On-screen, the boys were being chased on their bikes — a friendly alien stowed in a handlebar basket — when men in suits blocked their path. Seconds away from disaster, the boys’ bicycles lifted into the air. They flew. The music swelled.

That swell was no prerecorded soundtrack: Musicians of the Minnesota Orchestra blew horns, bowed strings and crashed cymbals, creating live the score for “E.T. the Extra-Terrestrial” as the classic 1982 film played above them at Orchestra Hall in Minneapolis.

Like other symphony orchestras across the country, the Minnesota Orchestra is banking on the growing popularity of such concerts, which attract big crowds and introduce classical music to new audiences. This season, the orchestra is performing live soundtracks to five films — a record number — ranging from classics such as “It’s a Wonderful Life” to popular flicks such as this weekend’s “Harry Potter and the Sorcerer’s Stone.”

Between Beethoven and Mahler, they’re making room for John Williams.

“It’s still great music,” said Grant Meachum, director of the Live at Orchestra Hall concert series. “It’s just a totally different kind of great music.”

It’s a trend powered partly by production companies making more popular films available to orchestras — customizing them for this kind of experience: All dialogue and other sounds remain. The latest and perhaps highest-profile film to get the orchestral treatment is the first “Harry Potter” film, which the Philadelphia Orchestra premiered in June.

The film will soon make its way to hundreds of cities around the world, said Justin Freer, founder of CineConcerts, which has partnered with Warner Bros. to sell the eight-movie “Harry Potter” package to orchestras.

The company, which launched with the live orchestra version of “Gladiator,” has “more than doubled the amount of concerts we’ve presented every year for the last four years,” said Freer, who is also a conductor and composer. “Orchestras have realized that these have helped to serve as a bridging of the gap between the audiences that have traditionally been coming to their symphonic halls and the new audiences they’ve been attempting to attract.”

Last season, the Minnesota Orchestra performed just two live scores, for two very different holiday films: “The Nightmare Before Christmas” and “Home Alone.”

On any show within its Live at Orchestra Hall series, which features popular musical fare, the organization hopes to make a profit of at least $10,000, Meachum said. The orchestra’s performance of “The Nightmare Before Christmas” beat that by $30,000, he said. “Home Alone” did well, too.

“Both just obliterated what we thought they could do at the box office,” Meachum said.

So this season became a test: How many film projects could the orchestra perform without audiences losing interest? Meachum expects that “Harry Potter” will have broad appeal. “Ratatouille” enticed families with young kids. “E.T.” attracted families and “Gen Xers with a taste for nostalgia,” he said. With each show, “the question is: What era of nostalgia do we want to hit?”

Beautifully done

But he maintains that the best reason to play these films isn’t to make money or attract big audiences: It’s because the orchestra does them so beautifully.

“The fact that we have this orchestra that is playing Mahler and Sibelius week in and week out — to see them really dig into something contemporary but immediate is just fascinating and really fantastic,” Meachum said. “It gives you the chills.”

These kinds of concerts require a certain kind of conductor.

“I liken it to playing a demented video game,” said Sarah Hicks, the orchestra’s principal conductor for Live at Orchestra Hall. She must react to the orchestra and the film, she said, making sure that the score matches the action and doesn’t overlap with the dialogue.

Much of that depends on the monitor in front of her. The screen displays not only the film but myriad ways to keep time: pulsing lights in the center, vertical lines streaming lengthwise, a counter in the corner. Measure 114, beat 1, 2, 3. In her ear: a digital metronome called a “click track” to help keep tempo.

The setup also includes a microphone that would allow her to communicate with the technical staff, should the monitor go out or the orchestra get off course. “The oh-crap microphone,” as Hicks calls it. “I haven’t had to use that yet,” she said, laughing.

That’s impressive, considering that Hicks has conducted at least 80 of these concerts. The increasing popularity of this sort of performance has put Hicks — and other conductors like her — in demand. This fall, she led orchestras in Denmark and Australia, Nashville and San Francisco.

For the Minnesota Orchestra, she conducted Disney-Pixar’s “Ratatouille.” Up next: “It’s a Wonderful Life” this month and, in the summer, “Star Trek.”

Living out fantasies

Herbert Winslow, who plays French horn for the Minnesota Orchestra, goes to movies and is “wowed by the music, the score — but especially the French horn.” He laughed: “John Williams wouldn’t exist if it wasn’t for the French horn.”

So it’s fun for Winslow, associate principal horn, to live out his fantasies by playing the scores live, he said.

He appreciates the composers who have worked on films, he said, noting Dimitri Tiomkin’s score for “It’s a Wonderful Life.” “That’s a great composer,” he said. “No matter if it’s film or not.

“There’s nothing cheesy at all about the writing in the films we’ve been doing.”

For “E.T.” in October, attendees and musicians alike dressed in Halloween costumes. Paul Bunyan appeared in the orchestra. So did Eleven, from “Stranger Things,” wearing a pale pink dress and striped socks. In the hall’s center, a girl dressed as a princess sat on the edge of her seat.

Laura Ivey and Tristana Ward brought their son, Tegan Ward-Ivey, to the concert for his ninth birthday. Ivey, 43, was about that age when she first saw “E.T.” Later, while living in California, she attended this kind of concert, with an orchestra creating the live score.

“I love John Williams,” she said. “He’s one of my favorites for films. And I love orchestra music.

“The whole idea of putting them together is a fun experience.”