The last time producer Hall Bartlett commissioned a name composer to score a film, it was Neil Diamond for Jonathan Livingston Seagull. The movie was a bust, and Diamond’s florid score seemed hilariously out of place. Now, for the cinematic version of Oscar Lewis’ landmark anthropological study of a Mexican family, The Children of Sanchez, Bartlett has made a more appropriate choice. In three weeks last September, the maestro of soft jazz composed and recorded 23½ hours of music. True, this two-record excerpt uses themes from such Mangione hits as Bellavia and Echano. True also, his repetitions of brief musical ideas make him sound at times like an ersatz Ravel. But there is real urgency in the score (especially Fanfare), poignant moments in Lullabye and a lovely duet chase with Jeff Tkazyik on trumpet and Mangione on flugelhorn in Medley. The film will be hard put to live up to the music.