Los Angeles Festival : KCET-TV SERIES SETS STAGE FOR LOS ANGELES FESTIVAL : Musical Attractions Spotlighted This Weekend on Channel 28’s ‘Stage’ Series

One genuine preview, one background-piece and one unrelated opera performance make up the musical portions of the “Setting the Stage” series on KCET-TV Channel 28 this weekend. The series promises to offer previews of attractions at the monthlong Los Angeles Festival, which opens Thursday.

Tonight from 11:05 to midnight, the station broadcasts an encore performance of “John Cage,” a film made on the occasion of the American composer’s 70th birthday in 1982 by British director Peter Greenaway. As one critic put it when “John Cage” was shown here two years ago, the film is delightful, the music “excruciatingly redundant.”

Preceding “Cage” at 11 p.m. is a five-minute excerpt, with awful sound, of “Hungers,” the Morton Subotnick/Ed Emshwiller evening-long, multimedia piece scheduled to receive its world premiere at the Festival, Sept. 24-27.

It is an intriguing foretaste of what promises to be a complicated, kaleidoscopically colorful, high-tech collage of music and visual images, a combination that deserves to be called an electronic opera.

Completely unrelated, except that the work in question is the same one to be presented here, is the Glyndebourne Festival Opera production (filmed in England in 1983) of Rossini’s “Cenerentola.” It will be shown Sunday, from 11 a.m. to 1:30 p.m.

With American-mezzo Kathleen Kuhlmann in the title role, Italian conductor Donato Renzetti in charge in the pit and the veteran Glyndebourne director John Cox in charge of staging, the performance seems to have little in common with the upcoming and brand-new Music Center Opera production, to be given here four times in the Dorothy Chandler Pavilion, Sept. 18-26.