In a continuing effort to attract more listeners to its movie soundtracks, 20th Century Fox created a holiday ad for The Secret Life of Walter Mitty that gives some Pandora users a taste of the music service's still-secret algorithm for the first time.
The Ben Stiller-directed fantasy drama Walter Mitty hits theaters on Christmas Day. The ad, "Discover the Secrets," is targeted primarily at female Pandora users 18 and older who are listening to playlists featuring holiday music.
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It's the first ad of its kind on Pandora. Here's how it works: say you are listening to Brian McKnight on a holiday station. The ad will pop up telling you what attributes that specific song has, according to Pandora's algorithm ("piano accompaniment" and "R&B roots"), that will be used to determine what similar songs to play next for you.

Pandora's long-running Music Genome Project painstakingly identifies 450 musical characteristics using humans, not software. Pandora recently told Mashable that it has "trained music analysts" figure out the identity breakdown of each song in order to better tailor stations for each Pandora user.
Previously, 20th Century Fox tried appealing to users of another audio service — SoundCloud — with what it described as SoundCloud's first-ever movie trailer.
To drum up more buzz for The Secret Life of Walter Mitty, Stiller put together a playlist of 100 songs that he said inspired him while filming. The playlist forms the basis for this Pandora station.
Stiller stars in the film alongside Kristen Wiig, Shirley MacLaine, Adam Scott, Kathryn Hahn and Sean Penn. The Walter Mitty soundtrack went on sale earlier this week.

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Image: 20th Century Fox