S = Sound[{SoundNote["C", .5, "Piano"], SoundNote["B", .25],
   SoundNote["C5", .5], SoundNote["C5", .25], SoundNote["D", .25],
   SoundNote["D", .5], SoundNote["B", .5], SoundNote["B", .25],
   SoundNote["A", .5], SoundNote[{"E", "G"}, .5],
   SoundNote[{"C", "G", "F", "G4"}, 1], SoundNote[{"E", "G"}, .25],
   SoundNote[{"F", "A"}, .5], SoundNote[{"A", "C", "E"}, 1],
   SoundNote["A", .25], SoundNote["G", .5], SoundNote["E", .5],
   SoundNote["C", .25], SoundNote["E", .25], SoundNote["G", .25],
   SoundNote[{"A", "C", "E"}, 1], SoundNote["B", .25],
   SoundNote["A", .25], SoundNote["G", 1], SoundNote["E", .25],
   SoundNote["C", .25], SoundNote["E", .25],
   SoundNote[{"B3", "D"}, .5], SoundNote[{"A3", "C"}, .5],
   SoundNote["E", .5], SoundNote["C", .25], SoundNote["E", .25],
   SoundNote[{"B3", "D"}, .5], SoundNote[{"A3", "C"}, .5],
   SoundNote["B", .25], SoundNote["C5", .5], SoundNote["C", 1],
   SoundNote["B", .25], SoundNote["C5", .5], SoundNote["C", 1],
   SoundNote["B", .25], SoundNote["C5", .5], SoundNote["D5", .5],
   SoundNote["C5", 1], SoundNote[{"C2", "C", "E", "G"}, 2] }]
Export["heidi_liu.midi",S,"Midi"]