As a composer, Aaron Copland ranged from one extreme to another. Early and late in his career, he tended toward jagged dissonance, earning at one point the nickname ''the Brooklyn Stravinsky.'' But he is best known for the sentimental, proudly American music he wrote in his more conservative middle years, such as the ballet scores for Appalachian Spring, Rodeo, and Billy the Kid. Copland's divergences are described in this hour-long cassette, but never explained.
In the documentary Aaron Copland: A Self Portrait, which centers on an extensive interview with the composer, who died Dec. 2 at the age of 90, Copland comes off as a gracious charmer. That view is clearly held by several of his colleagues, including the late conductor-composer Leonard Bernstein, composer William Schuman, and choreographer Agnes DeMille. The archival research on display here is impressive, from the extensive use of still photos to a smattering of performance clips. We see Copland conducting several times, as well as narrating his ''Lincoln Portrait'' as Bernstein conducts. We also hear Michael Tilson Thomas performing a Copland solo-piano piece and watch Martha Graham and DeMille dancing. But this wealth of recollection and performance never amounts to more than a collection of sweet moments. The tape never helps us understand what made Copland Copland. B