From the heraldic tun-ta-dah of Alfred Newman's old 20th Century-Fox fanfare, to "The Merry-Go-Round Broke Down," a loony tune that opened many a Warner Bros. cartoon, "Previn and the Pittsburgh" offers a welcome and satisfying hour of movie music and Hollywood lore tonight at 8 on Channel 26.

Host-conductor Andre Previn spent a few years writing music for the movies himself ("The Four Horsemen of the Apocalypse" is among the hobos he spiffed up considerably), so he is entirely qualified in declaring, "Music has saved more bad films than all the lifeguards in the world have saved had swimmers."

Joining him to kibitz about the adversary relationship between composer and producer are Oscar winners John Williams and a very venerable Miklos Rozsa, the Hungarian-born composer who can't remember, when asked by Previn, exactly how many films he has scored but knows it is "over 100," and estimates there was a minimum of 100 minutes of music for each.Incredible.

Previn conducts an excerpt from Max Steiner's "Now, Voyager" and two cues from the Bernard Herrmann score for Alfred Hitchcock's "Psycho." Rozsa conducts segments from his own "Ben-Hur," including the unfailingly stirring "March of the Charioteers," and Williams conducts suites from "Close Encounters" and the current "Superman."

Unfortunately, the program is not nearly so compelling visually as was last year's movie music show. Director Rodney Greenberg shows no flair for cutting to music, though he does attempt a slicing motif with the bows of violins and cellos on the "Psyco" stuff, and some other-worldly solarized images on "Close Encounters." But the progam looks as though producer Steven Dick has suffered either budget cuts or idea drop-off, or both.