Gustav Mahler: Sterben werd' ich, um zu leben ("To Live, I Will Die"), its title deriving from the composer's adaptation of a poem by Klopstock in the "Resurrection" Symphony, remains somewhere between fact and fiction. It's a pseudo-documentary--in German, with sometimes inaccurate English subtitles-- that includes lingering scenes of Viennese interiors and Austrian countryside, almost always to the accompaniment of Mahler's music, punctuated by sparely staged fictional scenes and camera-direct narration from actresses playing soprano Anna von Mildenburg, composer Alma Schindler (who became his wife), and virtuous