from his first “Top of the Pops” sighting in the late ’70s until he realized that Sparks followed him back on Twitter and mustered the nerve to DM his musical heroes five years ago.

“Everybody was smiley then, and the idea of people coming on and sort of staring down the camera — when you’re a kid watching that, it’s beguiling and sort of terrifying and definitely stood out from ‘The Wombles’,” says Wright. “I didn’t understand the lyrics, but I wanted to be smarter to understand it. So I put Sparks in the same bracket as Monty Python, where I would think, ‘Who are these philosophers? I want to understand what the joke is.’ I felt a similar way with Sparks: ‘I know there’s something more to this than just the catchy tune.’”

That goes for fans of 50 years, too. “Neil Gaiman speaks to it in the documentary,” Wright says. “You can enjoy it on a superficial level, but you want to decode it. Sparks feels like a bit of a riddle to solve. You kind of have to do half the work.” Wright is thrilled to have made a film that may help with the other half.