Kyle Patrick Alvarez’s C.O.G. is the first film to be based on the work of David Sedaris. It’s clearly a passion project for Alvarez, and the picture is faithful to the events of the autobiographical story “C.O.G.,” about Sedaris working in rural Oregon to see how “real” people live (and to cheese off his father in the process). But the choice not to include narration robs the movie of Sedaris’s voice, and consequently much of its joy, as does the decision to portray the character of David (Jonathan Groff) as a smug, Yale-educated atheist who’s running away from home because his mother rejected him for being gay. What was very funny in print becomes serious and occasionally dour onscreen, with fewer laughs than you would expect from a Sedaris project. The faithfulness to the original story is almost jarring for those who’ve read it, since the character has been changed into an insufferable nozzle, playing up the worst stereotypes of the intellectual atheist, so when amusing, Sedaris–specific details appear, they no longer fit this version of David. Still, if C.O.G. opens the floodgates for Sedaris adaptations, here’s hoping someone (maybe even Alvarez, who has the chops) will do justice to “The Santaland Diaries.”