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Ricardo Dearatanha, Mct
Two Steps From Hell founders/composers Nick Phoenix, left, and Thomas Bergersen, sit at the mixing table. There's a whole business for composing music directly for movie trailers.

LOS ANGELES — In a recording studio on Sunset Boulevard, Thomas Bergersen and Nick Phoenix are banging on two giant taiko drums built for their company. The brawny musicians exude the fierce intensity prevalent in much of their music — until they suddenly get off-beat and let out loud laughs that reveal just how much fun this is for them.

Bergersen and Phoenix revel in the world of music for movies, but not in the same way as film score maestros like Hans Zimmer and John Williams. In 2006, Bergersen and Phoenix founded their company — named Two Steps From Hell and devoted to music for movie trailers.

A common misconception is that the music in trailers is from the film itself. That's rarely the case, because a film's score is one of the last elements completed in postproduction.

Sometimes a trailer features music from a previously released film; for example, music from Michael Bay's "The Island" appeared in an "Avatar" trailer. But for many trailers, the soundtrack is composed by a company devoted to music for movie advertising. These companies — known as trailer music libraries — emerged in the 1990s, after studios began showing trailers to focus groups, creating the need for music earlier in the marketing campaign.

Initially, trailer music composition was little known outside the movie industry. Now, with the releases of trailers becoming events unto themselves, the number of companies has grown and the public is more aware of their work. Some companies even sell their songs online and have cultivated fan followings.

"It's great that people are becoming exposed to this type of music because most of it is a form of classical, and I think classical music used to be underground, not many people listened to it, but now it's much more in the mainstream," said Armen Hambar of Future World Music.

Almost every element of a film that viewers see in a trailer is derived from the script — from costumes to set design. But the music in trailers is usually written without a particular film in mind. Bergersen, who studied music in Norway and at USC, and Phoenix, who played keyboard in bands growing up, write their music (typically one- to three-minute tracks) for albums that they send to studio clients and trailer-editing houses. They make about two albums a year.

The trailer editor selects tracks from these albums, licenses them (fees run $5,000 to $10,000 per track for international use, Bergersen said), and then edits the available footage with that music. A trailer usually features at least three tracks. A typical formula, especially for dramas and event movies, is a soft start that gradually builds, leading to a climax that fades and "hopefully leaves people stunned," Bergersen explained.

Today, many films have two or three previews, and are seen not just in theaters; often they're released first online, where they become conversation starters and are picked apart by bloggers.

The trailer for the 2009 film "Star Trek" put Two Steps on the map. The track "Freedom Fighters" — majestic yet ethereal, with a much slower build than most trailer music — captured the attention of fans. Bergersen says the track may have gotten such a strong response because it was the only piece in the trailer. "It gave people some time to latch onto the music," he said.

The trailer broke records upon its release online: It was viewed more than 1.8 million times on apple.com during its first 24 hours.

Two Steps also had a shot that year at one of the "Avatar" trailers. Its track "Archangel" was in contention, but the studio ultimately went with a different editing house's version of the preview, using a track by Beverly Hills trailer music library Audiomachine.

"Archangel," driven by strings and 32 singers from the Mormon Tabernacle Choir, has yet to be used in a trailer. But some of Two Steps' tracks have been used multiple times, like "Heart of Courage," which was in marketing for "The Chronicles of Narnia: The Voyage of the Dawn Treader," BBC's "Frozen Planet" and the video game Mass Effect 2. And it made it into advertising for "Avatar" with the trailer for the August 2010 rerelease.

Until recently, trailer music was available only for licensing. But as trailers began to be released online, fans started asking how they could download this music.

"It used to be kind of frowned upon to release anything that's exclusive to trailers for a public release, but things have changed," said Hambar, whose company made its mark with "Dream Chasers" in the "How to Train Your Dragon" trailer.

Two Steps, Future World Music and Immediate Music (one of the first libraries, founded in 1993) have released albums on iTunes. Audiomachine released its first commercial album last week. Most tracks are the libraries' "best hits," or tracks that fans already know from trailers. But some, including "Archangel," are released before they're licensed.

Two Steps has sold more than 300,000 copies of its two albums on iTunes — a robust supplement to licensing music from its 17 albums available to clients.

Two Steps From Hell now has more than 62,000 fans on Facebook. "When we sat down to make this company, we never thought it would take off the way it did and end up with a bunch of fans," Bergersen said.

Some trailer composers are tempted to venture into film scoring — Bergersen and Phoenix were part of Zimmer's composing staff for "Pirates of the Caribbean: On Stranger Tides," for instance — but most say they stick with trailer music because of the freedom.