John Powell, whose credits include such popular animated films as “Shrek,” “Happy Feet” and “Kung Fu Panda,” returned to that arena with music for one of the year’s best-reviewed films, “How to Train Your Dragon.”

“I like animation because I find that I don’t get to write joyful music in live-action movies,” he says. “Really joyful music is something I enjoy doing, and in animation there are so many more moments when you can really turn that on.”

In “Dragon,” there are several: When Viking boy Hiccup first ascends with his dragon friend Toothless, and later when Astrid joins them in glorious flight.

“The directors left room for music,” he says. “They knew that it was going to have an emotional impact.”

Powell says he was striving for “a kind of grandeur, a little more symphonic” than most animated films. And DreamWorks Animation honcho Jeffrey Katzenberg likes easy-to-grasp melodies, he explains; accessible tunes were a must, too.

The grand-scale theatrics of “Dragon” demanded a 110-piece London orchestra and choir, but many of its quieter moments reveal exotic elements that are surprisingly personal for the composer. Because the setting is an ancient Viking land, Powell researched Nordic music and found it had much in common with Celtic music. Plus, many of the characters in the film sported Scottish accents.

“The truth is that Vikings did live in northern parts of Scotland,” Powell notes. “My grandmother was from the North Uist, which is one of the Hebrides (off the north coast of Scotland), so family-wise I’m very Scottish anyway.” Thus the Celtic colors of pennywhistle, hardanger fiddle and warpipes (bagpipes) appear throughout the score.

The Scottish pipes posed a special challenge: “They can play in one scale, one key,” Powell says. “There’s really very little that they can do. You certainly couldn’t put one piper in with an orchestra; they’re an incredibly loud instrument. They frighten people.” So when Powell recorded 20 of them at once, “we all had earplugs in.”

“Dragon” was by far Powell’s biggest film this year. “Fair Game,” the fact-based drama about outed CIA agent Valerie Plame, marks his fourth film with director Doug Liman (“The Bourne Identity”), and it was a very different experience.

“I just wrote pieces and sent them to him,” without regard to the specifics of the film, Powell says. Liman used fragments of the music, which features guitar, strings and odd, electronically processed percussive sounds (“jittery, pulsing things,” he says).

“They’re two very different films,” Powell says. “One took every inch of my abilities to work with the picture, as carefully as I could, and the other took my Zen abilities to disconnect from the film and write to what the director described. If that’s the two ends of the spectrum of composing for film at the moment, then this year I really went to both of them.”

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