Added simple sequencer

This sequencer only does one-second-long intervals and doesn't try to time it exactly.

sequencer.py

@@ -6,6 +6,7 @@ mido.get_input_names()
 mido.get_output_names()
 """
 
+
 def testOutput():
     outputs = mido.get_output_names()
     lmmsOutPort = None
@@ -17,20 +18,120 @@ def testOutput():
         return
 
     with mido.open_output(lmmsOutPort) as lmmsOut:
-    	for i in range(1, 10):
-	    	song = [100, 80, 40, 80, 100]
-	    	for note in song:
-		        testNote = mido.Message('note_on', note=note, velocity=127, time=0.1)
-		        lmmsOut.send(testNote)
-		        testNote = mido.Message('note_on', note=20, velocity=127, time=0.1)
-		        lmmsOut.send(testNote)
-		        time.sleep(0.1)
-		        testNote = mido.Message('note_off', note=note, velocity=127, time=0.2)
-		        lmmsOut.send(testNote)
-		        testNote = mido.Message('note_off', note=20, velocity=127, time=0.2)
-		        lmmsOut.send(testNote)
-		        time.sleep(0.1)
+        for i in range(1, 10):
+            song = [100, 80, 40, 80, 100]
+            for note in song:
+                testNote = mido.Message(
+                    'note_on', note=note, velocity=127, time=0.1)
+                lmmsOut.send(testNote)
+                testNote = mido.Message(
+                    'note_on', note=20, velocity=127, time=0.1)
+                lmmsOut.send(testNote)
+                time.sleep(0.1)
+                testNote = mido.Message('note_off', note=note,
+                                        velocity=127, time=0.2)
+                lmmsOut.send(testNote)
+                testNote = mido.Message(
+                    'note_off', note=20, velocity=127, time=0.2)
+                lmmsOut.send(testNote)
+                time.sleep(0.1)
+
+
+def chooseDevice(devices, searchString):
+    matchingDevice = None
+    for device in devices:
+        if searchString.lower() in device.lower():
+            matchingDevice = device
+    return matchingDevice
+
+
+def testIO():
+    #synthOutPort = chooseDevice(mido.get_output_names(), 'LMMS')
+    synthOutPort = chooseDevice(mido.get_output_names(), 'OP-1')
+    keyboardInPort = chooseDevice(mido.get_input_names(), 'CH345')
+
+    if not synthOutPort or not keyboardInPort:
+        return
+
+    with mido.open_output(synthOutPort) as synthOut:
+        with mido.open_input(keyboardInPort) as keyboardIn:
+            while True:
+                message = keyboardIn.receive()
+                print(message)
+                synthOut.send(message)
+
+
+def simpleSequencer():
+    #synthOutPort = chooseDevice(mido.get_output_names(), 'LMMS')
+    synthOutPort = chooseDevice(mido.get_output_names(), 'OP-1')
+    keyboardInPort = chooseDevice(mido.get_input_names(), 'CH345')
+
+    if not synthOutPort or not keyboardInPort:
+        return
+
+    with mido.open_output(synthOutPort) as synthOut, mido.open_input(keyboardInPort) as keyboardIn:
+        # 16th notes at 240 bpm should be fine
+        frameRate = (60 / 240) / 4
+        # Prevent the program from locking up if the frame rate gets too bad
+        maximumCatchupTime = 0.25
+        timeRoomForError = 0.0001
+        sequence = []
+        sequenceLastStartTime = 0.0
+        sequenceTimeLength = 1.0
+        sequenceLastNotePlayedTime = 0.0
+        lastTime = time.time()
+        timeAccumulated = 0.0
+        try:
+            while True:
+                currentTime = time.time()
+                sequenceTime = currentTime - sequenceLastStartTime
+                frameDelta = currentTime - lastTime
+                if frameDelta > maximumCatchupTime:
+                    frameDelta = maximumCatchupTime
+                lastTime = currentTime
+                timeAccumulated += frameDelta
+
+                print(frameDelta)
+
+                while timeAccumulated >= frameRate:
+                    print('Updated')
+
+                    # Poll input
+                    message = keyboardIn.poll()
+                    while message:
+                        print(message)
+                        sequence.append((message, sequenceTime))
+                        synthOut.send(message)
+                        message = keyboardIn.poll()
+
+                    # Play sequencer notes if it's time
+                    # TODO: sort notes by time
+                    for note in sequence:
+                        # TODO: this comparison should have a margin of error equal
+                        # to the frame rate
+                        if note[1] <= sequenceTime and note[1] >= sequenceLastNotePlayedTime:
+                            synthOut.send(note[0])
+                            sequenceLastNotePlayedTime = max(sequenceLastNotePlayedTime, note[1])
+
+                    # Restart sequence if necessary
+                    if sequenceTime >= sequenceTimeLength:
+                        sequenceLastStartTime = currentTime
+                        sequenceLastNotePlayedTime = 0.0
+
+                    timeAccumulated -= frameRate
+                    timeAccumulated = max(0.0, timeAccumulated)
+
+                sleepTime = frameRate - timeAccumulated - timeRoomForError
+                if sleepTime > 0:
+                    print('Sleep ' + str(sleepTime))
+                    time.sleep(sleepTime)
 
+        finally:
+            print('Resetting synth due to exception')
+            synthOut.reset()
+            #synthOut.panic()
 
 if __name__ == '__main__':
-    testOutput()
+    # testOutput()
+    # testIO()
+    simpleSequencer()