There's an early scene in Jeremy Saulnier's arresting new thriller Green Room that's so punk rock it hurts.

The Ain't Rights, a young, noisy band touring the Pacific Northwest, are sitting for an interview with a mohawked music journalist. He leads by asking why the group is so hard to track down online.

"The music is shared live," Pat (Anton Yelchin), the bass player, replies with a slight holier-than-thou edge. "It's time and aggression, and then it's over. You got to be there."

If you were to ask Philadelphians Will and Brooke Blair, in their younger years, to expound on the same topic, the musicians would likely give a similar answer: Flesh-and-blood performance is king, and the rest is just window dressing.

But the siblings, who make up the local production team the Blair Brothers, have since transitioned from onstage careers into a different sort of sonic discipline - scoring films with a mind toward maximizing emotion.

In Green Room, now in theaters, the Ain't Rights - Yelchin, Joe Cole, Callum Turner, and Alia Shawkat - are taken hostage by a club owner (Patrick Stewart) and his boot-stompin' lackeys.

"I miss [playing live] a good bit, but we love what we're doing now for different reasons," says Will, checking in from their Fishtown studio as his brother put the final touches on a video series that will be shown soon on ESPN. "Working for someone else, surprisingly, provides the most open-ended sort of freedom that we've ever had."

Will, 37, and Brooke, 38, grew up in Alexandria, Va., in a household that encouraged expression. Saulnier, a childhood friend who lived nearby, showed an early interest in movie-making, and the Blairs found their own artistic footholds. "When he was veering off toward film as a way to stay out of trouble," says Will, "we went toward music."

The Blairs' older brother, Macon, is the star of the director's 2013 breakthrough, Blue Ruin, and he plays a vital role in Green Room, too.

After attending Virginia Commonwealth University, Will, a drummer, and Brooke, a guitarist, fell in with a live hip-hop act called Infectious Organisms, touring extensively and opening for the Roots, OutKast, and Run-DMC. They ended up in Philadelphia in 2001, where they formed East Hundred, a poppy five-piece that released the full-length Passenger in 2009. (Saulnier shot the music video for "Slow Burning Crimes," the lead track on the album.)

When that band broke up, the brothers were left "scratching our heads creatively," says Will. The duo, which had scored various shorts as well as Saulnier's 2007 debut, Murder Party, wanted to break into film music, but there wasn't a clear way to do that in Philadelphia.

Then Saulnier came calling with an opportunity to work on Blue Ruin, a beautiful and brutal revenge flick featuring Macon as a broken man avenging the murder of his family.

The movie went on to become an indie success story, a critical darling recognized by the International Federation of Film Critics at the 2013 Cannes Film Festival.

"Nothing's over the top. Nothing's perfectly choreographed or orchestrated. . . . [Saulnier] makes a really strong push to make things as realistic as possible," says Brooke.

That often translates to conscious minimalism. In Green Room, named for the backstage space the Ain't Rights get trapped in after a gig ends very badly, the raucous sound produced by the band is a dramatic contrast to the Blairs' subtle, ambient score work. Their notes swell and sweat but never quite burst, cultivating an organic anxiety that helps Saulnier's action stand out on screen.

"The level of tension - it feels so real because nothing seemed forced," says Brooke. The brothers' core musical processes do well bolstering the verisimilitude.

Balancing live instrumentation with synthesized effects creates a result both tactile and versatile.

"We never want anything to sound completely electronic," Brooke says. "We start outside the computer and end up in the computer. My hope is we're still retaining some sense of a human element."

Having your musical cues dictated by someone else's art might sound like a limiting experience, but Will feels the opposite is true. As a member of a band, you are often "trapped in your own expectations," he says, whereas in this line of work, "it becomes less about what we think is super-cool and more about serving the movie itself."

And word of their skills has spread. Recent projects include Diverge, a science fiction film from newcomer James Morrison; and Edge of Winter, a drama starring soon-to-be Spider-Man Tom Holland and The Killing's Joel Kinnaman.

Seeing two brothers who work together so closely, of course, raises an obvious question: Don't you guys fight all the time? The Blairs definitely don't always see eye to eye in the studio, but they've honed their process in a way that ensures disagreements end in positive output. "The head-butting is a part of getting there," says Brooke. "We end up pushing ourselves into new territory neither of us think to go to on our own."