In a cramped backstage area at New York's Metropolitan Opera House, French mezzo-soprano Sophie Koch adjusts her 19th-century dress.
Around her are other singers, a costume assistant, two cameramen and a dozen stagehands ready to move a tree and a park bench to change the sets for the second act of Jules Massenet's Werther.
Koch smiles, breathes deeply and climbs a wooden staircase. A few seconds later, she is on stage with German tenor Jonas Kaufmann before a standing-room-only crowd in the 3,800-seat Met.
It's a special Saturday afternoon at New York's storied opera house, the focal point of Lincoln Centre. In the US and around the world, hundreds of thousands of fans are watching her on movie screens retransmitting the performance of the opera - adapted from a novel by Goethe - in real time and in high definition (HD).
"We will have at least between 200,000 and 250,000 people watching this live today," says the Met's general manager, Peter Gelb. "In fact, 67 per cent of our audience in movie theatres is outside of America. We are a truly global arts company. I don't think any other company can say that about themselves. We are an example of innovation."
The Met first offered HD retransmissions of its performances during the 2006-2007 season, with about 250 theatres participating in eight countries. ( The Met: Live in HD has been running in Hong Kong since 2009 and the programme is sponsored by the Foundation for the Arts and Music in Asia.)
More than 14 million tickets have since been sold, and the performance of Werther - a tale of doomed love - was shown live in 2,000 theatres in 66 countries. Gelb calls it a "huge global success".
Twelve HD cameras bring 12 performances to global audiences each season. They are subtitled in eight languages: English, French, German, Italian, Portuguese, Spanish, Russian and Swedish. In Asia, performances are shown with a delay, given the time difference.
The Met each season stages 30 different works, including a handful of premieres. The productions are lavish - and costly, drawing tourists and New Yorkers alike to Lincoln Centre. But opera-goers do not see the Herculean backstage efforts, and the army of workers who ensure that each production is perfect down to the last detail.
"There is no other art form in the world that requires - simultaneously - a full symphony orchestra, a gigantic chorus, usually dancers, a massive amount of scenery, supernumerary actors. It's an artistic army," Gelb says.
For Richard Eyre's new production of Werther, which took place at 1pm, the Met's army of workers arrived in the morning. The stage had been set up the night before.
"I arrived at 10.30am for a 1pm performance because we were doing the HD thing. There is special make-up for those performances, so that process takes longer than usual, and I wanted to be wide awake to be in top shape," says Koch, making her Met debut in Werther.
As make-up artists tend to Koch and the other performers, members of the orchestra arrive. Backstage, American soprano Patricia Racette - who will act as emcee for the HD broadcast - reviews her lines for the introduction and the intermission.
As curtain time approaches, the pressure mounts, but most cast and crew members remain light-hearted and smiling.
"These are gladiators going out there onto the stage and the public, who understand that, respond. That's the secret of the success of the Met programmes in movie theatres - they are alive," Gelb says.
Kaufmann says he is a "great fan" of the HD broadcasts, adding: "It's a big challenge. You have to be so credible."
The production is helmed from a truck parked behind the Met. Gelb monitors the camera work - the cuts and the close-ups. Beyond what can be learned backstage, a few Met secrets emerge from the HD broadcast. Given that the Met puts on several different operas a week, there is no rest for the weary. As the production of Werther unfolds, singers rehearse Puccini's La Boheme - three levels below ground.