Make multiple instruments work

Use separate tracks and channels. Thanks to Eric Floehr and Robin-Andrews for reporting. Closes #12.

demo_tracks.py

@@ -0,0 +1,22 @@
+from pyknon.genmidi import Midi
+from pyknon.music import NoteSeq
+
+# Notes on two tracks
+
+notes1 = NoteSeq("C4.'' B8' A4 D")
+notes2 = NoteSeq("E4 F G4. A8")
+
+m = Midi(2, tempo=100, instrument=[12, 14])
+m.seq_notes(notes1, track=0)
+m.seq_notes(notes2, track=1)
+m.write("tracks.mid")
+
+# Chords on two tracks
+
+chords1 = [NoteSeq("C2 E G"), NoteSeq("G2 B D")]
+chords2 = [NoteSeq("C,4 E"), NoteSeq("E, G"), NoteSeq("G, B"), NoteSeq("B, D'")]
+
+midi = Midi(2, tempo=60, instrument=[40, 20])
+midi.seq_chords(chords1, track=0)
+midi.seq_chords(chords2, track=1)
+midi.write("chords.mid")

pyknon/genmidi.py

@@ -16,21 +16,23 @@ def __init__(self, number_tracks=1, tempo=60, instrument=0):
         self.midi_data = MIDIFile(number_tracks)
 
         for track in range(number_tracks):
+            channel = track
             self.midi_data.addTrackName(track, 0, "Track {0}".format(track))
             self.midi_data.addTempo(track, 0, tempo)
             instr = instrument[track] if isinstance(instrument, list) else instrument
-            self.midi_data.addProgramChange(track, 0, 0, instr)
+            self.midi_data.addProgramChange(track, channel, 0, instr)
 
     def seq_chords(self, seqlist, track=0, time=0):
         if track + 1 > self.number_tracks:
             raise MidiError("You are trying to use more tracks than we have.")
 
+        channel = track
         for item in seqlist:
             if isinstance(item, NoteSeq):
                 volume = item[0].volume
                 dur = item[0].midi_dur
                 for note in item:
-                    self.midi_data.addNote(track, 0, note.midi_number, time, dur, volume)
+                    self.midi_data.addNote(track, channel, note.midi_number, time, dur, volume)
                 time += dur
             elif isinstance(item, Rest):
                 time += item.midi_dur
@@ -42,9 +44,10 @@ def seq_notes(self, noteseq, track=0, time=0):
         if track + 1 > self.number_tracks:
             raise MidiError("You are trying to use more tracks than we have.")
 
+        channel = track
         for note in noteseq:
             if isinstance(note, Note):
-                self.midi_data.addNote(track, 0, note.midi_number, time, note.midi_dur, note.volume)
+                self.midi_data.addNote(track, channel, note.midi_number, time, note.midi_dur, note.volume)
             else:
                 # we ignore the rests
                 pass