A musical crowd-pleaser that hits every predictable note in working its way to a triumphant conclusion, “The Sapphires” replaces the Irish background of “The Commitments” with one focused on Australian Aboriginal culture but is obviously cut from the same cloth. But it’s not a bad pattern, and it’s easy, and relatively painless, to be won over by the picture’s good-heartedness—and its stream of irresistible tunes.

Aboriginal writer Tony Briggs has teamed with Keith Thompson to adapt his play, based—very loosely, it appears, on the experiences of his mother—for the screen. It concerns a quartet of young women who combined to form a soul group that toured US army bases in Vietnam during the 1960s. That tour represented a triumph for the struggle against long-standing prejudice against Aborigines in Australia and, at least in this telling, brought romance to some of the girls.

The members of the Sapphires, as the “Cummeraganja Songbirds” came to be called, were three sisters—feisty, abrasive Gail (Deborah Mailman), submissive Cynthia (Miranda Tapsell) and teen Julie (Jessica Mauboy)—who all live on the equivalent of a reservation, and mixed-race cousin Kay (Shari Sebbens), whose lighter skin took her away from her family to a state-operated school that taught her a sense of condescension toward her extended family. They’re brought together—and cajoled from their preference for country-western repertoire to the Motown sound—by Irish expatriate Dave (Chris O’Dowd), a boozy keyboardist who hears the three sisters at a local talent contest where they were dissed by the bigoted crowd and thinks they have promise.

It’s Dave who persuades their dubious parents to allow the sisters to go off to Melbourne for an audition before military types and who molds the four girls into an ensemble in which Julie, who has the strongest voice despite being the youngest, becomes lead singer. He also must serve as a reluctant referee between Kay and Gail, who resents her cousin for having distanced herself from her roots and “passed” for white.

And it’s O’Dowd who serves as the real sparkplug of the movie, tossing off humorous lines with deadpan glee while maintaining a nice balance between quirkiness and warmth. He also manages to make Dave’s relationship with Gail—which formulaically mutates from snarky hostility to love—engaging, if only barely credible. Meanwhile Kay strikes up a romance with an American pilot (Tory Kittles) whose skin is much darker than hers, while Julie’s central position in the group begins to go to her head and she finds herself courted by a major promoter.

While the more intimate material progresses—not entirely smoothly, from a narrative standpoint—the girls and Dave are hopping from camp to camp, allowing for a succession of toe-tapping musical numbers that will bring a smile to the faces of the nostalgically inclined. And in the end they’re the soul of the movie, in more ways than one. The technical package—including Warwick Thornton’s cinematography and Tess Schofield’s costumes, which contribute enormously to the period detail—is excellent even when the picture stumbles in terms of background historical accuracy.

“The Sapphires” doesn’t always mix its anti-prejudice message and its feel-good nostalgia with complete smoothness. But despite some ragged edges it provides a reasonably good time.