Mahler’s Eighth Symphony is nicknamed the “Symphony of a Thousand,” but it isn’t usually performed by 1,000 people. Earlier this month, however, the Los Angeles Philharmonic did just that: a Mahler 8 with 1,027 musicians, led by the charismatic conductor Gustavo Dudamel. Not only that: They’re doing it again in Venezuela on Feb. 18. If you won’t be in Caracas, you can still catch this once-in-a-lifetime event because it’s coming as a live HD broadcast to a movie theater near you.

(Cinemas in Alexandria, Tysons Corner, Ballston Commons and Bowie are among the screens showing it in the D.C. area.)

More performing arts are finding their way into movie theaters. Ballet and opera, theater and orchestra performances are part of a burgeoning new field that the movie theater industry refers to as “alternative content.” Yet it may be a little too alternative. In today’s glutted media landscape, it’s hard for an organization like the Los Angeles Philharmonic, a vibrantly exciting orchestra but without the street cred of the hoary greats, to get the word out.

“Our biggest challenge is in the marketing,” says Deborah Borda, president of the Los Angeles Philharmonic. “We have to compete against Harry Potter and whatever else is happening, and it’s literally that kind of competition.”

The Metropolitan Opera, under Peter Gelb, pioneered live HD movie-theater simulcasts in 2006. Conventional wisdom pounced on him: Clearly, the man who had once headed Sony Classical when the “Titanic” soundtrack set sales records was now going to sell out opera, cheapen the art form, or even, heaven forbid, market it.

Critics have had to eat their words, since the HD broadcasts are the most successful single element of Gelb’s tenure, and have proved truly visionary. They have raised the profile of opera, created excitement where there was none, and rather than bankrupting the company, as many predicted, they have made money. In 2010-11 they netted an impressive $11 million.

This was possible for two reasons. First, the Met had an advantage most arts organizations do not: an international audience built up over decades of weekly radio broadcasts. Second, Gelb thought like a Hollywood studio head — like a businessman. He invested heavily — $1 million per broadcast — but also recouped his investment through television and DVDs. Rather than selling out the art form, this approach revitalized it.

The movie business seems an unlikely savior for opera. To borrow a term from Kurt Hall, chairman of NCM Fathom, the company that markets the Met broadcasts, it’s “niche-y.” But opera does offer an audience of aficionados willing to go to movie theaters to see performances at times the theaters might otherwise be nearly empty.

Emerging Pictures, another alternative content provider, offers an “Opera in Cinema” series of taped and live performances from La Scala, Covent Garden and other great European houses. It doesn’t sell out often, but it does a growing business. Although the conventional wisdom is that opera moviecasts are a way to reach new audiences, anecdotal evidence suggests that the people who go are already opera fans. Josh Levin, general manager of West End Cinema, which shows the “Opera in Cinema” series in Washington, calls them “the opera equivalent of jazzheads.”

The Met’s success has led to a wider embrace of performing arts. Emerging Pictures has supplemented its “Opera in Cinema” series with an even more successful “Ballet in Cinema” series.

“There was really a hunger for it,” says Christiane Little, that company’s director of opera marketing, describing audiences made up of older viewers and young girls.

NCM Fathom’s “alternative content” runs the gamut from opera to sports events to rock concerts, a performance by Lang Lang last fall to, on Feb. 16, a live walk-through of the Leonardo show at London’s National Gallery. But it is heavy on the performing arts: Series include “The Met:Live in HD,” “LA Phil Live” and live broadcasts of spoken drama from Britain’s National Theatre.

“The arts is a very interesting category for us,” says Kurt Hall, chairman of NCM Fathom. “It shows so well on the big screen; it’s not heavily distributed on TV or other distribution models; and it provides a unique experience, which is what gets people out to the theaters.”

Yet you can’t just show this stuff and hope people will come. Fathom is learning a lesson all too familiar to many arts organizations; live performance can be a hard sell. The National Theatre broadcasts, in particular, have remained obstinately “niche-y.”

“If you look at the amount of money the motion picture industry spends to get a picture launched,” Hall says, “we can’t spend that.”

It’s not clear that 3-D enhances the operatic experience for fans — though Hall is looking closely both at last year’s “Carmen” in 3-D and at an upcoming “Madama Butterfly.”

But performing arts organizations have to think beyond merely getting their product into theaters. Simply being there isn’t enough, as the San Francisco Opera learned when it rushed into national cinemas in 2007-08. The opera has since scaled back to California and up the West Coast. The National Theatre, in its third season of live broadcasts, may be learning the same thing.

“We are not looking at these broadcasts as a new business,” wrote Bogdan Roscic, president of Sony Classical, in an e-mail exchange. “We are doing them if and when we feel they can be a meaningful part of a specific project. For example, in the case of Goat Rodeo, the [Jan. 31 ] concert was filmed for a PBS broadcast later in the year and also as the basis for a DVD. Plus, some new music which was part of the concert was recorded for an iTunes EP.

“This is not a commercial opportunity first and foremost,” he added. “It is about communicating/marketing.”

You just have to be a company with money for a large-scale investment.

“A healthy business model involves the investment of at least 5 percent of your earnings into research and development,” says the Los Angeles Philharmonic’s Borda. “Most orchestras are just hanging on. The way forward is to free up money to test and define what the future is.”

Borda calls the broadcasts “a grand experiment . . . how we retool these organizations for the 21st century.”

Idealistic thoughts; but the organization may have lifted its gaze from the bottom line. There are no plans to release the broadcasts as DVDs; it’s not part of the orchestra’s contract with Deutsche Grammophon. And a central lesson that HD broadcasts holds for the performing arts is: Think like a real for-profit business, and market, market, market.

“If you can’t reimagine yourself,” Borda says, “you face — well, one shouldn’t take survival for granted.”

Upcoming broadcasts

Feb 16: “Leonardo Live,” a walk-through of the Leonardo da Vinci show at London’s National Gallery (Regal Ballston Common, Regal Potomac Yard; AMC Tysons Corner; Regal Bowie Stadium; others).

Feb 18: LA Phil Live: Gustav Mahler’s 8th Symphony, led by Gustavo Dudamel from Caracas (Regal Ballston Common, AMC Tysons Corner; Regal Bowie Stadium; others).

Feb 19, 20, 21: Opera in Cinema: “Il Trittico” from Covent Garden (West End Cinema/AFI).

Feb 25 (repeats March 14): The Met in HD: “Ernani” (AMC Mazza Gallerie, other area cinemas).

Feb 28/March 7: “Love Never Dies” by Andrew Lloyd Webber (Regal Ballston Common, Regal Potomac Yard; AMC Tysons Corner; Regal Bowie Stadium; others).

March 1: NT Live: “The Comedy of Errors” (Regal Fairfax Towne Center; AMC Columbia); repeats April 9 at the Shakespeare Theatre.

March 3: NT Live (repeated): “Traveling Light” by Nicholas Wright at the Shakespeare Theatre.

March 11, 13: “Cendrillon” from Covent Garden (West End Cinema).

March 13 (repeats March 17): “La Boheme LIVE” from Barcelona (AFI). Repeats March 25, 27 (West End Cinema).

March 18: LA Phil Live (pre-recorded): Dudamel and Herbie Hancock play Gershwin (area cinemas).

March 18, 20: Ballet in Cinema: “Le Corsaire” from the Bolshoi (West End Cinema).

March 29: NT Live: “She Stoops to Conquer” (repeats May 1 at the Shakespeare Theatre).

April 1, 3: Ballet in Cinema: “Romeo and Juliet” from Covent Garden (West End Cinema).

April 7 (repeats April 25): The Met in HD: “Manon” (Regal Ballston Common).

April 8, 10: Opera in Cinema: “Aida” from the Bregenz Festival (West End Cinema).

April 14 (repeats May 2): The Met in HD: “La Traviata” (Regal Ballston Common).

April 22, 24: Opera in Cinema: “Rigoletto” from the Royal Opera House (West End Cinema).

May 6, 8: Ballet in Cinema: “The Bright Stream” from the Bolshoi (West End Cinema).