BOOK REVIEW / NONFICTION : Rise and Fall of a True American Art Form, the Musical : A SONG IN THE DARK; The Birth of the Musical Film <i> by Richard Barrios</i> ; Oxford University Press $18.95, paperback; $45, hardcover, 448 pages

Some make the claim for jazz, some for scrimshaw, but film historian Richard Barrios declares that it is the movie musical that ranks as an authentic American art form, or so he insists in “A Song in the Dark.”

“Musical film is a peculiarly American concept, alternately loved and derided,” writes Barrio in his monograph on the earliest years of the movie musical.

“Innocence and cynicism, decorum and ebullience seem to meet at the point where some quintessential images are forged--Astaire and Rogers dancing cheek to cheek, Garland on the trolley, Kelly in the rain, Monroe and her diamonds.”

In “A Song in the Dark,” Barrios expounds on the movie musical in detail and at length, yet his focus is remarkably tight. The book opens with the release of Vitaphone’s “Don Juan” in 1926 and closes on “The Gay Divorcee” in 1934, when edginess and awkwardness gave way to what Barrios regards as more efficient but less adventuresome movie-making.

“A Song in the Dark” is chock-a-block with the minutiae of the motion-picture industry. For example, Barrios explains that “goat glands,” a sly reference to “spurious attempts at medical rejuvenation,” was the insider’s term used to describe silent movies to which short sound sequences were hastily grafted in order to capitalize on the sudden demand for talkies.

And when Marion Davies appeared in “Marianne,” a musical especially commissioned for her by William Randolph Hearst, the role required her to fake a French accent: “Paris via Culver City,” the author cracks. Still, Barrios notes a secondary gain for the awkward actress: “Davies was so occupied with maintaining the French intonation that she was distracted from her chronic stammer.”

Writing with the cool self-confidence of one who has watched far more movies, good and bad, than all but a handful of his readers, the author anoints “The Broadway Melody,” rather than “The Jazz Singer,” as “the first true musical film.”

“The evolution and creation and reception of this one film,” writes Barrios, “were instrumental in establishing the talking picture as something more than a garish fad or a conduit for overblown solo acts like Al Jolson.”

Barrios, ever the iconoclast, is never reluctant to tell us exactly what he thinks about even the most legendary stars and star vehicles: “It is absolutely no secret that ‘The Jazz Singer,’ ” he writes, “is, to all intents and purposes, a lousy movie.”

Producers, directors, choreographers, composers and lyricists are all duly noted as Barrios catalogues the musicals of the era, but it is the stars that hold the greatest allure for him--and for whom he demonstrates the greatest sympathy.

Barrios laments the stunted movie career of Fanny Brice. He bemoans the fact that the American debut of Maurice Chevalier, “a gift to the infant musical,” was a movie “cobbled out of garbage.” And he observes of Ramon Novarro, a gay actor on the MGM roster, that his “inability to project conventionally forceful heterosexuality contributed vastly to his demotion from the ranks.”

Barrios may be a fan at heart, but he is also a realist--he declares the movie musical to be quite dead, thanks to the decline and fall of the studio system and the sea changes in the movie audience.

“We are,” he writes, “beyond the end of the rainbow, no matter how much we choose to bask in its glow.”

In some instances, as Barrios points out, the death of the musical is quite literal. “There remain ninety minutes of ‘Gold Diggers of Broadway’ that quite possibly will never been seen again,” he observes, and sometimes it seems that the subtext of his book is the urgency of film preservation.

Yet Barrios is only grudgingly appreciative of home video, which serves as a reliquary for the old movies that he celebrates.

He praises Universal’s 1929 vehicle for Paul White, “King of Jazz,” for example, but he declares himself unhappy with the color-corrected version now available on videocassette because it “completely misrepresents the film’s original look.”

Still, for anyone who is drawn to the American Movie Classics channel on cable, or the “Oldies” shelf at the local video store, Richard Barrios and his book will serve as a hugely well-informed and immensely authoritative--if sometimes outrageously opinionated--companion.