a = {SoundNote[{"C2"}, {0, 0.5}], SoundNote[{"C4", "G4", "C5"}, {0.5,  1}],
   SoundNote[{"G2"}, {0.75, 1}], SoundNote[{"C3"}, {1, 1.5}],
   SoundNote[{"C4", "G4", "C5"}, {1.5, 2}], SoundNote[{"G2"}, {1.75,  2}],
   SoundNote[{"F2"}, {2, 2.5}], SoundNote[{"A3", "C4", "F4"}, {2.5, 3}],
   SoundNote[{"F1"}, {2.75, 3}], SoundNote[{"C2"}, {3, 3.5}],
   SoundNote[{"A3", "C4", "F4"}, {3.5, 4}], SoundNote[{"F2"}, {3.75,  4}],
   SoundNote[{"A2"}, {4, 4.5}], SoundNote[{"A3", "C4", "E4"}, {4.5, 5}],
   SoundNote[{"E2"}, {4.75, 5}], SoundNote[{"G2"}, {5, 5.5}],
   SoundNote[{"G3", "B3", "D4"}, {5.5, 6}], SoundNote[{"G1"}, {5.75,  6}],
   SoundNote[{"C2"}, {6, 6.5}], SoundNote[{"G3", "C4", "E4"}, {6.5, 7}],
   SoundNote[{"G2"}, {6.75, 7}], SoundNote[{"C3"}, {7, 7.5}],
   SoundNote[{"G3", "C4", "E4"}, {7.5, 8}], SoundNote[{"G2"}, {7.75,  8}]}
S = Sound[{a, a, a}]
Export["david_tune.midi", S, "Midi"]