THE ALBUMS FAME/THE ORIGINAL SOUNDTRACK FROM THE MOTION PICTURE, RSO Records (RX-1-3080).; From the original motion picture SOUNDTRACK -- XANADU, MCA Records (MCA-6100).

The trouble with most soundtrack albums is the abundance of music filler that's entertaining while you're in the threater, but a distinct bore on your home stereo. Of two recent samples, "Fame" has less fat then "Xanadu," and actually offers some rock cuts that stand on their own non-visual merits.

A schizophrenic album, "Xanadu" is split between Electric Light Orcestra and Olivia Newton-John pop. Newton-John, whose singing career has now far surpasses that of Cheryl Ladd, specializes in ethereal Muzak, written for the film by John Farrer. Her wisp of talent comes together with the ELO formula for orchestral rock on the title track, where her fragile soprano aptly notes, "And there you are a shooting star." Poof. ELO's trademark sound, replete with urgent, space-age synthesizer gimmicks, manages a frothy sameness on every track. Jeff Lynne's high-pitched vocals are mirrored by the group's falsetto backup voices, which also echo their shelf-full of releases from the last decade (Lynne's responsible for ELO's songwriting as well).

The best cut of the lot is ELO's "All Over The World." While it's not as rousing, as "Dancing in the Streets" (the old Martha and the Vandellas hit), it retreads the same idea: "Everybody walkin' down the street/everybody movin' to the beat" -- with those irritating ELO backup voices name-dropping international cities. The melody is catchy, the beat is lively and Olivia's strongest performance is on "Magic," a dreamy rock ballad with a haunting electric guitar refrain.

The only mystery behind "Xanadu's" commercial odd-coupling is how much they paid Gene Kelly for his involvement, including a duet with Olivia. As a pop crooner, he makes a wonderful tap dancer. A big-band backing, an entire chorus of whistles and lyrical promises of eternal love can't bail the duo out of this embarrassing fluff.

Unless you're an avid soundtrack collector, the "Xanadu" mesh is better left as subliminal background during a flimsy film than purchased for living room listening. At $8 a throw in area record stores, this punishment doesn't come cheap, either.

On another wavelength, and geared to a younger, funkier audience, "Fame" offers a satisfying cross section of pop-rock tunes by previously unknown talents. Disco dance music, slow ballads, a choral number and show biz finale are all packed into a soundtrack from the film inspired by students at New York's performing arts high schools. So far, they've graduated to top 10 record status, and are still climbing the charts.

As the latest disco sensation, Donna Summers soundalike Irene Cara steals the show throughout side one. Her disco-rock rendition of the title track is so totally convincing, you believe she's the song's undiscovered up-and-coming star when she belts out the promise, "I'm gonna live forever, remember my name." Searing synthesizer and deep gurgles beneath the backing vocals create a smooth Broadway rock extravaganza.

With unadorned piano accompaniment, Cara also puts across a tearful ballad, "Out Here On My Own." But her forte is clearly wild boogie rock.

The longest cut on the LP, "Red Light," is a disco-rock finger-snapper.

Linda Clifford's vocal shines on this track, with the requisite toughness and shrill edge. The background voices deliver an infectious "doo-doo" chorus, but the more clever cut is "Hot Lunch Jam," a heavy rock session built around Cara's sizzling vocal in the school cafeteria. Pounding drums and a high-gloss horn section complement the appetizing lyrics: "If it's yellow then it's jello/If it's blue it could be stew."

To show that kids aren't all loud rock, a couple of soft ballads are thrown in, approaching Paul Simon's brand of hypersensitivity. Paul McCrane wrote and performs one number (a seeming non sequitur in the film and not the most distinguished cut here), and as further relief from the disco beat, students in the real-life Contemporary Gospel Chorus of the High School of Music and Art harmonize on a resounding "Never Alone," sounding white but full-voiced on the gospel number. But it's their rambunctious rocking that's selling the album.