Walk Hard, a parody of warts-and-all pop-star biopics, comes out of the Judd Apatow factory (he produced and co-wrote it), and at first it appears to be nothing more or less than this year's model of Epic Movie, Not Another Teen Movie, and all those other happy-idiot genre spoofs that descend from the Airplane! school of artfully hyperbolic razzing. Directed by Jake Kasdan, the movie tells the story of Dewey Cox (John C. Reilly), a doltish country-rocker who becomes a star, meets a stage partner (sparkly Jenna Fischer) as prudish as a nun, and enjoys a rise to legend status matched only by his druggy, Daddy didn't love me! fall. A handful of the jokes score (the boy Dewey slicing his brother in half, which inspires his dad's refrain of ''The wrong kid died!''), a few fall flat (a not-dirty-enough tweak of dirty dancing), and most are mildly clever enough to keep you grinning.
The movie walks the line of surreal vulgarity (you will not, repeat not, expect the penis), yet most of it, intentionally, is less nutzoid than your average megaplex genre parody. It's a teensy bit straighter, and that's a good thing, since it allows Kasdan to take on not just the clichés of the biopic but the emotions as well. He skewers the spirit of rock history. As Dewey moves into the hippie '60s, then the variety-show '70s, Reilly lends his weariness a goofy heart. Walk Hard isn't merciless (except for maybe one wicked sequence with the Beatles), and that's because it so loves what it's sending up: the pleasure, ego, and sheer exhaustion of what happens behind the music. B